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APPLICATION NOTE
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
SUMMARY
I I.1 I.2 I.3 I.4 I.5 II III III.1 III.1.1 III.1.2 III.2 III.3 III.3.1 III.3.2 III.4 III.4.1 III.4.2 III.5 III.5.1 III.5.2 III.5.3 III.6 III.7 III.7.1 III.7.2 III.7.3 III.8 III.9 IV IV.1 IV.2 IV.3 INTRODUCTION OF L3914A/16A/ST3917A/B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SPEECH + DIALLER FAMILY CHART. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BLOCK DIAGRAM OF L3914A/16A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BLOCK DIAGRAM OF ST3917A/B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L3914A/16A PINS ASSIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ST3917A/B PINS ASSIGNMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OVERVIEW OF L3914A/16A/ST3917A/B (SPEECH CIRCUIT) . . . . . . . . . . . . . . . . . . FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DC CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Basic Formula without RA & RB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DC Mask Change with RA & RB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BALANCE RETURN LOSS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TWO TO FOUR WIRES CONFIGURATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sidetone Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bridge Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIDETONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sidetone Suppression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optimization of Sidetone Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TRANSMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmit Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmit Gain Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmit Response Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DTMF GAIN ADJUSTMENT AND CONFIDENCE TONE . . . . . . . . . . . . . . . . . . . . . . . . RECEIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Receive Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Receive Gain Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Receive Response Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PACIFIER TONE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AGC CONTROL FOR LINE LOSS COMPENSATION . . . . . . . . . . . . . . . . . . . . . . . . . . DIALLER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MAKE/BREAK RATIO ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TIMING DIAGRAM FOR L3914A/16A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TIMING DIAGRAM FOR ST3917A/B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Page
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AN849/0996
SPEECH AND DIALLER L3914A/16A AND ST3917A/B SUMMARY (continued)
IV IV.4 IV.4.1 IV.4.2 IV.4.3 IV.5 IV.5.1 IV.5.2 V V.1 V.2 V.3 VI VI.1 VI.2 VII VII.1 VII.2 VII.3 VIII VIII.1 VIII.2 VIII.3 VIII.4 VIII.5 DIALLER (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUNCTIONAL TESTS PROCEDURES FOR L3914A/16A . . . . . . . . . . . . . . . . . . . . . . . Programming and Repertory Dialing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pause/Last Number Redialed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Digits Buffer for LNB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUNCTIONAL TESTS PROCEDURES FOR ST3917A/B. . . . . . . . . . . . . . . . . . . . . . . . Cascading Last Number Redialed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LNR Inhibition if more than 32 Digits are Stored . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . THE DIFFERENT FEATURES BETWEEN L3914A, L3916A AND ST3917A/B . . . . . . AUTO-RELEASE HOLD (ONLY FOR L3914A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TRANSMIT MUTE FUNCTION AND TONE MODE INDICATOR (ONLY FOR ST3917A/B) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LIGHTED DIALLING LED (ONLY FOR L3916). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PINS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PINS DESCRIPTION FOR L3914A/16A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PINS DESCRIPTION FOR ST3917A/B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPLICATIONS FOR USA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Schematic Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brief Description.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measurements Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX A - DEMOBOARD FOR MULTI COUNTRY APPLICATION BY JUMPER SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX B - PCB LAYOUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX C - COMPONENT LAYOUT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX D - COMPONENT LISTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX E - TYPICAL APPLICATION CIRCUIT WITH BRIDGE CONFIGURATION
Page
21 21 21 21 21 21 21 21 22 22 22 22 23 23 24 26 26 26 27 30 30 31 32 33 35
2/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
I - INTRODUCTION OF L3914A/16A/ST3917A/B These devices are an integrated circuit incorporating the speech and diallercircuit into one chip which are designed for USA market. By changing a few components values or by adding a few external components, it is possible to use it in several other countries. COMMON FEATURES - 2 to 4 wires conversion - Line loss compensation for long line - Symmetrical high impedance microphone inputs suitable for dynamic, Electret or Piezoelectric transducer - Asymmetrical earphone output suitable for dynamic transducer - Internal muting to disable speech during dialling - Tone/pulse dialler with 32 digits for last number redial buffer - Pacifier tone provides audible indication of valid key press in a buzzer or/and in the earphone - Timed pabx pause and flash initiates timed break I.1 - Speech + Dialler Family Chart
Device L3914A L3924A L3934A L3916A L3926A L3936A ST3917A ST3917B M/B Ratio 40/60 Cp = 0, Rp = Cp = 0, Rp = Cp = 0, Rp = Cp = 0, Rp = Cp = 0, Rp = Cp = 0, Rp = Yes No M/B Ratio 33/67 Cp=4.7F, Rp=100k Cp=4.7F, Rp=100k Cp=4.7F, Rp=100k Cp=4.7F, Rp=100k Cp=4.7F, Rp=100k Cp=4.7F, Rp=100k No Yes Flash (ms) 585 300 100 585 300 100 585/300/100 585/300/100 Lighted Dial LED No No No Yes Yes Yes Yes Yes HOLD Function Yes Yes Yes No No No No No
- Continuous tone for each digit until key release - Uses inexpensive 3.579545MHz ceramic resonator L3914A/16A - Three 18 digits one-touch memories for emergency redial and ten 18 digits two-touch memories - Hold function for parallel phone with 400ms validation timer to prevent false release (L3914A only) - Lighted dialled led which consume 25% of total line current (L3916A only) ST3917A/B - Make/break ratio : 40/60(ST3917A)and 33/67(ST3917B) - 4 selectable options on flash duration, softswitch inhibition in one of the options with 100ms flash timing - 2 selectable options : transmit mute/led keyboard illumination or led indicator for tone mode dialling
Notes: 1. L3924A/34A are metal mask options of L3914A with different Flash timing. 2. L3926A/36A are metal mask options of L3916A with different Flash timing.
The descriptions in this application for L3914A and L3916A are also applied to L3924A/34A/26A/34A.
3/35
R8 D9 C8 VCC RXIN
12 11 15 17
D6 C5 VDD
23 6 14
Q2 PULSE LED LN
I.2 - Block Diagram of L3914A/16A Figure 1 : Block Diagram of L3914A/16A
L3914A/16A
DIALLER SPEECH PULSE DTMF TRANSMIT & DTMF RECEIVE
10 19
GRX
RGRX
1
2
3
Flash
R1
28
4 4x5 KEYPAD
5
6
Prog
27
RXOUT GTX
7
8
9
P/LND
R3
26
0
#
HOLD
R4
25
RGTX
I - INTRODUCTION OF L3914A/16A/ST3917A/B (continued)
C4
4
CGTX
E1 E2 E3
MEM
24
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
C3
3 2
CONTROL LOGIC 13 MEMORY RAM CURRENT CONTROL & CURRENTREF
RX HOLD
C2
1
C1 PACIFIER TONE GENERATOR
HS1B
8
HKS
GDTMF
5 21 7 20
22 18 13 16 9
CDTMF
RDTMF
X1 Buzzer R10 TONE PULSE R20
C11
C12 R15 R14 R21 C15 R11 ZB Mic
C9
AN849-01.EPS
R18 MICREG IREF ILINE GND
OSC
MODE
MIC+
C6
*
R5
CGRX
R2
R19
4/35
R3 TIP D1 - D4 Diode Bridge RING Q1 R7 R9 R5 D8 C7 R12 D7 C4 R4 HS1A** HS1A * R6
Note : - HS1A* : For L3914A - HS1A** : For L3916A
R3 TIP D1 - D4 Diode Bridge RING Q1 R4
HS1A R7 R6
R8 R5 D8 C7 R12 D9 C8 V CC RXIN
12 11 15 17
R9 D7 C4
D6 C5 VDD
23 6 14
Q2 PULSE LED LN
R19 C6
I.3 - Block Diagram of ST3917A/B Figure 2 : Block Diagram of ST3917A/B
ST3917A/B
DIALLER RECEIVE PULSE GENERATOR DTMF GENERATOR TRANSMIT & DTMF SPEECH
10 19
GRX
RGRX
1
2
3
Flash
R1
28
4 4x4 KEYPAD
5
6
SS
27
RXOUT GTX RGTX
7
8
9
Pause
R3
26
I - INTRODUCTION OF L3914A/16A/ST3917A/B (continued)
C3
3 2 1
CGTX
16 9
*
CONTROL LOGIC LNR MEMORY RAM
4
0
#
LND
R4
25
CGRX RX GND
R2
C2
C1
LED
VDD
ROW COL PACIFIER TONE GENERATOR
8
SEL
CURRENT CONTROL & CURRENTREF
GND
HS1B
HKS
GDTMF
5 7 21 20
22 18 13
CDTMF
RDTMF
X1 Buzzer R10 TONE PULSE R20
C11
C12 R15 R14 R21 C15 R11 ZB Mic
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
C9
AN849-02.EPS
R18 MICREG IREF ILINE
OSC
MODE
MIC+
5/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
I - INTRODUCTION OF L3914A/16A/ST3917A/B (continued) I.4 - L3914A/16A Pins Assignment
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Name C1 C2 C3 C4 OSC PULSE MODE HKS GND Function Keypad Column 1 Keypad Column 2 Keypad Column 3 Keypad Column 4 Oscillator Pin Pulse Output Pin Pacifier Output and Tone/Pulse Mode Select Hookswitch Input Ground Pin for all Voltage Reference
I.5 - ST3917A/B Pins Assignment
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Name C1 C2 C3 SEL OSC Function Keypad Column 1 Keypad Column 2 Keypad Column 3 Option Select Pin Oscillator Pin
PULSE Pulse Output Pin MODE HKS GND Pacifier Output and Tone/Pulse Mode Select Hookswitch Input Ground Pin for all Voltage Reference
RXOUT Receive Amplifier Output GRX RXIN IREF VCC LED ILINE LN REG GTX MICMIC+ Receive Gain Adjustment Receive Amplifier Input Current Reference Speech Circuit Supply LED Output Pin Slope Adjustment Positive Line Terminal Voltage Regulator Decoupling Transmit Gain Adjustment Inverting Microphone Input Non-inverting Microphone Input
RXOUT Receive Amplifier Output GRX RXIN IREF VCC LED ILINE LN REG GTX MICMIC+ Receive Gain Adjustment Receive Amplifier Input Current Reference Speech Circuit Supply LED Output Pin Slope Adjustment Positive Line Terminal Voltage Regulator Decoupling Transmit Gain Adjustment Inverting Microphone Input Non-inverting Microphone Input
GDTMF DTMF Level Adjustment VDD R5 R4 R3 R2 R1 Dialler Positive Supply Keypad Row 5 Keypad Row 4 Keypad Row 3 Keypad Row 2 Keypad Row 1
GDTMF DTMF Level Adjustment VDD Dialler Positive Supply
MU/MFI Transmit Mute and Tone Mode Indicator R4 R3 R2 R1 Keypad Row 4 Keypad Row 3 Keypad Row 2 Keypad Row 1
6/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
II - OVERVIEW OF L3914A/16A/ST3917A/B(SPEECH CIRCUIT) T h e in t e rn a l f u nc t iona l blo ck of t h e L3914A/16A/ST3917A/B(for speech circuit only) is shown in Figure 3. The speech circuit can be divided into two modes : the speech mode and the dialling mode. The speech mode can be further sub-divided into two sections : the speech transmitting and the speech receiving mode. In the speech transmitting mode, the speech signal from the microphone is being amplified by the transmit pre-amplifier (GM1). Since it is in the speech mode, the mute switch as controlled by the MUTE CONTROL will be at position 1 which enabled the speech path and disabled the DTMF path. This allows the amplified speech signal to propagate to the transmit output amplifier. The amplified speech signal will then be sent to the line. In the speech receiving mode, the speech signal from the line is being amplified by the receive pre-amplifier (GM4). The mute switch is at position 1 and therefore the speech signal will be passed to the final receive amplifier. The amplified speech signal will then be delivered to the earphone. Figure 3 : Internal Block Diagram of Speech Circuit
Mic RGTX MIC20 21
In the speech mode, the Automatic Gain Control (AGC) will regulate the gain of both the transmit and receive pre-amplifier according to the line current. Likewiseforthe dialling mode,therearetwo sections: the DTMF transmit and the Dial-Pulse transmit. In the DTMF dialling mode, the DTMF signal generated from the DTMF generator isfiltered and then amplified by the transmit pre-amplifier (GM2). The filtered DTMF signal is also attenuated by the receive pre-amplifiers (GM3). The mute switch in this case will be at position 2 which disabled the speech path and enabled the DTMF path. The DTMF signal will be amplified by the final transmit amplifier and sent to the line. In addition, the DTMF signal will also be amplified by the final receive amplifier and delivered to the earphone. In the Dial-Pulse mode, the speech mode will be disabled. No DTMF signal will be generated. However, a pacifier tone generated by the Pacifier Tone Generator will be sent to the final receive amplifier. The amplified signal will then be sent to the earphone. The pacifier tone is also delivered to an optional external buzzer at the mode pin.
MIC+ 64k GM1 1 2 Mute Switch
GTX
19
PULSE GENERATOR LOGIC CONTROL DTMF GENERATOR 14 MEMORY RAM PACIFIER TONE GENERATOR
MUTE CONTROL
Transmit Amplifier Ri1
17
LN ZLINE ZSET
IL
18
REG C15
Ri2 DTMF Filter GM2
40k
GM3
C16
2 1 70k 20k Mute Switch GM4
2 1 Mute Switch Receive Amplifier CURRENT REFERENCE
10
RXOUT RGRX C6 Earphone
11 16
GRX
MODE Buzzer
7
23
VDD RDTMF
22
GDTMF CDTMF
12
RXIN
13
IREF
ILINE R15
R10
C8 R11 R14
TONE PULSE C9
R17
5M
CURRENT MIRROR
R16
AGC
R18
R19
7/35
AN849-03.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION III.1 - DC Characteristics This device provides a two slope DC characteristics curves. The steeper slope is for line current from 4mA to 10mA. The flatter slope is for line current from 10mA onwards so as to limit the power dissipation for short loop application. III.1.1 - Basic Formula without RA & RB VLN = R14 x [ILINE - (ICC + IDD)] Ri2 + Ri1 + x V1 + (Ri1 x I1) Ri2 with V1 = 1.4V, Ri1 = 16.9k, Ri2 = 39k and ICC + IDD = 2mA. @ IL = 5mA, I1 = 12A @ IL = 10mA, I1 = 70A @ IL = 100mA, I1 = 98A Where VLN is the line voltage at Pin 17 (LN) without RA or RB. Changing the values of R14 will change the second slope of the DC curve which has a line current ranging from 10mA to 120mA. This will affect the microphone gain, DTMF gain, sidetone, maximum output swing on LN and the DC Characteristics (especially at lower voltage). For this reason, it is recommended to maintain R14 at 20. As shown in Figure 4, by connecting RA and RB it is possible to shift the DC curve up and down with respect to the line current. This is illustrated in Figure 5. III.1.2 - DC Mask Change with RA and RB 1) RA between LN and REG pins -Ri12 V1 V = + I1 x Ri1 + RA Ri2 Therefore, VLNA = VLN + V. Note : RA value cannot be lower than 9.1k, otherwise this will affect the return loss. 2) RB between REG and ILINE pins Ri1 V = V1 x Values of these components are chosen in such a way that a compromise is made between balance return loss and the frequency curve of the sending amplifier. For real impedance, Z12 and Z14 are real, i.e. resistive load : Z12 = R12 ; Z14 = R14. For complex impedance, Z12 and Z14 are complex, i.e. : Z12 = R12 + R22//C17 Z14 = R14 + R23//C18 The AC impedance of the speech circuit for both real and complex impedances is shown in Figures 6 and 7. Figure 4 : Block Diagram of DC Regulator
R12 VLN
14 VCC
ZLINE
17
D8
ICC
23 VDD
Ri1 REG
18
RA
BATT
IDD C5 C7
Ri2 I1 V1 ILINE
16 9
RB
C15
GND
R14
Figure 5 : DC Characteristics
VLN (V) (P in 17) RB Witho ut RA a nd RB RA
4.1 3.5 3.2 2.2
RB
Therefore, VLNB = VLN + V. III.2 - Balance Return Loss The AC impedance of the circuit is mainly determined by R9, R12 and C4.
ILN (mA) 4 10 120
8/35
AN849-05.EPS
AN849-04.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figure 6 : Real AC Impedance of the Speech Circuit
Imp ed a n c e o f Ap plication Circ u it Impe d an ce o f Reg u lator
Zeq
R12 470 R9 3.3k C4 10n F
Ri1 R14 C1 5 1.6H R1 4 20
R11 16.9k
Figure 7 : Complex AC Impedance of the Speech Circuit
Im p e da n c e of App lic a tio n Circ u it Imp e d a n c e o f Re gu la to r
C4 10nF
R12
Ri1 R14 C15 1.6H
R11 16.9k
Ze q
R9 3.3k
R14 R22 C17
C15 4.7 F
III.3 - Two to Four Wires Conversion The device performsthe two to four wires conversion by means of Sidetone configuration (refer to Figure 8) or bridge configuration (refer to Figure 9). The two wires are connected to the Tip and Ring of the telephone line and the four wires are connected to the transmitting signal from MIC+, MIC- and the receiving signal from the earphone and ground. - In transmitting mode : The AC signal from the microphone is sent to one diagonal of the bridge across pins 16 and 17. Major portion of the signal will be sent to the line, but small portion will be lost on ZB. - In receiving mode : The AC signal coming from the line input to the diagonal of the bridge across Pin 12 and 9. After amplification, it will be applied to the receiver. III.3.1 - Sidetone Configuration To optimize the balancing of the bridge : ZB ZLINE = ZB + R15 ZLINE+ ZSET
where : - ZSET = R9//R12/C4. - ZLINE is the line impedance between Tip and Ring of telephone line. - ZB is a complex impedance function of the line length. The values chosen for ZB should be for an average value of the line length. Note : the application diagrams described in this application note are using this Sidetone configuration. III.3.2 - Bridge Configuration To optimize the balancing of the bridge : R18 ZB = ZSET // ZLINE R14 where : - ZSET=R9//R12/C4. - ZLINE is the line impedance between Tip and Ring of the telephone line. Note : Refer to Appendix E in Section VIII.5 for the typical application circuit.
9/35
AN849-07.EPS
C7 100 F
R23
C18
AN849-06.EPS
C7 100 F
C15 4.7 F
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figure 8 : Sidetone Configuration
LN
17
RXIN GND 9
8 1
12
Receiver Rt
ILINE
Figure 9 : Bridge Configuration
LN
17
ZLINE
E
T
S
Z
AN849-08.EPS
16
ZB
To obtain optimumsidetone suppression, condition b) has to be fulfilled, resulting in : R15 ZB = x ZLINE = k x ZLINE ZSET R15 . where k is a scale factor ; k = ZSET The scale factor k (value of R15) is chosen to meet the following criteria : - |ZB//R15|<>R14 to avoid influencing the transmit gain. In practice ZLINE varies considerably with line length and line type. Therefore, the values chosen for ZB should be for an average line length giving satisfactory sidetone suppression with short and long lines. The suppression also depends on the accuracy of the matching between ZB and the impedance of the average line. Figure 10 : Sidetone Network, ZB
ZLINE
E
T
1 R
S
9
Z
R 1 R 9
5 1
R 1 R 4
RXIN GND 9
12
Receiver Rt
R16
R 8 1 1 R 4
16
ILINE
AN849-09.EPS
C16
R17
AN849-10.EPS
III.4 - Sidetone However, the balancing condition is only an ideal case because there is always a portion of the transmitted signal, called SIDETONE, present at the receiver. III.4.1 - Sidetone Suppression Suppression of the transmitted signal in the earpiece is obtainedby the Sidetone network comprising ZLINE//ZSET, R19, R18, R15, R14 and ZB (refer to Figure 8). Maximum compensation is obtained when the following conditions are fulfilled : a) R14 x R19 = ZSET x [R18 + (R15//ZB)] ZB ZLINE b) = ZB + R15 ZLINE + ZSET If fixed values are chosen for ZSET, R19, R18 and R14, then condition a) is always fulfilled provided |R15//ZB|<III.4.2 - Optimization of Sidetone Network The practical procedures to adjust the component values of ZB : - Replace R16 + R17 by a 1k trimmer and send a 100Hz signal at the microphone input. Adjust the trimmer so that the 100Hz signal is at its minimum value at the earphone output. - Fix R16 to 1/3 of the trimmer value. - Replace R17 by a 1k trimmer and C16 by a variable capacitor and send a 1kHz signal at the microphone input. - Adjust the trimmer and the variable capacitor so that the 1kHz signal is at its minimum at the earphone. - Fix R17 and C16 with the final values of the trimmer and variable capacitor.
10/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) III.5 - Transmit Figure 11 : Block Diagram of Transmit Amplifier
CGTX Mic
MIC20
MIC+
21
GTX
19
RGTX Tra nsmit Amplifie r
VLN Ri1
18
GM1 64k VDF DTMF DAC GDF VDTMF GM2
Mute S witch
REG C15
Mute Control
Ri2 I1
40k AGC
22
CURRENT SOURCE
13 16 9
GDTMF
IREF R11
ILINE R14
GND
CDTMF
RDTMF
AN849-11.EPS
C9
III.5.1 - Transmit Characteristics The Figure 11 shows the internal block diagram of the transmit amplifier section. The transmit signal (VMIC) from the microphone passes through the pre-amplifier (GM1) to the line driver circuit which is the same circuit used by the DC line interface. This is to provide a better dynamic and lower line current operation. III.5.2 - Transmit Gain Adjustment The maximum transmit gain between Pin 21 (MIC+), Pin 20 (MIC-) and pin 20 (LN) is : VLN RGTX ZLINE//ZSET = 1.386 x x GTX = VMIC R11 R14 where : ZSET = R12//R9//C4 and ZLINE is the line impedance between Tip and Ring of telephone line.
RGTX minimum value : 20k (41.4dBat GTX max.) RGTX maximum value : 82k (53.6dBat GTX max.) The Figures 12 and 13 shows the transmit gain as a function of line current ILN and transmit gain as a function of RGTX. III.5.3 - Transmit Response Curve The overall telephone set transmit gain and the response curve depend on the type of microphone used. C10, C11, C12, R13, RGTX, CGTX, R20 and R21 are used to fix these parameters whenever a electret microphone is used. RGTX is used to fix the internal transmit gain. C11, C12, R13 are used to fix the slope for low frequency. C10 and CGTX are used to fix the high frequency rolloff. R20 and R21 are used to fix the gain of the microphone.
ZSET
17
11/35
ZLINE
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figure 12 : Transmit Gain versus Line Current of L3914A/16A
56 54 Transmit Gain (dB) 52 50 48 46 44 42 40 0 20 40 60 80 Line Curre nt (m A) 100 120
RGTX = 43k
AN849-12.EPS
fRE Q = 1kHz, VMIC = 2mVRMS
and VDF is the DTMF level of approximately 150mVRMS generated internally. - The gain of DTMF at pin 17 (LN) with respect to Pin 22 (GDTMF) is : V17 GDTMF =
V22
RGTX = 100k
RGTX = 68k
Figure 13 : Transmit Gain versus Line Current of ST3917A/B
56 54 Transmit Gain (dB) 52 50
RGTX = 100k fRE Q = 1kHz, VMIC = 2mVRMS
48 46 44 42 40 0 20 40 60 80 Line Curre nt (m A) 100 120
RGTX = 56k
AN849-13.EPS
RGTX = 68k
III.6 - DTMF Gain Adjustment and Confidence Tone The absolute value of the DTMF gain is modified through the new RDTMF, CDTMF connected on Pin 22 (GDTMF) and the resistor RGTX. The GDTMF input impedance is equal to 40k. - DTMF level (VDTMF) at Pin 22 (see Figure 14) is given by : VDTMF = GDF VDF where : GDF = 0.09 RDTMF//CDTMF//40k R11
RGTX ZSET//ZLINE R11 R14 - Confidence tone level available to earphone (see Figure 14). During DTMF dialing, the internal muting control will disable the speech circuit. The DTMF signal will pass through the pre-amplifier to the earphone. This acts as a feedback signal to the user. The confidence tone attenuation between Pin 10 (RXOUT) and pin 22 (GDTMF) can be obtained as follows : V10 RGRX CRDTMF = 0.095 CRDTMF = V22 R11 where RGRX and R11 are in k. The confidence tone level between Pin 10 (RXOUT) and pin 17 (LN) is obtained as follows : CRDTMF V10 V10 V22 CDTMF = = CDTMF = V17 V22 V17 GDTMF - Components setting of DTMF transmit level and confidence tone. Higher DTMF gain can be adjusted with higher value of RDTMF at pin 22. But RDTMF should not be larger than 7k because this will affect the AGC decoupling at speech mode. If RDTMF is set, CDTMF should be selected such that the cutoff frequency for DTMF filtering is about 4kHz. 1 fCUTOFF= 2CDTMF x RDTMF A higher confidence tone level can be achieved by c o nne ct ing a re sist or a nd ca pa citor (20k + 100nF) between Pin 22 (GDTMF) and Pin 11 (GRX), refer to Figure 14. However, we need to re-adjust the DTMF network, RDTMF and CDTMF, to achieve the proper level if the extra network is connected. GDTMF = 0.347
12/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figure 14 : Block Diagram of DTMF Amplifier
C15 RGTX GTX
19 19 18
R14 ILINE
REG LN
17
GM2 40k VDTMF VDF GDF AGC GM4 Mute Fa cility 20k CURRENT SOURCE
22
DC LINE INTERFACE
CURRENT MIRROR GM3 Mute Fa cility GRX
11
RGRX RXOUT 2VBE
10
C6
12
DTMF
13
IR EF R11
RXIN C8
Ea rphone
CDTMF
RDTMF S pe e ch S igna l from Line 20k 100nF
ZLINE
ZSET
C9
III.7 - Receiving III.7.1 - Receive Characteristics The Figure 15 shows the internal block diagram of the receive amplifier. The receive signal coming from the telephone line is amplified by the pre-amplifier (GM4) which has a single ended input and non-inverting output Figure 15 : Block Diagram of Receive Amplifier
17
The amplification from RXIN to RXOUT is achieved by adjusting the external resistance RGRX. The receive amplifier has a single ended output with an output impedance of 35 typically.
ZLINE
ZSET
R19
Line Reg. C ontrol Spee ch Mode GM4 GRX
11
R18
AGC
20k
CURRENT SOURCE
RGRX RXOUT 2VBE
10
R16
R15
16
ILINE
13
12
C6 RXIN C8
AN849-15.EPS
IREF
VO UT
Earphone
C16
R17
R14
R11
13/35
AN849-14.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) III.7.2 - Receive Gain Adjustment The equivalent circuit of the first stage of the receive amplifier can be simplified as shown in Figure 16. Figure 16 : Equivalent Circuit of First Stage of Receive Amplifier
VLN R19
C8
12
R18 R16 R15
VI
20k
RXIN
and the gain, GRX between Pin 17 (LN) and Pin 10 (RXOUT) is : VOUT = GRX1x GRX2 GRX = VLN where GRX should take in account the attenuation due tothe sidetone network interface,the decoupling capacitor, C8 connected on Pin 12 (RXIN) and the 20k input impedance of Pin 12 (RXIN) (see Figure 16). RGRX minimum value : 33k (21.4dBat GRX max.) RGRX maximum value : 330k (41.4dBatGRXmax.) Figures 17 and 18 show the effect of L3914A/16A receive gain as a function of line current, I LN and as a function of RGRX. Figure 17 : L3914A/16A Receive Gain versus Line Current at Re = 150
AN849-16.EPS
ZB R17 C16 R14 VI'
40 35 Transmit Gain (dB) 30 25 20
RGRX = 33k RGRX = 100k RGRX = 68k RGRX = 300k
The gain of the first stage of the receive amplifier can be obtained as follows : R18 + ZB//(R15 + R14) (1) VI' = VLN R19 + [R18 + ZB//(R15 + R14)] 20k and VI = VI' (2) 1 + 20k jC8 Substituting equation (1) into (2), we can obtain the first stage of receive gain, GRX1 :
GRX1 = VI VLN R18 + ZB//(R25 + R14) R19 + [R18 + ZB//(R15 + R14)]
15 10 0 20 40 60 80 Line Curre nt (mA) 100 120
AN849-17.EPS AN849-18.EPS
fREQ = 1kHz, VINP = 5mVRMS, Re = 150
Figure 18 : L3914A/16A Receive Gain versus Line Current at Re = 300
20k
Transmit Gain (dB)
1 + 20k jC8
40 35 30
RGRX = 100k RGRX = 300k
GRX1 =
The absolute value of the receive gain is modified through the resistor RGRX connected between Pin 11 (GRX) and Pin 10 (RXOUT). The maximum receive gain, GRX2 between Pin 12 (RXIN) and Pin 10 (RXOUT) can be obtained as follows : VOUT RGRX GRX2 = = 1.386 x VI R11 where RGRX and R11 are in k.
25 20
RGRX = 68k RGRX = 33k
15 10 0
fRE Q = 1kHz, VINP = 5mVRMS , Re = 300
20
40 60 80 Line Curre nt (mA)
100
120
14/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figures 19 and 20 show the effect of ST3917A/B receive gain as a function of line current, ILN and as a function of RGRX. Figure 19 : ST3917A/B Receive Gain versus Line Current at Re = 150
35 Transmit Gain (dB)
III.7.3 - Receive Response Curve If it is necessary to compensate the response curve of the transducer, it is possible to put a capacitor in parallel with RGRX or to adjust C6 and C8 values. III.8 - Pacifier Tone The Figure 21 shows the pacifier tone and mode detection circuit during pulse mode. The mode detection circuit is to detect the Tone/Pulse mode at off-hook. The pacifier tone circuit is to provide audible tone from dialler's circuit through the internal MOS switch and resistor RP to the earphone to indicate valid key press during pulse dialling and non-DTMF key press in Tone mode. There have 2 solutions to achieve higher pacifier tone : - Put a resistor RP across Pin 7 (MODE) and Pin 11 (GRX) as mentioned in data sheet, @ IL = 15mA, RP = ; typical level is 60mVRMS RP = 430k ; typical level is 600mVRMS - Add external component at Pin 7 (MODE) as shown in Figures 22 and 23. Because the output impedance at Pin 10 (RXOUT) is 35, it is recommended that a series resistor (R) should be added to Pin 10 to avoid the loading effect to pacifier tone generated at Pin 7 (MODE). However, this will cause a 6dB loss at receiving. Nominal value of earphone is about 150, so R works as a potential divider in order to decide the tone level available at earphone. With a typical VDD = 3V, the pacifier tone level at earphone will be about 110mVPP.
30
25
RGR X = 100k RGRX = 62k
20
AN849-19.EPS AN849-20.EPS
fRE Q = 1kHz, VINP = 5mVRMS , Re = 150
15
0
20
40 60 80 Line Curre nt (m A)
100
120
Figure 20 : ST3917A/B Receive Gain versus Line Current at Re = 300
35 Transmit Gain (dB)
30
25
RGRX = 10 0k RGRX = 62k
20
15
fRE Q = 1kHz, VINP = 5 mVRMS , Re = 300
0
20
40 60 80 Line Curre nt (mA)
100
120
Figure 21 : Block Diagram of Pacifier Tone Generator
R PAC 4.7M Ena ble VDD TONE R10
7
T/P Se lect
VRXIN
PULSE Buzze r
MODE DETECTION CIRCUIT
2VBE
10
RXOUT
C6 Earphon e
AN849-21.EPS
15/35
RGRX
MODE
Pacifier Tone
DTMF IN
11
GRX
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
III - FUNCTIONAL DESCRIPTION (continued) Figure 22 : Connection of RC Network between
VDD 0 Pa cifier Tone MODE 2k 10 F
10
7
RXOUT
R 150
C6 4.7 F 15 0
AN849-22.EPS
The AGC range is fixed with a gain control ranging from 0 to 6dB. For : IL 20mA, AGC = 0dB IL 60mA, AGC = -5dB (L3914A/16A) IL 60mA, AGC = -6dB (ST3917A/B) To achieve a higher AGC, connect a diode and a resistor between Pin 13 (IREF) and Pin 16 (ILINE). (see Figure 25). Figure 24
TX/RX AGC 0
Figure 23 : Connection of a resistor between Pin 7 and earphone
MODE 7 2k
AN849-23.EPS
1 50
160
ILN ILL IS L
Figure 25
ILINE
16
1N4148
1M
16/35
AN849-25.EPS
III.9 - AGC Control for Line Loss Compensation The AGC control block regulates the current that must be sent to the transmit and receive preamplifiers which in turn adjust the gain of the amplifier according to the line length. The AGC function is implemented internally in the device.
IREF
13
AN849-24.EPS
AGC
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
IV - DIALLER The common features available are : - 32 digits for Last Number Redial - Provide Tone/Pulse switchable dialling - Pacifier tone for audible indication of valid key pressed in a Buzzer or/and in the Earphone - Timed PABX Pause - Flash initiates Time Break - Continuous tone for each digit until key release ST3917A/B - Last number redial inhibition for dialling of greater than 32 digits. - Cascading Last number redial. - Make/Break ratio : 40/60(ST3917A)and 33/67(ST3917B). - 4 selectable options on Flash duration, softwitch inhibition in one of the option with 100ms Flash timing. - 2 selectable options : Transmit mute/LED keyboard illumination or LED indicator for tone mode indicator. The timing diagram for Tone and Pulse mode dialling for L3914A/16A and ST3917A/B are shown in the Figures 26, 27, 28, 29, 30 and 31. IV.1 - Make/break Ratio Adjustment By adding a capacitor Cp on the pulse output (Pin 6) and the Rp between the base of Q2 and the LN input (Pin 17) of L3914A/16A, the make/break ratio can be changed from 40/60 to 33/67. Refer to the typical application circuit in Appendix A of Section VIII.1.
L3914A/16A The L3914A/16A provide manual dialling of an infinite number of digits, but if more than 32 digits are dialled, it would wrap around in the LNR. Other features include : - Three 18 digits one-touch memories for emergency redial and ten 18 digits two-touchmemories. - HOLD function for parallel phone with 400ms valida tio n timer to prevent false release (L3914A). - Lighted dialled LED which consume 25% of total line current (L3916A).
17/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
IV - DIALLER (continued) IV.2 - Timing Diagram for L3914A/16A Figure 26 : Tone Mode Timing
Dial Sequence 1
*
1
FLASH 3
ENTER
Keyboard Input Keyboard Scan HSK Input DTMF Output PULSE Output
ENTER
ENTER
FLASH
ENTER
3
*
KEYBOARD SCAN
FLASH PERIOD
N1
N2
1/TR
tHFP
2
AN849-26.EPS
Notes : For this example, key entries are 100ms, but 32ms. N1 : Pre-signal Delay. N2 : Inter-signal Delay.
Figure 27 : Pulse Mode Timing
Dial Sequence 2 1 PAUSE 1
ENTER
Keyboard Input 2
ENTER
1
ENTER
PAUSE
ENTER
1
N3
Keyboard Scan DIAL DIGIT 2 PULSE Output KEYBOARD SCAN 250Hz
N6
DIAL DIGIT 1
PAUSE 3.1SEC
DIAL DIGIT 1
N5
HSK Input Pacifier Tone
N8 N9 TB TM
N7
OFF-HOOK
N7
tMO
ONHOOK
18/35
AN849-27.EPS
Notes : N3 : Keypad Debounce Time. N4 : Pacifier Tone Duration. N5 : Pre-digital Pause. N6 : Inter-digit Pause.
N7 : Mute Overlap Time. N8 : Break Time. N9 : Make Time.
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
IV - DIALLER (continued) IV.3 - Timing Diagram for ST3917A/B Figure 28 : Tone Mode Timing with Lighted Dial LED (Pin 24 to VDD or GND)
Dial Sequence 1
*
1
FLASH 3
ENTER
Keyboard Input Keyboard Scan HSK Input DTMF Output (Pin 17) PULSE Output LED Output Current (Pin 15)
ENTER
ENTER
FLASH
ENTER
3
*
N3
KEYBOARD SCAN
FLASH PERIOD
N1 1/TR
N2 N3 tHFP
N1
Figure 29 : Tone Mode Timing with Tone Indicator (pin 24 to any row)
Dial Sequence 1 3 FLASH LND
ENTER
Keyboard Input Keyboard Scan HSK Input DTMF Output (Pin 17) PULSE Output LED Output Current (Pin 15) 1
ENTER
3
ENTER
FLASH
ENTER
LND
N3
KEYBOARD SCAN
FLASH PERIOD
N1 1/TR
N2 N3 tHFP
N1
19/35
AN849-29.EPS
Notes : For this example, key entries are 90ms, but 32ms. N1 : Pre-signal Delay. N2 : Inter-signal Delay. N3 : Keyboard Debounce Time.
AN849-28.EPS
Notes : For this example, key entries are 90ms, but 32ms. N1 : Pre-signal Delay. N2 : Inter-signal Delay. N3 : Keyboard Debounce Time.
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
IV - DIALLER (continued) IV.3 - Timing Diagram for ST3917A/B (continued) Figure 30 : Pulse Mode Timing with Lighted Dial LED (Pin 24 to VDD or GND)
Dial Sequence 2 1 PAUSE 1 ENTER 1 ENTER PAUSE ENTER 1
ENTER Keyboard Input N3 Keyboard Scan 2
KEYBOARD SCAN 250Hz DIGIT 2 DIGIT 1 3.4s PAUSE DIGIT 1
PULSE Output N5 HSK Input Pacifier Tone LED Output Current (Pin 15)
AN849-30.EPS
N7 N8 TB TM
N6 OFF-HOOK ONHOOK
Notes : N3 : Keypad Debounce Time. N4 : Pacifier Tone Duration. N5 : Pre-digital Pause. N6 : Inter-digit Pause.
N7 : Break Time. N8 : Make Time.
Figure 31 : Pulse Mode Timing with Tone Indicator using "*" or "TONE" Key
Dial Sequence 2
*
1 FLASH LND
ENTER
Keyboard Input 2
ENTER
*
ENTER 1
ENTER
PAUSE
ENTER LND
N3
Keyboard Scan DIAL DIGIT 2 PULSE Output DIAL DIGIT * KEYBOARD SCAN 250Hz DIAL DIGIT 1 FLASH LND
N5 N7N8 TBTM
DTMF Output (Pin 17)
N9
N5
N9
N10
HSK Input Pacifier Tone LED Output Current (Pin 15) OFF-HOOK
N9
ONHOOK
N4
20/35
AN849-31.EPS
Notes : N3 : N4 : N5 : N6 :
Keypad Debounce Time. Pacifier Tone Duration. Pre-digital Pause. Inter-digit Pause.
N7 : Break Time. N8 : Make Time. N9 : Softswitch Delay (Auto). N10 : Softswitch Delay (Manual).
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
IV - DIALLER (continued) IV.4 - Functional Tests Procedure for L3914A/16A IV.4.1 - Programming and Repertory Dialing
Procedure Step 1 Step 2 Step 3 Hook OFF ON OFF Sequence Dial PROG Keypress 1, 2, 3, E1 E1 Data in E1 1, 2, 3 1, 2, 3 1, 2, 3 TIP/RING Output
1, 2, 3
IV.4.2 - Pause/Last Number Redialed
Procedure Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Hook OFF ON OFF ON OFF ON OFF Sequence Dial 1, 2, 3 .. 0 LNR 1, PSE, 2 LNR Keypress Data in E1 1, 2, 3 .. 0 1, 2, 3 .. 0 1, 2, 3 .. 0 1, 2, 3 .. 0 1, PSE, 2 1, PSE, 2 1, PSE, 2 1, PSE, 2 TIP/RING Output 1, 2, 3 .. 0 1, 2, 3 .. 0
Note: PSE key would provide a 3.1s (Tone) or 3.4s (Pulse) delay into the dialling sequences.
IV.4.3 - 32 Digits Buffer for LNR
Procedure Step 1 Step 2 Step 3 Hook OFF ON OFF Sequence Dial 32 Digits Keypress Data in E1 32 Digits LNR 32 Digits 32 Digits TIP/RING Output 32 Digits 32 Digits
IV.5 - Functional Tests Procedure for ST3917A/B IV.5.1 - Cascading Last Number Redialed
Procedure Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Sequence Hook OFF ON OFF OFF ON OFF Dial 1, 2, 3 .. 0 Keypress Data in E1 1, 2, 3 .. 0 1, 2, 3 .. 0 LNR 4, 5, 6 LNR 1, 2, 3 .. 0 1, 2, 3 .. 0, 4, 5, 6 1, 2, 3 .. 0, 4, 5, 6 1, 2, 3 .. 0, 4, 5, 6 TIP/RING Output 1, 2, 3 .. 0 1, 2, 3 .. 0 4, 5, 6 1, 2, 3 .. 0, 4, 5, 6
IV.5.2 - LNR Inhibition if more than 32 Digits are Stored
Procedure Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Hook OFF ON OFF OFF ON OFF 1, 2, 3 LNR Sequence Dial 32 Digits Keypress Data in E1 32 Digits LNR 32 Digits 32 Digits TIP/RING Output 32 Digits 32 Digits 1, 2, 3
21/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
V - THE DIFFERENT FEATURE BETWEEN L3914A, L3916A & ST3917A/B V.1 - Auto-release Hold (only for L3914A) The AUTO-RELEASE HOLD FUNCTION is completely integrated on the chip. The line is seizing, when the HOLD key is pressed, L3914A maintains the telephone line closed, mutes the conversation and the ON-HOLD LED starts to blink. The LED continues blinking at the rate of 1Hz when the user hang up the phone and intended to take the call from another parallel telephone. The telephone line current is then precisely measured and stored in digital mean inside the chip. By detecting the change in line current, L3914Aautomatically releases the telephone line as soon as the parallel phone is picked up for more than 400ms. It is controlled by an internal timer to prevent fault trigger caused by noise and to tolerate short line break signals (example : Call waiting signalling) sent by the main telephone exchange or PABX equipment during HOLD period. This feature can also be used to mute the telephone conversation temporarily (without hanging the phone). To resume the conversation, simply press the HOLD key again. The threshold of parallel phone release is 4.5mA +5% of line current. V.2 - Transmit Mute Function and Tone Mode Dialling Indicator (only for ST3917A/B) When Pin 24 (MU/MFI) is connected to GND, the transmit amplifier of the speech circuit is disabled and hence the speech transmitting path is muted. Under such mode, the LED is used as a lighted dial indicator as in L3916A. However, if Pin 24 (MU/MFI) is tied to any row of the dialler circuit, the LED functions as a Tone mode dialling indicator. In this case, there will be no mute function. The LED for Tone mode dialling indicator is used in the following conditions : - At Tone mode, LED will light up at off-hook. The LED will turn off only when the telephone goes on-hook. Examples : Tone mode 1) Off-hook (LED turns on) D1, D2, D3 On-hook (LED turns off) 2) Off-hook (LED turns on) LND On-hook (LED turns off) - At Pulse mode after off-hook, LED is off during pulse dialling. When dialling is followed by the "*" or "TONE" softswitch key depressed, the LED will light up immediately at the softswitch after pulse dialling is completed to indicate the signalling mode change from pulse to tone.
22/35
After returning to on-hook and back to off-hook, the device will be in pulse mode and then LED is turned off. Redialling from LND memory buffer willl repeat the softswitch, i.e. mixed mode redialling, the LED will light up to indicate the switch to tone mode or tone dialling. The LED will turn off only when the telephone goes on-hook or is resetted by the Flash key. Examples : Pulse mode 1) Off-hook (LED is off) D1, D2 (LED remains off), * (LED turns on), D3, D4 On-hook or Flash (LED turns off) 2) Off-hook (LED is off) LND D1, D2 (L ED rema ins o ff ), (LED turns on) D3, D4 On-hook or Flash (LED turns off) - At pulse mode, after off-hook, LED is off during pulse dialling. When switching the Tone/Pulse mechanical switch to Tone mode, LED will turn on. Example : Pulse mode 1) Off-hook (LED is off) D1, D2 Switch "Tone/Pulse " mechanical switch to Tone mode (LED turns on) D3, D4 On-hook (LED turns off) The function of the LED for Tone mode indicator is described in the timing waveform in Section IV.3. For line current up to 20mA, the ILN-ICC is sourced into the LED with a maximum current limit of 19mA. For line curent greater than 20mA, this sourced current is limited at 20mA(typical). V.3 - Lighted Dialling Led (only for L3916A) The indication is activated in off-hook mode, consuming 25% of the line current flows into the LED. If the LED is not connected, the Pin 15 (LED) should be connected to Pin 17 (LN). Figure 32 : Lighted Dial LED Current versus Line Current
30 25 ILED (mA) 20
ILED VDD = 3V
15 10 5 0 0 20 40 60 80 Line Curre nt (mA) 100 120
AN849-32.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VI - PINS DESCRIPTION I.1 - Pins Description for L3914A/16A Pin 1 Column 1 of keypad Pin 2 Column 2 of keypad Pin 3 Column 3 of keypad Pin 4 Column 4 of keypad Pin 5 OSCILLATOR PIN Ceramic resonator = 3.579545MHz. Pin 6 PULSE OUTPUT This pin drives the line break transistors in order to send Break/Make pulses in loop disconnect mode. The number of pulses depends on the key depressed. Pin 7 MODE/PACIFIER TONE This pin selects the TONE/PULSE mode and provide a Pacifier Tone during Pulse mode. A logic `1' selects the Tone mode. A logic `0' selects the Pulse mode. Pin 8 HKS/HOOKSWITCH This pin is connected to the Hookswitch. This pin detects the ON and OFF Hook condition. Pin 9 GND/GROUND This is the ground pin for the device. All voltages are referenced to this pin. Pin 10 RXOUT/RECEIVE OUT Earphone output Output impedance : 35 Pin 11 GRX/RECEIVE GAIN ADJUST Pin 12 RXIN/RECEIVE IN Input impedance = 20k Pin 13 IREF A 3.6k resistor, R11 is connected to set the internal current level. The line currents where the AGC turns on and off points can be modified by changing the value of R11. Refer to Figures 33 and 34 for the transmit and receive AGC curves versus R11 respectively. Pin 14 VCC/SPEECH CIRCUIT SUPPLY Supply for the speech circuit. A 100F capacitor is connected to this pin to provide DC decoupling. Recommended value is 100F/16V. Too large capacitor would have longer turn on time (see Figure 35). Pin 15 LED INPUT PIN A LED is connected for OFF-HOOK INDICATION. This current in the LED is equal to 25% of the line current. Figure 33 : Transmit AGC versus R11 of L3914A/16A
4 2 0 dB -2 -4
R9 = 3.6k R9 = 2.2k R9 = 2.7k
Re f Line Level = -10dBm (0dB)
-6 -8 -10 0 20 40
R9 = 4.3k R9 = 5.1 k
AN849-33.EPS AN849-35.EPS AN849-34.EPS
60 IL (mA)
80
100
120
Figure 34 : Receive AGC versus R11 of L3914A/16A
4 2 0 dB -2 -4 -6 -8 R e a rphone = 150 -10 0
Re f Ea rphone Leve l = -14.7dBm (0dB)
R9 = 2.2k R9 = 2.7k R9 = 3.6k R9 = 4.3k R9 = 5.1k
20
40
60 IL (mA)
80
100
120
Figure 35
VCC C7 100 F
14
Pin 16 ILINE A 20 resistor is connected to set the DC slope. Pin 17 LN/POSITIVE LINE TERMINAL Positive line terminal of the device. The transmit and DTMF signal are sent to the line through this pin. Pin 18 REG The capacitor C15 connected to this pin regulates the LN voltage and gives a high AC impedance for the transmit output stage.
23/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VI - PINS DESCRIPTION (continued) Pin 19 GTX/TRANSMIT GAIN ADJUSTMENT The RGTX resistor connected to this pin adjusts the transmit gain between 43.5dB and 51.5dB. Pin 20 MIC- MICROPHONE INPUT INVERTING Pin 21 MI C+ MI CRO PHO NE INPUT NONINVERTING The microphone has an input impedance of 64k diff erential input and 32k f o r asymmetrical input. R20 and R21 a re microp hone b ias resistors. C10, C11, C12 and R13 adjust the gain and the bandwidthto be compatible with the IC's gain. C13 and C14 are used for RFI suppression. Figure 36
VCC R20 C13 1.2k 4.7nF C11 100nF
VI.2 - Pins Description for ST3917A/B Pin 1 Column 1 of keypad Pin 2 Column 2 of keypad Pin 3 Column 3 of keypad Pin 4 OPTION SELECT FOR FLASH DURATION This pin is used to select various Flash durations by connecting it either to a row, column, VDD or GND. The four options are summarized as follow :
Options 1 2 3 4 SEL VDD GND Row Column Flash (ms) 100 600 300 100 Softswitch Inhibited Enabled Enabled Enabled
MIC+
21
C10 470nF
R13 220
20
AN849-36.EPS
C14 4.7nF
R21 1.2k
C12 100nF
MIC-
Pin 22 GDTMF/DTMF GAIN ADJUSTMENT RDTMF and CDTMF fix the DTMF level on line and the cutoff frequency for DTMF filter. The value of CDTMF and RDTMF are chosen such that : 1 = 4kHz
2RDTMFx CDTMF
Pin 23
Pin Pin Pin Pin Pin
24 25 26 27 28
where 4kHz is the low pass frequency for the DTMF signal. VDD DIALLER POSITIVE SUPPLY Supply for the dialling circuit. It is supplied from V CC via a diode. The Zener diode D6 protects the dialling circuit in on-hook mode. The capacitor C5 and the resistor R5 are required for memory retention during onhook. Row 5 of keypad Row 4 of keypad Row 3 of keypad Row 2 of keypad Row 1 of keypad
Pin 5 OSCILLATOR PIN Ceramic resonator = 3.579545MHz Pin 6 PULSE OUTPUT This pin drives the line break transistors in order to send Break/Make pulses in loop disconnect mode. The number of pulses depends on the key depressed. Pin 7 MODE/PACIFIER TONE This pin selects the TONE/PULSE mode and provide a Pacifier Tone during Pulse mode. A logic `1' selects the Tone mode. A logic `0' selects the Pulse mode. Pin 8 HKS/HOOKSWITCH This pin is connected to the hookswitch. This pin detects the on-hook and off-hook condition. Pin 9 GND/GROUND This is the ground pin for the device. All voltages are referenced to this pin. Pin 10 RXOUT/RECEIVE OUT Earphone output. Output impedance is 35. Pin 11 GRX/RECEIVE GAIN ADJUST The RGRX resistor connected to this pin adjusts the receive gain between 21dB and 41dB. Pin 12 RXIN/RECEIVE IN Input impedance = 20k Pin 13 IREF A 3.6k resistor is connected to set the internal current level. The line currents where the AGC turns on and off points can be modified by changing the value of R11. Refer to Figures 37 and 38 for the transmit and receive AGC curves versus R11 respectively.
24/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VI - PINS DESCRIPTION (continued) Figure 37 : Transmit AGC versus R11
4 2 0 dB -2 -4
R9 = 3.6 k R9 = 2.2k R9 = 2.7k
-6 -8 -10 0 20 40
R9 = 4.3k R9 = 5.1k
AN849-37.EPS
Re f Line Level = -10d Bm (0dB)
60 IL (mA)
80
100
120
Figure 38 : Receive AGC versus R1
4 2 0 dB -2 -4 -6 -8 R e a rphone = 15 0 -10
Re f Earp hone Leve l = -14.7dBm (0 dB)
AN849-38.EPS
R9 = 2.2k R9 = 2.7k R9 = 3.6k R9 = 4.3k R9 = 5.1k
0
20
40
60 IL (mA)
80
100
120
Pin 16 ILINE A 20 resistor is connected to set the DC slope. Pin 17 LN/POSITIVE LINE TERMINAL Positive line terminal of the device. The transmit and DTMF signals are sent to the line through this pin. Pin 18 REG The capacitor C15 connected to this pin regulates the LN voltage and gives a high AC impedance for the transmit output stage. Pin 19 GTX/TRANSMIT GAIN ADJUSTMENT The RGTX resistor connected to this pin adjusts the transmit gain between 43.5dB and 51.5dB. Pin 20 MIC- MICROPHONE INPUT INVERTING Pin 21 MI C+ MI CRO PHONE I NP UT NO NINVERTING The microphone has an input impedance of 64k differential input and 32k f o r asymmetrical input. Pin 22 GDTMF/DTMF GAIN ADJUSTMENT RDTMF and CDTMF fix the DTMF level on line and the cutoff frequency for DTMF filter. The value of CDTMF and RDTMF are chosen such that : 1 = 4kHz
2RDTMFx CDTMF
Pin 14 VCC/SPEECH CIRCUIT SUPPLY Supply for the speech circuit. A 100F capacitor is connected to this pin to provide DC decoupling. Recommendedvalue is 100F/16V. Too large capacitor would have longer turn on time. Figure 39
VCC C7 100 F 25V
14
AN849-39.EPS
where 4kHz is the low pass frequency for the DTMF signal. Pin 23 VDD DIALER POSITIVE SUPPLY Supply for the dialling circuit. It is supplied from VCC via a diode. The zenerdiode D6 protects the dialling circuit in on-hook mode. The capacitor C5 and the resistor R5 are required for memory retention during on-hook. Pin 24 TRA NS MI T MUTE AND TO NE INDICATOR SELECTION By connecting this pin to GND will disable the transmit amplifier of the speech circuit. By connectingthis pin to any row will disable the transmit mute function and the Tone indictor mode is selected. The table below summarized the logic of MU/MFI functions :
MU/MFI Open GND Row Transmit Muting Active Muted Not Available LED Lighted Dial Indicator Lighted Dial Indicator Tone Mode Indicator
Pin 15 LED OUTPUT PIN When the MU/MFI pin is connected to either VDD or GND, the LED is used for keyboard illumination or off-hook indication. When the MU/MFI pin is connected to any row, it functions as a Tone mode indicator. For line current up to 20mA, the maximum LED current is 19mA. For line current more than 20mA, the LED current is 20mA (typical).
Pin 25 Pin 26 Pin 27 Pin 28
Row 4 of Row 3 of Row 2 of Row 1 of
keypad keypad keypad keypad
25/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VII - APPLICATION FOR USA VII.1 - Schematic Diagram Figure 40 : Application Circuit for EIA Standard
R3 10 TIP D1 D5 TPA270 R4 10 RING D2 4 x 1N4004 D3 R5 10M C1 1F LS1240A LN GND CAP
1 2 3 8 7
D4
HS1A
Q1 2SA1013 R6 100k D7 10V R9 3.3k Q2 BF393 C4 10nF
R7 200k R25 220k D12 1N4148 + D6 5.1V R8 10k
R1 2.2k LN CAP + C2 10F
6 NC 5
C3 RES 4 100nF R2 14k
BUZ Buzzer
C5 470F
1 2 3
C1 C2 C3 C4 OSC
L3916A
R1 28 R2 27 R3 26 R4 25 R5 24
1 4 7
2 5 8 0
3 6 #
FLASH PGM
9 LND/PSE MEM
X1 3.579MHz SW2 R10 100k
4 5 6 7 8
E1 E2 E3
*
PULSE VDD 23 MODE/PT HKS GND MIC+ 21 C DTMF 8.2nF C10 470nF MIC- 20 CGTX 100pF C12 100nF C14 4.7nF R21 1.2k C11 R13 100nF 220 C13 4.7nF GDTMF 22 RDT MF 4.7k C9 0.47F + R20 1.2k
HS1B
9
C6 4.7F
+
R GRX 62k
10 RXOUT 11 GRX
CGRX 100pF GTX 19
12 RXIN
RGTX 56k C15 4.7F +
REG 18 LN 17 D11 1N4148 R15 390 R18 3.9k R19 130k
R11 3.6k D8 BAT42 C7 100F +
13 IREF 14 VCC
ILINE 16 LED 15 R14 20 R16 50
VII.2 - Brief Description A complete telephoneapplication circuit comprising only two chips, L3914A/16A(Speech and 14 memories dialler) or ST3917A (Speech and dialler with LNR only) and a ringer IC. The application circuit has been optimized for EIA-standard based on L3916A. All measurement results are enclosed as follows.
26/35
AN849-40.EPS
R12 470
C8 100nF
R17 300 D9 LED
C16 220nF
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VII - APPLICATION FOR USA (continued) VII.3 - Measurements Results (L3916A) Figure 41 : DC Characteristics
14
EIA
Figure 42 : Return Loss
20
5km
12 TIP & RING (V) 10 8 6 4 2
AN849-41.EPS
Frequency (Hz)
T&R
15
0km
VLN
10
EIA
EIA
5
AN849-42.EPS
0 0 20 40 60 80 Line Curre nt (mA) 100 120
0 100
1000 Re turn Los s (dB)
Figure 43 : Transmit Dynamic
1.6
R GTX = 56k
Figure 44 : Transmit Distortion
20 Transmit Distortion (%)
ILN = 100mA ILN = 20mA fREQ = 1kHz, RGTX = 56k
1.4 1.2 VLN (Vrms) 1.0 0.8 0.6 0.4
AN849-43.EPS
15
10
5
AN849-44.EPS
0.2 0 0 20
fREQ = 1kHz, THD = 2% 40 60 80 Line Curre nt (mA) 100 120
0 0 0.4 0.8 1.2 VLN (VRMS) 1.6 2.0
Figure 45 : Receive Dynamic
0.5
Re = 300 Re = 150
Figure 46 : Receive Distortion with Re = 150
14 Receive Distortion (%) 12 10 8 6 4 2 0 0 0.1 0.2 0.3 0.4 Re ce ive Outp ut (VRMS) 0.5 0.6
ILN = 20mA
AN849-46.EPS
Receive Output (VRMS)
0.4
fREQ = 1kHz RGRX = 62k, Re = 150
0.3 0.2 0.1 0 0 20 40 60 80 Line Curre nt (mA) 100 120
AN849-45.EPS
ILN = 100mA
27/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VII - APPLICATION FOR USA (continued) VII.3 - Measurements Results (L3916A) (continued) Figure 47 : Receive Distortion with Re = 300
14 Receive Distortion (%) 12 10 fREQ = 1kHz RGRX = 62k, Re = 300
Figure 48 : DTMF Output Level
0 -2 VLN (dBm)
low Freq.
8 6 4 2 0 0 0.1
ILN = 100mA
-4 -6 -8
High Freq.
ILN = 20mA
AN849-47.EPS
0.2 0.3 0.4 Re ce ive Output (VRMS )
0.5
0.6
-10 0 10 20 30 40 50 60 70 80 90 100 110 120 Line Curre nt (mA)
Figure 49 : Transmit Frequency Response at 0 & 4.5km
Measuring Object : Level Range : Impedance Range : 120 60 dB Measuring Condition : V Zero Level (Fundamental) : dB X Axis Speed : Zero Level (Harmonic) : dB Y Axis Speed : W M mm/sec mm/sec 30 12
100 50
25
10
80
40
0km - 45.8
20
8
60
30 4.5km - 42.8
15
6
40
20
10
4
20
10
5
2
0
0 20 102 103
FREQUENCY IN CYCLES PER SECOND
104
0 20000
0
28/35
AN849-49.EPS
AN849-48.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VII - APPLICATION FOR USA (continued) VII.3 - Measurements Results (L3916A) (continued) Figure 50 : Receive Frequency Response at 0 & 4.5km
Measuring Object : Level Range : Impedance Range : 120 60 dB Measuring Condition : V Zero Level (Fundamental) : dB X Axis Speed : Zero Level (Harmonic) : dB Y Axis Speed : W M mm/sec mm/sec 30 12
100 50
25
10
80
40 0km - 48.1
20
8
60
30
15
6
40
20
4.5km - 51.4
10
4
20
10
5
2
0
0 20 102 103
FREQUENCY IN CYCLES PER SECOND
104
0 20000
0
Figure 51 : Sidetone Frequency Response at 0 & 4.5km
Measuring Object : Level Range : Impedance Range : 120 60 dB Measuring Condition : V Zero Level (Fundamental) : dB X Axis Speed : Zero Level (Harmonic) : dB Y Axis Speed : W M mm/sec mm/sec 30 12
100 50
25
10
80 40
0km - 9.8
20
8
60 30
15
6
40 20
10
4
20 10 4.5km - 9
5
2
0
0 20 102 103
FREQUENCY IN CYCLES PER SECOND
104
0 20000
0
29/35
AN849-51.EPS
AN849-50.EPS
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VIII - APPENDIX VIII.1 - Appendix A - Demoboard for Multi Country Application by Jumper Selection Figure 52 : Demoboard Schematic
R3 10 TIP D1 D5 TPA270 R4 10 RING D2 4 x 1N4004 D3 R5 10M C1 1F
LS1240A
JP1 D4 HS1A JP2 Q1 2SA1013 R6 100k D10 120V R7 200k R8 10k D12 1N4148 + D6 5.1V
L3914A L3916A ST3917A/B
See Note 1 D7 10V C4 10nF
RVDD 1k DVDD 1N4148 CVDD 22F
R25 220k
R9 3.3k
RP* 100k JP3 JP4 JP5 JP6 JP12 JP7 JP15 VDD
R1 2.2k LN CAP + C2 10F
Q2 BF393
LN GND CAP
1 2 3
8 7
6 NC 5
C3 RES 4 100nF R2 14k
BUZ Buzzer
C5 470F
1 2
C1 C2 C3 C4 OSC
R1 28 R2 27 R3 26 R4 25 R5 24
1 4 7
2 5 8 0
3 6
FLASH PGM\SS*
JP10 JP9 JP8
CP* 4.7F
+ X1 3.579MHz
3 4 5
9 LND/PSE\PSE* # HOLD\LND* MEM\MUTE*
* E1 E2 E3
RDTMF 3.3k +
Important Notes : JP1 : L3914Aonly JP2 : L3916A/ST 3917A/B only JP3 : Flashduration : 100ms for ST3917A/B only JP4 : Flashduration : 300ms for ST3917A/B only JP5 : Flashduration : 100ms for ST3917A/B only JP6 : Flashduration : 600ms for ST3917A/B only JP7 : For L3914A/16 only with JP3, 4, 5, 6 A and 8 unused JP8 : For ST3917A/B only JP9 : Mute switch and lighted dial indicator for ST3917A/Bonly JP10 : Tone dialing indicatorfor ST3917A/Bonly JP11 : MIC+ supply from VCC JP12 : Internal VDD ; JP15 unused JP13 : For real load only JP14 : For real load only JP15 : ExternalV DD ; JP12 unused and JP11 must be used
6
Buzzer SW2 R10 100k R24 2k
7 8
PULSE VDD 23 GDTMF 22 MODE/PT HKS GND MIC+ 21 C10 470nF MIC- 20 CGTX 100pF RGTX 56k GTX 19 REG 18 LN 17 RB R15 390
Z14
C9 0.47F R20 1.2k
CDTMF 8.2nF C11 R13 100nF 220 C13 4.7nF JP11
HS1B
9
C6 4.7F
+
RGRX 62k
10 RXOUT 11 GRX
C12 100nF + C15 4.7F
CGRX 100pF
C14 4.7nF R21 1.2k
12 RXIN
R11 3.6k
Notes :
D11 1N4148 RA R18 3.9k
ZB
D8 BAT42 C7 100F + R12 470
13 IREF 14 VCC
ILINE 16 LED 15 R19 130k
1. If CVDD, DVDD and RVDD are used, JP11 and D8 should be removed and R12 = 820 2. If JP11 and D8 are used, R12 = 470 and CVDD, DVDD and RVDD should be removed 3. Z12 = R12 + C17//R22 for complex load only with JP13 unused 4. Z14 = R14 + C18//R23 for complex load only with JP14 unused
R14 20 C8 100nF JP14 R23 C18 D9 LED +
R16 50
R22 JP13 C17
R17 300
C16 220nF
AN849-52.EPS
5. CP and RP are used for M/B ratio : 33/67 only \SS*, \PSE* and \LND\Mute* are for L3917 only
30/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VIII - APPENDIX (continued) VIII.2 - Appendix B - PCB Layout Figure 53 : PCB Layout
31/35
AN849-53.EPS
R6 HOOKSW SW?? H/S C D E C6 REC R22 R12 C6
R3 R9 D3 C2 BUZZER R6 RP Q1 D7 B C D Q2 J3 C17 R2 IC1 C3 R17 R19 R16 C16 R15 C18 LED 6 PGM R21 C- C12 CGIX C+ C11 J1 RVDD R13 J12 J15 C9 # CDTMF RDTMF C5 CVDD E3 D6 C1 R4 C2 R3 R2 -VE +VE R4 R4 J4 J3 J6 J7 J5 MEM DVDD J9 J10 IC2 L3914 X1 BUZZER R10 HOLD D8 C10 RGRX CGRX C11 C13 9 R20 LND/ PSE RGIX C8 J14 R11 CP C15 R18 R14 R23 C7 3 R3 F C4 REC GND
D4
R4
D10
TIP RING
D5
D1
D2
R7
C3 R1
R1 R5
AN849-54.EPS
?? C4 C2 C1
32/35
J1 J2 SGS-THOMSON Microelectronics L3914/16/17 DEMO-BOARD KEYPAD J8
C1
R1
VIII - APPENDIX (continued)
T
Figure 54 : Component Layout
R
TIP
1
2
VIII.3 - Appendix C - Component Layout
RING
VLINE
VDD
4
5
GND
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
7
8
*
0
E1
E2
TONE PULSE
SW2
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VIII - APPENDIX (continued) VIII.4 - Appendix D - Component Lists
Designation RINGER R1 R2 C1 C2 C3 LINE INTERFACE Q1 Q2 R3 R4 R6 R7 R8 R9 D1-D4 D5 D10 SPEECH CIRCUIT R5 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 RGTX RGRX RDTMF RP RVDD RA RB C4 C5 C6 10M 100k 3.6k 470 220 20 390 50 300 3.9k 130k 1.2k 1.2k Optional Optional Optional 220k 56k 62k 4.7k 100k optional 1k Optional Optional Optional 10nF 470F/10V 4.7F/6V Memory Supply in On-hook Mode Mode Input Pull-up Internal Bias Current Impedance Network Transmit Response Curve Adjustment DC Slope Sidetone Bridge Sidetone Network Sidetone Network Sidetone Bridge and Receive Interface Sidetone Bridge and Receive Interface Electret mic Power Supply Electret mic Power Supply Complex Impedance Network Tx Response Curve Compensation if Complex Impedance used Isolation for Mode Pin R24 = 2k if External Buzzer is Used elseR24 = Short Circuit VDD Dialler Power Supply in Pulse Mode Transmit and DTMF Gain Adjustment Receive Gain Adjustment DTMF Output Level Adjustment Make/Break Ratio Adjustment - L3914A/16A Only Separate Microelectret Power Supply Line DC Level Adjustment, to reduce it Line DC Level Adjustment, to increase it RFI Protection VDD Dialler Power Supply Decoupling Output Receive Path Decoupling 2SA1013 BF393 10 10 100k 200k 10k 3.3k 1N4004 TPA270 120V ZENER Pulse Interface Pulse Interface Line Current Protection Line Current Protection Pulse Interface Pulse Interface Pulse Output Current Limiter Pulse Interface Rectifier Bridge Line Protection Line Protection 2.2k 14k 1F/250V 10F/35V 100nF Impedance in Ring Mode Output Frequency Control Impedance in Ring Mode & AC Decoupling Rectifier Cap Sweep Rate Control Value Comments
33/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VIII - APPENDIX (continued) VIII.4 - Appendix D - Component Lists (continued)
Designation C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 CGTX CGRX CDTMF CP CVDD D6 D7 D8 D9 D11 D12 DVDD X1 JP1 JP2 JP3 JP4 JP5 JP6 JP7 JP8 JP9 JP10 JP11 JP12 JP13 JP14 JP15
Notes : 1. 2. 3. 4. 5. 6.
Value 100F/16V 100nF 0.47F/16V 470nF 100nF 100nF 4.7nF 4.7nF 4.7F/16V 220nF Optional Optional 100pF 100pF 8.2nF 4.7F/6V Optional 22F/16V Optional 5.1VZener 10V Zener BAT42 LED 1N4148 1N4148 1N4148-Optional 3.5795MHz
Comments VCC Speech Power Supply Decoupling Input Receive Path Decoupling DTMF Input Decoupling Transmit Response Curve Adjustment Transmit Response Curve Adjustment Transmit Response Curve Adjustment RFI Protection RFI Protection Internal Regulator Decoupling Sidetone Network Complex Impedance Network Tx Response Curve Compensation if Complex Impedance used Transmit Output Decoupling Receive Output Decoupling DTMF Filter Adjustment Make/break Ratio Adjustment - L3914A/16A Only Separate Microelectret Power Supply Decoupling VDD Protection in On-hook Mode L3914A/16A/ST3917A/B Protection VCC/VDD Isolation in Pulse Mode Off-hook Indicator or Tone Mode Dialing Indicator for ST3917A/B Transient Protection VDD Dialler Power Supply in Pulse Mode VCC/VDD Isolation in Pulse Mode Ceramic Resonator For L3914A Only For L3916A/ST3917A/B Flash Duration of 100ms with Softswitch Inhibition for ST3917A/B Only Flash Duration of 300ms for ST3917A/B Only Flash Duration of 100ms for ST3917A/B Only Flash Duration of 600ms for ST3917A/B Only For L3914A/16A Only with JP3, 4, 5, 6 & 8 Removed For ST3917A/B Only Transmit Mute and Lighted Dial Indicator for ST3917A/B Only.If JP9 is Connected, JP10 should be Removed and Vice Versa. Tone Mode Dialling Indicator for ST3917A/B Only Electret Mic Power Supply from VCC VDD Dialer Power Supply from VCC with JP15 Removed For Real Load Only For Real Load Only External V DD Dialer Power Supply with JP12 Removed
SPEECH CIRCUIT (continued)
JUMPER CONNECTION
If CVDD, DVDD and RVDD are used, D8 and JP11 should be removed and R12 should be 820. If D8 and JP11 are used, CVDD, DVDD and RVDD should be removed and R12 should be 470. For complex load, Z12 = R12 + R22//C17 with JP13 NOT connected. For complex load, Z14 = R14 + R23//C18 with JP14 NOT connected. For real load, Z12 = R12 and Z14 = R14 with JP13 and JP14 connected. CP and RP are only used for Make/Break ratio of 33/67 only.
34/35
SPEECH AND DIALLER L3914A/16A AND ST3917A/B
VIII - APPENDIX (continued) VIII.5 - Appendix E - Typical Application Circuit with Bridge Configuration Figure 55 : Typical Applicaiton Circuit with Bridge Configuration
R3 10 TIP D1 D5 TPA270 R4 10 RING D2 4 x 1N4004 D3 D4 HS1A JP1 JP2 Q1 2SA1013 R6 100k D10 120V R7 200k R8 10k D12 1N4148 + D6 5.1V L3914A L3916A ST3917A/B JP7 R9 3.3k RP* 100k JP3 Q2 BF393 JP4 JP5 JP6 VDD JP15 R1 28 R2 27 R3 26 R4 25 R5 24 JP10 JP9 JP8 VDD 23 R24 2k
7 8
See Note 1 D7 10V C4 10nF
RVDD 1k DVDD 1N4148 CVDD 22F
R5 10M C1 1F LS1240A LN GND CAP
1 2 3 8 7
R25 220k
R1 2.2k LN CAP + C2 10F
JP12
6 NC 5
C3 RES 4 100nF R2 14k
BUZ Buzzer
C5 470F
1 2 3
C1 C2 C3 C4 OSC
1 4 7
2 5 8
3 6
FLASH PGM\SS* HOLD\LND* MEM\MUTE*
CP* 4.7F
+ X1 3.579MHz
4 5
9 LND/PSE\PSE*
*0# E1 E2 E3
+
Important Notes : JP1 : L3914A only JP2 : L3916A/ST3917A/B only JP3 : Flash duration : 100ms for ST3917A/B only JP4 : Flash duration : 300ms for ST3917A/B only JP5 : Flash duration : 100ms for ST3917A/B only JP6 : Flash duration : 600ms for ST3917A/B only JP7 : For L3914A/16A only with JP3, 4, 5, 6 and 8 unused JP8 : For ST3917A/B only JP9 : Mute switch and lighted dial indicator for ST3917A/B only JP10 : Tone dialing indicator for ST3917A/B only JP11 : MIC+ supply from VCC JP12 : Internal VDD ; JP15 unused JP13 : For real load only JP14 : For real load only JP15 : External VDD ; JP12 unused and JP11 must be used D8 BAT42 Notes : 1. If CVDD, DVDD and RVDD are used, JP11 and D8 should be removed and R12 = 820 2. If JP11 and D8 are used, R12 = 470 and CVDD, DVDD and RVDD should be removed 3. Z12 = R12 + C17//R22 for complex load only with JP13 unused 4. Z14 = R14 + C18//R23 for complex load only with JP14 unused 5. CP and RP are used for M/B ratio : 33/67 only \SS*, \PSE* and \LND\MUTE* are for L3917 only C7 100F +
Buzzer SW2 R10 100k
6
PULSE RDTMF 3.3k C9 0.47F
GDTMF 22 MODE/PT HKS GND MIC+ 21 C10 470nF MIC- 20 CGTX 100pF RGTX 56k GTX 19
12 RXIN
R20 1.2k
CDTMF 8.2nF C11 R13 100nF 220 JP11 C13 4.7nF
HS1B
9
C6 4.7F +
RGRX 62k
10 RXOUT 11 GRX
C12 100nF C15 4.7F + D11 1N4148 RB RA
CGRX 100pF REG 18 LN 17
13 IREF 14 VCC
C14 4.7nF R21 1.2k
R11 3.6k
ILINE 16 LED 15 R15 390 Z14 D9 LED JP14 R14 20 R23 C18 + C16 1nF ZB R17 39k R16 22k
R12 470 C8 100nF
R22 JP13 C17
Bridge Configuration
AN849-55.EPS
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without noti ce. This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics. (c) 1996 SGS-THOMSON Microelectronics - All Rights Reserved Purchase of I2C Components of SGS-THOMSON Microelectronics, conveys a license under the Philips I2C Patent. Rights to use these components in a I2C system, is granted provided that the system confo rms to the I2C Standard Specifications as defined by Philips. SGS-THOMSON Microelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco The Netherlands - Singapore - Spain - Sweden - Switzerland - Taiwan - Thailand - United Kingdom - U.S.A.
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