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(R)
SP334
Programmable RS-232/RS-485 Transceiver
s +5V Only Operation s Software Programmable RS-232 or RS485 Selection s Three RS-232 Drivers and Five Receivers in RS-232 Mode s Two RS-485 Full-Duplex Transceivers in RS-485 Mode s Full Differential Driver Tri-State (Hi-Z) Control s Receiver Output Tri-State Control
DESCRIPTION... The SP334 is a programmable RS-232 and/or RS-485 transceiver IC. The SP334 contains three drivers and five receivers when selected in RS-232 mode; and two drivers and two receivers when selected in RS-485 mode. The RS-232 transceivers can typically operate at 230kbps while adhering to the RS-232 specifications. The RS-485 transceivers can operate up to 10Mbps while adhering to the RS-485 specifications. The RS-485 drivers can be disabled (High-Z output) by the TXEN enable pin. The RS-232 and RS-485 receiver outputs can be disabled by the RXEN enable pin.
TI3 TXEN(n/c) TX4(n/c) TX3 VCC TX1 TX2 GND C1+ V+ C2+ C1- C2- V-
1 2 3 4 5 6 7 8 9 10 11 12 13 14
SP334
28 27 26 25 24 23 22 21 20 19 18 17 16 15
TI2 TI1 RXEN RS232/RS485 RI5 RX5 RX4 RX3 RX2 RX1 RI4 RI3 RI2 RI1
(in RS-232 mode)
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. VCC...........................................................................+7V Storage Temperature..........................-65C to +150C Power Dissipation 28-pin Plastic DIP...........................1000mW 28-pin Plastic SOIC.......................1000mW Package Derating: 28-pin Plastic DIP oJA....................................................40 C/W 28-pin Plastic SOIC oJA....................................................40 C/W
SPECIFICATIONS
Typically 25C @ Vcc = +5V unless otherwise noted.
MIN. LOGIC INPUTS VIL VIH LOGIC OUTPUTS VOL VOH Output Tri-state Leakage RS-232 DRIVER DC Characteristics HIGH Level Output LOW Level Output Open Circuit Voltage Short Circuit Current Power Off Impedance AC Characteristics Slew Rate Transition Time Maximum Data Rate Propagation Delay tPHL tPLH RS-232 RECEIVER DC Characteristics HIGH Threshold LOW Threshold Receiver Open Circuit Bias Input Impedance AC Characteristics Maximum Data Rate Propagation Delay tPHL tPLH RS-485 DRIVER DC Characteristics Open Circuit Voltage Differential Output 120
TYP.
MAX. 0.8
UNITS Volts Volts Volts Volts A
CONDITIONS
2.0 0.4 2.4 10
IOUT= -3.2mA IOUT= 1.0mA 0.4V VOUT +2.4V
+5.0 -15.0 -15 300
+15 -5.0 +15 100
Volts Volts Volts mA V/s s kbps
RL=3k, VIN=0.8V RL=3k, VIN=2.0V VOUT = 0V Vcc = 0V, Vout = 2.0V RL=3k, CL= 50pF VCC = +5.0V, TA @ +25C RL=3k, CL=2500pF ; between 3V, TA @ +25C RL=3k, CL=2500pF Measured from 1.5V of VIN to 50% of VOUT; RL=3k
30 1.56 235 2 2 8 8
s s
0.8 3 120
1.7 1.2 5 235 0.25 0.25
3.0 +2.0 7
Volts Volts Volts k kbps
VIN = +15V to -15V
1 1
s s
Measured from 50% of VIN to 1.5V of VOUT.
1.5
6.0 5.0
Volts Volts
RL=54, CL=50pF
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
2
SPECIFICATIONS
Typically 25C @ Vcc = +5V unless otherwise noted.
MIN. RS-485 DRIVER Balance Common-Mode Output Output Current Short Circuit Current AC Characteristics Maximum Data Rate Output Transition Time Propagation Delay tPHL tPLH Driver Output Skew RS-485 RECEIVER DC Characteristics Inputs Common Mode Range Receiver Sensitivity Input Impedance AC Characteristics Maximum Data Rate Propagation Delay tPHL tPLH Differential Receiver Skew
TYP.
MAX. 0.2 3.0
UNITS Volts Volts mA mA Mbps ns
CONDITIONS |VT| - |VT| RL=54 Terminated in -7V to +10V RL=54 Rise/fall time, 10%-90% See Figures 3A & 5 RDIFF=54, CL1=CL2=100pF RDIFF=54, CL1=CL2=100pF per figure 5, tSKEW = |tDPLH - tDPHL|
28.0
250
10 30 80 80 5 120 120 20
ns ns ns
-7.0 12 10 130 130 10 15
+12.0 0.2
Volts Volts k Mbps
-7V VCM +12V -7V VCM +12V
200 200 20
ns ns ns
See Figures 3A & 7 RDIFF=54, CL1=CL2=100pF RDIFF=54, CL1=CL2=100pF tSKEW= | tPLH - tPHL |; RDIFF=54, CL1=CL2=100pF, see Figure 8
ENABLE TIMING RS-485 Driver Enable Time Enable to Low Enable to High Disable Time Disable From Low Disable From High RS-485 Receiver Enable Time Enable to Low Enable to High Disable Time Disable From Low Disable From High POWER REQUIREMENTS Supply Voltage VCC Supply Current ICC No Load (Tx Disabled) No Load (RS-232 Mode) No Load (RS-485 Mode) ENVIRONMENTAL Operating Temperature Commercial (..C..) Industrial (..E..) Storage Temperature
100 100 100 100 100 100 100 100
150 150 120 120 150 150 120 120
ns ns ns ns ns ns ns ns
See Figures 4 & 6 CL=15pF, S1 Closed CL=15pF, S2 Closed See Figures 4 & 6 CL=15pF, S1 Closed CL=15pF, S2 Closed See Figures 2 & 8 CL=15pF, S1 Closed CL=15pF, S2 Closed See Figures 2 & 8 CL=15pF, S1 Closed CL=15pF, S2 Closed
+4.75 12 20 15
+5.25 20 50 50
Volts mA mA mA TXEN = 0V RS232/RS485 = 0V RS232/RS485 = +5V
0 -40 -65
+70 +85 +150
C C C
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
3
RECEIVER INPUT GRAPH
RS-485 RECEIVER +1.0mA
-7V
-3V +6V +12V
-0.6mA
1 Unit Load Maximum Input Current versus Voltage
TEST CIRCUITS
A R VOD R B
Figure 1. Driver DC Test Load Circuit Figure 2. Receiver Timing Test Load Circuit
Receiver Output CRL
Test Point S1 1K S2
1K VCC
VOC
CL1 DI A B CL2 RL
A RO B 15pF
Output Under Test
500 CL
S1
VCC
S2
Figure 3a. Driver/Receiver Timing Test Circuit
Figure 4. Driver Timing Test Load #2 Circuit
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
4
SWITCHING WAVEFORMS
f 1MHz; tR 10ns; tF 10ns 1.5V 0V B DRIVER OUTPUT A tDPLH tDPHL VO 1/2VO tPLH tPHL 1/2VO 1.5V
+3V DRIVER INPUT
DIFFERENTIAL VO+ OUTPUT 0V VA - VB VO- tSKEW = |tDPLH - tDPHL|
Figure 5. Driver Propagation Delays
tR
tF
+3V TxEN A, B VOL VOH A, B 0V 0V 5V
f = 1MHz; tR 10ns; tF 10ns 1.5V tZL 2.3V Output normally LOW 1.5V tLZ 0.5V 0.5V tHZ
2.3V tZH
Output normally HIGH
Figure 6. Driver Enable and Disable Times
V0D2+ A-B V0D2-
f = 1MHz; tR 10ns; tF 10ns 0V INPUT 0V
VOH RECEIVER OUT VOL
1.5V tPHL
OUTPUT tPLH
1.5V
Figure 7. Receiver Propagation Delays
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
5
+3V RXEN 0V 1.5V f = 1MHz; tR 10ns; tF 10ns tZL 1.5V Output normally LOW 1.5V tLZ 0.5V 0.5V tHZ
5V RECEIVER OUT VIL VIH RECEIVER OUT 0V tSKEW = |tPHL - tPLH|
Figure 8. Receiver Enable and Disable Times
1.5V tZH
Output normally HIGH
TTL Input
Driver Output
Figure 9. Typical RS-232 Driver Output
Figure 10. Typical RS-485 Driver Output
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
6
TI3 TXEN(n/c) TX4(n/c) TX3 VCC TX1 TX2 GND C1+ V+ C2+ C1- C2- V-
1 2 3 4 5 6 7 8 9 10 11 12 13 14
SP334
28 27 26 25 24 23 22 21 20 19 18 17 16 15
TI2 TI1 RXEN RS232/RS485 RI5 RX5 RX4 RX3 RX2 RX1 RI4 RI3 RI2 RI1
(in RS-232 mode)
Figure 11. SP334 Pinout
+5V
+5V
5 9 0.1F VCC 12 C111 C2+ 13 C225 RS232/RS485
Vcc
400K
C1+
0.1F V+ V- 10 14 0.1F
5 9 0.1F 12 11 0.1F 13 2 C1+ C1C2+ C2TXEN
Vcc
400K
0.1F V+ V- 10 14 0.1F
SP334
VCC
0.1F 0V
SP334
TTL/CMOS
27 TI1
Vcc
400K
T1
TX1 6 RS-232 TX2 7 TX3 4 3 R1 R2 RI1
5K
TTL/CMOS
TX2 7 RS-485 T1 TX1 6 RS-485 RS-485 RS-485 RS-485 RS-485 RS-485 RS-485
28 TI2 TTL/CMOS TTL/CMOS N/C TTL/CMOS TTL/CMOS 1 2 TI3
Vcc
400K
T2 T3
RS-232
TTL/CMOS
27 TI1
Vcc
400K
RS-232 N/C RS-232
TX4 3 T3 TX3 4 RI1 15
TTL/CMOS
1 TI3
19 RX1 20 RX2
15 16
RI2
5K
RS-232
TTL/CMOS
19 RX1
R1
15K
RI2 16
15K
TTL/CMOS
21 RX3
R3 R4
RI3
5K
17
RS-232
RI4 18 TTL/CMOS TTL/CMOS 21 RX3 R3 26 RXEN 8 GND RS232/RS485
15K
TTL/CMOS TTL/CMOS
RI4
5K
22 RX4
18 24 26
RS-232
RI3 17
15K
23 RX5 GND
R5
RI5
5K
RS-232 TTL/CMOS
25
+5V
8
RXEN
Figure 12. Typical Operating Circuit
SP334DS/10 Programmable RS-232/RS-485 Transceiver (c) Copyright 2000 Sipex Corporation
7
THEORY OF OPERATION The SP334 is made up of four separate circuit blocks -- the charge pump, drivers, receivers, and decoder. Each of these circuit blocks is described in more detail below. Charge-Pump The charge pump is a Sipex-patented design (U.S. 5,306,954) and uses a unique approach compared to older less-efficient designs. The charge pump still requires four external capacitors, but uses a four-phase voltage shifting technique to attain symmetrical 10V power supplies. Figure 17(a) shows the waveform found on the positive side of capcitor C2, and figure 17(b) shows the negative side of capcitor C2. There is a free-running oscillator that controls the four phases of the voltage shifting. A description of each phase follows. Phase 1 -- VSS charge storage --During this phase of the clock cycle, the positive side of capacitors C1 and C2 are initially charged to +5V. Cl+ is then switched to ground and charge on C1- is transferred to C2-. Since C2+ is connected to +5V, the voltage potential across capacitor C2 is now 10V. Phase 2 -- VSS transfer -- Phase two of the clock connects the negative terminal of C2 to the VSS storage capacitor and the positive terminal of C2 to ground, and transfers the generated -l0V to C3. Simultaneously, the positive side of capacitor C 1 is switched to +5V and the negative side is connected to ground. Phase 3 -- VDD charge storage -- The third phase of the clock is identical to the first phase -- the charge transferred in C1 produces -5V in the negative terminal of C1, which is applied to the negative side of capacitor C2. Since C2+ is at +5V, the voltage potential across C2 is l0V. Phase 4 -- VDD transfer -- The fourth phase of the clock connects the negative terminal of C2 to ground and transfers the generated l0V across C2 to C4, the VDD storage capacitor. Again, simultaneously with this, the positive side of
capacitor C1 is switched to +5V and the negative side is connected to ground, and the cycle begins again. Since both V+ and V- are separately generated from VCC in a no-load condition, V+ and V- will be symmetrical. Older charge pump approaches that generate V- from V+ will show a decrease in the magnitude of V- compared to V+ due to the inherent inefficiencies in the design. The clock rate for the charge pump typically operates at 15kHz. The external capacitors must be a minimum of 0.1F with a 16V breakdown rating. External Power Supplies For applications that do not require +5V only, external supplies can be applied at the V+ and V- pins. The value of the external supply voltages must be no greater than l0V. The current drain for the 10V supplies is used for RS232. For the RS-232 driver the current requirement will be 3.5mA per driver. The external power supplies should provide a power supply sequence of :+l0V, then +5V, followed by -l0V. Drivers The SP334 has three independent RS-232 singleended drivers and two differential RS-485 drivers. Control for the mode selection is done by the RS-232/RS-485 select pin. The drivers are pre-arranged such that for each mode of
VCC = +5V
+5V C1
+ -
C4
+ - +
C2
+ - -
VDD Storage Capacitor VSS Storage Capacitor
-5V
-5V
C3
Figure 13. Charge Pump Phase 1.
VCC = +5V
C4
+ - +
C1
+ -
C2
+ - -
VDD Storage Capacitor VSS Storage Capacitor
-10V
C3
Figure 14a. Charge Pump Phase 2.
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
8
VCC = +5V
+5V C1
+ -
C4
+ - +
5V with a full load of 3k and 2500pF applied as specified. These drivers can also operate at least 120kbps.
VDD Storage Capacitor VSS Storage Capacitor
C2
+ - -
-5V
-5V
C3
Figure 15. Charge Pump Phase 3.
VCC = +5V
+10V C1
+ -
C4
+ - +
C2
+ - -
VDD Storage Capacitor VSS Storage Capacitor
When programmed to RS-485 mode, the differential RS-485 drivers produce complaint RS-485 signals. Each RS-485 driver outputs a unipolar signal on each output pin with a magnitude of at least 1.5V while loaded with a worst case of 54 between the driver's two output pins. The signal levels and drive capability of the RS-485 drivers allow the drivers to also comply with RS-422 levels. The transmission rate for the differential drivers is 10Mbps. Receivers The SP334 has five single-ended receivers when programmed for RS-232 mode and two differential receivers when programmed for RS-485 mode. Control for the mode selection is done by the same select pin as the drivers. As the operating mode of the receivers is changed, the electrical characteristics will change to support the requirements of the appropriate serial standard. Unused receiver inputs can be left floating without causing oscillation. To ensure a desired state of the receiver output, a pull-up resistor of 100k to +5V should be connected to the inverting input for a logic low, or the non-inverting input for a logic high. For single-ended receivers, a pull-down resistor to ground of 5k is internally connected, which will ensure a logic high output.
C3
Figure 16. Charge Pump Phase 4.
operation the relative position and functionality of the drivers are set up to accommodate the selected interface mode. As the mode of the drivers is changed, the electrical characteristics will change to support the requirements of clock, data, and control line signal levels. Unused driver inputs can be left floating; however, to ensure a desired state with no input signal, pull-up resistors to +5V or pull-down resistors to ground are suggested. Since the driver inputs are both TTL or CMOS compatible, any value resistor less than 100k will suffice. When in RS-232 mode, the single-ended RS232 drivers produce compliant RS-232E and ITU V.28 signals. Each of the three drivers output single-ended bipolar signals in excess of
+10V a) C2+ GND
GND b) C2-10V
Figure 17. Charge Pump Waveforms
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
9
The RS-232 receiver has a single-ended input with a threshold of 0.8V to 2.4V. The RS-232 receiver has an operating voltage range of 15V and can receive signals up to 120kbps. RS-232 receivers are used in RS-232 mode for all signal types include data, clock, and control lines of the RS-232 serial port. The differential RS-485 receiver has an input impedance of 15k and a differential threshold of 200mV. Since the characteristics of an RS422 receiver are actually subsets of RS485, the receivers for RS-422 requirements are identical to the RS-485 receivers. All of the differential receivers can receive data up to 10Mbps. Enable Pins The SP334 drivers can be enabled by use of the TXEN pin. A logic HIGH will enable the driver outputs and a logic LOW will tri-state the
+5V
outputs. The drivers can only be tri-stated in RS-485 mode. The drivers are always active in RS-232 mode. The receiver outputs can also be tri-stated by use of the RXEN pin. A logic LOW will enable the receiver outputs and a logic HIGH will tri-state the outputs. The receiver tri-state capability is offered for both RS-232 and RS-485 modes. The input impedance if the receivers during tri-state is at least 12k. Applications The SP334 allows the user flexibility in having a RS-232 or RS-485 serial port without using two different discrete active ICs. Figure 18 shows a connection to a standard DB-9 RS-232 connector. In RS-485 mode, the SP334 is a full duplex transceiver, however, a half duplex configuration can be made by connecting the driver outputs to the receiver inputs.
5 9 0.1F VCC 12 C111 C2+ 13 C225 RS232/RS485
Vcc
400K
C1+
0.1F V+ V- 10 14 0.1F
SP334
0.1F 0V
TxD
27 TI1
Vcc
400K
T1
TX1 6
RTS DTR
28 TI2
Vcc
400K
T2 T3
TX2 7 TX3 4
1
DCD DSR RxD
1 TI3
6
RxD CTS
19 RX1 20 RX2
R1 R2
RI1
5K
15 16
RI2
5K
DSR
21 RX3
22 RX4
R3 R4
RI3
5K
17
RTS TxD CTS DTR RI SG
9
DCD RI
RI4
5K
18 24 26
5
23 RX5 GND
R5
RI5
5K
8
RXEN
Figure 18. SP334 Configuration to a DB-9 Serial Port
SP334DS/10 Programmable RS-232/RS-485 Transceiver (c) Copyright 2000 Sipex Corporation
10
PACKAGE: 28-PIN PLASTIC SMALL OUTLINE (SOIC)
E
H
D A O e B A1 L
DIMENSIONS (Inches) Minimum/Maximum (mm) A A1 B D E e H L O
28-PIN 0.093/0.104 (2.352/2.649) 0.004/0.012 (0.102/0.300) 0.013/0.020 (0.330/0.508) 0.698/0.706 (17.73/17.93) 0.291/0.299 (7.402/7.600) 0.050 BSC (1.270 BSC) 0.394/0.419 (10.00/10.64) 0.016/0.050 (0.406/1.270) 0/8 (0/8)
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
11
ORDERING INFORMATION
Model Temperature Range Package Types SP334CT ........................................................................... 0C to +70C .................................................................................. 28-pin Plastic SOIC SP334ET ........................................................................ -40C to +85C .................................................................................. 28-pin Plastic SOIC Please consult the factory for pricing and availability on a Tape-On-Reel option.
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation Headquarters and Sales Office 22 Linnell Circle Billerica, MA 01821 TEL: (978) 667-8700 FAX: (978) 670-9001 e-mail: sales@sipex.com Sales Office 233 South Hillview Drive Milpitas, CA 95035 TEL: (408) 934-7500 FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
SP334DS/10
Programmable RS-232/RS-485 Transceiver
(c) Copyright 2000 Sipex Corporation
12

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