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Features
* Very High Transmitting Frequency Accuracy Compared to SAW Solutions * * * * * * *
(Enables Receivers at Lower Bandwidth than With SAW Resonators) Lower Cost than the Usual Discrete Solutions Using SAW and Transistors Supply Voltage 2.2V to 4.0V in the Temperature Range of -40C to 85C XTO Output for Clocking the Microcontroller, Thereby, Together with the ATAR090 or ATAR890, Resulting in the Optimum System Cost-effectiveness One-chip Solution With Minimum External Circuitry Single-ended Open-collector Output (Same Antennas Can Be Used as in Discrete Solutions, Simpler Matching of Magnetic Loop Antennas) ESD Protection According to MIL-STD 883 (4 KV HBM) Except Pins XTO1, XTO2, ANT and LF Very Small SSO16 Package, Pitch 0.635, 150 mil
UHF ASK Transmitter ATA2745
1. Description
The ATA2745 is a PLL transmitter IC which has been developed especially for the demands of RF low-cost data transmission systems at data rates up to 20 kBaud. The transmitting frequency range is 310 MHz to 440 MHz. It can be used in ASK systems. The main applications of the ATA2745 are in the areas of outside temperature metering, socket control, garage door openers, consumption metering, light/fan or airconditioning controls, jalousies, wireless keyboards, and various other consumer market applications.
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Figure 1-1.
System Block Diagram
UHF ASK Remote control transmitter UHF ASK Remote control receiver
Microcontroller
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1 Li cell
ATA2745
Encoder ATARx9x
XTO PLL
ATA3745
Demod. Control 1...3
Keys
IF Amp
Antenna Antenna VCO PLL XTO
Power amp.
LNA
VCO
Figure 1-2.
Block Diagram
ASK
OR
GND
EN
PWRSET
Power up
VCC PWRVCC
VCO
CLK
PA
ANT
f
GND
PWRGND1
64
LFVCC PWRGND2
f n
XTO
XTO1
LFGND
LF
NC
ATA2745
2
ATA2745
ATA2745
2. Pin Configuration
Figure 2-1. Pinning SSO16
ASK
1
16
GND
EN
2
15
PWRSET
VCC
3
14
PWRVCC
CLK
4
13
ANT
ATA2745
GND 5 12 PWRGND1
LFVCC
6
11
PWRGND2
LFGND
7
10
XTO1
LF
8
9
NC
Table 2-1.
Pin 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Pin Description
Symbol ASK EN VCC CLK GND LFVCC LFGND LF NC XTO1 PWRGND2 PWRGND1 ANT PWRVCC PWRSET GND Function Modulation input ASK Enable input Supply voltage Clock output Ground Supply voltage VCO VCO ground Circuit PLL loop Not connected Connection for crystal Power GND2 Power GND1 RF output Supply voltage power amplifier Applied to VCC Ground
3
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3. General Description
The fully integrated VCO and the single-ended open-collector output allow particularly simple, low-cost RF miniature transmitters to be assembled. The single-ended output enables a considerably simplified adaptation of both a magnetic loop antenna of any form or a / 4 antenna. This is because the load impedance must not be balanced as would be the case with a differential output. The XTO's frequency can be selected to be either 13.56 MHz or 9.844 MHz (USA). At these frequencies, crystals have a very fast start-up time (< 1.5 ms), whereby a wait time of 5 ms to 10 ms is required until the transmitter IC is locked. This means that the processor does not need to poll a lock detect output.
4. Functional Description
4.1 ASK Transmission
The ATA2745 is activated by EN = VS. VASK must remain 0V for 5 ms, then the output power can be modulated by means of pin ASK. VEN remains equal to VS during the transmission of the message. The ASK input activates the power amplifier and the PLL.
4.2
Take-over of the Clock Pulse in the Microcontroller
The clock of the crystal oscillator can be used for clocking the microcontroller. The ATAR090 and ATAR890 have the special feature of starting with an integrated RC oscillator to switch on the ATA2745 with VEN = VS. 5 ms later, the 3.39-MHz clock frequency is present, so that the message can be sent with crystal accuracy.
5. Application Circuit
The following component values are recommendations for a typical application. C4, C5, and C6 are block capacitors. The values of these capacitors depend on the board layout. C4 = 1 nF, C5 = 1 nF, and C6 = 22 nF are typically used here. For C5, the impedance between f = 100 MHz and f = 1 GHz should be as low as possible. CLoop1 and CLoop2 are selected so that the antenna oscillates in resonance and the matching to the appropriate impedance transformation is possible. LFeed is an inductor for the antenna's DC current supply. A typical value is LFeed = 220 nH. LFeed can be either printed on the PC board or be a discrete component.
4
ATA2745
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ATA2745
5.1 Output Power Measurement
The following output network (Figure 5-1 on page 5) can be used for output power evaluation, the exact values of L10 and C10 are dependent on the layout. L10 and C10 form the transformation network to adopt the output impedance of the IC to 50. The following table shows the values for an output power of 2 mW and an RPWRSET = 1.2 k. Table 5-1.
f [MHz] 315 433.92
Transformation Network
C10 [pF] 2.7 1.8 L10 [nH] 56 33 ZLoad-opt [] 260 + j330 185 + j268
Figure 5-1.
Measurement Output Network
VS PWRVCC L10 ANT C10 50
ZLoad-opt
Figure 5-2.
Application Circuit
+VS = 2.2 ... 4.0 V
ASK
ASK 1
GND
OR Power up VCO PA
16 PWRSET 15 PWRVCC 14 ANT 13 C4 LFeed R PWRSET CLoop2
EN
EN 2 VCC C6 3 CLK 4
CLK 3.39 MHz
GND 5 LFVCC 6 C5 LFGND 7 R4 C1 LF 8 C2
f 64 f n
PWRGND1 12 PWRGND2 11
CLoop1
XTO
XTO1 10
13.56 MHz
ATA2745
NC 9
C3
Antenna
5
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6. Absolute Maximum Ratings
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Parameters Supply voltage Power dissipation Junction temperature Storage temperature Ambient temperature Symbol VS Ptot Tj Tstg Tamb -55 -40 Min. Max. 6 250 150 125 85 Unit V mW C C C
Electrostatic sensitive device. Observe precautions for handling.
7. Thermal Resistance
Parameters Junction ambient Symbol RthJA Value 180 Unit K/W
8. Electrical Characteristics
All parameters are refered to GND (pin 5), VS = 3V, Tamb = 25C, unless otherwise specified The possible operating ranges refer to different circuit conditions: VS = 2.2V to 4.0V at Tamb = -40C to +85C Parameters Supply current (power down) Test Conditions VASK, VFSK 0.3V, VS < 3.6V Symbol ISoff ISon IStransmit PRef PRef 1 Min. Typ. 2 4.7 10 3 Max. 10 6.2 12.5 5 Unit A mA mA dBm
Supply current (power up, output OFF) VASK = GND, VEN = VS, VS = 3V Supply current (power up, output ON) VASK = VS, VS = 3V, RPWRSET = 1.2 k Output power Output power variation for f = 315 MHz compared to f = 433.92 MHz VS = 3V, Tamb = 25 C, f = 433.92 MHz RPWRSET = 1.2 k f = 315 MHz Pout = PRef + PRef At Pout = 2.0 mW, the load impedance must be selected to meet the Vout maximum requirement, the supply current is not dependent on the load impedance tolerance fo (n x fPC) where fPC = 6.78 MHz Load capacitance at CLK 3 pF f = 230 MHz to 470 MHz f < 230 MHz, f > 470 MHz Crystal frequency = 13.56 MHz
1.5
dB
Maximum peak output antenna voltage
Voutmax
VS - 0.7V
V(peak)
Spurious emission
Em Em fXTO 13.56 - 30 ppm 13.56
-40 -58 13.56 + 30 ppm
dBC dBC MHz
Oscillator frequency XTO
6
ATA2745
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ATA2745
8. Electrical Characteristics (Continued)
All parameters are refered to GND (pin 5), VS = 3V, Tamb = 25C, unless otherwise specified The possible operating ranges refer to different circuit conditions: VS = 2.2V to 4.0V at Tamb = -40C to +85C Parameters Loop bandwidth Test Conditions For best LO noise Loop filter components: C2 = 3.9 nF, C1 = 15 nF, R4 = 220 Referring to the phase comparator fPC = 6.78 MHz At 1 MHz At 36 MHz Symbol BLoop PNPLL PNVCO PNVCO fVCO Clkout CCLK fXTO = 13.56 MHz fXTO = 9.84 MHz Duty cycle of the modulation signal = 50% VCLK = 0.2 x VCLK = 0.3 x VCLK = 0.8 x VCLK = 0.7 x VS VS VS VS Rs Rs fmodASK Iol Iol Ioh Ioh VASKl VASKh IASKh VEN VFSKl VFSKh IFSKh 0 310 fout / 128 10 80 100 20 Min. Typ. 100 Max. Unit kHz
Phase noise PLL Phase noise VCO Frequency range of the VCO Clock output (CMOS microcontroller compatible) Load capacitance at CLK Series resonance R of the crystal ASK modulation frequency rate CLK output - Output current Low - Output current Low - Output current High - Output current High ASK input - Low level input voltage - High level input voltage - Input current High Enable ASK - Low level input voltage - High level input voltage - Input current High
-111 -90 -122
-105
dBC/Hz dBC/Hz
440
MHz MHz pF kHz
150 200 -150 -200
100 0.3
A A A A V V A V V A
1.7 140 0.3 1.7 140
7
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9. Ordering Information
Extended Type Number ATA2745M-TCQY Package SSO16 Remarks Taped and reeled, Pb-free
10. Package Information
8
ATA2745
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ATA2745
11. Revision History
Please note that the following page numbers referred to in this section refer to the specific revision mentioned, not to this document. Revision No. 4898B-RKE-08/06 History * Put datasheet in a new template * Section 9 "Ordering Information" on page 8 changed
9
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