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A7202B---868MHz / 915MHz OOK/ASK Receiver with 1~10Kbps data rate

1. General Description

A7202B is a very easy-to-use CMOS RF Receiver for sub 1GHz license free ISM band (868/915MHz). It is an OOK/ASK single chip RF receiver with high sensitivity receiver (-107dBm @ 2.4Kbps, 868.3/914.8MHz). This device integrates a double balanced image reject mixer, low IF frequency (400KHz) architecture, IF filter, I/Q limiter with RSSI generation, as well as a fully VCO and PLL synthesizer. A7202B's carrier frequency FRF is determined by the frequency of the reference crystal FXTAL. The integer-N PLL synthesizer ensures that each RF value, ranging from 854 MHz to 938 MHz with PLL steps of 800KHz, can be achieved. This is done by using a crystal as a reference frequency according to: FRF = FXTAL x N / 30, where N is the PLL feedback divider ratio (N=2171 for 868MHz band and N=2289 for 915MHz band, i.e. crystal = 12MHz for 868.4MHz). Dut to AIF (Auto IF) function, user has no need to consider IF offset between TX and RX, but, just use this formula ( FRF = FXTAL x N / 30 ) directly to calculate RX radio frequency. For easy-to-use, A7202B has a special mode called HW control mode. In HW control mode, user just needs to apply pin setting for radio control, i.e. Band =1 for 915MHz and Band = 0 for 868MHz. DF1, DF2, DF3 (data filter pins) and DS (data slicer pin) applying proper capacitors for different data rate application (1K to 10Kbps) to get the best RX sensitivity. Hence, A7202B is very easy to use with a low cost MCU or decoder. Those features are all integrated in a small SSOP 20 pins package. For packet receiving, there is no RX FIFO inside A7202B. MCU (or Decoder) just needs to decode the coming packet (preamble + sync word + payload) from DATA_OUT pin. To get the best RX sensitivity, refer to section 9.6 for recommended preamble format to be 70% high and 30% low for this device.

2. Typical Applications

n Remote Control. ? Wireless Toys. n Alarm and Security System. ? RKE (Remote Keyless Entry). n Smart Energy Management. ? Garage Door Opener. n AMR (Auto Meter Reading) ? Home Automation.

3. Features

n ASK Operating range: VDD=2,4~3,0V. T= - 40~+85℃. n Easy to use n HW control mode (no need MCU for radio control). n Auto calibration. n Auto start-up sequence, XtalàAuto CalibrationàPLLà RX. n RX current 11mA. n Shut down mode current 0,5 uA. n High RX sensitivity – 107 dBm at BER<1E-3 (2.4Kbps, 868.4/914.8MHz). n Customized digital I/O level (2,0 ~ 3,6V) by VIO pin. n Fully integrated VCO, on chip loop filter and PLL synthesizer. n RF range from 854 MHz to 938 MHz with PLL steps of 800KHz by 12MHz Xtal. n Two balanced Image Reject Mixer and Limiter. n Integrated IF Filter Bandwidth = 250KHz. n Tunable data filter via external capacitors depending on data rate. n Tunable data slicer via an external capacitor depending on data rate. n Support low cost Xtal (12MHz with ± 50ppm stability). n Very few external components: No need external IF/SAW filters. n Analog RSSI output