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A7201B
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General Description
A7201B is a very easy-to-use CMOS RF receiver for sub 1GHz license free ISM band (868/915MHz). It is a FSK/ASK single chip RF receiver with high sensitivity receiver (-107dBm @ 2.4Kbps, 868.4/914.8MHz ASK/FSK). 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. A7201B'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 / 2R, where N is the PLL feedback divider ratio and R is crystal divider to support 12MHz crystal. Besides, A7201B supports AIF (Auto IF) function, user has no need to consider IF offset between TX and RX, but, use this formula ( FRF = FXTAL x N / 2R ) directly to calculate radio frequency in both TX and RX site.

A7201B supports ASK data rate from 1K to 10Kbps and FSK from 1K to 20Kbps which is determined via external capacitors applied on data filter and data slicer. In FSK modulation, recommend to let received modulated signal be ± 12.5KHz frequency deviation (Fdev). In ASK modulation, Fdev is not a necessary part.

For easy-to-use, A7201B has only two control registers, register 0 and 1. MCU can configure two registers via 3-wire SPI bus. In addition to SPI control mode, A7201B has a special mode called HW control mode. In HW control mode, user just needs to apply pin setting. Then radio control is done (register 0 and register 1 are in default values). No matter HW or SPI control mode, A7201B is very easy to use by a low cost MCU or decoder. Those features are all integrated in a small SSOP 20 pins package.

For packet handling, there is no RX FIFO inside A7201B. Hence, in RX mode, MCU or Decoder can receive the packet (preamble + sync word + payload) from DATA_OUT pin. Be aware that A7201B needs different preamble formats between ASK and FSK in order to get the best RX sensitivity.
 FSK Operating range: VDD=2,4~3,3V. T=-40~+85℃.
 ASK Operating range: VDD=2,4~3,0V. T=-40~+85℃.
 Easy to use
 HW or 3-wire SPI control mode selection.
 HW control mode (no need MCU for radio control, default IFB = mid.).
 Auto calibration.
 Auto start-up sequence, XtalAuto CalibrationPLL RX.
 RX current 11mA (FSK and ASK).
 Shut down mode current 0,5 uA.
 High RX sensitivity (FSK / ASK) down to – 107 dBm at BER<1E-3 (2.4Kbps, 868.4/914.8MHz).
 Customized digital I/O level (2,0 ~ 3,6V) by VIO pin.
 Fully integrated VCO, on chip loop filter and PLL synthesizer.
 RF range from 854 MHz to 938 MHz with PLL steps of 800KHz.
 Two balanced Image Reject Mixer and Limiter.
 Integrated IF Filter = mid. (250KHz in ASK, 150KHz in FSK).
 Tunable data filter via external capacitors depending on data rate.
 Tunable data slicer via an external capacitor depending on data rate.
 Support low cost crystal (12MHz with ± 50ppm stability).
 Very few external components: No need external IF/SAW filters.
 Analog RSSI output.
Remote Control.
Wireless Toys.
Alarm and Security System.
RKE (Remote Keyless Entry).
Smart Energy Management.
Garage Door Opener.
AMR (Auto Meter Reading)
Home Automation.
Datasheet
Application Note
Reference circuit design (Module)
Reference code
Evaluation kit (EK)
Development Kit (DK)
Production test tool
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