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General Description |
A7136 is a monolithic low-IF architecture CMOS FSK/GFSK TRX for wireless applications in the 169/315/433/470/868/ 915MHz ISM bands. This device is especially suitable for battery-powered application and the 470MHz ~ 510MHz wireless AMR (Auto Meter Reading) in China and 169.4MHz/433.8MHz/868.3MHz wireless M-bus in Europe. The RF synthesizer contains a VCO and a low noise fractional-N PLL with an output channel frequency resolution of 61Hz for 433/470 MHz band. The VCO frequency operates at the wanted radio frequency to cover all RF band. A7136’s control registers are accessed via 3-wire or 4-wire SPI interface including TX/RF FIFO, VCO frequency, to chip calibration procedures. Another one, via SPI as well, is the unique Strobe Command, A7136 can be controlled from power saving mode (deep sleep, sleep, idle, standby), PLL mode, TX mode and RX mode. In addition to SPI, the digital connections between A7136 and MCU are GIO1 and GIO2 (multi-function GPIO) to indicate A7136’s status so that MCU could use either polling or interrupt for radio control. For packet handling, A7136 supports direct mode and FIFO mode. In direct mode, MCU or Encoder shall deliver the defined packet (preamble + sync word + payload) to GIO1 or GIO2/TXD pin. Then, in RX mode, MCU or Decoder can receive the coming packet (preamble + sync word + payload) in bit sequence from GIO1 or GIO2/RXD pin. In FIFO mode, preamble is self-generated by A7136. User just needs to assign the sync word to this device by ID R/W command via SPI. For payload, the built-in separated 128-bytes TX/RX FIFO are used for this purpose to let user R/W the wanted payload. User can also enable additional packet features like CRC for error detection, FEC (hamming 7 by 4) for 1-bit data correction per code word, Manchester coding, as well as data whitening for data encryption / decryption. Additional device features such as on-chip regulator, RSSI for clear channel assessment, a thermal sensor, low battery detector, carrier detect, preamble detect, frame sync in FIFO mode, auto-ack and auto-resend, AIF (Auto IF function), AFC (Auto Frequency compensation), Auto calibration (VCO, IF Filter), PLL/CLK Generator, on-chip compensated capacitors of Xtal loading, and WOR (Wake on RX) to support the ability to periodically wake up from sleep mode to RX mode and listen for incoming packets without MCU interaction, which can be used to simplify system development and cost. Overall, A7136’s highly integrated features and low current consumption offer a reduced BOM cost for a high performance ISM bands product. All features are integrated in a small QFN 4X4 24 pins package. |