|
General Description |
A7139 is a monolithic low-IF architecture CMOS FSK/GFSK TRX for wireless applications in the 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 868.3MHz wireless M-bus in Europe. A7139 is one of AMICCOM’s Mini Power Consumption Family in sub 1GHz ISM band product line. A7139 is optimized for very low power consumption (i.e. 434MHz band, 3.8mA @ RX mode). In addition, A7139 can offer a very good link budget with a high efficient class-E power amplifier up to 20dBm and a low phase noise receiver (-107dBm RX sensitivity @ 100Kbps / FSK / 433.92MHz). Therefore, A7139 is very suitable for battery powered application with a nice LOS (line-of-sight) wireless range. A7139 incorporates a baseband modem with the programmable data rate divider from 2K to 250Kbps. For a battery powered system, A7139 supports fast PLL settling time, Xtal settling time and on-chip Regulator settling time to reduce average power consumption. The RF synthesizer contains a VCO and a low noise fractional-N PLL with an output channel frequency resolution of 366 Hz. The VCO frequency operates at the wanted radio frequency to cover all RF band. Since A7139 is a low-IF architecture TRX with programmable IFBW (IF Filter Bandwidth, 50KHz/100KHz/150KHz/250KHz), the RXLO shall be configured to offset an intermediate frequency (IF) to TXRF regarding to the IFBW setting. A7139’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, A7139 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 A7139 and MCU are GIO1 and GIO2 (multi-function GPIO) to indicate A7139’s status so that MCU could use either polling or interrupt for radio control. For packet handling, A7139 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 A7139. User just needs to assign the sync word to this device by ID R/W command via SPI. For payload, the built-in separated 64-bytes TX/RX FIFO are used to be 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, can be used to simplify system development and cost. Overall, A7139’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. |