The MAX7032 is a low-cost, crystal-based fractional-N transceiver.

The MAX7032 is a low-cost, crystal -based, fractional-N transceiver designed for OOK/ASK data transmission and reception in the 300MHz to 450MHz frequency band, with data rates up to 33kbps (Manchester encoding) or 66kbps (NRZ code). The device can provide a typical output power of +10dBm into a 50Ω load, and a typical receive sensitivity of -114dBm (ASK data) and -110dBm (FSK data). The MAX7032 has independent transmit and receive pins (PAOUT and LNAIN) and provides an internal RF switch for connecting the transmit and receive pins to a common antenna.

The MAX7032's transmit frequency is generated by a 16-bit fractional-N phase-locked loop (PLL), while the receiver's local oscillator (LO) frequency is generated by an integer-N PLL. This hybrid architecture eliminates the need for separate transmit and receive crystal reference oscillators because the fractional-N PLL can set the transmit frequency to within 2kHz of the receive frequency. The fractional-N PLL's 12-bit resolution provides frequency multiplication in steps of fXTAL / 4096. The receiver has a fixed-N PLL, eliminating the need for a fractional-N PLL, which effectively saves current consumption and minimizes the receiver's current consumption.

Because the MAX7032 transmitter PLL has a fractional-N frequency division architecture, users can accurately set the frequency offset of the transmitted FSK signal, completely solving the related problems caused by the oscillator frequency pulling the FSK signal. All frequency generation components are integrated into the chip, and only a crystal oscillator, a 10.7MHz IF filter and a few discrete components are needed to form a complete antenna/digital data solution.

The MAX7032 is available in a small 5mm x 5mm, 32-pin thin QFN package and operates over the -40°C to +125°C automotive temperature range.

Key Features

Single Supply Operation: +2.1V to +3.6V or +4.5V to +5.5V

Single Crystal Transceiver

User-adjustable 300MHz to 450MHz carrier frequency

ASK/OOK and FSK modulation and demodulation

User-adjustable FSK frequency deviation via fractional-N PLL registers

Flexible transmitter frequency synthesizer with fXTAL/4096 carrier frequency spacing

+10dBm output power into 50Ω load

Built-in TX/RX switch

Built-in transmit and receive PLL, VCO and loop filter

> 45dB image rejection ratio

Typical RF sensitivity* ASK: -114dBm; FSK: -110dBm

IF band selectable by external filter

RSSI output with high dynamic range

Automatic low power management mode

< 12.5mA transmit mode current

< 6.7mA Receive Mode Current

< 23.5µA Search Mode Current

< 800nA shutdown current

Fast power-on start-up, < 250µs

Small 32-pin Thin QFN package