MAX7031

Low-Cost, 308MHz, 315MHz, and 433.92MHz FSK Transceiver with Fractional-N PLL


Description

The MAX7031 crystal-based, fractional-N transceiver is designed to transmit and receive FSK data at factory-preset carrier frequencies of 308MHz, 315MHz, or 433.92MHz with data rates up to 33kbps (Manchester encoded) or 66kbps (NRZ encoded). This device generates a typical output power of +10dBm into a 50Ω load, and exhibits typical sensitivity of -110dBm. The MAX7031 features separate transmit and receive pins (PAOUT and LNAIN) and provides an internal RF switch that can be used to connect the transmit and receive pins to a common antenna.

The MAX7031 transmit frequency is generated by a 16-bit, fractional-N, phase-locked loop (PLL), while the receiver's local oscillator (LO) 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 is preset to be 10.7MHz above the receive LO. Retaining the fixed-N PLL for the receiver avoids the higher current-drain requirements of a fractional-N PLL and keeps the receiver current drain as low as possible.

The fractional-N architecture of the MAX7031 transmit PLL allows the transmit FSK signal to be preset for exact frequency deviations, and completely eliminates the problems associated with oscillator-pulling FSK signal generation. All frequency-generation components are integrated on-chip, and only a crystal, a 10.7MHz IF filter, and a few discrete components are required to implement a complete antenna/digital data solution.

The MAX7031 is available in a small, 5mm x 5mm, 32-pin, thin QFN package, and is specified to operate in the automotive -40°C to +125°C temperature range.
MAX7031: Typical Application Circuit MAX7031: Typical Application Circuit Enlarge+

Key Features

  • +2.1V to +3.6V or +4.5V to +5.5V Single-Supply Operation
  • Single-Crystal Transceiver
  • Factory-Preset Frequency (No Serial Interface Required)
  • FSK Modulation
  • Factory-Preset FSK Frequency Deviation
  • +10dBm Output Power into 50Ω Load
  • Integrated TX/RX Switch
  • Integrated Transmit and Receive PLL, VCO, and Loop Filter
  • > 45dB Image Rejection
  • Typical RF Sensitivity*: -110dBm
  • Selectable IF Bandwidth with External Filter
  • RSSI Output with High Dynamic Range
  • < 12.5mA Transmit-Mode Current
  • < 6.7mA Receive-Mode Current
  • < 800nA Shutdown Current
  • Fast-On Startup Feature, < 250µs
  • Small, 32-Pin, Thin QFN Package

Applications/Uses

  • 2-Way Remote Keyless Entry
  • Garage Door Openers
  • Home Automation
  • Local Telemetry Systems
  • Remote Controls
  • Remote Sensing
  • Security Systems
  • Smoke Alarms
Part Number Solutions Features Applications Frequency Range
(MHz)
ISUPPLY
(mA)
Footprint
(mm x mm)
MAX7031 
Automotive
ISM, RKE, SRD; 315-433.92MHz Bands
Remote Controls
Remote Sensing
Security Systems
Smoke Alarms
+10dBm Output Power into 50Ω Load
FSK Modulation
Factory-Preset Frequency
Integrated Tx/Rx Switch
Single-Crystal Transceiver
AMR
ISM
Remote Controls
Remote Sensing
Security Systems
Smoke Alarms
308 to 433.92 11.6 5.0 x 5.0
See All ISM RF Transceivers (9)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

 

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