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

Product Details

Key Features

Simplified Block Diagram

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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

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.

Simplified Block Diagram

MAX7031: Typical Application Circuit MAX7031: Typical Application Circuit Zoom icon

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.