300MHz to 450MHz Frequency-Programmable ASK/FSK Transmitter

Transmit any Frequency in the 300MHz to 450MHz Band with One Crystal While Keeping Your Antenna Matched

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The MAX7057 frequency-programmable UHF transmitter is designed to transmit ASK/FSK data at a wide range of frequencies from 300MHz to 450MHz. The MAX7057 has internal tuning capacitors at the output of the power amplifier that are programmable for matching to an antenna or load. This allows the user to change to a new frequency and match the antenna at the new frequency simultaneously. The MAX7057 transmits at a data rate up to 100kbps nonreturn-to-zero (NRZ) (50kbps Manchester coded). Typical transmitted power into a 50Ω load is +9.2dBm with a +2.7V supply. The device operates from +2.1V to +3.6V and typically draws under 12.5mA of current in FSK mode (8.5mA in ASK mode) when the antenna-matching network is designed to operate over the 315MHz to 433.92MHz frequency range. For narrower operating frequency ranges, the matching network can be redesigned to improve efficiency. The standby current is less than 1µA at room temperature.

The MAX7057 reference frequency from the crystal oscillator is multiplied by a fully integrated fractional-N phase-locked loop (PLL). The multiplying factor of the PLL is set by a 16-bit number, with 4 bits for integer and 12 bits for fraction; the multiplying factor can be anywhere between 19 and 28. The 12-bit fraction in the synthesizer sets a tuning resolution equal to the reference frequency divided by 4096; frequency deviation can be set as low as ±2kHz and as high as ±100kHz. The fractional-N synthesizer eliminates the problems associated with oscillator-pulling FSK signal generation. The MAX7057 has a serial peripheral interface (SPI) for selecting all the necessary settings.

The MAX7057 is available in a 16-pin SO package and is specified to operate in the -40°C to +125°C automotive temperature range.
MAX7057: Typical Application Circuit MAX7057: Typical Application Circuit Enlarge+

Key Features

  • Programmable Frequency Operation with Single Crystal
  • Internal Variable Capacitor for Antenna Tuning with Single-Matching Network
  • 100kbps Data Rate (NRZ)
  • +2.1V to +3.6V Single-Supply Operation
  • < 12.5mA (FSK), < 8.5mA (ASK) DC Current Drain
  • < 1µA Standby Current
  • ASK/FSK Modulation
  • 47% Carrier Tuning Range Using One Crystal


  • Gaming Machines
  • Industrial Controllers
  • System Monitoring
  • White Goods

MAX7057EVKIT: Evaluation Kit for the MAX7057

Tools & Models

  • MAX7057 Gerber File
  • Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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