300MHz to 450MHz High-Efficiency, Crystal-Based +13dBm ASK Transmitter

The MAX7044 crystal-referenced phase-locked-loop (PLL) VHF/UHF transmitter is designed to transmit OOK/ASK data in the 300MHz to 450MHz frequency range. The MAX7044 supports data rates up to 100kbps, and provides output power up to +13dBm into a 50Ω load while only drawing 7.7mA at 2.7V.

The crystal-based architecture of the MAX7044 eliminates many of the common problems with SAW-based transmitters by providing greater modulation depth, faster frequency settling, higher tolerance of the transmit frequency, and reduced temperature dependence. The MAX7044 also features a low supply voltage of +2.1V to +3.6V. These improvements enable better overall receiver performance when using the MAX7044 together with a superheterodyne receiver such as the MAX1470 or MAX1473.

A simple, single-input data interface and a buffered clock-out signal at 1/16th the crystal frequency make the MAX7044 compatible with almost any microcontroller or code-hopping generator.

The MAX7044 is available in an 8-pin SOT23 package and is specified over the -40°C to +125°C automotive temperature range.

Applications

* Garage Door Openers * Remote Keyless Entry (RKE) * RF Remote Controls * Security Systems * Tire-Pressure Monitoring (TPM) * Wireless Computer Peripherals * Wireless Game Consoles * Wireless Sensors

* +2.1V to +3.6V Single-Supply Operation

* OOK/ASK Transmit Data Format

* Up to 100kbps Data Rate

* +13dBm Output Power into 50Ω Load

* Low 7.7mA (typ) Operating Supply Current*

* Uses Small, Low-Cost Crystal

* Small 3mm x 3mm 8-Pin SOT23 Package

* Fast-On Oscillator: 250µs Startup Time