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Smallest 300MHz TO 450MHz transmitter

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MAXIM Integrated Products, represented by Arrow Electronics , has introduced the MAX1472, the world's smallest VHF/UHF PLL-based ASK transmitter, housed in a tiny, 3mm x 3mm 8-pin SOT23 package.

The transmitter is suitable for low-cost, high-volume applications where space is critical such as key fobs, security products, garage-door openers, and remote sensors operating in the 300MHz to 450MHz band.

The MAX1472 is designed to run directly from a lithium cell as it operates down to 2.1V, consuming only 100nA of current in standby mode.

During transmission, the MAX1472 can output from -10dBm to +10dBm of power into a 50Ω load.

For a +10dBm power level, the MAX1472 consumes 5.5mA of current at 315MHz when using a 50% duty-cycle encoding scheme, such as Manchester. Current consumption drops to 3mA at 0dBm output.

The part can accept data rates up to 100kbps.

Once the MAX1472's enable pin is activated, it takes only 250 microseconds for the device's PLL and crystal to settle so the device is available to transmit.

Because the part is targeted at small, portable applications, the MAX1472 accepts crystal frequencies between 9MHz to 15MHz, which are widely available in inexpensive, surface-mount packages.

An EV kit for the MAX1472 is available directly from Maxim and from authorised distributors. Maxim also has established relationships with crystal suppliers who can provide reference samples of crystals upon request.

As the MAX1472 uses a crystal-based PLL, most of the problems of an LC- or SAW-based transmitter are eliminated. The inherent accuracy of the crystal frequency allows for a narrower IF bandwidth in the receiver to improve system sensitivity.

With a receiver like Maxim's MAX1470 or MAX1473, 9dB improvement in sensitivity is possible by narrowing the IF bandwidth from 600kHz to 50kHz.

Improved sensitivity translates directly to greater range or more reliable transmissions.

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