General Description

The AS3902 is a single channel low power 433 MHz ASK transmitter. It uses a fully integrated PLL stabilized RF-oscillator which avoids frequency pulling by approaching the antenna with objects as it occurs at SAW resonator based transmitters. ASK modulation is performed by switching the transmitter on and off by an applied data stream.

The AS3902 contains a bi-directional three line micro-controller (µC) interface to support the

µC with a clock and a reset signal and to operate the highly efficient power up/down management (including clock-free total shut-down) of the AS3902 by the µC.

As external components the AS3902 need only a reference XTAL, three capacitors and up to two resistors.

Key Features

• Supports the European 433 MHz ISM band.

• No frequency pulling by (antenna) load variation due to PLL synthesizer.

• Designed to be conform to EN 300 220-1 requirements.

• ASK data rate range from 0 to 32 kbit/s.

• Supports clock and reset signals for the external µC. Therefore no separate µC XTAL is required.

• Supports total shut down mode without any running XTAL oscillator.

• Typically 2 external resistors and 3 capacitors required.

• FSK operation by XTAL pulling possible.

• 315 MHz US ISM band application possible.

• Wide supply range between 2.7 V to 5 V.

• Low TX current, typical 8 mA @ transmitting a High (“H“), 1 mA @ transmitting a Low (“L“).

• Wide operating temperature range from –40 °C to +85 °C.

• Miniature surface mount 8 pin MSOP (preferred) or SOIC package.

Applications

• Short range radio data transmission.

• Remote keyless entry systems.

• Domestic and consumer remote control units.

• Cordless alarm systems.

• Remote metering.

• Low power telemetry.