AS3901

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. 
Supports FSK (data rates 0. 32 kb/s) or ASK modulation (data rates 0. 20kb/s) 
No data synchronization for FSK or ASK needed.
Supports clock and reset signals for the external C. 
Supports different power down modes, one without any running XTAL oscillator. 
Wide supply range between 2.7 V to 5 V. 
Only one XTAL and very few external elements required. 
Wide operating temperature range from 40 C to +85 C. 
Low TX current, typical 7 mA.

Short range radio data transmission. 
Remote keyless entry systems. 
Security applications and alarm systems. 
Domestic and consumer remote control units. 
Remote metering. 
Low power telemetry.

The AS3901 is a low power FSK/ (ASK) transmitter intended for the European 433 MHz and the US 315 MHz ISM band application. The AS3901 uses a PLL stabilized oscillator which avoids frequency pulling by approaching the antenna with objects as it occurs at SAW resonator based transmitters.

FSK modulation is performed by an I/Q-based continuous phase FSK modulator with a well defined frequency deviation of 16 kHz. The AS3901 is operating completely asynchronous to the TX data stream and therefore needs no data clock or other possible by switching the
driving amplifier and FSK modulator on and off by an applied transmit data stream.

The C clock frequency and the FSK frequency deviation can be kept almost constant for both frequency bands by selecting the correct scaling factors by the 433/315 pin. As external components the AS3901 needs only a reference XTAL and 5 capacitors.