ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

Rev. 6, August 2000

Page 2 of 18

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.

• 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 µC.

• 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.

General Description

The AS3901 is a low power FSK/ (ASK) transmitter intended for the European 433 MHz

and the US 315 MHz ISM band application. It 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 FSK modulator 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 µC 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.

TSSOP-14

STDBY

CLK

DATA

TX

NRES

ANT1

ANT2

GNDRF

GND

VDD

1

2

3

4

5

6

7

XTAL2

433

XTAL1

VDDRF

8

9

10

11

12

13

14