Radiometrix Ltd, SILRX-UHF Data Sheet

page 10

Applications note

Four Channel Receiver with battery saver

Fig 7 shows a simple four channel paging receiver with 256 setable codes. The CMOS 555 timer

provides a duty cycle power save circuit which latches ON when a signal is present. The values used in

the example give 4ms ON; 400 ms OFF, i.e. 1:100 duty cycle. The total quiescent current is less than

200µA, thus a 9V alkaline battery (500 mA/hr) will give a life of over 2000 hours. The ON time is

determined by the receiver’s power up settling time (3 ms worst case) + any tolerance of the duty cycle

oscillator. The OFF time is controlled by R8 in the circuit and should be selected to suit the application

depending upon the required response time and any limits imposed upon the duration of the

transmission. It is recommended that the OFF time be no longer than 1/2 for the transmission

preamble duration.

Ordering information

SAW based OEM Transmit and Receive modules.

TXM-418-5

UK Transmitter on 418 MHz, Type approved to MPT1340

TXM-418-10

Fast transmitter on 418 MHz, Type approved to MPT1340

RXM-418-5

matching UK receiver module on 418 MHz

SILRX-418-5

Low current UK receiver module on 418 MHz

BiM-418-10

Bi-directional short range module on 418 MHz

RPC-418-5

Self-contained module wich integrates the BiM transceiver with a Radio Packet

Controller

EVAL-418-A

Evaluation kit for TXM & RXM

EVAL-418-B

SILRX supplementary PCB for EVAL-418-A

BiM-KIT

Evaluation kit for BiM-UHF modules.

All modules are available in a 433.92 MHz version for use in other European countries.

figure 7: Four Channel Receiver with power save