RF83 datasheet(19/22 Pages) ETC2

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RF83//RF83C/RF83L/RF83CL ASK/OOK Receiver V2.0

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To activate the Wake-Up function, a received constant RF carrier must be present for 128 counts or the

internal system clock. The internal system clock is derived from the reference oscillator and is 1/256 the

reference oscillator frequency. For example:

Where:

fT = 6.4MHz

fS = fT/256 = 25kHz

PS = 1/fS = 0.04ms

128 counts x 0.04ms = 5.12ms

fT = reference oscillator frequency

fS = system clock frequency

PS = system clock period

The Wake-Up counter will reset immediately after a detected RF carrier drops. The duration of the

Wake-Up signal output is then determined by the required wake up time plus an additional RF

carrier on time interval to create a wake up pulse output.

WAKEB Output Pulse Time = TWAKE + Additional RF Carrier on Time

For designers who wish to use the wakeup function while squelching the output, a positive

squelching offset voltage must be used. This simply requires that the squelch resistor be connected

to a voltage more positive than the quiescent voltage on the CTH pin so that the data output is low

in absence of a transmission.

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