RXD
pin 12
Digital output from internal data slicer. The output is a squared version of the signal on pin 13 (AF) and may be
used to drive a decoder directly. The data is true data, i.e. as fed to the transmitter. Output is “open-collector”
format with internal 10kΩ pullup to Vcc (pin 17).
AF
pin 13
Buffered & filtered analogue output from FM demodulator. Standing DC bias of 1V approx. Useful for test
purposes or for driving external decoders. External load should be >10kΩ // <100pF
TXD
pin 14
This DC-coupled transmitter modulation input will accept either serial digital data or high level linear signals.
Drive signal must be limited to 0V min, 5V max. See page 7 for suggested drive methods. Input impedance
>50kΩ.
TX select
pin 15
Active-low Transmit select. 47kΩ internal pull-up to Vcc.
RX select
pin 16
Active-low Receive select. 47kΩ internal pull-up to Vcc.
Pin 15 TX
Pin 16 RX
Function
1
1
Power down (<10µA)
1
0
Receiver enabled
0
1
Transmitter enabled
0
0
Self test loop-back*
* Loop-back allows the receiver to monitor the transmitted signal. Under these conditions the Tx radiated signal
level will be reduced to approximately -10dBm).
Vcc
pin 17
+5V DC +ve supply pin. The supply should be clean, <20mVP-P ripple.
Radiometrix Ltd, BIM2/3G Data Sheet
page 3