Module test circuits
Radiometrix
TX1
1
2
3
4
5
6
7
5kHz max.
3V
RF out
50
Ω
TXD
Vcc
En
0V (GND)
0V
Fig.5: TX1 test circuit
RX1
1
2
3
Radiometrix
4
5
6
7
8
9
RXD
RF in
50Ω
AF out
Vcc
RSSI
En
0V (GND)
Fig.6: RX1 test circuit
Applications information
Power supply requirements
Both modules have built-in regulators which deliver a constant 2.85V to the module circuitry when the
external supply voltage is 2.9V or greater, with 40dB or more of supply ripple rejection. This ensures
constant performance up to the maximum permitted rail, and removes the need for external supply
decoupling except in cases where the supply rail is extremely poor (ripple/noise content >0.1V
p-p
).
Note, however, that for supply voltages lower than 2.85V the regulator is effectively inoperative and
supply ripple rejection is considerably reduced. Under these conditions the ripple/noise on the RX1
supply rail should be below 20mV
p-p
to avoid problems. If the quality of the supply is in doubt, it is
recommended that a 10µF tantalum or similar capacitor be added between pin 7 of the module (Vcc)
and ground together with a 10Ω series feed resistor between pin 7 and the supply rail.
The Enable pin allows the module to be turned on or off under logic control with a constant DC supply
to the Vcc pin. The module current in power-down mode is less than 1µA.
NOTE:
If this facility is used, the logic control signal must have a slew rate of 40mV/µs or more. Slew
rates less than this value may cause erratic operation of the on-board regulator and therefore the
module itself.
The Enable pin should be tied directly to the Vcc pin if this facility is not required.
Radiometrix Ltd., TX1 & RX1 Data Sheet
page 6
RADIOMETRIX [ RADIOMETRIX LTD ]
