RX3A receiver
5
869/914MHz
SAW BPF
10.7MHz IF filter
RSSI
MIXER
10.7MHz
ceramic
discriminator
IF2/Lim
10.7MHz
IF1
10.7MHz
LNA 2
LNA 1
1
RF in
Audio LPF
fRF - 10.7MHz)
AF
buffer
8
AF out
CL
32
VCO
data
slicer
9
RXD
RT
CT
XTAL OSC.
10k
Ω
+2.8V
Low
Loop filter
7
V
Crystal
26/28MHz detector
Phase
regulated
to circuit
dropout
regulator
cc
(Fixed frequency PLL Osc.)
4
En
6
0V
2, 3
RF gnd
Fig.3: RX3A block diagram
Pin description
48 mm
4.5 mm
RF IN
(pin 1)
50Ω RF input from antenna.
Internally DC-isolated. See
antenna section of applications
notes for suggested antennas and
feeds.
RX3A
Radiometrix
RF GND
(pins 2 & 3)
PCB level
RF ground, internally connected to
the module screen and pin 6 (0V).
These pins should be connected to
the RF return path - e.g. coax
25.4 mm
1 = RF IN
2 = RF GND
3 = RF GND
4 = En
5 = RSSI
6 = 0V
7 = Vcc
braid, main PCB ground plane etc.
1
2
3
4
5
6
7
8
9
8 = AF out
9 = RXD
En
(pin 4)
9 holes of 0.7 mm dia. pin spacing 2.54mm
Rx enable. <0.15V shuts down
module (current <1µA). >1.7V enables
the receiver. Impedance ~1MΩ. Observe
slew rate requirements (see apps notes).
Fig.4: RX3A physical dimensions
RSSI
(pin 5)
Received signal strength indicator with >65dB range. See applications notes for typical characteristics.
0V (pin 6)
DC supply ground. Internally connected to pins 2 & 3 and module screen.
Vcc (pin 7)
+2.7V to +16V DC supply. Max ripple content 0.1VP-P. Decoupling is not generally required.
AF out (pin 8)
Buffered and filtered analogue output from the FM demodulator. Standing DC bias 1V approx. External
load should be >10kΩ // <100pF.
RXD
(pin 9)
Digital output from the internal data slicer. The data is true data, i.e. as fed to the transmitter.
Output is “open-collector” format with internal 10kΩ pull-up to Vcc (pin 7).
Radiometrix Ltd, TX3A & RX3A Data Sheet
page 3
RADIOMETRIX [ RADIOMETRIX LTD ]
