Functional description
The TX3A transmitter module uses a frequency modulated crystal-locked PLL and operates
between 2.2V and 16V at a current of 7.5mA nominal. At 3V supply it delivers nominally
0dBm (1mW) RF output. The SIL style TX3A measures 32 x 12 x 3.8 mm, excluding pins.
The RX3A module is a single conversion FM superhet receiver capable of handling data rates
of up to 64kbps. It will operate from a supply of 2.7V to 16V and draws 11mA when receiving.
The RX3 features a fast power-up time for effective duty cycle power saving and a signal
strength (RSSI) output with 60dB of range. Full screening and a SAW front-end filter give
good immunity to interference. The SIL style RX3A measures 48 x 17.5 x 4.5 mm, excluding
pins.
TX3A transmitter
supply
5
regulator
2.2 -- 12V
4
En
868/915 MHz
band pass
filter
ref
osc
35kHz
LPF
buffer
64
÷
φ
2
V C O
7
TXD
RF out
Loop
Filter
3
RF gnd
6
1
0V
Fig 1 :TX3A block diagram
Pin description
RF GND (pins 1&3)
3.8 mm
32 mm
RF ground, internally connected to the
module screen and pin 6 (0V). These
pins should be directly connected to the
RF return path - e.g. coax braid, main
PCB ground plane etc.
12.0
mm
12.5
mm
Radiometrix
TX3A
RF OUT
(pin 2)
50Ω RF output to the antenna.
Internally DC-isolated. See antenna
section of apps notes for details of
suitable antennas.
PCB level
1 = RF GND
15.24 mm
2 = RF OUT
3 = RF GND
4 = En
5 = Vcc
6 = 0V
2
3
4
5
6
7
1
En
(pin 4)
7 = TXD
Tx enable. <0.15V shuts down module
(current <1µA). >1.7V enables the
7 holes, 0.7 mm dia, pin spacing 2.54 mm
transmitter. Impedance ~1MΩ. Observe
slew rate requirements (see apps notes).
Fig2: TX3A physical dimensions
Vcc
(pin 5)
+2.2V to +16V DC supply. Max ripple content 0.1VP-P. Decoupling is not generally required.
0V (pin 6)
DC supply ground. Internally connected to pins 1 & 3 and module screen.
TXD (pin 7)
DC-coupled modulation input. Accepts serial digital data at 0V to 2.5V levels.
See applications notes for suggested drive methods. Input is high impedance (>100kΩ).
Radiometrix Ltd, TX3A & RX3A Data Sheet
page 2
RADIOMETRIX [ RADIOMETRIX LTD ]
