Figure 3: LMT1 footprint (top view)
Pin description – LMT1
Pin
1a
Name
Vcc
Function
3.1 – 15V power supply (10mW)
4.1V – 15V power supply (100mW)
Ground
Transmit Enable (active low)
DC coupled input for 3V CMOS logic. Rin=47kΩ
See note 10 below for phase modulation (–PM) version
Not present in LMT1
2a
3a
4a
0V
TXE
TXD
5a
1b
No pin
P0/PGM
Parallel Channel select LSB
Serial frequency programming / configuration1
Parallel Channel select
Parallel Channel select
Parallel Channel select MSB
Not present in LMT1
2b
3b
4b
5b
P1
P2
P3
No pin
Notes:
1. Serial programming is by an inverted, CMOS logic level, 2400 baud UART data stream applied to
the P0 pin.
2. Channel select inputs have pull-ups (50kΩ) to 3v internal rail. Do not exceed 3V logic levels on this
port.
3. Channel select inputs are active low
4. TXE has a 100kΩ pull-up to Vcc
5. All pins are on an 0.1" grid
6. The pins 5a/b are not present, but are included in footprint for compatibility with other units in this
family
7. In the 'off' state a PIN switch open circuits the RF output pin. There are no 'off' state spurii.
8. Unit will operate (with marginally reduced specifications and lower (6-8mW) output power) from a
3.0V rail. This must be well regulated and without noise or ripple, as in this state the unit's internal
regulator no longer operates, and provides no supply rejection.
9. 100mW versions should not be run continuously from supply voltages > 9v
10. Phase Modulation (-PM) version LMT1: 2.6V peak-to-peak level 2100Hz sinewave tone via an
external 680pF series capacitor will produce FM deviation of 4.2kHz.
GND
2.6Vpk-pk 2100Hz
680pF
RF
TXD
LMT
The external 680pF series capacitor on LMT1 TXD input provides a defined 6dB per octave pre
emphasis response, to mimic the behavior of a Phase Modulated transmitter.
Radiometrix Ltd
LMT1/LMR1 Data Sheet
page 3
RADIOMETRIX [ RADIOMETRIX LTD ]
