Radiometrix Ltd
LMT2/LMR2 Data Sheet
page 5
Pin description – LMR2
Pin
Name
Function
1a
Vcc
3.1 – 15V power supply
2a
0V
Ground
3a
RXE
Receiver Enable (active high)
4a
RXD
Data out (open collector, no pullup)
5a
AF out
700mV p-p audio. DC coupled, approx 0.8v bias.`
1b
P0/PGM
Parallel Channel select LSB
Serial frequency programming / configuration1
2b
P1
Parallel Channel select
3b
P2
Parallel Channel select
4b
P3
Parallel Channel select MSB
5b
RSSI
DC level between 0.5v and 2.2v. 60dB dynamic range
NOTES:
1. Serial programming is by an inverted, cmos logic level, 2400 baud RS232 datastream applied to
the P0 pin.
2. Channel select inputs have pullups (50k
Ω) to 3v internal rail. Do not exceed 3v logic levels on
this port.
3. Channel select inputs are active low
4. All pins are on an 0.1" grid
5. Data recovery circuit used for RXD is not a simple 'average and compare' type. It is a peak
sampling quasi-DC coupled design, allowing a greater than usual flexibility in data format.
6. Unit will operate (with marginally reduced specifications) 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.
Figure 5: LMR2 footpint (top view)