Martel Electronics SP400-BLUE - Manual (Page 3)

PIN FUNCTIONS
1. V+ Positive power supply to the meter.
2. GND 0V power supply to the meter (3.0 to 7.5V meter power supply applications only).
3. BL-
Connect to the meter's negative supply voltage to switch on the LED backlighting.
For meter supply voltages above 7.5V, add a series resistor Rs.
See Applications for suitable circuit diagrams.
4. INH Positive measuring input.
5. INL Negative measuring input.
6. DP1 Connect to V+ to display DP1 (199.9).
7. DP2 Connect to V+ to display DP2 (19.99).
8. DP3 Connect to V+ to display DP3 (1.999).
9. V- Negative power supply to the meter (6.0 to 15.0V meter power supply applications only).
A negative supply is generated internally and mirrors the positive supply. For example: if V+ is +5V, then
the internally generated V- is -5V. When measuring with the input referenced to the same supply rail as
that of the panel meter, then the limitations on the input range are (V- + 1.5V) to (V+ - 1.5V).
LCOM Normally Open. Connects INL to COM.
LBAT Normally Closed. Cut this link to disable the low battery warning sign.
Note:
Solder Links:
Page 3 of 4
CIRCUIT DIAGRAM
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Pins 11 and 18 not fitted as standard
RA and RB factory fitted options
SP 400-BLUE
3½ Digit Backlit LCD Voltmeter Module