Rabbit Fox LP3500, User Manual, Page: 37 / 143

User’s Manual 31
3.6 A/D Converter Inputs (LP3500 only)
The single 8-channel A/D converter chip used in the LP3500 (the LP3510 does not have
analog capabilities) has a resolution of 12 bits for differential measurements or 11 bits for
single-ended measurements. Four of the channels can be jumpered individually for 4–20 mA
using jumpers across pins on header J3, and all 8 channels can be used over several
software-scaled voltage ranges.
The A/D converter chip has an internal amplifier that works with the resistor divider net-
work on the analog inputs as shown in Figure 16.
Figure 16. Buffered A/D Converter Inputs
The A/D converter chip can be programmed in software to operate over the voltage ranges
shown in Table 6.
Table 6. A/D Converter Input Ranges
Gain Code Multiplier
Voltage
Range
0 1 0–20 V
1 2 0–10 V
2 4 0–5 V
3 5 0–4 V
4 8 0–2.5 V
5 10 0–2 V
6 16 0–1.25 V
7 20 0–1 V
100 pF
52.3 k W
953 k W
R
IN
AIN0
AGND
+ V
AIN1
J3
100 W
Jumper pins to
configure for
4–20 mA
ADC