BL4S200 User’s Manual
45
3.6 Analog Reference Voltages Circuit
Figure 18 shows the analog voltage reference circuit.
Figure 18. Analog Reference Voltages
The A/D converter chip supplies the 2.5 V reference voltage, which is then amplified and
buffered to provide the 3.00 V, 1.95 V, and 1.116 V reference voltages used by the digital
output circuits.
The D/A converter chip provides the reference voltages for the digital inputs to provide
single-ended unipolar or differential measurements [0 V], or to provide single-ended bipolar
measurements [V = (voltage range) ÷ 9]. Because the D/A converter chip operation is con-
figured by the
anaOutConfig()
function, it is important to run the
anaOutConfig()
function before running
anaInConfig()
if you plan to use the analog outputs to ensure
that the reference voltages are established first before the analog inputs are configured.
3.32 k
W
1.95 V
3.00 V
+2.5 V
6
5
20 k
W
100 k
W
11.8 k
W
0.1 µF
12.4 k
W
1.116 V
10 k
W
0.1 µF
12
13
10
9
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