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Calibration
iv)
Adjust the OFFSET trimpot so that the input code from the
A/D converter flickers evenly between 00hex and 01hex.
This is the OFFSET adjustment.
For BIPOLAR ranges adjust trim pot 2 for 00hex to 01hex
transition. eg for range -5 to +5 bipolar the 000+1/2LSB
voltage is -4.9988 Volt.
For UNIPOLAR ranges adjust trim pot 1 for 00hex to
01hex transition. eg for range 0 to +5 unipolar the
000+1/2LSB voltage is 610 uVolt.
v)
Using Figures 4-7 & 4-8 determine the precision voltage
source output for the 1 1/2 LSB code below FSR, the Full
Scale Reading, the FSR-1.5LSB value.
vi)
Adjust the GAIN trimpot so that the input code from the
A/D converter flickers evenly between FEhex and FFhex.
This is the GAIN adjustment.
Adjust trim pot 3 for for FEhex to FFhex transition.
eg for range -5 to +5 bipolar the FSR-1.5LSB value is
+4.9963 Volts.
eg for range 0 to +5 unipolar the FSR-1.5LSB value is
+4.9982 Volts.
Figure 4-7. Unipolar ADC Calibration Values.
_______________________________________ _
DIGITAL
OUTPUT
CODE
FSR
FSR-1LSB
FSR-1.5LSB
000 hex
1 LSB
1/2 LSB
000+1/2LSB
Chapter 4
ANALOGUE INPUT RANGE
0 to 1.25 0 to+2.5V 0 to +5V
+1.2500V
+2.5000V
+1.2497V
+2.4994V
+1.2495V
+2.4991V
0.0000V
0.0000V
0.305mV
0.61mV
0.153mV
0.305mV
153uV
305uV
UNIPOLAR
+5.0000V +10.0000V
+4.9988V
+4.9982V
0.0000V
1.22mV
0.61mV
610uV
AD1200 Reference
0 to +10V
+9.9976V
+9.9963V
0.0000V
2.44mV
1.22mV
1220uV
Page 79
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