Measurement Computing USB-7204 User Manual
Page 22
USB-7204 User's Guide
Specifications
22
Note 1:
Input current is a function of applied voltage on the analog input channels. For a given input
voltage, V
in
, the input leakage is approximately equal to (8.181*V
in
–12) µA.
Note 2:
Maximum throughput scanning to computer memory is machine dependent. The rates specified are for
Windows XP only.
Note 3:
The AD7870 converter only returns 11-bits (0-2047 codes) in single-ended mode and 12-bits in
differential mode. Firmware versions prior to 2.04 have LSB justified data. Firmware versions from
2.04 on have MSB justified data.
Note 4:
External Gated Sync holds off the first clock pulse after setting up a scan to ensure adequate setup time
for the first conversion.
Table 2. Accuracy, differential mode
Range
Accuracy (LSB)
±20 V
5.1
±10 V
6.1
±5 V
8.1
±4 V
9.1
±2.5 V
12.1
±2 V
14.1
±1.25 V
20.1
±1 V
24.1
Table 3. Accuracy, single-ended mode
Range
Accuracy (LSB)
±10 V
4.0
Table 4. Accuracy components, differential mode - All values are (±)
Range
% of Reading
Gain Error at full scale (FS)
(millivolts (mV))
Offset (mV)
Accuracy at FS (mV)
±20 V
0.2
40
9.766
49.766
±10 V
0.2
20
9.766
29.766
±5 V
0.2
10
9.766
19.766
±4 V
0.2
8
9.766
17.766
±2.5 V
0.2
5
9.766
14.766
±2 V
0.2
4
9.766
13.766
±1.25 V
0.2
2.5
9.766
12.266
±1 V
0.2
2
9.766
11.766
Table 5. Accuracy components, single-ended mode - All values are (±)
Range
% of Reading
Gain Error at FS (mV)
Offset (mV)
Accuracy at FS (mV)
±10 V
0.2
20
19.531
39.531