Datasheet

Page 4
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DC Specifications
1. Input impedance: Refer to Table A on page 10.
2. The accuracy could be improve to 0.05%+10 for U1251B or 0.05%+5 for U1252B and U1253B by using the Null function to zero out the thermal effect before
measuring the signal.
3. These specifications are defined for 2-wire ohms using Math Null. Without Math Null, add 0.2 ohm additional error.
4. Maximum open voltage: < +4.2 V
5. The accuracy of 500 Ω and 5 kΩ is specified after NULL function, which is used to subtract the test lead resistance and the thermal effect.
6. For the range of 50 MΩ and 500 MΩ, the R.H. is specified for <60%.
7. The accuracy is specified for <50 nS and after NULL function with open test lead.
8. Always use the NULL function to zero out thermal effect with open test lead before measuring the signal. If the NULL function is not used, an additional 20
counts needs to be added to the DC current accuracy. Thermal effect could occur due to the following:
– Wrong operation to measure the high voltage of 50 V ~ 1000 V for resistance, diode, and mV measurements.
– After battery-charging has completed.
– After measuring a current greater than 440 mA, it is suggested that the meter be left to cool down for twice the measuring time used.
9. Current can be measured up to 10 A continuously. An additional 0.5% needs to be added to the specified accuracy if the signal measured is in the range of
10 A~20 A for 30 seconds maximum. After measuring a current of > 10 A, leave the meter to cool down for twice the measuring time used before application
of low current measurement.
Function Range Resolution Test current/
burden voltage
Accuracy ± (% of reading + no. of least significant digit)
U1251B U1252B/U1253B
Voltage
1
50.000 mV 0.001 mV – 0.05 + 50
2
0.05 + 50
2
500.00 mV 0.01 mV – 0.03 + 5 0.025 + 5
1000.0 mV 0.1 mV –
5.0000 V 0.0001 V –
50.000 V 0.001 V –
500.00 V 0.01 V – 0.03 + 5
1000.0 V 0.1 V –
Resistance
3
500.00 Ω
5
0.01 Ω 1.04 mA 0.08 +10 0.05 + 10
5.0000 kΩ
5
0.0001 kΩ 416 µA 0.08 + 5 0.05 + 5
50.000 kΩ 0.001 kΩ 41.2 µA
500.00 kΩ 0.01 kΩ 4.12 µA
5.0000 MΩ 0.0001 MΩ 375 nA 0.2 + 5 0.15 +5
50.000 MΩ
6
0.001 MΩ 187 nA 1 + 10 1 + 5
500.00 MΩ
6
0.01 MΩ 187 nA N/A 3+10 < 200 MΩ / 8+10 > 200 MΩ
500.00 nS
7
0.01 nS 187 nA 1 + 20 1 + 10
Current 500.00 µA 0.01 µA 0.06 V (100 Ω) 0.1 + 5
8
0.05 + 5
8
5000.0 µA 0.1 µA 0.6 V (100 Ω)
50.000 mA 0.001 mA 0.09 V (1 Ω) 0.2 + 5
8
0.15 + 5
8
440.00 mA 0.01 mA 0.9 V (1 Ω)
5.0000 A 0.0001 A 0.2 V (0.01 Ω) 0.3 + 10 0.3 + 10
10.000 A
9
0.001 A 0.4 V (0.01 Ω) 0.3 + 5
Diode test
8
– 0.1 mV 1.04 mA 0.05 + 5