ADCMT 4601 I-V Meter, Руководство по эксплуатации

Страница: 144 / 236

4601 I-V Meter Operation Manual
5.9.2 Operational Principles
5-52
5.9.2 Operational Principles
5.9.2.1 Voltage Source/Voltage Measurement/Current Measurement Terminal Circuit
• The voltage source/voltage measurement/current measurement circuit of the 4601 contains a DA
converter SrcDAC for setting the voltage source.
This circuit also has two DA converters for setting the current limits: HiLimitDAC and LoLimitDAC.
SrcDAC is 16-bit precision, and HiLimitDAC and LoLimitDAC are 13-bit precision.
The output from the DA converters is input to three error amplifiers: Src (A1), HiLmt (A2), and
LoLmt (A3) respectively.
• SrcDAC is a DA converter for voltage source and Src (A1) is an error amplifier for voltage source.
Also, HiLimitDAC is a DA converter for current limiter on the HI side, and HiLmt (A2) is an error
amplifier for current limiter on the HI side. Likewise, LoLimitDAC and LoLmt (A3) work as current
limiters on the LO side.
• Source and limiter are switched by the switching circuit shown in the above figure, comparing the
feedback amount for each, then switching to the larger one.
• Current range switching is done by switching the current detection resistor Rs. Consequently, the
current measurement always takes place in the same range as that of current limiter.
• Voltage range switching is done by A
5
, and the voltage measurement and voltage source always take
place in the same range.
• The A
5
and A
6
amplifiers have high input impedance to minimize leakage.
• The A
7
amplifier also has a high input impedance to reduce errors in 4-wire connection.
• The AD converter employs an integral type AD, and the integration time can be set between 5

s to
200 ms.