| Theory of Operation | 4 |
| Overall Functional Description | |
Operation in the 11A DC Range |
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For the dc current function, the 5700A is configured for the dc 2.2V range. The 5700A 2V dc range drives an error amplifier with an input impedance of 40 kΩ. The gain of this amplifier is determined by this 40 kΩ resistor with a 4 kΩ feedback resistor, and the value of the precision shunt. The 5725A uses a 0.02Ω shunt for the 11A function. There is no feedback to the 5700A.
The 5725A monitors the error amplifier output voltage using the
A
Operation in the 11A AC Range |
For ac current operation, input to the 5725A comes from the 5700A Oscillator. The 5700A Oscillator is configured for the 2.2V ac range, with sensing back to the 5700A Oscillator coming from the current shunt through the calibration amplifier circuit (on the Current Assembly).
Voltage and Current Standby Modes |
When a change in output function is selected, the 5725A goes through voltage or current standby mode before connecting the output to the 5725A binding posts, or to the 5700A. Voltage or current standby allows for local sensing within the 5725A, and for establishment of a known input condition in current and ac voltage.
Voltage Standby |
In voltage standby, the 5700A binding posts are completely disconnected from the rest of the instrument circuitry, and the 5725A high voltage output and sense lines
Current Standby |
In current standby, the binding posts are disconnected from the instrument circuitry, but all 5725A/5700A connections are made as in the operate mode. In dc current standby, the 5700A DAC supplies a voltage that corresponds to the dc current selected. In ac current standby, 5725A relay settings are identical to those for dc current standby. The 5700A Oscillator supplies an ac voltage level that corresponds to the selected output current and frequency.