Each “A” Series high-voltage power supply (HVPS) is a remotely programmable constant-voltage HVPS offering output voltage from 0VDC up to the maximum rating of each particular unit in the series. All power supplies respond to a remote-adjustable voltage range of 0 to +5VDC. (An internal clamp limits remote voltages in excess of +5VDC, so positive units cannot exceed 20% of their maximum nominal output.)

For an application that requires a constant-current output, it is possible to use the current monitor feature to permit the HVPS to operate in a regulated-current mode. A circuit may be added externally to the “A” Series unit to convert the HVPS from voltage regulation to current regulation as shown in the suggested schematic below.

Suggested constant current regulator for both positive and negative 20W “A” Series HVPS units.

Note 1:
There is a current-adjust pot, which can be used to set the desired current-limit point. This circuit arrangement works for either a -P (positive) or -N (negative) HVPS. The suggested circuit shown assumes a +24V input power source. Downward adjustment of the 49.9kΩ and 22kΩ resistors will enable the circuit to operate off a +12V buss.

Note 2:
When it is desired to limit the output of the HVPS, a 5kΩ rheostat-connected pot can be connected from the Remote Adjust Input (pin 6) to either Signal Ground Return (pin 5), for -P units, or to the +7.1V zener voltage, for -N units.

Below is an example of a negative HVPS constant current regulator.

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