How to Set Current Limit on a Bench Power Supply

A current limit is the maximum current the supply will attempt to deliver before reducing its output voltage. It is not a universal safety value and should be chosen from the circuit’s expected behavior.

Know the normal current first

Use service information, a known-good unit or previous measurements when possible. Startup current can be higher than steady-state consumption, so an excessively low limit may prevent a healthy board from booting.

Start conservatively during fault diagnosis

If a short is suspected, begin with a controlled limit appropriate to the rail and components involved. Observe voltage and current rather than immediately raising the setting.

Understand CV and CC modes

In constant-voltage mode the supply maintains the selected voltage. In constant-current mode the load has reached the current limit and the supply reduces voltage to keep current controlled.

Record the behavior

Note the selected voltage, current limit, actual current and whether the board starts. These values make later comparisons much more meaningful.