TUTORIAL

Setting OVP and OCP on a Triple Output DC Power Supply

Your Device Under Test (DUT) is expensive. Learn the difference between current limiting (CC mode) and hardware Over-Voltage/Over-Current Protection (OVP/OCP).

Constant Current (CC) vs. OCP

Many engineers confuse setting the standard Current Limit with OCP.

  • Current Limit (CC Mode): If your circuit draws more current than the limit you set, the power supply drops the voltage to maintain that exact current. The power stays ON. This is useful for charging batteries or driving LEDs.
  • Over-Current Protection (OCP): If OCP is triggered, the power supply completely shuts off the output and sounds an alarm. This is a hard fault protection mechanism designed to prevent fires or catastrophic board failure.

Best Practices for Setting Protection

  1. Determine Normal Operating Limits: Let's say your prototype board normally runs at 5.0V and draws a maximum of 1.2A during heavy processing.
  2. Set the OVP (Over-Voltage Protection): Set OVP about 10-15% above your operating voltage. For a 5.0V circuit, set OVP to 5.5V. If someone accidentally bumps the voltage knob, the supply will shut off before frying your 5V logic chips.
  3. Set the OCP (Over-Current Protection): Set OCP about 20% above your maximum expected current. For a 1.2A max draw, set OCP to 1.5A. If a short circuit occurs, the supply shuts down instantly.

Hardware vs. Software Protection

Cheap power supplies rely on the main microprocessor to poll the voltage/current and trigger protection in software. This can take tens of milliseconds—plenty of time to destroy a sensitive IC. Premium lab supplies use dedicated analog hardware comparators for OVP/OCP, reacting in microseconds.

Protect Your Engineering Investment

Don't risk a $5,000 prototype board on a cheap power supply. Our models feature microsecond hardware OVP/OCP.

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