Voltage Stability
A performance metric measures the capability of a power supply to maintain a constant output voltage as the output current changes. This load regulation is expressed as a percentage of the nominal voltage or as a millivolt change per ampere of load current. A lower value indicates a more stable supply that is less affected by load changes.
This performance is critical for supplying stable power to sensitive microprocessors and analog circuits.
Feedback Loop
Power supplies use a feedback control loop to monitor the output voltage and adjust the regulation mechanism in response to changes in the current drawn. If the load increases suddenly, the loop must respond rapidly to prevent the voltage from dropping. Loop response time and stability determine the transient behavior.
Measurement Method
Evaluation involves connecting a variable electronic load to the supply output and measuring the voltage at minimum and maximum operating currents. High precision digital multimeters are used to detect the small changes in output voltage. The measurement should be taken directly at the output terminals to avoid including the voltage drop across the connection leads.
Automated test setups sweep the load current to generate a regulation curve.
Line Loss
Resistance in the circuit board traces and cables can cause additional voltage drops that degrade the apparent regulation at the load. Remote sensing uses dedicated feedback lines to measure the voltage directly at the load, compensating for these losses. This approach maintains high regulation performance.
