Teledyne LeCroy Power Supply Load Regulation Measurements page | 1 of 2
Power-Supply Load Regulation Measurements TECHNICAL BRIEF
February 20, 2013
Summary
Power supply specifications
include a large number of
load-dependent parameters
including load or output
regulation. Teledyne LeCroy
oscilloscopes offer parameter
math, which helps measure
load regulation directly.
Power-Supply Load Regulation Measurement Tools
Parameters and parameter math make it easy to measure power supply
load or output regulation.
Load regulation of the output voltage, V, is defined as:
V/ V FULL LOAD X 100%
Where
V = V NO LOAD – V FULL LOAD
Figure 1 shows a typical load-regulation measurement on a small flyback
power supply.
Figure 1: Using parameters and parameter math to measure load regulation
The trace C2 is the output current, and in this case a square wave load
variation has been applied. Trace C3 is the output voltage which is
nominally 5V. Vertical zoom has been applied to C3 in trace Z3 so the
ripple due to the load variation is visible. The parameter P1 is measuring
the mean output voltage which is 4.96V. Parameters P2 measures the top
or higher mean output value of the output: this is the nominal no-load
Teledyne LeCroy Power Supply Load Regulation Measurements page | 2 of 2
output. Parameter P3, base, reads the mean loaded output voltage. P4 is the amplitude of the output variation
due to the load and is the difference between the top and the base values. This is the V in our equation.
Parameter math in P5 and P6 is used to calculate load regulation. P5 takes the ratio of the amplitude (P4) to the
loaded output voltage (P3). The ratio in P4 is multiplied by 100% using the parameter rescale math function in
P6. The output units are changed to % to reflect this calculation. The reading P6, 0.8%, is the load regulation.
By combining automatic measurement parameters with parameter math, we are able to read out load regulation
directly from our measurement of the output voltage waveform.
Channel 2 shows the output current.
