Power converter ac load regulation or output transient response is usually
specified as an output-load disturbance and the associated recovery time
to some steady-stage value. The disturbance is usually a step change in
output/load current. Its amplitude is usually 25% or 50%. The response
is specified as a maximum output-voltage deviation, in millivolts, and
an associated recovery time. The recovery time is defined, in microseconds,
from the point at which the output transient leaves the specification
range to the point at which it returns and remainas within the specification
range. This test can be performed straightforwardly using a switch-able
load, or a set-up can be configured using a switching power MOSFET to
switch incremental load current in and out of the output circuit.
Procedure:
Set Vin to its nominal values and Iout to its appropriate starting point.
Apply the current step and observe the output voltage. The output transient
response is measured in two parts: the peak amplitude Vp of the output
voltage perturbation and the recovery time Tr. Depending upon the specific
design of the power converter, the output may recover exponentially or
it may ring for a while.
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