APPLICATION NOTE 7
SWITCHER QUASI REGULATED OUTPUT VOLTAGE REGULATION
1.0 Often referred to as "primary side regulation", Jerome offers this technology under the name "quasi regulated". A letter Q suffix is added to the part number to indicate this option.
2.0 With quasi regulation, the output voltage will increase under light loading conditions, line regulation remains good however, typically better than +/-1% from 90 to 264 Vac. The increase in output voltage is specified as follows:
From 100% load to 20% load, maximum increase of 10% from the full load voltage,
From 20% load to no load, maximum increase of 30% from the full load voltage.
Typically, the increase in output voltage will be 1/2 to 3/4 of the maximum specified limit.
3.0 Although the voltage regulation with changes in load current does not compare to the fully regulated power supply versions, the quasi regulated technique has several merits which need to be considered such as:
a) Lower cost, due to the elimination of the secondary side control circuitry and the optoisolator. This can account for a 4 to 5% drop in power supply price.
b) Higher reliability, again due to the elimination of the secondary side control circuit and optoisolator.
FIGURE 1, QUASI REGULATED OUTPUT CHARACTERISTICS