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Then the power is supplied to the Load. When Q
is ON, power is not output from the secondary
1
side. The output voltage is fed back in the control IC according to the error amp rectifier. Then
depending on how T
is controlled, stabilization occurs. Also, when the current load becomes
ON
too large, in order to decrease the voltage output, the increase in
is controlled and the
output voltage is stabilized.
Therefore, basically the timing: Ton/Toff of Q1 controls the output voltage.
[Surge Absorber Circuit]
This circuit is for absorbing surge voltage generated by the transformer.
[Control Circuit and Detecting Circuit]
The control circuit amplifies the output with increased voltage detected in the error detecting
circuit. Then it drives the main transistor.
In this power supply, the duty ratio is defined by changing the ON period of the main transistor.
This is shown as follows.
When the output voltage of the 24V circuit increases, the current of the photo coupler PC101
increases, the pulse width of the output control IC becomes narrower and the ON period of
Q101 becomes shorter.
[Over Current Limiter (O.C.L)]
The highest drain current (Q101) is limited by a limiter circuit (IC101) of 24V. The 24V output is
161
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