TM
11-6625-3041-30/TO
33A1-8-908-12
1-26. MULTI VDC (A1) REGULATION (CONT)
As the dc supplies (including the feedback voltage) charge
Error
Amp
up, the output of the Error Amp at U3-6 decreases.
As the Error Amp output decreases on successive clock
cycles, the ramp voltage at U2-3 (required to turn on the
Switcher Crowbar) decreases.
With less and less ramp voltage required to turn off the
Switcher
Switcher, the Switcher turns off earlier and earlier (i.e, the
Switcher turns off with less and less current flowing through
it). This results in less and less energy being transferred to
the flyback secondaries.
Thus, as the dc supplies reach their proper value, they receive
less and less energy from the Switcher. In fact, they receive
only enough energy to keep them within 5 percent of their
proper value, as determined by the +5V and +10V supplies used
to provide the feedback voltage.
Because of the loads on the supplies, they are constantly dis-
charging, which requires the Switcher to supply some energy
on every Clock cycle.
1-39