The actual level of the ramp voltage needed to be summed into the current
ramp signal at the end of the maximum on-time is
The components connected between the emitter-follower and the current-
sensing filter capacitor can be thought of as a resistor divider. An additional
0.17V needs to appear at pin 7 (through a 1K resistor) so the amount of current
that must be contributed to that node is 0.17V/1K which is 170mA. The capac-
itive coupling of the PNP to pin 7 essentially centers the oscillator waveform
upon the current ramp. So,
Designing the voltage feedback loop
The voltage feedback loop must be isolated from the primary to the secondary.
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