SCY99079ADR2G View Datasheet(PDF) - ON Semiconductor

Part Name

Description

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SCY99079ADR2G

PWM Current-Mode Controller for High-Power Universal Off-Line Supplies

ON Semiconductor 

VCC

VFB

IpFlag

Timer

Can be very

slow...

DAP018A/B/C/D/F

regulation

VCClatch

VCCreset

Duration given

by aux. cap.

Current loop

action keeps FB

OK (CC operation)

VCC(on)

VCC(min)

Drv

< 100ms

< 100ms

Figure 35. First Fault Mode Case

First fault mode case, the auxiliary winding collapses but feedback is still there (0.22 mF timer capacitor)

2. In the second case, the converter operates in

regulation, but the output is severely overloaded.

However, due to the bad coupling between the

power and the auxiliary windings, the controller

VCC does not go low. The peak current is pushed

to the maximum and the timer starts to count.

Upon completion, all pulses are stopped and

dual−startup hiccup mode is entered. If the fault

goes away, the SMPS resumes operation.

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