NCP1028 ON Semiconductor, NCP1028 Datasheet - Page 15

• Manufacturer Part Number: NCP1028
• Description: High?voltage Switcher For Medium Power Offline Smps
• Manufacturer: ON Semiconductor

Fault Condition – Output Too Low
feedback is ensured by a two-loop control imposing either
constant output voltage (CV) or constant output current
(CC), for instance in a battery charger. In CC mode, the
output voltage falls down below the original target but the
feedback loop is kept closed by the CC controller. For that
This particular mode of operation occurs when the
Figure 28. In this particular case, the output goes low but the timer is not started since the FB pin is still held
by the optocoupler. Due to the UVLO circuit, the controller safely stops operation at V
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NCP1028
15
reason, the controller becomes un-able to detect a real
output short-circuit since Ipflag will never be asserted.
Due to a good winding coupling, the primary side auxiliary
collapsing will ensure a proper fault detection via the
UVLO internal circuit. Figure 28 depicts this operating
way.
CC
= VCC
(min)
.