400DAFBA2 datasheet(21/47 Pages) ONSEMI

21 / 47 page

NCP12400

www.onsemi.com

Figure 48. Ac Line Drop−out Timing Diagram

time

HV stop

time

VCC

time

DRV

VCC(on)

VCC(min)

Waits next

VccON before

starting

Brown−out

detected

time

VHV

HV timer elapsed

VHV(start)

VHV(stop)

Brown−out

condition

resets the

Internal Latch

tHV

When VHV crosses the VHV(start) threshold, the controller

can start immediately. When it crosses VHV(stop), it triggers

a timer of duration tHV, this ensures that the controller

doesn’t stop in case of line cycle drop−out.

When VHV crosses the VHV(start) threshold, the controller

starts when the VCC crosses the next VCC(on) event. When

it crosses VHV(stop), it triggers a timer of duration tHV, this

ensures that the controller doesn’t stop in case of line cycle

drop−out. The device restart after the ac line voltage

drop−out is protected to the parasitic restart initiated e.g. the

spikes induced at HV pin immediately after the device is

stopped by the residual energy in the EMI filter. The device

restart is allowed only after the 1st watch dog signal event.

The basic principle is shown at Figure 49 and detail of the

device restart is shown at Figure 50.

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