Document Number: 002-08397 Rev. *A

Page 13 of 40

MB39C602

5. Power Down Sequencing

When AC power is removed from the AC line, the current does not flow to Secondary Winding even if HV MOSFET is switching.

The LED current is supplied from the output capacitance and decreases gradually. Similarly, the voltage at the VDD pin

decreases because the current does not flow into Auxiliary Winding. The switching stops and MB39C602 becomes shutdown

when the voltage at the VDD pin falls below the threshold voltage of UVLO.

UVLO threshold

UVLO threshold

UVLO threshold 8V