No.

Name

Function

18

VCC

Supply voltage of both the signal part of the IC and the gate-drivers. A bypass capacitor to GND is

necessary to sustain the IC during startup and low power modes.

The voltage on the pin is internally clamped to protect the internal circuits from temporary excessive supply

voltages.

19

N.C.

The pin is not internally connected to isolate the high-voltage section and ease compliance with safety

regulations (creepage distance) on the PCB.

20

VAC

High-voltage startup generator input.

The pin has to be connected directly to the mains voltage through two dedicated diodes.

If the voltage on the pin is higher than 50 V, an internal current source charges the capacitor connected

between the pin VCC and GND until the voltage on the VCC pin reaches the startup threshold.

Normally, the generator is re-enabled when the voltage on the VCC pin falls below the UVLO threshold.

The pin is also used as the line voltage sensing input.

This pin is internally connected to a 20 MΩ resistor divider. It is used for all line sense related functions: the

AC brown-out, surge detection, line disconnection, input voltage feed-forward, line synchronization.

When a line disconnection is detected, the internal current source is activated to discharge the X-capacitor.

STNRG011A

Pin function

DS13973 - Rev 2

page 7/31