Operation descriptions

VIPER17

26/31

Equation 9

Equation 10

minimum mains and maximum load.

The BR pin is a high impedance input connected to high value resistors, thus it is prone to

pick up noise, which might alter the OFF threshold when the converter operates or gives

origin to undesired switch-off of the device during ESD tests.

It is possible to bypass the pin to ground with a small film capacitor (e.g. 1-10 nF) to prevent

any malfunctioning of this kind.

If the Brown-out function is not used the pin has to be connected to GND.

Figure 31. Brown-out protection: BR external setting and timing diagram

Rh

Rl

AC_OK Disable

BR

0.1V

VinOK

Vcc

+

-

0.45V

15u

HV Input bus

HV Input bus

VinOK

Vcc

(pin 3)

VDS

Vout

BR

0.45V

15 µA

t

t

t

t

t

t

t

HV Input bus

VinOK

Vcc

(pin 3)

VDS

Vout

0.45V

15 µA

t

t

t

t

t

t

t

BRHYST

BR

BR

INoff

BRHYST

INoff

INon

BRHYST

BRHYST

L

I

V

V

V

V

V

V

I

V

R

×

−

−

−

+

−

=

BRHYST

BRHYST

L

L

BRHYST

BRHYST

INoff

INon

H

I

V

R

R

I

V

V

V

R

+

×

−

−

=