VIPER37

Operation description

Doc ID 022218 Rev 1

31/35

In order to enable the brownout function, the BR pin voltage must be higher than the

8.13

The device is protected against short-circuit of the secondary rectifier, short-circuit on the

secondary winding, or a hard-saturation of the flyback transformer. Such an anomalous

To distinguish a real malfunction from a disturbance (e.g. induced during ESD tests) a

“warning state” is entered after the first signal trip. If, in the subsequent switching cycle, the

signal is not tripped, a temporary disturbance is assumed and the protection logic is reset in

cycles, a real malfunction is assumed and the Power MOSFET is turned off.

The shutdown condition is latched as long as the device is supplied. While it is disabled, no

removed the device enters auto-restart mode. This behavior results in a low-frequency

intermittent operation (hiccup-mode operation), with very low stress on the power circuit.

See the timing diagram of

Figure 34.

Figure 34.

Timing diagram: hiccup-mode OCP

time

time

time

Hiccup-mode

Secondary diode

short circuit

Normal operation