Figure 14. DISABLE function – circuit details

During the disable condition, due to the absence of energy transferred from the auxiliary winding, the internal

HV-startup is intermittently turned on to keep the device supplied between VCC_OFF and VCC_ON.

Figure 15. DISABLE function – timing

5.9

Protections

A comprehensive set of protections is embedded to ensure a high level of reliability of the final application without

adding extra components and/or circuitry.

5.9.1

AC brown-in (BI function)

At startup, as soon as the VCC pin voltage reaches the VCC_ON turn-on threshold the device monitors the AC line

input voltage through the HV pin and starts the operation if the input voltage is higher than the VHVPK_BI brown-in

threshold (around 81 Vac). After the first startup, in case of a brown-out/brown-in cycle, as soon as the brown-in is

detected the internal HV-startup is turned on to bring VCC voltage to the turn-on threshold VCC_ON.

De-bounce time TDB_ACBI of 1 ms typ. is provided to avoid false triggering at the first startup. After that, the

de-bounce time is increased to 40 ms.

L4985

Protections

DS13769 - Rev 3

page 17/27