L6981 datasheet(17/49 Pages) STMICROELECTRONICS

Part #	L6981

Description	38 V, 1.5 A synchronous step-down converter with low quiescent current

PDF	49 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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17 / 49 page

6.5.1

Low consumption mode part number

The overvoltage protection continuously compares the FB pin with 120% nominal output voltage and enables

the low-side MOSFET at the beginning of the switching cycle keeping it active until 1.5 A typ. negative current

limitation is reached, in order to discharge the output capacitor.

The following graph shows the LCM part number behavior during an OVP event.

Figure 18. OVP event low consumption mode part number

Isw(t)

SW(t)

VOUT (t)

VOVP

VOVP_HYST

VOUT, LCM

ISKIP

IVY_SINK

ISKIP_LNM

VIN

VOUT

TON,min LS

Body Diode HS

As soon as the output voltage goes out of the OVP hysteresis (typ. 2%) the L6981 device sets the switching node

on high impedance. It restarts the switching activity accordingly with the main loop regulation of the peak current

mode architecture.

L6981

Overvoltage protection

DS13554 - Rev 1

page 17/49

L6981 Datasheet(PDF) 17 Page - STMicroelectronics