R6986 datasheet(18/62 Pages) STMICROELECTRONICS

Part #	R6986

Description	38 V, 2 A synchronous step-down switching regulator

PDF	62 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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18 / 62 page

Functional description

R6986

18/62

DocID026996 Rev 2

Figure 6. Soft-start phase with precharged COUT

During normal operation a new soft-start cycle takes place in case of:



Thermal shutdown event



UVLO event



The device is driven in INH mode

The soft-start capacitor is discharged with a 0.6 mA typ. current capability for 1 msec time

max. For complete and proper capacitor discharge in case of fault condition, a maximum

CSS = 67 nF value is suggested.

The application example in Figure 7 shows how to enable the R6986 and perform the soft-

start phase driven by an external voltage step, for example the signal from the ignition

switch in automotive applications.

Figure 7. Enable the device with external voltage step

RUP

RDWN

CSS

SS/INH

ISS CH

VSTEP

Ignition switch

1 A typ in INHIBIT

4 Atyp in SS

ISS DISCH

UVLO

Thermal shutdown

= 600 Atyp

R6986 Datasheet(PDF) 18 Page - STMicroelectronics