L9396 datasheet(37/109 Pages) STMICROELECTRONICS

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DS12539 Rev 6

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L9396

Pre-drivers

108

Pre-drivers

4.1

Fail safe pre-driver

The device integrates a pre-driver of an external FET for fail safe purposes. It can be used

as a HS pre-driver in case the external FET is used as a switch. The device controls the fail

safe pre-driver in On/Off via SPI. The function remains active while no internal voltage faults

or watchdog faults are detected.

This pre-driver implements a monitor against over current thanks to the diagnostics on

drain-source monitoring of the external FET (in case of overcurrent SPI bit 15 of

DRV_CONTROL_1 register goes high). If charge pump level goes below the disable

voltage, the pre-driver is turned off. When the level returns above the disable voltage, the

pre-driver returns to normal operation.

Table 17. Fail Safe pre-driver electrical characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Units

VDG_ON

VDG On voltage

(VDG-VDS)@-0.1mA

5.2

VDG_OFF

VDG Off voltage

(VDG-VDS)@0.1 mA

Rpd_VDG_VDS

Pull down resistor at VDG-

VDS

-130

270

kΩ

VDG_Isource

VDG current source

V(VDG)=V(VDS)

V(CP)– V(VDG)=2V

0.2

VDG_Isink

VDG current sink

V(VDG)-V(VDS)=1V

QFS_turn-on_00

QFS turn-on threshold

voltage

V(VDBATT) – V(VDS)

VDS_TH=’00’

0.25

0.75

QFS_turn-on_01

QFS turn-on threshold

voltage

V(VDBATT) – V(VDS)

VDS_TH=’01’

0.75

1.25

QFS_turn-on_10

QFS turn-on threshold

voltage

V(VDBATT) – V(VDS)

VDS_TH=’10’

1.25

1.8

QFS_turn-on_11

QFS turn-on threshold

voltage

V(VDBATT) – V(VDS)

VDS_TH=’11’

1.75

2.4

IVDBATT_ds

VDBATT leakage current

for drain-source monitor

FAIL SAFE DRIVER

ENABLE=0

µA

tQFS_ON

Filter time of QFS turn-on

guaranteed by scan

µs

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