VNF1248F datasheet(42/79 Pages) STMICROELECTRONICS

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Table 33. Current sense undervoltage thresholds

Symbol

Parameter

Test conditions

Min.

Typ.

Max.

Unit

CS_UV

Current sense undervoltage TH1 L2H

CS_UV = 00

2.78

2.87

Current sense undervoltage TH1 H2L

CS_UV = 00

2.98

3.08

3.18

tCS_UV_DEGLITCH

Current sense fault deglitch filtering

HS_GATE ON

-10%

10%

μs

tCS_UV_RETRY_TIME

Current sense fault clear autoretry time

CR#3[23:22] = 00

-5%

100

μs

CR#3[23:22] = 01

-5%

250

μs

CR#3[23:22] = 10

-5%

500

μs

CR#3[23:22] = 11

-5%

1000

μs

In case of fault detection, after a de-glitch filtering time of 10 μs , VNF1248F switches off the output, sets to 1 the

proper status flag in SR#1 → CS_UV register bit (visible also by SPI GSB.DIAGS bit) and waits for a time, defined

by CR#3→CS_UV_RETRY_T register field, before clearing the fault (status flag set to 0) and trying to restart

again the output. If the fault is not detected (after another 10 μs filtering time elapse), output channel is kept on

and device behaves as before fault occurrence, otherwise output channel is turned off again, fault is latched

(SR#1 → CS_UV flag set, DIAG pin driven low) and VNF1248F waits for external intervention (by SPI command

or DIN input) to clear fault and restart driving the external FET.

Protection is active when external FET is turned on.

11.9

Reverse battery and loss of ground

For 12 V applications, the external MOSFET is either switched off or remains off and the device protects itself in

the event of a reverse battery connection or loss of ground (GND).

Note that an external component is required for reverse battery protection, as detailed in Table 63.

VNF1248F

Protections

DS14109 - Rev 7

page 42/79

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