L9945 datasheet(125/144 Pages) STMICROELECTRONICS

125 / 144 page

Figure 35. OC detection through DSM or shunt measurement in high side configuration with PMOS

BATT34

HS PMOS

GNSP3

VBATT

SNGP3

DRN3

RPU

TjFET

RSH

PGND34

VOC

VPS

ADC

BCF

OC_Batt_comp_xx

Batt_fact

_config

OC_DS_Shunt_xx

Tj ADC

TCF

OC_Tem

p_comp

Others

OC_config_xx

VSENSE

BOARD

DAC

ΔT = TjFET - Tj

GADG1003171245PS

Note:

VOC compensation against temperature and battery variations is shown in Figure 35.

6.4

OFF state diagnostics

The following diagnostic codes can be set to the output OFF state:

•

The diagnostic code corresponding to normal operation while in OFF state is "No OL/STG/STB failure"

(110);

•

The "No failure" (100) code will be reported only once, after an ON->OFF transition, assuming that the "No

OC failure" latch was set while in ON state;

•

The "OL failure" (011) or "STG/STB failure" (010) codes are reported respectively in case of open load and

short to ground/battery failures.

Short To Battery (STB), Open Load (OL) and Short To Ground (STG) are part of the OFF state diagnostics. This

device measures the voltage on the output node Vout to determine if the output is shorted to battery/ground

(respectively for HS/LS configurations) or if the output node is floating (open load). Depending on channel

configuration, different faults can be detected:

•

LS diagnostics

–

Vout < VLVT indicates a STG (see Figure 36)

–

VLVT < Vout < VOL indicates an OL

–

Vout > VOL is a normal condition for LS configuration

L9945

Safety & diagnostics

DS12275 - Rev 10

page 125/144

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