L9779WD-SPI datasheet(30/141 Pages) STMICROELECTRONICS

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Functional description

L9779WD-SPI

30/141

DocID027721 Rev 2

Smart reset circuit monitors VB over voltage and generates RST signal if the over voltage

lasts more than tVBOV2. When over voltage lasts more than tVBOV1 and less than

tVBOV2, RST is not asserted, but all drivers are switched off without losing any

configuration. In both cases the flag VB_OV is latched and resets every Read Diag

operation.

When RST is asserted to reset the µC, also all logic will be reset except logic involved in

reset management, power up management, and power down management units. As a

consequence all flags are cleared except those set by the smart reset unit, all drivers are

disabled except the low battery drivers, all configuration registers are cleared and OUT_DIS

bit goes to 1. A more detailed description of the module under reset can be found in the next

table. The table summaries also relations with other conditions that switch off drivers and

regulator.

Table 8. Internal reset

Event

RST

driven

low

Logic under reset

Logic not reset

Power-up/down

manager output

Information

FLAG

Power down

Yes

Internal registers

Interfaces drivers

LB interfaces drivers

LB internal registers

CAN & K-LINE & VRS

Smart reset function

Power-up/down

manager

MRD=OFF

VDD5=OFF

V3V3=OFF

VTRACK1,2=OFF

N/A

Power latch

+KEY_ON rising

edge

Yes

For

TNL

Internal registers

Interfaces drivers

LB interfaces drivers

LB internal registers

CAN & K-LINE & VRS

Smart reset function

Power-up/down

manager

MRD=ON

VDD5=ON

V3V3=ON

VTRACK1,2=ON

TNL_RST

VDD5 under

voltage

t<THOLD

Yes

Internal registers

Interfaces drivers

CAN & K-LINE & VRS

LB interfaces drivers

LB internal registers

Smart reset function

Power-up/down

manager

MRD=ON

VDD5=ON

V3V3=ON

VTRACK1,2=ON

CRK_RST

VDD5 under

voltage

t>THOLD

Yes

Internal registers

Interfaces drivers

LB interfaces drivers

LB internal registers

CAN & K-LINE & VRS

Smart reset function

Power-up/down

manager

MRD=ON

VDD5=ON

V3V3=ON

VTRACK1,2=ON

VDD5UV_

RST

VDD5 over voltage

Interfaces drivers

Internal registers

LB interfaces drivers

LB internal registers

CAN & K-LINE & VRS

Smart reset function

Power-up/down

manager

MRD=ON

VDD5=ON

V3V3=ON

VTRACK1,2=ON

VDD5_OV

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