L9788 datasheet(56/264 Pages) STMICROELECTRONICS

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Main relay driver (low-side driver)

L9788

56/264

DS12308 Rev 4

Main relay driver (low-side driver)

This driver is used to drive the main relay only.

The on/off status of the driver depends on the following sources of power on: KEY_IN

WK_IN WAKE_UP_TIMER POWER_HOLD (MSC), CAN see Table 20. The Main Relay

Driver can be also switched on/off by a MSC command protected by lock. This is intended to

use in the permanent battery supply scheme only if power up was done by wk_in/EOT/ CAN

according to Table 25. MSC micro commands protected by lock are available for fast on and

off diagnosis.

Figure 20. Main relay low-side driver stage

The low-side (main relay) can work down to VB_IN= VOFF_VB_IN, during cold crank

conditions. The driver has integrated diagnosis, with over-current and overtemperature

protection circuit during the driver on. The driver turn on/off slew-rate is internally controlled.

The Main Relay Driver on/off status is controlled by the power up/down modes or by the

msc commands according to Table 25.

These notes are linked to Table 25

GADG2911161143PS

LOAD L/R

Ground loss

detection

OC & OT protection

ON state

OL & STG detection

OFF state

Driver

MSC Command

VBAT

OUTx

PGND

MAIN RELAY DRIVER

L9788 Datasheet(PDF) 56 Page - STMicroelectronics