L9788 datasheet(123/264 Pages) STMICROELECTRONICS

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DS12308 Rev 4

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L9788

Pre-drivers - ExtFET (MOS_Gate1/2/3/4/5) - PRD[1:5]

263

When the Predriver is used for O2H load no blanking time is applied to OVC detection.The

OVC dectection is done reading the voltage drop on this external Rshunt by the VDS

comparator of another predriver (not used).

This means that when the Predriver 1 and Predriver 3 are used for O2H load the Predriver 2

and Predriver 4 can't be used.

Bit O2H_PDRV = CONFIG_REG_16_1[7:6]= 00: all 5 predriver channels can be used

Bit O2H_PDRV = CONFIG_REG_16_1[7:6]= 11:



predriver 2 & Predriver 4 can't be used;



predriver 1 & predriver3 work with low gate current and sink current (typ = 250 µA);



it is possible to read the Overcurrent on external Rshunt of Predriver1&3 using the Vds

comparator of Drain2 and Drain4;



Predriver 5 works as in O2H_PDRV = CONFIG_REG_16_1[7:6]= 00.

There is a dedicated ground pin PDR_GND used for source pin of External Mos or ground

connection of External shunt resistor. The internal voltage reference for VDS comparator

threshold (Vth_VDS_xxx parameter) is connected to this ground pin PDR_GND. Application

has to connect this PDR_GND pin to the source of external MOS or ground of external

shunt resistor in order to obtain a good accuracy of overcurrent threshold.

Pre-driver after power up is OFF, output LOW.

Figure 49. PreDriver3 configured for O2H load bit O2H_PDRV_3 =

CONFIG_REG_16_1[7] = 1:

Figure 50. PreDriver1 configured for O2H load bit O2H_PDRV_1 =

CONFIG_REG_16_1[6] = 1:

VDS3comp

VDS4comp

OFF Diag3

NOT USED

Rshunt

GADG0512161223PS

VDS1comp

VDS2comp

OFF Diag1

NOT USED

Rshunt

GADG0512161253PS

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