L9658 datasheet(29/64 Pages) STMICROELECTRONICS

29 / 64 page

L9658

Functional description

Doc ID 14219 Rev 3

29/64

device turns the low side driver off and terminate the diagnostic within the specified time,

tPROP_DLY.

–VSQL less than SGTH threshold voltage

–(VSQHx – VSQLx) greater than VI_TH

–VSQH greater than SBTH threshold voltage

The state of each comparator above is reported through SPI. When the device detects one

of the above conditions, the respective SPI status bit to indicate the condition is set. Any of

the above conditions will be considered as normal in a low side MOS diagnostic.

The low side driver is turned off when tTIMEOUT is expired. A fault detection filter, tFLT_DLY, is

provided to protect against short-transients on SQH and SQL pins.

Figure 16.

Low side diagnostic flow chart

TIMEOUT = 2ms

SPI Command:

Disconnect I

BIAS

SPI Command:

LS FET Test

FLT_DLY= 20μs

Note:

SPI Transmission and SPI

Command can be sent in

the same CS_D.

Turn on LS FET

END

Switch OFF LS FET

Disconnect I

BIAS

SPI Transmission

Clear V

I_TH, SBTH, and SGTH bits

SPI Response:

Send V

I_TH, SBTH and SGTH bits

SPI Command:

Disconnect I

BIAS

(SQH-SQL) > V

I_TH

SQH > SB

during t

FLT_DLY

SQL < SG

during t

FLT_DLY

Set SPI.Diag.SG

Set SPI.Diag.V

I_TH

Set SPI.Diag.SB

t > t

TIMEOUT

SQH < SB

AND

SQL > SG

Set SPI.Diag.SB

AND

Set SPI.Diag.SG

SPI Command:

D6..D4 == D2..D0

Set SPI.Diag.SB

AND

Set SPI.Diag.SG

AND

Set SPI.Diag.V

I_TH

SPI Command

Diag Mode D11=0

Cmd Mode Message

BEGIN

SQH > SB

during t

FLT_DLY

SPI Command:

Connect I

BIAS

SQL < SG

during t

FLT_DLY

Clear SBth and SGth bits

SPI Response:

Send SBth and SGth bits

Set SPI.Diag.SB

Set SPI.Diag.SG

SPI Transmission

Clear SPI.Diag.SG

Clear SPI.Diag.SB

SQH < SB

during t

FLT_DLY

SQL > SG

during t

FLT_DLY

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