L9305 datasheet(36/107 Pages) STMICROELECTRONICS

36 / 107 page

The package option codification is stored inside NVM and verified at power up, in case the package option will not

allow for multiple fail safe pre-drivers the unused drivers will be kept disabled.

In case of CRC fault during NVM download the default configuration with only one pre-driver enabled will be

applied.

7.1

Fail safe predriver diagnostic

The Fail Safe pre-driver has a VDS monitoring that is used to protect the external FET in case of short circuit to

ground. Through SPI registers four different VDS thresholds are programmable (FSCONF register, bits D[1:0]).

Once FS_G0 is driven high, after a blanking time (T_FS_VDS_blank) to allow full turn-on of the external FET, the

device starts monitoring the falling differential voltage between FS_D0 and FS_S0: if the differential voltage does

not drop below the VDS voltage threshold within the over-current filter time (T_FS_VDS_flt), the device disables

the Fail Safe pre-driver and sets the VDS fault flag in the SERVFLT1 register, bit D[10].

The fault SPI bit is latched until read; once the fault condition disappears to re-enable the Fail Safe pre-driver, the

fault has to be cleared and the enable bit must be set again via SPI. The Fail Safe operation is inhibited until the

fault register is cleared.

7.2

Fail safe predriver electrical characteristics

4.75≤ VDD ≤ 5.5; 5.5 V ≤ VBATP ≤ 19 V; VBATP - 1 V ≤ FS_Dx ≤ VBATP+1 V; -40 °C ≤ Tj ≤ 175 °C unless

otherwise noticed. All voltages refer to AGND pin.

Table 21. Fail safe predriver electrical parameters

Symbol

Parameter

Test condition

Min Typ Max Unit

FS_ON

External FET gate driving for

ON state

FS_G – FS_S

–

FS_Gx,

FS_Sx

FS_OFF

External FET gate driving for

OFF state

FS_G – FS_S

–

FS_Gx,

FS_Sx

FS_Isource

FS current source capability

FS_G = 0 V

0.5

1.5

FS_Gx

FS_Isink

FS current sink capability

FS_G = VBATP

FS_Gx

FS_S_Ibias_IDLE

FS_S bias current from CP

supply in IDLE state

Fail safe Pre-driver enabled, CMD off,

FS_Dx = VBATP = 13V, VDD = 5V

-450 -400 -200

µA

FS_Sx

FS_S_Ibias_RUNNING

FS_S bias current from CP

supply in RUNNING state

Fail safe Pre-driver enabled, CMD on, VDD

= 5 V, FS_Dx = VBATP = 13 V

-300 -200 -100

µA

FS_Sx

FS_D_Ileak_dis

FS_D leakage current with

device in IDLE state

Fail safe Pre-driver disabled, FS_Dx =

VBATP = 13 V, FS_Sx = open, VDD = 0 V

-1

–

µA

FS_Dx

FS_Dx_Rpd

FS_Dx resistor toward FS_Sx

pin for VDS threshold

generation

Fail safe Pre-driver disabled, FS_Dx =

VBATP = 13 V, FS_Sx = 0 V, VDD = 0V

140

250

kΩ

FS_Dx,

FSx

FS_D_Ileak_idle

FS_D leakage current in IDLE

mode

Fail safe Pre-driver disabled, CMD on,

FS_Dx = VBATP = 13 V, VDD = 5 V

250

370

500

µA

FS_Dx

FS_D_Ileak_en_on

FS_D leakage current in ON

state

Fail safe Pre-driver enabled, CMD on,

FS_Dx = VBATP = 13 V, VDD = 5 V

140

250

340

µA

FS_Dx

FS_D_Ileak_en_on

FS_D leakage current in ON

state

Fail safe Pre-driver enabled, CMD off, FS_D

= VBATP = 13 V, VDD = 5 V

250

360

550

µA

FS_Dx

FS_VDS_00

VDS_threshold_0

FS_PREDRIVER_TH = 00

0.15 0.25 0.35

FS_Dx,

FS_Sx

FS_VDS_01

VDS_threshold_1

FS_PREDRIVER_TH = 01

0.4

0.5

0.6

FS_Dx,

FS_Sx

FS_VDS_10

VDS_threshold_2

FS_PREDRIVER_TH = 10

0.65 0.75 0.85

FS_Dx,

FS_Sx

FS_VDS_11

VDS_threshold_3

FS_PREDRIVER_TH = 11

0.9

1.1

FS_Dx,

FS_Sx

L9305

High side fail safe pre-driver

DS12774 - Rev 10

page 36/107

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