L9908 datasheet(69/153 Pages) STMICROELECTRONICS

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Figure 42. Shoot-Through diagnosis on PWM inputs: functional operation

Note:

PWM STD Filter integrates INHn/INLn timing overlap on multiple PWM periods, in this way STD Fault on PWM

inputs can be detected also in case minimum timing overlaps are spread over multiple and not adjacent periods.

The second diagnosis level consists in a dedicated digital counter for each half bridge (HS/LS couple) set/reset by

the logic NOR of the HS/LS VGS comparators and integrates the time interval where the HS and the LS are on

together.

If HSn_OFF=LSn_OFF=’0’ occurs for an interval longer than T_stp_vgs_flt the flag STP_VGS_n is set. The error

flag remains set until the failure condition is removed and the flag is cleared by the SPI command.

Figure 43. Shoot-through protection on Ext. FET Vgs functional operation

Note:

VGS STD Filter integrates Vgs_LSn/Vgs_HSn timing overlap on multiple PWM periods, in this way STD Fault on

Ext. FET Vgs can be detected also in case minimum timing overlaps are spread over multiple and not adjacent

periods.

The STD diagnosis can be disabled on the single half bridge by a dedicated SPI bit as follows:

Table 63. Shoot-Through Protection on PWM inputs enable bit

STPn_PWM_DIS

Description

Shoot-through protection on PWM input enabled (Default)

Shoot-through protection on PWM input disabled

L9908

Half bridges gate drivers

DS13546 - Rev 3

page 69/153

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