L9788 datasheet(39/264 Pages) STMICROELECTRONICS

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DS12308 Rev 4

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L9788

Operation behavior

263

Figure 11. Timer enabled for a new detection

Note:

Same mechanism applied to WAKE_IN_DET, WAKE_UP_EOT_DET and

WAKE_UP_CAN_DET.

3.2

Secure Engine Off (SEO) function

Secure Engine Off functional switches off, with a certain delay from KEY_OFF, the engine

by a hardware path and without any dependence on external micro and no matter what are

the other conditions (e.g. the power hold mode).

After the falling edge of the filtered KEY_IN a programmable counter is started. The clock of

the timer does not depend on any micro clock or function.

SEO_OUT pin is the output of KEY_IN after a T_SEO_DELAY (CONFIG_REG3 [6:7])delay.

Input pin INJ_ENA enables the internal drivers as listed above (INJ[1:4], is configured), so

the configuration of enable/disable of SEO function is realized by hardware in the following

way:

For PFI application, SEO_OUT is connected to INJ_ENA, when key goes off internal drivers

can be switched off.

For GDI application, SEO_OUT is connected to GDI injector driver enable if present,

INJ_ENA is always enabled. When key off, only the external GDI injector driver is switched

off.

During SEO time the external micro can switch on/off the drivers

SEO output is implemented with a push pull output stage, the T_SEO_DELAY can be

programmed according to Table 14.

GADG2511160723PS

WK_IN pin

WAKE_CAN_DET

WAKE_IN_DET

Impulse timer

Tfin_wk

The time-out of impulse timer

clears the WAKE_IN_DET

Table 13. Finish wake timer electrical characteristics

Symbol

Parameter

Min

Typ

Max

Unit

Tfin_wk

Finish wake timer

0.94

1.06

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