L9679P datasheet(40/272 Pages) STMICROELECTRONICS

部件名	L9679P

功能描述	Automotive advanced airbag IC for mid/high end applications

PDF	272 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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40 / 272 page

Start-up and power control

L9679P

40/272

DocID029275 Rev 1

Figure 12. ERBOOST regulator state diagram

6.4

Energy reserve capacitor charging and discharging circuits

The energy reserve capacitor connected to VER pin can be charged in an efficient way by

means of a current generator. Its capability is 50 mA nominal, so that for example a 10 mF

capacitor can be charged in approximately 4.8 s to 24 V. The current generator is activated

or deactivated by SPI command only while in ACTIVE mode. When not in ACTIVE mode,

the generator is always switched off in order to decouple ERBOOST node voltage from VER

reserve voltage.

Figure 13. ER charge state diagram

L9679P also offers a safe control to discharge the ER capacitor by means of a fixed current

generator. This discharge can be controlled via SPI command while not in SLEEP mode.

Furthermore, this discharge circuit is mutually exclusive with the ER charging circuit, to

avoid inefficient way of controlling the charge on the VER energy reserve capacitor.

L9679P 数据表(PDF) 40 Page - STMicroelectronics