L9680 datasheet(40/277 Pages) STMICROELECTRONICS

部品番号	L9680

部品情報	Automotive advanced airbag IC for mid/high end applications

PDF	277 Pages

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メーカー	STMICROELECTRONICS [STMicroelectronics]

ホームページ	http://www.st.com

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40 / 277 page

Start-up and power control

L9680

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DocID029257 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 65 mA nominal, so that for example a 10 mF

capacitor can be charged in approximately 4 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

L9680 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.

L9680 データシート(PDF) 40 Page - STMicroelectronics