L9680 datasheet(13/277 Pages) STMICROELECTRONICS

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L9680

Description

276

Description

The L9680 is an advanced airbag system chip solution targeted for mature airbag market

and integrated safety markets. This device is family compatible with the L9678 and L9679

devices. Safety system integration is enabled through higher power supply currents and

integrated active wheel speed sensor interface. The active wheel speed interface is shared

with the PSI-5 satellite interface to create a generic remote safety sensor interface

compliant to both systems.

High frequency power supply design allows further cost reduction by using smaller and less

expensive external components. All switching regulators operate at 1.882 MHz while buck

converters have integrated synchronous rectifiers.

Additional attention is given to system integrity and diagnostics. The reserve capacitor is

electrically isolated from the boost regulator by a 65 mA nominal fixed current source,

controlling in-rush an additional capacitor discharge fixed current source is integrated to

diagnose the reserve capacitor value and ESR. The same current sources can be used to

discharge the capacitor at shutdown.

Thanks to low quiescent current, the device can be directly connected to battery. In this way,

the device start-up and shutdown are controlled through the wake-up input function. The

power supply and crossover function are controlled automatically through the internal state

machine.

The user can select both ECU logic voltage (VCC at 3.3 V or 5.0 V) and energy reserve

output voltage (at either 23 V or 33 V). Deployment voltage is set to a maximum of 25 V for

all profiles and can be controlled through external safing switch circuit using the high side

safing switch reference enabled through the system SPI interface or the arming logic.

L9680 데이터시트(PDF) 13 Page - STMicroelectronics