L9678P datasheet(11/203 Pages) STMICROELECTRONICS

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L9678P, L9678P-S

Description

202

Description

The L9678P IC is a system chip solution targeted for emerging market applications. Base

system designs can be completed with the L9678P, SPC560Px microcontroller and an on-

board acceleration sensor or PSI5 sensor.

Energy reserve voltage is derived through a cost effective high frequency boost regulator.

High frequency operation allows the user to pick up low value and cheap inductance. The

voltage is programmable to 23 V or 33 V nominal.

Battery voltage is sensed through the VBATMON pin providing start-up and shutdown

control for the system. Once battery voltage drops below the minimum operating voltage,

the device enables the integrated crossover switch to permit orderly shutdown.

L9678P offers two linear regulators (5 V with external pass transistor and fully integrated

3.3 V). User can use one of these regulators to supply µC. Input/output pins are compatible

with both ranges by dedicated supply pin VDDQ. External pass transistor gives the flexibility

to easily address different current loads in case of different micro-controllers.

One optional 7.2 V linear regulator with external pass transistor can be used to supply

remote sensor interface.

External acceleration data is received through the PSI-5 remote sensor interface. Both

channels have independent decoders. Sensor data and diagnostics are available via SPI.

The safing logic monitors inertial sensors (remote sensors via PSI-5 or on-board sensors via

SPI) to determine if a crash event is in progress, thereby enabling deployment to occur.

Parameters for sensor configuration and thresholds are user programmable.

Squib deployment uses four independent high and low side drivers, capable of deploying at

25 V max. Diagnostic data control is provided through the SPI interface.

The Hall-effect, resistive or switch sensor interface can be used to determine the state of

external switch devices, such as buckle switches, seat track position sensors, weight

sensors, deactivation switches.

The integrated clock module provides a fixed clock signal for the microcontroller. The clock

module provides the user the option of deleting the commonly used resonator or crystal.

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