L9678P PMIC IC For Automotive Airbag System 64-Pin TQFP Package Power Management Chip With Energy Reserve And Sensor Interface

Introduction

The L9678P is a power management integrated circuit (PMIC) designed for emerging market applications of automotive user configurable airbag system. It provides energy reserve voltage, multiple linear regulators, battery voltage monitor and shutdown control, system voltage diagnostics, crossover switch, squib deployment drivers, safing logic, remote sensor interface, and integrated clock module. It works with SPC560Px microcontroller and an on-board acceleration sensor or PSI5 sensor to complete the base system design. It is compliant with AEC-Q100 standard and packaged in a 64-pin TQFP.

Features

Energy reserve voltage power supply: It uses a high frequency boost regulator (1.882 MHz) to derive the energy reserve voltage from the battery voltage. The output voltage is user selectable, either 23 V or 33 V ±5%. The energy reserve voltage is used to deploy the squibs in case of a crash event.

Multiple linear regulators: It offers two linear regulators (5 V and 7.2 V ±4%) with external pass transistors, and one fully integrated linear regulator (3.3 V ±4%). The user can use one of these regulators to supply the microcontroller. The input/output pins are compatible with both 5 V and 3.3 V ranges by dedicated supply pin VDDQ. The external pass transistors give the flexibility to easily address different current loads in case of different microcontrollers. The optional 7.2 V linear regulator can be used to supply the remote sensor interface.

Battery voltage monitor and shutdown control: It senses the battery voltage through the VBATMON pin and provides start-up and shutdown control for the system. Once the battery voltage drops below the minimum operating voltage, the device enables the integrated crossover switch to permit orderly shutdown. The device also supports wake-up control by external signals or internal timers.

System voltage diagnostics: It integrates an ADC to monitor the system voltage and provide diagnostic data via SPI interface. The system voltage includes the battery voltage, the energy reserve voltage, and the linear regulator outputs.

Crossover switch: It integrates a crossover switch to connect the energy reserve voltage to the squib deployment drivers when the battery voltage is too low. The crossover performance is max 3 Ω, 600 mA max.

Squib deployment drivers: It integrates four independent high and low side drivers to deploy the squibs at 25 V max. The drivers support 1.2 A @ 2 ms and 1.75 A @ 0.5/0.7 ms deployment profiles. The drivers also provide current monitoring, Rmeasure, STB, STG and leakage diagnostics, and high and low side driver FET tests via SPI interface.

Safing logic: It integrates a safing logic to monitor the inertial sensors (remote sensors via PSI-5 or on-board sensors via SPI) and determine if a crash event is in progress, thereby enabling deployment to occur. The parameters for sensor configuration and thresholds are user programmable via SPI interface. The safing logic also integrates a safing FET linear regulator (20 V/25 V nominal) to supply the safing circuit.

Remote sensor interface: It supports the PSI-5 remote sensor interface to receive external acceleration data from two channels. Both channels have independent decoders. The sensor data and diagnostics are available via SPI interface.

Integrated clock module: It integrates a clock module to provide a fixed clock signal for the microcontroller. The clock module provides the user the option of deleting the commonly used resonator or crystal.

Applications

The L9678P can be used for various emerging market applications of automotive user configurable airbag system, such as:

Low-end airbag system with on-board or remote sensors

Airbag system with basic or advanced features

Airbag system with single or dual firing loops

Airbag system with different squib types and deployment profiles

Datasheet

For more information about the L9678P, please refer to the datasheet provided by STMicroelectronics. The datasheet contains detailed specifications, electrical characteristics, functional descriptions, application circuits, and package information of the L9678P.