L9678P-S Integrated Circuit for Low-End Airbag Applications with High Frequency Boost Regulator, Linear Power Supplies, and PSI-5 Interface

L9678P-S is a system chip solution targeted for emerging market applications. It integrates a high frequency boost regulator, linear regulators, and battery monitor. It provides user configurable airbag and power supply system solutions. It can work with SPC560Px microcontroller and an on-board acceleration sensor or PSI5 sensor.

The L9678P-S has the following features and functions:

Energy reserve voltage power supply: The L9678P-S uses a high frequency boost regulator to generate the energy reserve voltage for the airbag deployment. The boost regulator operates at 1.882 MHz, which allows the use of low value and cheap inductance. The output voltage is user selectable, either 23 V or 33 V ±5%. The boost regulator has overcurrent and overvoltage protection, as well as soft-start and soft-stop functions.

Battery voltage monitor and shutdown control: The L9678P-S monitors the battery voltage through the VBATMON pin, which 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 crossover switch connects the energy reserve voltage to the system voltage, allowing the microcontroller and the airbag drivers to operate until the energy reserve voltage is depleted. The battery voltage monitor also provides wake-up control for the device, as well as diagnostic data through the SPI interface.

User configurable linear power supplies: The L9678P-S offers two linear regulators (5 V with external pass transistor and fully integrated 3.3 V) and one optional 7.2 V linear regulator with external pass transistor. 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 transistor gives 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. The linear regulators have overcurrent and thermal protection, as well as enable and disable functions.

PSI-5 remote sensor interface: The L9678P-S can receive external acceleration data from two PSI-5 remote sensors. The PSI-5 interface is a two-wire interface that provides power and communication to the sensors. The L9678P-S has two independent decoders for the PSI-5 channels, which can handle different sensor types and configurations. The sensor data and diagnostics are available via SPI. The PSI-5 interface has overcurrent and short-circuit protection, as well as programmable current limit and voltage level.

Safing logic: The L9678P-S has a safing logic that monitors the 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. The safing logic has programmable parameters for sensor configuration and thresholds, as well as diagnostic data through the SPI interface. The safing logic can also handle different deployment scenarios, such as single-stage, dual-stage, or multi-stage airbags, as well as pre-tensioners and belt force limiters.

Squib/pyroswitch/pyroswitch deployment: The L9678P-S has four independent high and low side drivers, capable of deploying squibs, pyroswitches, or pyroswitches at up to 25 V max. The drivers have overcurrent and short-circuit protection, as well as diagnostic data through the SPI interface. The drivers can also handle different deployment modes, such as single-fire, dual-fire, or multi-fire, as well as programmable firing time and current limit.

Hall-effect, resistive or switch sensor interface: The L9678P-S has a sensor interface that can be used to determine the state of external switch devices, such as buckle switches, seat track position sensors, weight sensors, deactivation switches, etc. The sensor interface can handle different sensor types, such as Hall-effect, resistive, or switch sensors, as well as programmable voltage level and current limit. The sensor interface has overcurrent and short-circuit protection, as well as diagnostic data through the SPI interface.

Integrated clock module: The L9678P-S has an integrated clock module that provides a fixed clock signal for the microcontroller. The clock module provides the user the option of deleting the commonly used resonator or crystal, thereby reducing the system cost and complexity. The clock module has programmable frequency and accuracy, as well as diagnostic data through the SPI interface.

The L9678P-S is packaged in a 64-pin LQFP (10x10) package. It is AEC-Q100 qualified and operates in the temperature range of -40°C to +125°C. It is suitable for low-end airbag applications in emerging markets, where cost and performance are the main drivers. For more information, please refer to the datasheet1 or contact the manufacturer.