L9978 - Multifunction IC for Automotive Engine Management | STMicroelectronics
MPN: L9978 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.25 | $112.50 |
| 100 | $10 | $1,000.00 |
| 500 | $9 | $4,500.00 |
| 1,000 | $8.1 | $8,100.00 |
L9978 Overview
A PMIC (Power Management Integrated Circuit) is a class of integrated circuits that manages power requirements of a host system. In automotive engine management, the L9978 consolidates several power rails and driver functions that would otherwise require multiple discrete components. This integration reduces board space, improves thermal performance, and enhances system reliability. The L9978 sits within the hierarchy of power management ICs, specifically as a multifunction automotive PMIC, which itself is a subset of application-specific power management solutions.
Key features of the L9978 include one pre-boost regulator, one pre-buck regulator, a linear 5V regulator with 1A output current, and three independent self-protected 5V tracking regulators with 150mA output each. Additionally, it provides five channels of pre-drivers for external FET drivers, with pre-drivers 1 and 3 configurable for O2H (oxygen sensor heater) loads using an external shunt resistor on the source of the external N-channel MOSFET. This flexibility allows the L9978 to support various engine management topologies.
The L9978 is engineered for ISO26262 compliance, which is critical for automotive functional safety. Its AEC-Q100 qualification ensures it meets stringent automotive quality and reliability standards. The device operates over an extended temperature range and includes comprehensive protection features such as overcurrent, overvoltage, and thermal shutdown, ensuring robust operation in harsh automotive environments.
Typical applications include engine control units (ECUs), transmission control units, and other automotive body control modules that require multiple regulated power rails and pre-driver outputs. The L9978 is particularly well-suited for gasoline and diesel engine management systems where precise control of fuel injectors, ignition coils, and oxygen sensor heaters is essential.
When designing with the L9978, careful attention must be paid to the external FET selection and the layout of the pre-driver outputs to minimize parasitic inductance and ensure proper switching behavior. The tracking regulators require appropriate output capacitors for stability, and the thermal pad of the LQFP-EP package should be connected to a solid ground plane for effective heat dissipation.
Drop-in alternatives for L9978 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with L9978 (same form factor and footprint) — differing in Operating Temperature Range, Package, MSL Level, Output Type, Switching Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9788
✅ Drop-In✓ In Stock
$2.7 / Unit
View Datasheet →L9788
✅ Drop-In✓ In Stock
$2.7 / Unit
View Datasheet →L9788
✅ Drop-In✓ In Stock
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View Datasheet →L9978 Maximum Ratings & Electrical Characteristics
| Number of Pre-Boost Regulators | 1 |
| Number of Pre-Buck Regulators | 1 |
| Linear 5V Regulator Output Current | 1 A |
| Number of Tracking Regulators | 3 |
| Tracking Regulator Output Current | 150 mA |
| Number of Pre-Driver Channels | 5 |
| Pre-Driver Configurability | Pre-driver 1&3 configurable for O2H load |
| Package | 100-LQFP-EP (14x14) |
| Qualification | AEC-Q100 |
| Functional Safety | Engineered for ISO26262 compliant system |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
L9978 Pin Configuration
| Pin 1 | VSUP — Main supply voltage |
| Pin 2 | GND — Ground |
| Pin 3 | VCC5 — 5V linear regulator output |
| Pin 4 | VCC5_TRK1 — Tracking regulator 1 output |
| Pin 5 | VCC5_TRK2 — Tracking regulator 2 output |
| Pin 6 | VCC5_TRK3 — Tracking regulator 3 output |
| Pin 7 | PRE_DRV1 — Pre-driver 1 output |
| Pin 8 | PRE_DRV2 — Pre-driver 2 output |
| Pin 9 | PRE_DRV3 — Pre-driver 3 output |
| Pin 10 | PRE_DRV4 — Pre-driver 4 output |
| Pin 11 | PRE_DRV5 — Pre-driver 5 output |
| Pin 12 | BOOST_OUT — Pre-boost regulator output |
| Pin 13 | BUCK_OUT — Pre-buck regulator output |
| Pin 14 | EN — Enable pin |
Typical Applications
L9978 is suitable for 6 applications: Engine Control Unit (ECU), Transmission Control Unit (TCU), Oxygen Sensor Heater Control, Fuel Injection System, Ignition Coil Driver, Body Control Module (BCM).
Engine Control Unit (ECU)
The L9978 is designed for automotive engine management systems, providing multiple regulated power rails and pre-driver outputs for controlling fuel injectors, ignition coils, and other actuators. Its integrated regulators ensure stable power supply to the microcontroller and sensors, while the pre-drivers enable efficient switching of external FETs. The AEC-Q100 qualification and ISO26262 support make it suitable for safety-critical engine control applications.
Recommended
Transmission Control Unit (TCU)
In transmission control units, the L9978 provides the necessary power management and pre-driver outputs for solenoid valves and actuators. The multiple tracking regulators ensure clean power for analog sensors, while the pre-boost and pre-buck regulators handle higher voltage rails. The device's robust protection features and automotive qualification make it ideal for TCU applications.
Recommended
Oxygen Sensor Heater Control
The L9978's pre-drivers 1 and 3 are configurable for O2H (oxygen sensor heater) loads, using an external shunt resistor on the source of the external N-channel MOSFET. This allows precise control of the heater current, ensuring optimal sensor performance and fast warm-up times. The integrated protection features prevent damage from overcurrent or short circuits.
Recommended
Fuel Injection System
The L9978 provides pre-driver outputs that can be used to control external FETs for fuel injectors. The pre-boost regulator ensures a stable higher voltage rail for injector peak-and-hold current profiles, while the tracking regulators supply clean power to the injector driver circuits. This enables precise fuel metering and improved engine efficiency.
Recommended
Ignition Coil Driver
The L9978's pre-drivers can be used to drive external FETs for ignition coil control. The device's robust design and protection features ensure reliable operation under high voltage and current conditions. The integrated regulators provide stable power to the ignition control circuitry, enhancing overall system reliability.
Recommended
Body Control Module (BCM)
While primarily designed for engine management, the L9978 can also be used in body control modules that require multiple regulated power rails and pre-driver outputs. Its compact 100-LQFP-EP package and integrated features help reduce board space and component count, making it a versatile solution for various automotive electronic control units.
Recommended
Recommended Products Summary
Engineering reference data for L9978 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9788 |
|---|---|---|
| Package | 100-LQFP-EP (14x14) | 100-LQFP-EP (14x14) - same |
| Brand | STMicroelectronics | STMicroelectronics |
| Number of Pre-Boost Regulators | 1 | 1 |
| Number of Pre-Buck Regulators | 1 | 1 |
| 5V Linear Regulator Output Current | 1 A | 1 A |
| Number of Tracking Regulators | 3 | 3 |
| Tracking Regulator Output Current | 150 mA | 150 mA |
| Number of Pre-Driver Channels | 5 | 5 |
Key Differentiators
- Integrated pre-boost and pre-buck regulators (vs L9788)
- Three independent tracking regulators (vs L9788)
- Configurable pre-drivers for O2H loads (vs L9788)
Design Notes
The L9978 is available in a 100-LQFP-EP (14x14) package with an exposed thermal pad. For proper heat dissipation, connect the thermal pad to a solid ground plane with multiple vias. Ensure adequate copper area on the PCB to keep the junction temperature within safe limits, especially when operating at high ambient temperatures in automotive environments.
Place decoupling capacitors close to the power supply pins (VSUP, VCC5, VCC5_TRK1-3) to minimize noise and ensure stable operation. Use low-ESR ceramic capacitors with appropriate voltage ratings. For the pre-driver outputs, keep the traces short and wide to reduce parasitic inductance and ensure proper switching of external FETs.
When configuring pre-drivers 1 and 3 for O2H loads, ensure the external shunt resistor is placed correctly on the source of the N-channel MOSFET. Incorrect placement can lead to inaccurate current sensing and potential damage to the oxygen sensor heater. Also, verify that the external FETs are properly selected for the required voltage and current ratings.
Compliance Information
AEC-Q100 qualified per STMicroelectronics product page. RoHS compliant per distributor listings.
