L9954 - SPI Controlled Relay Driver | STMicroelectronics | Automotive
MPN: L9954 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.5 | $8.50 |
| 10 | $7.65 | $76.50 |
| 100 | $6.8 | $680.00 |
| 500 | $6.12 | $3,060.00 |
| 1,000 | $5.5 | $5,500.00 |
L9954 Overview
A relay driver is a specialized power management IC that provides the necessary current and voltage to energize relay coils, enabling the control of high-power loads such as motors, lamps, and solenoids through low-power logic signals. In automotive systems, relay drivers are essential for managing body control modules, lighting systems, and power distribution, where they replace discrete transistor circuits with a more integrated, reliable, and diagnostic-capable solution. The L9954 belongs to the family of smart power switches, which combine power MOSFETs with protection, diagnostic, and communication features.
Key features of the L9954 include SPI (Serial Peripheral Interface) for configuration and diagnostics, which allows a microcontroller to control and monitor each output channel individually. The device provides overcurrent, overtemperature, and open-load detection, enhancing system reliability. It also features a low quiescent current in standby mode, critical for automotive battery conservation. The outputs are protected against short circuits and can be configured for PWM (Pulse Width Modulation) control, enabling dimming or speed control of connected loads.
Technically, the L9954 is built using STMicroelectronics' BCD (Bipolar-CMOS-DMOS) technology, which integrates high-voltage power stages with low-voltage logic and analog circuits on a single chip. This architecture allows for efficient power handling and precise control. The SPI interface supports daisy-chaining of multiple devices, simplifying wiring in complex systems. The device is available in a PowerSO-36 package, which provides excellent thermal performance for high-current applications.
Typical applications include automotive body control modules, where the L9954 drives relays for lights, wipers, and door locks; industrial PLCs (Programmable Logic Controllers) for controlling actuators and valves; and smart power distribution units in vehicles. Its ability to handle high currents and provide comprehensive diagnostics makes it ideal for safety-critical systems.
When designing with the L9954, ensure proper thermal management by connecting the exposed pad to a large copper area on the PCB. The SPI lines should be kept short and shielded to avoid noise, and the supply pins must be decoupled with ceramic capacitors close to the device. The device's standby mode should be utilized to minimize battery drain when the system is idle.
Drop-in alternatives for L9954 — 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 L9954 (same form factor and footprint) — differing in Operating Temperature, Output Current per Channel, Standby Current.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9953
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
TLE6228GP
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
L9954 Maximum Ratings & Electrical Characteristics
| Number of High-Side Drivers | 10 |
| Number of Low-Side Drivers | 4 |
| Output Current per Channel | 500 mA |
| Total Output Current | 5 A |
| Logic Supply Voltage | 4.5 V to 5.5 V |
| Power Supply Voltage | 5.5 V to 28 V |
| Interface | SPI |
| Diagnostics | Overcurrent, Overtemperature, Open-load |
| Standby Current | 10 µA (typical) |
| PWM Capability | Yes |
| Package | PowerSO-36 |
| Mounting Type | Surface Mount |
| Operating Temperature | -40°C to +150°C |
| RoHS Status | Compliant |
| AEC-Q100 | Qualified |
L9954 Pin Configuration
| Pin 1 | VS — Power supply voltage |
| Pin 2 | OUT1 — High-side output 1 |
| Pin 3 | OUT2 — High-side output 2 |
| Pin 4 | OUT3 — High-side output 3 |
| Pin 5 | OUT4 — High-side output 4 |
| Pin 6 | OUT5 — High-side output 5 |
| Pin 7 | OUT6 — High-side output 6 |
| Pin 8 | OUT7 — High-side output 7 |
| Pin 9 | OUT8 — High-side output 8 |
| Pin 10 | OUT9 — High-side output 9 |
| Pin 11 | OUT10 — High-side output 10 |
| Pin 12 | GND — Ground |
| Pin 13 | OUT11 — Low-side output 1 |
| Pin 14 | OUT12 — Low-side output 2 |
| Pin 15 | OUT13 — Low-side output 3 |
| Pin 16 | OUT14 — Low-side output 4 |
| Pin 17 | VDD — Logic supply voltage |
| Pin 18 | SCK — SPI clock |
| Pin 19 | SI — SPI data input |
| Pin 20 | SO — SPI data output |
| Pin 21 | CS — Chip select |
| Pin 22 | RST — Reset |
| Pin 23 | EN — Enable |
| Pin 24 | GND — Ground |
Typical Applications
L9954 is suitable for 6 applications: Automotive Body Control Module, Industrial PLC Output Module, Smart Power Distribution Unit, Automotive Lighting Control, HVAC Actuator Control, Battery Management System.
Automotive Body Control Module
The L9954 is ideal for automotive body control modules, where it drives relays for lights, wipers, and door locks. Its 10 high-side and 4 low-side drivers provide ample channels for various loads, while SPI diagnostics enable real-time monitoring of each output. The device's AEC-Q100 qualification ensures reliability in harsh automotive environments, and its low standby current helps conserve battery power when the vehicle is off. In a typical body control module, the L9954 is controlled by a microcontroller via SPI, which configures each output and reads back fault status. The high-side drivers can directly switch lamps and motors, while the low-side drivers are used for grounding relay coils. The device's overcurrent and overtemperature protection prevent damage to the module and connected loads. Compared to discrete relay driver circuits, the L9954 reduces component count and PCB area, improving system reliability and reducing assembly cost.
Recommended
Industrial PLC Output Module
In industrial PLCs, the L9954 is used to drive relays and actuators in output modules. Its SPI interface allows a PLC CPU to control and diagnose each channel, simplifying wiring and reducing the number of discrete components. The device's wide power supply range (5.5 V to 28 V) accommodates various industrial voltage rails, and its PWM capability enables proportional control of valves or heaters. The L9954's robust protection features, including overcurrent and overtemperature shutdown, ensure safe operation in industrial environments. In a typical PLC output module, the L9954 is placed on a daughterboard with a connector for field wiring. The SPI lines are isolated using digital isolators to protect the PLC logic from industrial noise. The device's open-load detection helps identify broken wires or disconnected loads, reducing downtime. Compared to using multiple discrete drivers, the L9954 offers a compact, cost-effective solution with built-in diagnostics.
Recommended
Smart Power Distribution Unit
The L9954 is well-suited for smart power distribution units in vehicles and industrial systems, where it manages power to various loads with individual control and protection. Its 14 outputs can be configured to switch loads such as lights, fans, and solenoids, while SPI diagnostics provide real-time status of each channel. The device's low standby current is beneficial for systems that remain partially powered when idle. In a smart power distribution unit, the L9954 is typically controlled by a central ECU via SPI, which can turn loads on/off and monitor for faults. The device's high-side drivers are used for positive-side switching, while low-side drivers can be used for negative-side switching or as ground references. The L9954's thermal shutdown prevents overheating in high-current scenarios. Compared to traditional fuse boxes, the L9954 enables intelligent power management, reducing wiring complexity and improving system reliability.
Recommended
Automotive Lighting Control
The L9954 is used in automotive lighting control systems to drive relays for headlights, taillights, and interior lights. Its high-side drivers can directly switch lamps, and PWM capability allows for dimming functions. The device's open-load detection is crucial for detecting burnt-out bulbs, enabling warning messages to the driver. In a typical lighting control module, the L9954 is controlled by a body control module via SPI, which sets each output to on/off or PWM mode. The device's overcurrent protection prevents damage from short circuits, and its thermal shutdown ensures safe operation under high ambient temperatures. Compared to using discrete MOSFETs, the L9954 simplifies the design and reduces component count. Its AEC-Q100 qualification ensures reliability in automotive environments.
Recommended
HVAC Actuator Control
The L9954 is suitable for controlling HVAC actuators in automotive and building automation systems. It can drive relays for blower motors, damper actuators, and valve solenoids. The device's PWM capability enables variable speed control of motors, improving energy efficiency. In an automotive HVAC system, the L9954 is controlled by the climate control module via SPI, which adjusts the blower speed and damper positions. The device's diagnostics help detect stuck actuators or open circuits. Its wide supply voltage range accommodates both 12V and 24V systems. Compared to using multiple discrete drivers, the L9954 offers a compact solution with integrated protection and diagnostics.
Recommended
Battery Management System
The L9954 can be used in battery management systems (BMS) to control relays for cell balancing, pre-charge circuits, and disconnect switches. Its high-side drivers can switch the relay coils, while low-side drivers can be used for ground switching. The device's SPI interface allows the BMS controller to monitor and control each relay, ensuring safe operation. In a typical BMS, the L9954 is controlled by a battery management IC via SPI, which activates relays for charging and discharging. The device's overcurrent and overtemperature protection are essential for safety. Its low standby current is beneficial for minimizing battery drain when the system is idle. Compared to using discrete drivers, the L9954 simplifies the design and improves reliability.
Recommended
Recommended Products Summary
Engineering reference data for L9954 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9953 | TLE6228GP |
|---|---|---|---|
| Package | PowerSO-36 | PowerSO-36 | PowerSO-36 |
| Brand | STMicroelectronics | STMicroelectronics | Infineon |
| High-Side Drivers | 10 | 8 | 8 |
| Low-Side Drivers | 4 | 4 | 4 |
| Output Current per Channel | 500 mA | 500 mA | 500 mA |
| SPI Interface | Yes | Yes | Yes |
| AEC-Q100 | Qualified | Qualified | Qualified |
Key Differentiators
- More high-side drivers than L9953 (vs L9953)
- Cross-brand alternative with similar features (vs TLE6228GP)
- AEC-Q100 qualification (vs TLE6228GP)
Design Notes
The L9954 in PowerSO-36 package can dissipate significant power when driving multiple loads at high current. Ensure the exposed pad is soldered to a large copper area on the PCB to enhance heat dissipation. For example, driving 10 channels at 500 mA each with a 2V drop results in 10W dissipation, requiring a thermal pad area of at least 4 cm². Use thermal vias to connect the pad to inner and bottom layers for improved thermal performance.
Place decoupling capacitors (100 nF ceramic) close to the VDD and VS pins to filter high-frequency noise. Use a 10 µF electrolytic capacitor on the VS pin for bulk energy storage. Keep SPI lines (SCK, SI, SO, CS) short and route them away from high-current output traces to avoid noise coupling. Consider using series resistors on SPI lines to reduce ringing.
Do not exceed the absolute maximum ratings for supply voltages (VS up to 40V). Ensure the logic supply (VDD) is stable and within 4.5V to 5.5V. When using PWM control, ensure the PWM frequency is within the device's specified range to avoid excessive switching losses. Always initialize the device via SPI after power-up to configure outputs and clear any fault flags.
Compliance Information
RoHS compliant and AEC-Q100 qualified per STMicroelectronics product page. Halogen-free status not specified in available data.