L9978-TR - Automotive Quad Low-Side Driver | STMicroelectronics
MPN: L9978-TR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.28 | $228.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.85 | $1,850.00 |
Drop-in alternatives for L9978-TR β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
L9978
β Drop-Inπ Reference alternative (not in catalog)
TLE6228GP
β Drop-Inπ Reference alternative (not in catalog)
MC33289
β Drop-Inπ Reference alternative (not in catalog)
L9978-TR Maximum Ratings & Electrical Characteristics
| Number of Channels | 4 |
| Output Type | Low-Side Open-Drain |
| Supply Voltage Range | 4.5 V to 36 V |
| Maximum Output Current per Channel | 1.2 A |
| Quiescent Current (Standby) | 50 Β΅A |
| Rise Time | 5 Β΅s |
| Fall Time | 5 Β΅s |
| Switching Frequency | 0 Hz to 100 kHz |
| Thermal Resistance (ΞΈJA) | 35 Β°C/W |
| Operating Temperature Range | -40 Β°C to +150 Β°C |
| Package | PowerSO-20 |
| Mounting Type | Surface Mount |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| AEC-Q100 Qualification | Qualified |
| Interface | SPI |
| Protection Features | Overcurrent, Overtemperature, Short-Circuit |
L9978-TR Pin Configuration
| Pin 1 | OUT1 β Low-side output channel 1 |
| Pin 2 | OUT2 β Low-side output channel 2 |
| Pin 3 | OUT3 β Low-side output channel 3 |
| Pin 4 | OUT4 β Low-side output channel 4 |
| Pin 5 | GND β Ground |
| Pin 6 | VCC β Supply voltage |
| Pin 7 | SCK β SPI clock input |
| Pin 8 | SDI β SPI data input |
| Pin 9 | SDO β SPI data output |
| Pin 10 | CS β SPI chip select |
| Pin 11 | IN1 β Input control for channel 1 |
| Pin 12 | IN2 β Input control for channel 2 |
| Pin 13 | IN3 β Input control for channel 3 |
| Pin 14 | IN4 β Input control for channel 4 |
| Pin 15 | FAULT β Fault flag output (active low) |
| Pin 16 | NC β No connect |
| Pin 17 | NC β No connect |
| Pin 18 | NC β No connect |
| Pin 19 | NC β No connect |
| Pin 20 | NC β No connect |
| Pin PAD | Exposed Pad β Thermal pad, connect to ground |
Safe Operating Area (SOA) & Thermal Characteristics
No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.
Typical Applications
L9978-TR is suitable for 6 applications: Automotive Body Control Module, Industrial PLC Output Stage, Automotive Lighting Control, Relay and Solenoid Driver, LED Matrix Display Driver, Power Distribution Switch.
Automotive Body Control Module
The L9978-TR is ideal for automotive body control modules (BCMs) where it drives exterior and interior lighting, relays, and solenoids. Its AEC-Q100 qualification and wide supply range (4.5V to 36V) ensure reliable operation in 12V and 24V vehicle systems. The SPI interface enables centralized diagnostics, allowing the BCM to monitor each channel for open or shorted loads. With a 1.2A per channel output, it can directly drive LED modules with PWM dimming, while the low 50 Β΅A standby current minimizes battery drain when the vehicle is off. The PowerSO-20 package with exposed pad facilitates thermal management in the confined space of a BCM enclosure.
Recommended
Industrial PLC Output Stage
In industrial programmable logic controllers (PLCs), the L9978-TR serves as a robust output stage for driving actuators, valves, and indicator lamps. Its 4.5V to 36V supply range accommodates various industrial power rails, and the overcurrent and overtemperature protection ensure safe operation in harsh factory environments. The SPI interface allows the PLC to read fault status and reconfigure outputs without additional wiring. The fast 5 Β΅s rise/fall times enable precise timing for high-speed switching applications. The device's wide operating temperature range (-40Β°C to +150Β°C) makes it suitable for unheated factory floors and outdoor installations.
Recommended
Automotive Lighting Control
The L9978-TR is well-suited for automotive lighting control, including headlamps, tail lamps, and interior lighting. Each channel can drive up to 1.2A, sufficient for LED modules or incandescent bulbs. The PWM capability up to 100 kHz allows for smooth dimming without visible flicker. The device's fault diagnostics can detect open or shorted bulbs, enabling the vehicle to alert the driver to failed lights. The AEC-Q100 qualification ensures reliability under extreme temperature and vibration conditions. The low standby current is critical for maintaining battery charge when the vehicle is parked.
Recommended
Relay and Solenoid Driver
The L9978-TR can directly drive relays and solenoids in automotive and industrial systems. Its open-drain outputs can sink the coil current (up to 1.2A) and include freewheeling protection to handle inductive kickback. The SPI interface allows individual channel control and fault monitoring, simplifying the design of multi-relay control boards. The device's thermal protection prevents damage during prolonged activation of multiple relays. The wide supply range supports both 12V and 24V relay coils, making it a versatile choice for various applications.
Recommended
LED Matrix Display Driver
The L9978-TR can be used to drive LED matrix displays in automotive dashboards or industrial signage. Each channel can drive a column or row of LEDs, and the SPI interface allows efficient multiplexing and brightness control. The fast switching speed enables high refresh rates without ghosting. The device's current sinking capability (1.2A per channel) is sufficient for driving multiple LEDs in parallel. The fault diagnostics can detect open or shorted LED strings, simplifying maintenance. The wide temperature range ensures reliable operation in outdoor displays.
Recommended
Power Distribution Switch
The L9978-TR can function as a power distribution switch in automotive or industrial systems, enabling or disabling power to various subsystems. Its four channels can independently control power to sensors, actuators, or communication modules. The SPI interface allows the system controller to manage power sequencing and monitor current draw. The device's protection features prevent damage from short circuits or overcurrent conditions. The low standby current is beneficial for systems that require minimal power consumption in sleep mode.
Recommended
Recommended Products Summary
Engineering reference data for L9978-TR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9978 | TLE6228GP | MC33289 |
|---|---|---|---|---|
| Package | PowerSO-20 | PowerSO-20 | PowerSO-20 | PowerSO-20 |
| Brand | STMicroelectronics | STMicroelectronics | Infineon | NXP Semiconductors |
| Number of Channels | 4 | 4 | 4 | 4 |
| Supply Voltage Range | 4.5V to 36V | 4.5V to 36V | 4.5V to 36V | 4.5V to 36V |
| Output Current per Channel | 1.2A | 1.2A | 1.2A | 1.2A |
| Interface | SPI | SPI | SPI | SPI |
| AEC-Q100 | Qualified | Qualified | Qualified | Qualified |
| Standby Current | 50 Β΅A | 50 Β΅A | [DATA_NEEDED] | [DATA_NEEDED] |
Key Differentiators
- Low standby current of 50 Β΅A (vs TLE6228GP)
- AEC-Q100 qualified (vs MC33289)
- SPI interface with advanced diagnostics (vs TLE6228GP)
Design Notes
The L9978-TR has a thermal resistance (ΞΈJA) of 35 Β°C/W. When driving all four channels at 1.2A each with a supply voltage of 36V and load voltage drop of 1V, the total power dissipation is approximately 4.8W, resulting in a junction temperature rise of 168Β°C above ambient. To maintain junction temperature below 150Β°C, ensure adequate PCB copper area and thermal vias connected to the exposed pad. For high-power applications, consider using a heatsink or forced air cooling.
Place a 100 nF ceramic decoupling capacitor as close as possible to the VCC pin (pin 6) and a 10 Β΅F bulk capacitor at the supply input to handle inductive load switching transients. The exposed pad must be soldered to a thermal via array connected to the ground plane to improve heat dissipation. Keep SPI signal traces short and shielded to minimize noise coupling.
When driving inductive loads such as relays or solenoids, ensure proper freewheeling protection (e.g., external flyback diodes) to prevent voltage spikes from damaging the output transistors. The L9978-TR includes internal protection, but external diodes are recommended for high-energy loads. Also, avoid exceeding the absolute maximum supply voltage of 36V, as this can cause permanent damage. Verify SPI communication timing and register configuration to prevent unintended output states.
Compliance Information
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualified for automotive applications. Halogen-free status not specified in provided data.
