L9942 - Automotive Dual Low-Side Driver | STMicroelectronics
MPN: L9942 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 | $1.82 | $1,820.00 |
Drop-in alternatives for L9942 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:
L9942XP
β Drop-Inπ Reference alternative (not in catalog)
L9940
β‘ Same Packageπ Reference alternative (not in catalog)
VN7004
β‘ Same Packageπ Reference alternative (not in catalog)
L9942 Maximum Ratings & Electrical Characteristics
| Number of Outputs | 2 |
| Output Type | Low-Side |
| Supply Voltage Range | 4.5 V to 40 V |
| Maximum Output Current per Channel | 1.5 A |
| Quiescent Current (Standby) | 50 Β΅A |
| Operating Temperature Range | -40Β°C to +150Β°C |
| Package | PowerSO-20 |
| Mounting Type | Surface Mount |
| Interface | SPI (up to 5 MHz) |
| Diagnostic Output | Yes (SPI fault reporting) |
| Overcurrent Protection | Yes |
| Thermal Shutdown | Yes |
| Thermal Resistance (ΞΈJA) | 35 Β°C/W |
| RoHS Status | Compliant |
| AEC-Q100 Qualified | Yes |
L9942 Pin Configuration
| Pin 1 | OUT1 β Low-side output 1 |
| Pin 2 | OUT2 β Low-side output 2 |
| Pin 3 | GND β Ground |
| Pin 4 | VCC β Supply voltage |
| Pin 5 | SCK β SPI clock |
| Pin 6 | SDI β SPI data input |
| Pin 7 | SDO β SPI data output |
| Pin 8 | CS β Chip select |
| Pin 9 | DIAG β Diagnostic output |
| Pin 10 | EN β Enable input |
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
L9942 is suitable for 6 applications: Automotive Body Control Module, Relay Driver, LED Lighting Control, Industrial Automation, Power Distribution, Smart Home Systems.
Automotive Body Control Module
The L9942 is ideal for automotive body control modules (BCMs) where multiple low-side loads such as relays, solenoids, and LEDs need to be switched. Its dual outputs allow driving two loads independently, while the SPI interface provides diagnostics for fault detection. The wide supply voltage range (4.5V to 40V) accommodates both 12V and 24V vehicle systems. The AEC-Q100 qualification ensures reliability in harsh automotive environments. In a typical BCM, the L9942 can control power windows, door locks, and seat adjustment relays. The low quiescent current (50 Β΅A) helps reduce battery drain when the vehicle is off. The overcurrent and thermal protection features prevent damage to the device and loads, enhancing system safety.
Recommended
Relay Driver
The L9942 can drive two relays directly, making it suitable for industrial control panels and automotive relay boxes. Each output can sink up to 1.5A, which is sufficient for most automotive relays. The built-in flyback diode protection (external) is recommended to handle inductive kickback. The SPI interface allows the microcontroller to read relay status and detect faults such as open or shorted loads. In a typical relay driver application, the L9942 is placed between the microcontroller and the relay coils, with a flyback diode across each coil. The device's thermal shutdown protects against overheating when driving multiple relays simultaneously. The PowerSO-20 package provides adequate heat dissipation for continuous operation.
Recommended
LED Lighting Control
The L9942 can be used to control LED lighting in automotive and industrial applications. Each output can drive a string of LEDs with a constant current sink, and the SPI interface allows dimming and fault detection. The wide supply voltage range supports various LED configurations. In automotive lighting, the L9942 can control daytime running lights, tail lights, and interior lighting. The overcurrent protection prevents damage from shorted LEDs. The device's low quiescent current is beneficial for always-on lighting systems. The thermal shutdown ensures safe operation even when driving high-power LEDs. The PowerSO-20 package allows for compact PCB designs.
Recommended
Industrial Automation
In industrial automation, the L9942 can drive solenoids, valves, and actuators in process control systems. Its dual outputs allow controlling two devices independently, and the SPI interface provides real-time diagnostics. The wide operating temperature range (-40Β°C to +150Β°C) makes it suitable for harsh industrial environments. The device can be used in PLC output modules to drive external loads. The overcurrent and thermal protection features ensure reliable operation in continuous-duty applications. The PowerSO-20 package is compatible with standard surface-mount assembly processes. The low quiescent current is advantageous in battery-powered industrial sensors.
Recommended
Power Distribution
The L9942 can be used in power distribution units to switch loads on and off. Its dual outputs allow controlling two independent power rails. The SPI interface enables remote monitoring and control, making it suitable for smart power distribution systems. The device's wide supply voltage range supports various power bus voltages. In automotive power distribution, the L9942 can control power to different subsystems. The diagnostic features help identify faulty loads, reducing downtime. The thermal shutdown protects the device from overload. The PowerSO-20 package provides good thermal performance for high-current switching.
Recommended
Smart Home Systems
The L9942 can be used in smart home systems to control lighting, locks, and other loads. Its dual outputs allow controlling two devices, and the SPI interface enables integration with home automation controllers. The low quiescent current is ideal for battery-powered devices. The device's wide supply voltage range supports various power sources. In a smart home hub, the L9942 can drive relays for lighting and door locks. The diagnostic features provide feedback on load status, enhancing system intelligence. The PowerSO-20 package is suitable for compact PCB designs. The AEC-Q100 qualification ensures reliability in consumer applications.
Recommended
Recommended Products Summary
Engineering reference data for L9942 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9942XP | L9940 | VN7004 |
|---|---|---|---|---|
| Package | PowerSO-20 | PowerSO-20 | PowerSO-20 | PowerSO-20 |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Number of Outputs | 2 | 2 | 1 | 1 |
| Output Type | Low-Side | Low-Side | Low-Side | High-Side |
| Supply Voltage Range | 4.5V to 40V | 4.5V to 40V | 4.5V to 40V | 4.5V to 40V |
| Maximum Output Current per Channel | 1.5A | 1.5A | 1.5A | 1.5A |
| SPI Interface | Yes | Yes | Yes | No |
| AEC-Q100 Qualified | Yes | Yes | Yes | Yes |
Key Differentiators
- Dual low-side outputs in a single package (vs L9940)
- SPI interface for diagnostics and control (vs VN7004)
- Low-side driver topology (vs VN7004)
Design Notes
The PowerSO-20 package has a thermal resistance of 35Β°C/W. When driving 1.5A per channel at 12V, power dissipation is approximately 18W per channel, leading to a junction temperature rise of 630Β°C. This is not feasible without a heatsink. For continuous operation above 0.5A, use a heatsink or large copper area. For example, at 0.5A, dissipation is 6W, requiring a heatsink with thermal resistance below 10Β°C/W to keep junction temperature below 150Β°C.
Place a 100nF ceramic capacitor close to the VCC pin and a 10Β΅F electrolytic capacitor for bulk decoupling. For inductive loads, place a flyback diode (e.g., 1N4007) across each load to clamp voltage spikes. Ensure the PCB traces for OUT1 and OUT2 are wide enough to handle the output current without excessive voltage drop.
Do not exceed the absolute maximum supply voltage of 40V. Ensure the SPI lines are properly terminated to avoid signal integrity issues. The EN pin must be pulled high to enable the outputs; if left floating, the outputs may be disabled. Always initialize the SPI interface before enabling outputs to avoid unintended switching.
Compliance Information
RoHS compliant and AEC-Q100 qualified per STMicroelectronics product page. Halogen-free status not specified in provided data.
