L9977 - Automotive Dual H-Bridge Driver | STMicroelectronics
MPN: L9977 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.5 | $6.50 |
| 10 | $5.85 | $58.50 |
| 100 | $5.2 | $520.00 |
| 500 | $4.68 | $2,340.00 |
| 1,000 | $4.16 | $4,160.00 |
L9977 Overview
An H-bridge motor driver is a power management IC that allows bidirectional control of a DC motor by selectively switching four transistors in an 'H' configuration. It is a fundamental building block in automotive electronics, enabling functions such as window lift, seat adjustment, and mirror positioning. The L9977 belongs to the family of motor drivers, which are part of the broader power management IC category, and it is specifically optimized for the harsh automotive environment.
Key features of the L9977 include a low quiescent current of 50 µA in standby mode, making it suitable for always-on automotive modules. It offers overcurrent, overtemperature, and short-circuit protection, ensuring robust operation in fault conditions. The device also features a serial peripheral interface (SPI) for advanced diagnostics and control, allowing the microcontroller to monitor and configure the driver in real time. The PowerSO-36 package with exposed pad ensures efficient heat dissipation, enabling continuous operation at high currents.
From a technical perspective, the L9977 utilizes a smart power technology that integrates logic, protection, and power stages on a single die. This reduces external component count and improves reliability. The SPI interface supports daisy-chaining of multiple devices, simplifying PCB layout in multi-motor systems. The device is AEC-Q100 qualified, meeting the stringent quality and reliability standards required for automotive applications.
Typical applications include automotive body control modules, power window lift systems, seat position adjustment, and mirror folding. The L9977's ability to handle high currents and its robust protection features make it ideal for driving DC motors in these systems. Additionally, its low standby current is critical for battery-powered vehicles to minimize parasitic drain.
When designing with the L9977, ensure proper PCB layout with adequate copper area for thermal management, especially when driving high currents continuously. The SPI interface should be configured correctly to enable fault reporting and diagnostic functions. Also, consider adding external flyback diodes or using the integrated freewheeling diodes to protect against inductive load transients.
Drop-in alternatives for L9977 — 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 L9977 (same form factor and footprint) — differing in Package, Protection Features.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L9958
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$6.2 / Unit
View Datasheet →L9907
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
L9908
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
DRV8701
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
L9977 Maximum Ratings & Electrical Characteristics
| Number of Channels | 2 (Dual H-Bridge) |
| Output Current per Channel | 5.5 A (continuous) |
| Supply Voltage Range | 5.5 V to 36 V |
| Quiescent Current (Standby) | 50 µA |
| Control Interface | SPI |
| Protection Features | Overcurrent, Overtemperature, Short-Circuit |
| Package | PowerSO-36 |
| Mounting Type | Surface Mount |
| Operating Temperature Range | -40°C to +150°C |
| AEC-Q100 Qualified | Yes |
| RoHS Compliant | Yes |
| Standby Mode | Yes |
| Diagnostic Features | SPI fault reporting |
| Thermal Shutdown | Yes |
| Undervoltage Lockout | Yes |
L9977 Pin Configuration
| Pin 1 | VS — Battery supply voltage |
| Pin 2 | OUT1 — H-bridge 1 output |
| Pin 3 | OUT2 — H-bridge 1 output |
| Pin 4 | GND — Ground |
| Pin 5 | OUT3 — H-bridge 2 output |
| Pin 6 | OUT4 — H-bridge 2 output |
| Pin 7 | GND — Ground |
| Pin 8 | SCK — SPI clock |
| Pin 9 | SDI — SPI data input |
| Pin 10 | SDO — SPI data output |
| Pin 11 | CSN — SPI chip select (active low) |
| Pin 12 | EN — Enable pin |
| Pin 13 | DIAG — Diagnostic output |
| Pin 14 | VDD — Logic supply voltage |
| Pin 15 | GND — Ground |
| Pin 16 | VS — Battery supply voltage |
Typical Applications
L9977 is suitable for 6 applications: Power Window Lift, Seat Position Adjustment, Mirror Folding, HVAC Blower Control, Industrial Automation, Robotics.
Power Window Lift
The L9977 drives the DC motor for power windows, providing bidirectional control and high current capability. Its SPI interface allows precise control and diagnostics, while the low standby current minimizes battery drain when the window is not in use. The device's overcurrent and short-circuit protection ensure safe operation in case of a stalled motor or wiring fault. With a supply voltage range of 5.5V to 36V, it can operate directly from the car battery. The PowerSO-36 package with exposed pad helps dissipate heat generated during repeated window operations. Compared to relays, the L9977 offers smoother speed control and reduced electromagnetic interference. Its AEC-Q100 qualification guarantees reliability in automotive temperature extremes. The integrated freewheeling diodes protect against inductive spikes from the motor, eliminating the need for external diodes. The SPI interface enables the body control module to monitor motor current and detect obstructions, enhancing safety. Overall, the L9977 simplifies the power window module design while improving performance and safety.
Recommended
Seat Position Adjustment
The L9977 is ideal for seat position adjustment systems, where multiple DC motors are used to adjust the seat forward, backward, up, and down. Its dual H-bridge configuration allows independent control of two motors, such as one for horizontal movement and one for vertical tilt. The high output current of 5.5A per channel ensures sufficient torque for moving the seat under load. The SPI interface enables the seat control module to read diagnostic information, such as overcurrent conditions, which can indicate a mechanical blockage. The device's thermal shutdown protection prevents damage during prolonged operation. The low quiescent current is beneficial for vehicles with start-stop systems, where the seat module remains powered during engine off periods. The PowerSO-36 package's exposed pad aids in heat dissipation, ensuring reliable operation in confined spaces under the seat. The L9977's robust protection features reduce the need for external components, simplifying the PCB design. Its AEC-Q100 qualification ensures long-term reliability in the automotive environment. Overall, the L9977 provides a compact and efficient solution for seat adjustment systems.
Recommended
Mirror Folding
The L9977 can be used to control the folding and unfolding of side mirrors. The dual H-bridge allows independent control of the left and right mirrors, or one H-bridge for the folding motor and the other for the mirror adjustment motor. The device's low standby current is crucial for mirrors that remain powered even when the car is off, to allow folding via remote key. The SPI interface provides feedback on mirror position and fault conditions, enabling the body control module to detect if a mirror is obstructed. The overcurrent protection prevents damage if the mirror is manually forced. The wide supply voltage range accommodates voltage fluctuations during engine start. The PowerSO-36 package's thermal performance ensures reliable operation in extreme temperatures. The L9977's integrated protection features reduce external component count, saving PCB space. Its AEC-Q100 qualification ensures durability over the vehicle's lifetime. Overall, the L9977 offers a reliable and efficient solution for mirror control systems.
Recommended
HVAC Blower Control
The L9977 can drive the blower motor in automotive HVAC systems, providing variable speed control via PWM. The dual H-bridge allows control of both the blower motor and a damper actuator. The high current capability supports blower motors that draw several amps. The SPI interface enables the HVAC control module to set the speed and read diagnostic information, such as overcurrent due to a blocked air filter. The device's low standby current is beneficial for maintaining settings when the ignition is off. The thermal shutdown protection prevents overheating during prolonged high-speed operation. The wide supply voltage range ensures operation during cold cranking conditions. The PowerSO-36 package's exposed pad aids in heat dissipation, which is critical for continuous operation. The L9977's integrated freewheeling diodes protect against inductive spikes from the motor. Its AEC-Q100 qualification ensures reliability in the harsh automotive environment. Overall, the L9977 provides a robust solution for HVAC blower control.
Recommended
Industrial Automation
The L9977 is also suitable for industrial automation applications, such as controlling conveyor belts, pumps, and actuators. Its wide supply voltage range (5.5V to 36V) allows it to be used in 24V industrial systems. The dual H-bridge enables control of two motors or one motor with bidirectional speed control. The SPI interface provides easy integration with industrial microcontrollers and PLCs. The device's robust protection features, including overcurrent and overtemperature, ensure reliable operation in harsh industrial environments. The low quiescent current is beneficial for battery-powered industrial equipment. The PowerSO-36 package's thermal performance allows continuous operation at high currents. The L9977's AEC-Q100 qualification, while designed for automotive, also indicates high reliability suitable for industrial use. The integrated freewheeling diodes protect against inductive loads. Overall, the L9977 offers a cost-effective solution for industrial motor control applications.
Recommended
Robotics
The L9977 can be used in robotics to drive DC motors for wheel movement, arm actuation, and other mechanisms. Its dual H-bridge allows independent control of two motors, enabling differential drive for robots. The high output current supports motors with high torque requirements. The SPI interface enables precise speed and direction control from a robot's main controller. The device's protection features prevent damage from motor stalls or wiring faults. The low quiescent current is beneficial for battery-powered robots to extend battery life. The wide supply voltage range accommodates various battery configurations. The PowerSO-36 package's thermal performance ensures reliable operation during intensive robot movements. The L9977's integrated freewheeling diodes protect against back-EMF from the motors. Its AEC-Q100 qualification, while automotive-focused, indicates high reliability suitable for robotics. Overall, the L9977 provides a compact and efficient motor driver solution for robotics applications.
Recommended
Recommended Products Summary
Engineering reference data for L9977 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9958 | L9907 | L9908 | DRV8701 |
|---|---|---|---|---|---|
| Package | PowerSO-36 | PowerSO-36 | PowerSO-36 | PowerSO-36 | PowerSO-36 |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | Texas Instruments |
| Number of H-Bridges | 2 | 1 | 2 | 2 | 1 |
| Output Current per Channel | 5.5 A | 5.5 A | 6 A | 8 A | 4 A |
| Supply Voltage Range | 5.5V to 36V | 5.5V to 36V | 5.5V to 36V | 5.5V to 36V | 4.5V to 45V |
| SPI Interface | Yes | Yes | Yes | Yes | No |
| AEC-Q100 Qualified | Yes | Yes | Yes | Yes | Yes |
| Quiescent Current (Standby) | 50 µA | 50 µA | 60 µA | 70 µA | 1 mA |
Key Differentiators
- Dual H-bridge in a single package (vs L9958)
- Higher output current than DRV8701 (vs DRV8701)
- Lower standby current than DRV8701 (vs DRV8701)
Design Notes
The L9977 in PowerSO-36 package can dissipate significant heat when driving 5.5A continuously. Ensure adequate copper area on the PCB, especially around the exposed pad, to keep the junction temperature below 150°C. Use thermal vias to connect the pad to inner ground planes. For continuous operation at high currents, consider forced air cooling or a heatsink.
Place the L9977 close to the motor connectors to minimize trace inductance. Use wide traces for the motor supply and output pins to handle high currents. Decouple the VS pin with a 100nF ceramic capacitor and a 10µF electrolytic capacitor near the device. For the logic supply VDD, use a 100nF capacitor. Ensure the SPI lines are routed away from high-current traces to avoid noise coupling.
Do not exceed the absolute maximum supply voltage of 40V. Ensure the SPI interface is properly configured to avoid unintended motor activation. The EN pin must be pulled high to enable the outputs; a floating EN pin can cause unpredictable behavior. When driving inductive loads, the integrated freewheeling diodes are sufficient, but for very high currents, external Schottky diodes may be added to reduce power dissipation.
Compliance Information
AEC-Q100 qualified per STMicroelectronics product page. RoHS compliant. REACH compliance assumed based on ST's policy.
