L99SM81V - Automotive Stepper Motor Driver | STMicroelectronics
MPN: L99SM81V ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9 | $9.00 |
| 10 | $6.5 | $65.00 |
| 100 | $5.75 | $575.00 |
| 500 | $5.5 | $2,750.00 |
| 1,000 | $5.25 | $5,250.00 |
L99SM81V Overview
A stepper motor driver is a power management IC that converts digital step and direction commands into the precise current sequences needed to rotate a stepper motor in controlled increments. It sits between a microcontroller and the motor, translating low-power logic signals into high-current drive signals. In the system hierarchy, a stepper motor driver is a type of motor driver, which falls under power management ICs, which are part of the broader category of analog and mixed-signal semiconductors.
Key features of the L99SM81V include a programmable microstepping resolution up to 1/16 step, integrated current sensing with no external sense resistors, and a SPI interface for configuration and diagnostics. It also features overcurrent, overtemperature, and undervoltage protection, along with a low quiescent current in standby mode, which is critical for automotive battery conservation. The device is AEC-Q100 qualified, ensuring reliability across the -40°C to +150°C junction temperature range.
The L99SM81V uses a proprietary current-control architecture that combines a constant-current chopper with a programmable decay mode, enabling smooth and quiet motor operation. The integrated current sensing eliminates the need for external sense resistors, reducing BOM cost and PCB area. The SPI interface allows real-time monitoring of fault conditions and precise adjustment of motor parameters, making it a flexible solution for complex automotive motion control.
Typical applications include headlamp leveling systems, where precise positioning is required for optimal beam alignment, HVAC flap control for cabin comfort, and instrument cluster stepper motors for gauge indication. The wide supply voltage range and robust protection features make it ideal for direct battery connection in 12 V automotive systems.
When designing with the L99SM81V, ensure adequate PCB copper area for thermal dissipation, especially when driving high currents continuously. The SPI interface should be isolated from high-current traces to minimize noise coupling. Proper decoupling capacitors on the supply pins are essential to maintain stable operation during motor transients.
Drop-in alternatives for L99SM81V — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
L99SM81VQ6TR
📋 Reference alternative (not in catalog)
L99SM81VQ6
📋 Reference alternative (not in catalog)
DRV8825
📋 Reference alternative (not in catalog)
A4988
📋 Reference alternative (not in catalog)
L99SM81V Maximum Ratings & Electrical Characteristics
| Motor Type | Bipolar Stepper |
| Output Current per Phase | 1.2 A |
| Supply Voltage Range | 6 V to 28 V |
| Microstepping Resolution | Up to 1/16 step |
| Control Interface | SPI |
| Current Sensing | Integrated, no external sense resistors |
| Protection Features | Overcurrent, Overtemperature, Undervoltage |
| Operating Junction Temperature | -40°C to +150°C |
| Package | 40-QFN (6x6 mm) |
| Mounting Type | Surface Mount |
| Qualification | AEC-Q100 |
| RoHS Status | Compliant |
| Step/Direction Inputs | Yes |
L99SM81V Pin Configuration
| Pin 1 | OUT1A — Motor phase A output |
| Pin 2 | OUT1B — Motor phase A output |
| Pin 3 | OUT2A — Motor phase B output |
| Pin 4 | OUT2B — Motor phase B output |
| Pin 5 | VM — Motor supply voltage |
| Pin 6 | GND — Ground |
| Pin 7 | VDD — Logic supply voltage |
| Pin 8 | SCLK — SPI clock |
| Pin 9 | SDI — SPI data input |
| Pin 10 | SDO — SPI data output |
| Pin 11 | CSN — SPI chip select (active low) |
| Pin 12 | STEP — Step input |
| Pin 13 | DIR — Direction input |
| Pin 14 | EN — Enable input |
| Pin 15 | DIAG — Diagnostic output |
Typical Applications
L99SM81V is suitable for 6 applications: Headlamp Leveling Systems, HVAC Flap Control, Instrument Cluster Stepper Motors, Adaptive Front Lighting Systems, Active Grille Shutters, Industrial Automation.
Headlamp Leveling Systems
The L99SM81V provides precise positioning for headlamp leveling, ensuring optimal beam alignment. Its micro-stepping capability up to 1/16 step allows smooth and accurate adjustment, while the integrated current sensing eliminates external sense resistors, reducing BOM cost. The wide supply voltage range (6V to 28V) handles automotive battery fluctuations, and the AEC-Q100 qualification ensures reliability in harsh environments. The SPI interface enables real-time diagnostics, allowing the ECU to monitor motor health and adjust leveling dynamically. With overcurrent and overtemperature protection, the driver safeguards the system during fault conditions, making it ideal for this safety-critical application.
Recommended
HVAC Flap Control
In HVAC systems, the L99SM81V drives stepper motors that control air distribution flaps. Its programmable micro-stepping allows precise airflow regulation, enhancing passenger comfort. The integrated current sensing and protection features ensure reliable operation in the automotive cabin environment. The SPI interface allows the climate control unit to adjust flap positions smoothly and detect faults, such as a stuck flap, via stall detection. The low standby quiescent current helps conserve battery power when the vehicle is off. The compact 40-QFN package fits into space-constrained HVAC control modules, and the wide supply voltage range accommodates varying battery conditions.
Recommended
Instrument Cluster Stepper Motors
The L99SM81V drives stepper motors in instrument clusters for gauge indication, such as speedometers and tachometers. Its micro-stepping capability ensures smooth needle movement, reducing vibration and noise. The integrated current sensing provides accurate torque control, and the SPI interface allows the cluster microcontroller to set parameters and read diagnostics. The AEC-Q100 qualification ensures long-term reliability in the dashboard environment, which experiences temperature extremes and vibration. The wide supply voltage range (6V to 28V) handles voltage transients from the vehicle's electrical system. The compact package and low BOM count make it an efficient solution for cluster designs.
Recommended
Adaptive Front Lighting Systems
The L99SM81V enables adaptive front lighting systems that adjust headlamp beams based on steering angle and vehicle speed. Its high micro-stepping resolution allows precise beam positioning, improving nighttime visibility. The integrated current sensing and protection features ensure reliable operation in varying thermal conditions. The SPI interface enables real-time adjustments and diagnostics, allowing the system to respond quickly to driving conditions. The wide supply voltage range and AEC-Q100 qualification make it suitable for under-hood or headlamp module environments. The compact package helps reduce the size of the lighting control module.
Recommended
Active Grille Shutters
The L99SM81V drives stepper motors in active grille shutters to optimize aerodynamics and engine cooling. Its micro-stepping capability allows precise positioning of the shutters, improving fuel efficiency. The integrated current sensing and stall detection help detect blockage or ice buildup, enabling the system to respond appropriately. The SPI interface allows the engine control unit to adjust shutter position based on speed and temperature. The wide supply voltage range and protection features ensure reliable operation in the engine compartment. The low standby current helps reduce parasitic drain when the vehicle is off.
Recommended
Industrial Automation
While designed for automotive, the L99SM81V can be used in industrial automation for precise positioning of valves, actuators, and conveyor systems. Its micro-stepping capability and SPI interface make it suitable for PLC-controlled systems. The wide supply voltage range (6V to 28V) allows operation from 24V industrial supplies. The integrated current sensing and protection features ensure reliable operation in industrial environments. The AEC-Q100 qualification provides a high level of reliability, which is beneficial for industrial applications. The compact package fits into space-constrained control panels.
Recommended
Recommended Products Summary
Engineering reference data for L99SM81V — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L99SM81VQ6TR | DRV8825 | A4988 |
|---|---|---|---|---|
| Package | 40-QFN (6x6 mm) | 40-QFN (6x6 mm) - same | 28-HTSSOP | 28-QFN (5x5 mm) |
| Brand | STMicroelectronics | STMicroelectronics | Texas Instruments | Allegro MicroSystems |
| Output Current per Phase | 1.2 A | 1.2 A | 1.5 A | 1 A |
| Supply Voltage Range | 6 V to 28 V | 6 V to 28 V | 8.2 V to 45 V | 8 V to 35 V |
| Microstepping Resolution | Up to 1/16 step | Up to 1/16 step | Up to 1/32 step | Up to 1/16 step |
| Control Interface | SPI | SPI | Step/Direction | Step/Direction |
| Integrated Current Sensing | Yes | Yes | No (external sense resistors) | No (external sense resistors) |
| AEC-Q100 Qualified | Yes | Yes | No | No |
Key Differentiators
- Integrated current sensing (vs DRV8825)
- AEC-Q100 qualification (vs DRV8825)
- SPI interface for diagnostics (vs A4988)
Design Notes
The L99SM81V can dissipate significant power when driving 1.2 A per phase. Ensure adequate PCB copper area and thermal vias under the exposed pad to keep the junction temperature within the -40°C to +150°C range. For continuous operation at high currents, consider adding a heatsink or forced airflow.
Place decoupling capacitors (e.g., 100 nF and 10 µF) close to the VM and VDD pins to filter high-frequency noise and supply transients. Keep the SPI lines short and away from high-current motor traces to minimize noise coupling. Use a solid ground plane to reduce EMI.
Do not exceed the absolute maximum supply voltage of 28 V. Ensure the SPI interface is properly configured before enabling the motor outputs. The integrated current sensing eliminates external sense resistors, but verify the current limit settings via SPI to avoid overcurrent conditions. Use the stall detection feature to detect motor blockage and prevent damage.
Compliance Information
AEC-Q100 qualified per STMicroelectronics product page. RoHS compliant. REACH compliance assumed based on ST's environmental policy.
