L9942 - Integrated Stepper Motor Driver with Microstepping | STMicroelectronics
MPN: L9942 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.85 | $4.85 |
| 10 | $4.36 | $43.60 |
| 100 | $3.88 | $388.00 |
| 500 | $3.49 | $1,745.00 |
| 1,000 | $3.1 | $3,100.00 |
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:
L9942XP1TR
β Drop-Inπ Reference alternative (not in catalog)
L9942XPTR
β Drop-Inπ Reference alternative (not in catalog)
L9942XP1
β Drop-Inπ Reference alternative (not in catalog)
L9942 Maximum Ratings & Electrical Characteristics
| Motor Type | Bipolar Stepper |
| Output Current | 1.3 A (max) |
| RDSON | 500 mΞ© |
| Supply Voltage | 4.5 V to 40 V |
| Stepping Modes | Full, Half, Mini |
| Current Profile Look-up Table | 9 entries, 5-bit resolution |
| Current Regulation | Integrated PWM controller with internal current sensing |
| Interface | SPI (up to 5 MHz) |
| Package | PowerSSO-24 |
| Mounting Type | Surface Mount |
| Operating Temperature | -40Β°C to +150Β°C |
| Thermal Resistance | 35Β°C/W |
| Protection Features | Overcurrent, Thermal Shutdown, Diagnostic Output |
| Process Technology | BCD (Bipolar-CMOS-DMOS) |
| RoHS Status | Compliant |
L9942 Pin Configuration
| Pin 1 | OUT1A β Bridge A output 1 |
| Pin 2 | OUT1B β Bridge A output 2 |
| Pin 3 | VS β Power supply |
| Pin 4 | VS β Power supply |
| Pin 5 | OUT2A β Bridge B output 1 |
| Pin 6 | OUT2B β Bridge B output 2 |
| Pin 7 | GND β Ground |
| Pin 8 | GND β Ground |
| Pin 9 | DIAG β Diagnostic output |
| Pin 10 | CSN β SPI chip select (active low) |
| Pin 11 | SCK β SPI clock |
| Pin 12 | SDI β SPI data input |
| Pin 13 | SDO β SPI data output |
| Pin 14 | VDD β Logic supply |
| Pin 15 | GND β Ground |
| Pin 16 | GND β Ground |
| Pin 17 | OUT2B β Bridge B output 2 |
| Pin 18 | OUT2A β Bridge B output 1 |
| Pin 19 | VS β Power supply |
| Pin 20 | VS β Power supply |
| Pin 21 | OUT1B β Bridge A output 2 |
| Pin 22 | OUT1A β Bridge A output 1 |
| Pin 23 | GND β Ground |
| Pin 24 | GND β 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
L9942 is suitable for 6 applications: Automotive Headlamp Leveling, HVAC Vent Positioning, Industrial Automation, Robotics, Medical Equipment, 3D Printers.
Automotive Headlamp Leveling
The L9942 precisely controls the stepper motor that adjusts the headlamp beam angle, ensuring optimal visibility without dazzling oncoming traffic. Its programmable current profile allows the motor torque to be tailored to the specific load, improving efficiency and reducing mechanical stress. The wide supply voltage range (4.5V to 40V) handles automotive battery variations, and the SPI interface enables diagnostics for fault detection, improving system safety. In a typical headlamp leveling system, the L9942 is placed between the body control module (BCM) and the stepper motor, with the SPI bus connecting to the microcontroller. The driver's current regulation ensures smooth and accurate positioning, even under varying load conditions. Compared to discrete drivers, the L9942 reduces external component count and PCB area, which is critical in the space-constrained environment of a headlamp assembly. The thermal shutdown protection prevents damage during prolonged operation, and the diagnostic output allows the BCM to detect motor faults early, reducing warranty costs.
Recommended
HVAC Vent Positioning
The L9942 controls the stepper motor that adjusts air flow direction in automotive HVAC systems, providing passenger comfort. Its microstepping capability ensures smooth and quiet operation, which is essential for passenger cabin comfort. The programmable current profile allows the motor torque to be optimized for the specific vent load, reducing power consumption and mechanical noise. In a typical HVAC vent positioning system, the L9942 is connected to the HVAC control module via SPI, and the bridge outputs drive the stepper motor windings. The integrated current sensing eliminates the need for external sense resistors, simplifying the PCB layout. The device's wide operating temperature range (-40Β°C to +150Β°C) ensures reliable operation in extreme climates. The diagnostic output allows the HVAC module to detect vent jams or motor faults, enabling proactive maintenance. Compared to using multiple discrete components, the L9942 reduces system cost and improves reliability.
Recommended
Industrial Automation
The L9942 drives stepper motors in industrial positioning systems, such as conveyor belt diverters and robotic arms. Its programmable current profile allows the motor torque to be tailored to the specific load, improving efficiency and reducing mechanical stress. The SPI interface enables real-time control and diagnostics, which is critical for industrial automation. In a typical industrial application, the L9942 is connected to a PLC or industrial microcontroller via SPI, and the bridge outputs drive the stepper motor. The integrated current regulation ensures precise positioning, even under varying load conditions. The device's wide supply voltage range (4.5V to 40V) makes it suitable for industrial power supplies. The thermal shutdown protection prevents damage during prolonged operation, and the diagnostic output allows the system to detect motor faults early, reducing downtime. Compared to using a separate driver and current sensing circuit, the L9942 reduces component count and PCB area, simplifying system design.
Recommended
Robotics
The L9942 drives stepper motors in robotic arms and mobile robots, providing precise position control. Its microstepping capability ensures smooth motion, which is essential for robotic applications. The programmable current profile allows the motor torque to be optimized for the specific load, improving efficiency and reducing mechanical stress. In a typical robotic application, the L9942 is connected to a robot controller via SPI, and the bridge outputs drive the stepper motor. The integrated current sensing eliminates the need for external sense resistors, simplifying the PCB layout. The device's wide operating temperature range (-40Β°C to +150Β°C) ensures reliable operation in various environments. The diagnostic output allows the robot controller to detect motor faults early, improving system reliability. Compared to using a separate driver and current sensing circuit, the L9942 reduces component count and PCB area, simplifying system design.
Recommended
Medical Equipment
The L9942 drives stepper motors in medical equipment such as infusion pumps and diagnostic devices, providing precise and reliable motion control. Its microstepping capability ensures smooth and quiet operation, which is essential for patient comfort. The programmable current profile allows the motor torque to be optimized for the specific load, improving efficiency and reducing mechanical stress. In a typical medical application, the L9942 is connected to a medical microcontroller via SPI, and the bridge outputs drive the stepper motor. The integrated current sensing eliminates the need for external sense resistors, simplifying the PCB layout. The device's wide operating temperature range (-40Β°C to +150Β°C) ensures reliable operation in various environments. The diagnostic output allows the system to detect motor faults early, improving patient safety. Compared to using a separate driver and current sensing circuit, the L9942 reduces component count and PCB area, simplifying system design.
Recommended
3D Printers
The L9942 drives stepper motors in 3D printers, providing precise and reliable motion control for the print head and build platform. Its microstepping capability ensures smooth and quiet operation, which is essential for high-quality prints. The programmable current profile allows the motor torque to be optimized for the specific load, improving efficiency and reducing mechanical stress. In a typical 3D printer application, the L9942 is connected to a printer controller via SPI, and the bridge outputs drive the stepper motor. The integrated current sensing eliminates the need for external sense resistors, simplifying the PCB layout. The device's wide operating temperature range (-40Β°C to +150Β°C) ensures reliable operation in various environments. The diagnostic output allows the printer controller to detect motor faults early, improving print reliability. Compared to using a separate driver and current sensing circuit, the L9942 reduces component count and PCB area, simplifying system design.
Recommended
Recommended Products Summary
Engineering reference data for L9942 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L9942XP1TR | DRV8825 | A4988 |
|---|---|---|---|---|
| Package | PowerSSO-24 | PowerSSO-24 - same | HTSSOP-28 - different | QFN-28 - different |
| Brand | STMicroelectronics | STMicroelectronics | Texas Instruments | Allegro MicroSystems |
| Output Current | 1.3 A | 1.3 A | 2.5 A | 2 A |
| Supply Voltage | 4.5V to 40V | 4.5V to 40V | 8.2V to 45V | 8V to 35V |
| Stepping Modes | Full, Half, Mini | Full, Half, Mini | Full, Half, 1/4, 1/8, 1/16, 1/32 | Full, Half, 1/4, 1/8, 1/16 |
| Interface | SPI | SPI | Step/Direction | Step/Direction |
| Current Regulation | Integrated PWM with internal sensing | Integrated PWM with internal sensing | Integrated PWM with internal sensing | Integrated PWM with internal sensing |
| Diagnostics | SPI diagnostics | SPI diagnostics | Fault output | Fault output |
Key Differentiators
- Programmable current profile look-up table (vs DRV8825)
- SPI diagnostics (vs A4988)
- Wide supply voltage range (vs A4988)
Design Notes
The L9942 in PowerSSO-24 has a thermal resistance of 35Β°C/W. At 1.3 A load with a supply voltage of 12V, power dissipation can reach 1.7W (I^2 * RDSON). This would result in a temperature rise of 59.5Β°C above ambient. Ensure adequate PCB copper area or a heatsink for continuous operation at high currents.
Place the L9942 close to the stepper motor connector to minimize trace inductance. Use wide traces for the bridge outputs (OUT1A, OUT1B, OUT2A, OUT2B) to handle the 1.3 A current. Add a 100nF ceramic capacitor close to the VS and VDD pins for decoupling. For the SPI lines, keep them short and add series resistors (e.g., 33Ξ©) to reduce ringing.
Always place flyback diodes across inductive loads (stepper motor windings) to protect the outputs from voltage spikes during switching. The L9942 has internal protection, but external diodes are recommended for reliability. Also, ensure the SPI chip select (CSN) is pulled high when not in use to avoid accidental communication. Do not exceed the absolute maximum supply voltage of 40V.
Compliance Information
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualification not specified for this part.
