DUAL FULL-BRIDGE PWM MOTOR DRIVER WITH BRAKE # A3968SLBTRT - Microstepping DMOS Driver with Translator
## 1. Application Scenarios
### Typical Use Cases
The A3968SLBTRT is primarily employed in precision motion control systems requiring microstepping capability. Common implementations include:
- Bipolar stepper motor control in applications demanding smooth operation and reduced vibration
- Positioning systems requiring high resolution (up to 1/8 microstepping)
- Speed control applications where gradual acceleration/deceleration is critical
- Low-voltage systems (8-30V) requiring integrated power MOSFETs
### Industry Applications
Industrial Automation:
- CNC machine tool positioning
- 3D printer head and bed movement
- Robotic arm joint control
- Automated test equipment positioning
Consumer Electronics:
- Professional photography equipment (lens focus mechanisms)
- High-end office automation (printer paper feed, scanner mechanisms)
- Medical devices (infusion pumps, ventilator controls)
Automotive Systems:
- Instrument cluster pointers
- HVAC damper controls
- Advanced driver assistance systems
### Practical Advantages and Limitations
Advantages:
- Integrated Design : Combines translator and power output stages, reducing component count
- Microstepping Capability : Provides up to 1/8 microstepping for smoother motion
- Thermal Protection : Internal thermal shutdown circuitry prevents overheating
- Low Power Consumption : CMOS technology ensures efficient operation
- Mixed Decay Modes : Optimizes current control for different operating conditions
Limitations:
- Current Limitation : Maximum 750 mA per phase restricts high-power applications
- Voltage Range : 8-30V operating range may not suit high-voltage industrial systems
- Heat Dissipation : SOIC package thermal characteristics require careful thermal management
- Fixed Microstepping : Limited to predefined step modes without external control flexibility
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Current Regulation Issues:
- Pitfall : Motor stuttering or missed steps due to improper current sensing
- Solution : Ensure sense resistor (typically 0.5Ω) is placed close to the IC with proper power rating
Thermal Management Problems:
- Pitfall : Premature thermal shutdown during continuous operation
- Solution : Implement adequate heatsinking and consider derating current at elevated temperatures
Power Supply Concerns:
- Pitfall : Voltage spikes damaging the device during motor deceleration
- Solution : Use appropriate bulk capacitance (100-470μF) and fast-recovery diodes for back-EMF protection
### Compatibility Issues with Other Components
Microcontroller Interface:
- Compatible with 3.3V and 5V logic families
- Requires minimal interface circuitry for most modern microcontrollers
- Watch for timing constraints with high-speed processors
Motor Compatibility:
- Designed for bipolar stepper motors only
- Verify motor coil resistance matches current capability
- Ensure motor inductance doesn't exceed recommended values for desired stepping rates
Power Supply Requirements:
- Decoupling capacitors must handle high-frequency switching currents
- Separate analog and digital grounds to minimize noise
- Consider inrush current requirements during motor startup
### PCB Layout Recommendations
Power Stage Layout:
- Place bulk capacitors within 2cm of VBB pins
- Use wide traces for motor power paths (minimum 40 mil width for 1A current)
- Implement star grounding for power and logic sections
Thermal Management:
- Use thermal vias under the exposed pad connected to ground plane
- Provide adequate copper area for heat dissipation (minimum 1 square inch)
- Consider additional heatsinking for high-duty cycle applications
Signal Integrity:
- Route STEP, DIR, and ENABLE signals away from high-current paths
