Dual Full-Bridge MOSFET Driver with Microstepping Translator # A3986SLDTRT - DMOS Microstepping Driver with Translator
## 1. Application Scenarios
### Typical Use Cases
The A3986SLDTRT is primarily employed in precise motion control systems requiring smooth operation and accurate positioning:
- Bipolar stepper motor control in industrial automation equipment
- Microstepping applications (up to 1/16 step resolution)
- Closed-loop positioning systems where reduced vibration and noise are critical
- Battery-powered portable devices requiring efficient power management
### Industry Applications
Industrial Automation:
- CNC machine tools for precise axis control
- 3D printer extruder and bed leveling mechanisms
- Robotic arm joint positioning systems
- Automated test equipment with precise movement requirements
Medical Equipment:
- Laboratory automation systems (pipetting robots, sample handlers)
- Medical imaging device positioning (CT/MRI scanner beds)
- Surgical robot articulation controls
Consumer Electronics:
- High-end camera stabilization gimbals
- Professional audio equipment (fader controls, rotary encoders)
- High-precision printer head positioning
### Practical Advantages
Strengths:
- Reduced Audible Noise : Microstepping capability minimizes motor resonance
- High Efficiency : Low RDS(ON) DMOS outputs (typically 500 mΩ)
- Thermal Protection : Built-in thermal shutdown with hysteresis
- Simple Control Interface : Step and direction inputs reduce microcontroller overhead
- Wide Voltage Range : 8V to 35V operation suitable for various power systems
Limitations:
- Heat Dissipation : Requires proper thermal management at high currents (>1.5A)
- External Components : Needs external sense resistors and decoupling capacitors
- EMI Considerations : PWM switching can generate electromagnetic interference
- Cost Sensitivity : May be over-specified for simple two-phase drive applications
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Motor Stalling and Missed Steps:
- Problem : Insufficient current delivery during acceleration phases
- Solution : Implement current decay mode selection (slow/mixed/fast) based on motor characteristics
Thermal Overload:
- Problem : Junction temperature exceeding 165°C during continuous operation
- Solution :
- Use adequate heatsinking (thermal pad connection to PCB)
- Implement current derating above 70°C ambient temperature
- Monitor THERM flag output for pre-shutdown warning
Electrical Noise Issues:
- Problem : False step triggering from noisy control signals
- Solution :
- Implement Schmitt trigger inputs with pull-up/pull-down resistors
- Use twisted-pair cables for motor connections
- Add ferrite beads on power supply lines
### Compatibility Issues
Microcontroller Interface:
- Voltage Level Mismatch : 3.3V microcontrollers may not reliably drive 5V tolerant inputs
- Solution : Use level shifters or ensure microcontroller outputs meet VIH specifications
Power Supply Requirements:
- Inadequate Decoupling : Causes voltage spikes during switching transitions
- Solution : Place 100nF ceramic capacitors close to VMOT and VDD pins
- Back-EMF Protection : Required diode clamping for inductive load switching
Sensor Integration:
- Current Sensing : External sense resistors must have low inductance and proper power rating
- Position Feedback : Compatible with most optical and magnetic encoders
### PCB Layout Recommendations
Power Stage Layout:
- Priority 1 : Keep motor driver outputs (OUT1A, OUT1B, OUT2A, OUT2B) traces short and wide
- Current Sense Resistors : Place immediately adjacent to SENSE1/SENSE2 pins with Kelvin connections
- Thermal Management :
