The STMicroelectronics A5973D is a full-bridge, DMOS power driver designed for motor control applications, particularly suited for driving DC and stepper motors in high-current, low-voltage systems. It integrates four DMOS switches in a single package, allowing H-bridge operation with minimal external components. The device is engineered to provide high efficiency, thermal robustness, and ease of integration in automotive, industrial, and consumer applications.

## Functional Description

The A5973D contains four high-voltage, low RDS(on) DMOS transistors arranged in a full-bridge configuration. Each transistor is driven by internal logic circuits with dead-time control to prevent cross-conduction. The device supports bidirectional current flow through the load, enabling motor forward, reverse, and braking operations. It features built-in protection mechanisms including overcurrent detection, thermal shutdown, undervoltage lockout, and cross-conduction prevention. Input signals are compatible with standard TTL/CMOS logic levels, simplifying interfacing with microcontrollers and DSPs.

## Key Features

* Full-bridge DMOS H-bridge driver for DC and stepper motors.
* Supply voltage range: 8 V to 50 V.
* Continuous output current: 3.5 A RMS.
* Peak output current: 7 A non-repetitive.
* Low on-resistance: 0.28 Ω per DMOS transistor typical.
* TTL/CMOS compatible logic inputs.
* Built-in dead-time for shoot-through prevention.
* Thermal shutdown with hysteresis.
* Overcurrent protection with latched or auto-retry options.
* Undervoltage lockout for safe startup and operation.
* Fast switching times for high-frequency PWM motor control.
* Wide operating temperature: –40°C to +150°C.
* SOIC-16 package with exposed thermal pad for heat dissipation.

## Electrical Specifications

* Supply voltage (VBB): 8 V to 50 V.
* Logic supply voltage (VCC): 5 V typical.
* Output current (IO): 3.5 A RMS continuous.
* Non-repetitive peak current (IPK): 7 A maximum.
* DMOS on-resistance (RDS(on)): 0.28 Ω typical at VGS = 10 V.
* Output leakage current (IOFF): 1 μA typical at VBB = 50 V.
* Input logic high voltage (VIH): 2 V minimum.
* Input logic low voltage (VIL): 0.8 V maximum.
* Input current (IIH/IIL): 1 μA typical.
* Thermal resistance junction-to-ambient (RθJA): 45°C/W typical in free air.
* Thermal resistance junction-to-case (RθJC): 2°C/W typical.

## Motor Control Capabilities

* Forward and reverse operation with bidirectional current control.
* Braking and freewheeling modes supported via input logic configuration.
* PWM control supported up to 50 kHz with low switching losses.
* Dead-time insertion ensures safe operation at high switching frequencies.
* H-bridge topology allows efficient driving of single-phase and bipolar stepper motors.

## Protection Features

* Thermal shutdown: device enters high-impedance state above 150°C junction temperature, with hysteresis for automatic recovery.
* Overcurrent protection: prevents damage under short-circuit or stall conditions.
* Undervoltage lockout: inhibits output drive when supply voltage falls below 8 V.
* Cross-conduction prevention: dead-time logic prevents both high-side and low-side DMOS from conducting simultaneously.
* Short-circuit robustness: DMOS transistors can tolerate temporary load shorts.

## Switching Characteristics

* Turn-on time: 120 ns typical at VBB = 24 V.
* Turn-off time: 80 ns typical.
* Propagation delay: 200 ns typical.
* Fast switching enables precise PWM motor speed and torque control.
* Low switching losses due to optimized DMOS gate drive and low RDS(on).

## Thermal and Mechanical Considerations

* Package: SOIC-16 with exposed thermal pad for heat sinking.
* Maximum junction temperature: 150°C.
* Ensure sufficient copper area on PCB for efficient heat dissipation under continuous high-current operation.
* Thermal derating required when operating at elevated ambient temperatures to maintain junction below maximum rating.

## Applications

* Brushed DC motor drivers in automotive systems such as seat and window control.
* Bipolar stepper motor drivers in printers, scanners, and industrial automation.
* Robotics and mechatronic devices requiring precise motion control.
* Home appliances requiring low-voltage high-current motor control.
* Battery-powered systems with efficient H-bridge motor driving requirements.

## Design Considerations

* Proper decoupling of supply pins is recommended to minimize voltage spikes during switching.
* External flyback diodes are optional due to intrinsic DMOS body diodes but can be added to improve transient performance.
* PCB layout should minimize parasitic inductance in high-current paths to reduce voltage overshoot.
* Use thermal vias and large copper pours under the exposed pad to maintain low junction temperature during high-current operation.
* Select PWM frequency and dead-time based on motor characteristics to optimize torque and efficiency.
* Ensure that logic input timing meets VIH and VIL thresholds to avoid misoperation or unintended conduction.

## Summary

The STMicroelectronics A5973D is a robust, high-performance full-bridge DMOS driver optimized for DC and stepper motor applications. It combines low on-resistance DMOS transistors, integrated dead-time, and protection features in a compact package, enabling efficient, reliable motor control in automotive, industrial, and consumer applications. Fast switching, thermal resilience, and high current capability make the A5973D suitable for high-density, high-performance motor control systems.