onsemi STK672-632AN-E Hybrid IC Stepper Motor Driver: Datasheet, Pinout, and Application Circuit Guide
The onsemi STK672-632AN-E is a hybrid IC designed for use as a unipolar, 4-phase stepper motor driver. It integrates a built-in microstepping controller and a high-power output stage into a single, compact SIP (Single In-line Package) module. This integration simplifies design, reduces component count, and provides a highly reliable solution for driving stepper motors in applications requiring precise positioning and smooth motion control, such as office automation equipment, industrial machinery, and robotics.
A key advantage of this driver is its support for four excitation modes: Full-step, Half-step (1-2 phase), Quarter-step (W1-2 phase), and 16-microstep control. The microstepping capability is particularly valuable for minimizing motor vibration and achieving higher positional resolution, leading to quieter operation and smoother performance at low speeds.
Pinout Configuration
Understanding the pinout is critical for proper integration. The STK672-632AN-E features a 15-pin SIP package. The key pins are:
Pins 1, 2 (VCC): Logic power supply pins (+5V).
Pin 3 (CW/CCW): Selects motor rotation direction (Clockwise/Counter-Clockwise).
Pin 4 (CLK): Pulse input pin. Each rising edge triggers a single step (or microstep) in the selected direction.
Pin 5 (MO): Monitors the origin of the excitation phase signal for system synchronization.
Pin 6 (RESET): Active-low reset pin. When driven low, it initializes the internal translator circuit.
Pin 7 (MS1, MS2): These pins select the excitation mode (Full, Half, Quarter, or 16-microstep).
Pin 8 (VBB): Motor power supply pin. This is the high-voltage supply (typically up to +42V) for the motor coils.
Pins 9, 10, 13, 14 (OUT A, /A, B, /B): Output pins connected directly to the four phases of the stepper motor.
Pin 15 (GND): Ground reference for the IC.
Key Datasheet Specifications
Output Current: Up to 1.5 A per phase (continuous).
Motor Supply Voltage (VBB): +10 V to +42 V.
Logic Supply Voltage (VCC): +4.5 V to +5.5 V.
Excitation Modes: Full-step, Half-step, Quarter-step, 16-microstep.
Built-in Protection: The IC includes critical protection circuits such as thermal shutdown (TSD), overcurrent protection (OCP), and under-voltage lockout (UVLO) for the low-voltage supply, safeguarding the driver and motor from fault conditions.
Application Circuit Guide
Implementing the STK672-632AN-E is straightforward due to its high level of integration. A typical application circuit requires only a few external components:
1. Power Supplies: Two decoupled power rails are needed: a stable +5V for VCC (pins 1, 2) and a higher voltage (e.g., +24V or +36V) for the motor supply VBB (pin 8).
2. Current Sensing Resistors: Four low-ohm, high-wattage power resistors (e.g., 1Ω, 2W) are connected between the emitter outputs and ground to set the motor phase current. The voltage across these resistors provides feedback for the internal overcurrent protection circuit.
3. Controller Interface: A host microcontroller (MCU) or logic circuit is connected to the control pins (CLK, CW/CCW, MS1, MS2, RESET). The MCU simply needs to generate pulse and direction signals to control the motor's movement and mode.
4. Protection Diodes: Although the module has built-in clamp diodes for back EMF suppression, adding external fast-recovery diodes across each motor coil is highly recommended for enhanced reliability, especially with higher supply voltages or inductive loads.
ICGOODFIND Summary
The onsemi STK672-632AN-E is a highly integrated and robust solution for driving unipolar stepper motors. Its built-in microstepping controller significantly reduces the software and hardware burden on the system designer, while its comprehensive built-in protection features ensure operational safety and long-term reliability. It is an excellent choice for developers seeking to implement smooth, quiet, and precise motion control without the complexity of a fully discrete design.
Keywords: Stepper Motor Driver, Microstepping, Hybrid IC, STK672-632AN-E, Unipolar.
