The BD62221MUV is ROHM's integrated dual H-bridge motor driver for low-to-medium-power DC brush and stepper motor applications — office automation equipment, small industrial actuators, valve drives, robotics, and consumer appliances. The DMOS output stage provides low ON-resistance (0.55 Ω typical) without the gate drive complexity of discrete MOSFET H-bridges, enabling a compact 5 × 5 mm VQFN package with exposed thermal pad for heat dissipation into the PCB copper plane.

How does the PWM constant-current control work?

The BD62221MUV supports two PWM control methods. In direct PWM mode, the host microcontroller supplies PWM signals to the IN1/IN2 inputs, and the output H-bridge replicates the duty cycle — this is standard voltage-mode drive suitable for DC motors where speed is proportional to average applied voltage. In PWM constant-current mode, the VREF pin sets a reference voltage corresponding to the desired current limit. The IC monitors output current via the sense resistor on the RNF pin; when the sensed current reaches the VREF-defined threshold, the output stage chops (turns off) for the remainder of that PWM cycle. This current-mode control is essential for stepper motor applications where torque is proportional to winding current — not voltage — and must be held constant across varying supply voltage and motor back-EMF conditions. The external DAC can drive VREF for micro-stepping, subdividing each full step into smaller current increments for smoother motion and higher positioning resolution.

What protection features does the IC integrate?

The BD62221MUV includes a comprehensive protection suite that would otherwise require external components: thermal shutdown (TSD) disables outputs if junction temperature exceeds the safe threshold; over-current protection (OCP) monitors each output transistor current and shuts down on short-circuit; under-voltage lockout (UVLO) prevents operation below the minimum gate drive voltage where MOSFETs would operate in linear region and overheat; over-voltage lockout (OVLO) protects against supply transients above the 36 V absolute maximum; ghost supply prevention ensures the IC does not malfunction when power is disconnected and reconnected rapidly; and adjacent-pin short protection prevents damage if neighboring IC pins are accidentally bridged by solder or contamination. The spike noise cancel circuit eliminates the need for an external RC snubber or filter on the output, reducing BOM cost and PCB area.