Diodes' Motor Pre-Driver Simplifies Speed Control

By integrating an array of normally external components, including a PWM integrator and MOSFET buffers, this flexible pre- driver enables designers to greatly simplify system architecture and reduce overall board component count.

The pre-driver can closely control motor speed via the direct application of either an external PWM signal, DC voltage signal or thermistor network input. Through the integration of Hall bias and amplifier circuits, compatibility with all types of Hall effect sensor is assured. An open-collector frequency generator pin provides a tachometer output enabling external monitoring of rotation and speed. To prevent motor stalling or speed falling below a minimum value in the event of loss of control signals, the ZXBM1021 allows the setting of a minimum speed.

Offering high-side and low-side drive outputs, with 50mA sink and 100mA source/sink capability, the ZXBM1021 can be accurately matched to the needs of external H-bridge switches and motor powers without the need for additional buffering. A separate low-side output drive supply voltage pin also provides the ability to adjust external low-side MOSFET turn-on speed independently of turn- off speed to help minimize EMI noise and shoot-through.

An operating voltage range of 6.8V to 18V means the pre-driver will support 12V motors directly, and 24V and 48V motors via an external voltage regulator. With a programmable over current limit, the pre-driver is able to detect locked rotor conditions and protect the H-bridge and motor windings from over-heating or burn-out, instigating a soft start on removal of the rotor lock to minimize motor inrush current.

Supplied in the small footprint, low-profile and thermally enhanced U-QFN4040- 20 chip package and with a wide operating temperature range of -40oC to +110oC, the ZXBM1021 is well-suited for space-constrained and thermally demanding applications. A QSOP20-packaged variant will be introduced later in the year.