Diodes Incorporated
U QFN4040 20

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ZXBM1021 (Not Recommended for new design)

NRND = Not Recommended for New Design

Turn-on Time and Simple Integrated PWM Speed Control Single Phase BLDC Fan and Motor Pre-Driver with Soft-Start Adjutable Current Limit Adjustable Low Side Switch

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The  ZXBM1021  is a  high performance and integrated feature rich and simple to use  low noise single phase Brushless DC (BLDC)  motor control pre-driver  for  fans, blowers, extractors and motor drive solutions. 
For system flexibility the motor speed can be controlled by a DC voltage signal from either external control voltage or a PWM signal. The pre-driver output with source and sink capability of 100mA  to drive external power switch allows  power levels to be adjusted to suite  motor requirements. The device has a supply voltage range of 6.8V to 18V (which can be extended with an external voltage regulator) and the operating ambient temperature range of -40°C to 110°C.
To simplify system circuit and minimize external components, the device integrates PWM signal integrator, Hall-Effect sensor amplifiers, Hall-bias supply, and voltage reference output. To prevent motor stalling or speed falling below a minimum value in absence of appropriate control signals, ZXBM1021 allows to set the minimum speed.   
To prevent motor inrush current, the device has a soft start feature. To help protect the motor coil, the ZXBM1021 provides rotor lock protection which shutdown the output drive for a fixed period of time if rotor lock is detected. The device automatically restarts when the rotor lock is removed. The device monitors the motor current to provide a programmable over current limit. 
To help minimize  electromagnetic interference (EMI) ,  audible switching noise and shoot through challenges, ZXBM1021 provides a V+OP pin for low side drive outputs which allows to adjust  the current into the base of external power transistors or to control external power MOSFETs’  turn-on speed different to turn-off speed. 
A tachometer output is provided by open-drain Frequency Generator (FG) Pin which allows external interface to monitor motor rotation or speed.  The FG output is the magnetic change frequency. 
The ZXBM1021 is available in thermally capable space saving low profile U-QFN4040-20 and industry standard QSOP-20 packages.


  • Operating Voltage: 6.8V to 18V
    • Can be extended with external regulator
  • Speed control via external PWM, DC or Thermistor signals
    • Internal PWM Integrator
  • Low noise, high efficiency
  • Soft start
  • Integrated current control
  • Reference voltage output
  • Built-in Hall amplifier for direct connection of Hall element
  • Rotor Lock Protection
  • Lock detection, output shutdown and automatic re-start
  • Minimum speed setting
  • Frequency generator (FG) output
  • Thermally enhanced space saving low profile U-QFN4040-20 package and industry standard QSOP-2 packages
  • Totally Lead-Free & Fully RoHS Compliant 
  • Halogen and Antimony Free. “Green” Device


  • 12V/ 24V and 48V cooling fans, pumps and motors
  • Personal, server and mainframe computer cooling fans
  • Instrumnetation and equipment cooling fans
  • Cooling systems and motor control in home appliances
  • Central heating blowers and extraction systems
  • Industrial fans, blowers and extractors
  • Hand-held Power tools
  • Hand dryer BLDC motors
  • Pumps

Product Specifications

Product Parameters

Adjustable Current Limit Yes
Frequency Generator (FG) and Rotation Detect -
Hall Bias Voltage (V) 1.75
High Side Switch Drive Sink Current (mA) 50
Lock Detect, Shut-Down and Auto Start -
Low Side Switch Drive Source Current (mA) 100
Minimum Speed Setting Yes
Operating Ambient Temperature (°C) -40 to 110
Operating Voltage (V) 6.8 to 18
Reference Voltage Output (V) 5
Speed Control VSPD or PWM
SupplyCurrent (mA) 10
Tail End Current Control -

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Technical Documents

Recommended Soldering Techniques



Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN # Issue Date Implementation Date Subject
PCN-2594 2022-08-31 2023-02-28 Device End of Life (EOL)