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Driving Circuits for Brushed DC Motors – Summary

2022.08.24

table of contents

・Driving Circuits for Brushed DC Motors and Features
・Features and Application Examples of Brushed DC Motors

Up to this point, various methods for driving brushed DC motors have been explained. This article summarizes the preceding discussions in concise tables titled “Driving Circuits for Brushed DC Motors and Features” and “Features and Application Examples of Brushed DC Motors.”

Driving Circuits for Brushed DC Motors and Features

Circuit name		Possible rotation operations	Rotation rate control	Advantages	Disadvantages
H-bridge		Forward rotation, reverse rotation, stopped (Hi-Z), breaking	Not possible
H-bridge＋High-side voltage linear control		Forward rotation, reverse rotation, stopped (Hi-Z), breaking	Possible		・Large power consumption ・Larger circuit scale when using MOS power transistors
BTL amp linear voltage driving		Forward rotation, reverse rotation, breaking	Possible	・All operations possible with two-input linear driving	・Large power consumption ・Larger circuit scale ・Separate circuit needed for high output impedance
PWM driving with H-bridge circuit		Forward rotation, reverse rotation, stopped (Hi-Z), breaking	Possible	・Low power consumption ・Supports DC voltage input	・PWM circuit configuration required ・Noise source
PWM driving in the form of BTL amplifier input		Forward rotation, reverse rotation, breaking	Possible	・Low power consumption ・All operations possible with two-input linear driving	・Poor linearity ・Separate circuit needed for high output impedance ・PWM circuit configuration required ・Noise source
Single switch	On/Off	One- direction rotation, stopped (Hi-Z)	Not possible	・Simple circuit	・Diode required ・Sudden stopping not possible
Single switch	PWM driving	One- direction rotation, stopped (Hi-Z)	Possible	・Low power consumption	・Diode required; Diode heat generation must be considered ・Sudden stopping not possible ・PWM circuit configuration required ・Noise source
Half-bridge	On/Off	One- direction rotation, stopped (Hi-Z), breaking	Not possible	・Diodes unnecessary ・Sudden stopping possible	・Control input configuration must be considered (one or two inputs) ・Simultaneous-on prevention needed
Half-bridge	PWM driving	One- direction rotation, stopped (Hi-Z), breaking	Possible	・Low power consumption ・Diodes unnecessary ・Sudden stopping possible	・Control input configuration must be considered (one or two inputs) ・PWM circuit configuration required ・Noise source

Features and Application Examples of Brushed DC Motors

Features of Brushed DC Motors
Advantages	Disadvantages
・Easily made smaller, lighter ・Good efficiency ・Low cost ・Rotates just by applying a voltage ・Driving possible even at low voltages (operation possible at 1.5 V with 1 battery) ・Linear proportionality between rotation rate and applied voltage ・Rotation rate decreases in proportion to load ・Large startup torque ・Torque proportional to current ・Simple construction with just two wires ・Rotation direction changes with power supply polarity	・Brush means short lifetime ・Tends to be noisy ・Electric noise tends to occur ・Poor constant-speed characteristics ・DC power supply necessary ・Large currents flow when overloaded ・Sparking may occur ・Friction torque loss due to brush contact

Features of Brushed DC Motors

Advantages

Disadvantages

・Easily made smaller, lighter
・Good efficiency
・Low cost
・Rotates just by applying a voltage
・Driving possible even at low voltages (operation possible at 1.5 V with 1 battery)
・Linear proportionality between rotation rate and applied voltage
・Rotation rate decreases in proportion to load
・Large startup torque
・Torque proportional to current
・Simple construction with just two wires
・Rotation direction changes with power supply polarity

・Brush means short lifetime
・Tends to be noisy
・Electric noise tends to occur
・Poor constant-speed characteristics
・DC power supply necessary
・Large currents flow when overloaded
・Sparking may occur
・Friction torque loss due to brush contact

Application Examples of Brushed DC Motors
ODD（Optical Disc Drive） DVD/Blu-ray drives for PCs/game systems Blu-ray recorders/players	Loading: disc insertion/ejection
Ink-jet printers Multifunction printers	Paper feed Carriages: printing head movement Scanners
PPC（Plain Paper Copier）	Paper feed
Digital still cameras	Zoom, iris (diaphragm), lens cap
Mobile phones, tablet PCs	Vibrators
Toys	General operations Models, radio-controlled devices: driving, direction control Game controllers: vibration
General home appliances	Hair dryers: air blowing Shavers: blade rotating, reciprocal motion Tooth brushes: vibration Refrigerators: icemaker tray rotation etc.
Tools	Screwdrivers, drills, saws etc.: rotation
Automotive	Power windows: opening/closing Mirrors: opening/closing, angle adjustment Door lock: locking/unlocking Air conditioner dampers: changing air direction Corner pole: raising/lowering Head lights: light direction adjustment Car navigation system: display advance/retract etc.

Application examples are representative; in addition to these, there are various other applications that exploit the features of brushed DC motors.

【Download Documents】 Basics of Brushed DC Motors and Drive Methods

Brushed DC motors are the most versatile motors and are used in a great many applications. This handbook provides the basics of brushed DC motors, explaining their construction, principle of operation, characteristics, and driving methods.

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