Technical Information Site of Power Supply Design

Product Key Points

Lineup of Over 220 Motor Driver ICs

Remarkable Quietness through Intricate Control Functions and a Novel Control Method
Single-Phase Brushless DC Motor Driver IC

  • More than 220 motor driver ICs
  • BTL driving
  • I/O slope setting
  • PWM soft switching driving
  • Switching driving
  • Standby function
  • Stepping motor
  • Stepping motor driver
  • Brushed DC motor
  • 3-phase brushless DC motor (including high voltage models)
  • Single-phase brushless DC motor
  • Sinusoidal driving
  • Improved back electromotive force jump
  • Advance angle control driving
  • Wind loss correction

ROHM offers over 220 kinds of motor driver ICs, which have extensive track records. The types of motors supported are highly diverse, including brushed DC motors, stepping motors, single-phase brushless DC motors, and 3-phase brushless DC motors (including high-voltage models); there are lineups of products featuring high efficiency and reliability over a broad range of voltages, currents, and packages, and pin-compatible products are also available.

There are over 30 models of single-phase brushless DC motor drivers, supporting various driving methods and control technologies necessary for quiet operation and high efficiency. This lineup of drivers includes such features as sinusoidal driving, advance angle control driving, wind loss correction, I/O slope setting, improved back electromotive force jump, and standby functions.

Driving Method and Features of Single-Phase Brushless DC Motor Drivers

Here the driving method and driving waveform of ROHM single-phase brushless DC motor drivers are presented. Switching driving is by standard PWM driving, and output switching is comparatively fast, so that efficiency is high, but due to the sudden transitions of the coil current, there is an adverse effect on quietness. BTL driving is linear voltage driving by bridged driver amplifiers. Through soft switching, quietness is achieved, but efficiency suffers. PWM soft switching driving is a driving method in which, by using "soft" switching in output rising/falling intervals, distortion in the coil current is reduced and quietness is improved while achieving high efficiency. Sinusoidal driving is a driving method in which a coil current adjustment function is added to PWM soft switching driving; because a coil current that is close to a sine wave can be used for driving, extremely quiet driving is possible.

Features of ROHM Single-Phase Brushless DC Motor Drivers

●Sinusoidal driving
PWM soft switching is a method in which quietness is effectively achieved by smoothing output transitions (rising/falling); a Hall signal is used to generate a waveform. However, due to the temperature characteristic of the Hall signal, there are cases in which the coil current is distorted and noise increases.

In sinusoidal driving, on the other hand, by providing a function for adjustment of the coil current in PWM soft switching intervals by an external voltage, the coil current waveform can be smoothed and made to approach a sine wave. Distortion in the coil current waveform is further reduced, to achieve enhanced quietness.

●Advance angle control driving
In order to obtain maximum torque, the phase of the driver output signal relative to the Hall signal can be adjusted such that the phase difference between the magnet (rotor) magnetic field and the coil is 90°. The advance angle can be set up to 22.5° on the advance angle side.

●Wind loss correction
Wind loss is a loss due to the friction resistance of rotating parts with air and the like. For example, in a fan motor, even if the output duty with respect to the input duty is a straight line, depending on the motor characteristics, the increased rotation rate at intermediate duty levels may result in increased wind loss. By adjusting the linearity of the output duty using the ADJ pin, the linearity of the motor rotation speed can be improved, to further heighten the precision of speed settings.

●I/O slope setting
A function is provided for using a SLOP pin to set the slope of the output duty versus the PWM input duty. This function is convenient when adjusting the motor rotation rate vs. input characteristic. The output duty slope can be adjusted over the range 0.5 to 2. The figure shows a PWM input example.

●Improved back electromotive force jump
Output voltage jump that occurs upon changes in the rotation rate such as when power is turned on for forward or reverse idle, upon lock detection/reset, and when there are sudden changes in torque input, is suppressed.

●Standby function
This function reduces power consumption of the motor driver while the motor is stopped. By setting the PWM signal duty to 0%, the IC is put into a standby mode.
Products provided with standby functions

Power Supply Design Technical Materials Free Download

Power Supply Design Technical Materials Free Download

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