DRV8601 Datasheet, PDF (7/20 Pages) Texas Instruments – Haptic Driver for DC Motors (ERMs) and Linear Vibrators (LRAs) with Ultra-Fast Turn-On

DRV8601
www.ti.com
SLOS629B – JULY 2010 – REVISED JANUARY 2012
APPLICATION INFORMATION
DRIVING DC MOTORS USING THE DRV8601
The DRV8601 is designed to drive a DC motor (also known as Eccentric Rotating Mass or ERM in haptics
terminology) in both clockwise and counter-clockwise directions, as well as to stop the motor quickly. This is
made possible because the outputs are fully differential and capable of sourcing and sinking current. This feature
helps eliminate long vibration tails which are undesirable in haptic feedback systems.
Figure 13. Reversal of Direction of Motor Spin Using DRV8601
Another common approach to driving DC motors is the concept of overdrive voltage. To overcome the inertia of
the motor's mass, they are often overdriven for a short amount of time before returning to the motor's rated
voltage to sustain the motor's rotation. The DRV8601 can overdrive a motor up to the VDD voltage. Overdrive is
also used to stop (or brake) a motor quickly. The DRV8601 can brake up to a voltage of -VDD. Please reference
the motor's datasheet for safe and reliable overdrive voltage and duration.
The DRV8601 can accept a single-ended PWM source or single-ended DC control voltage and perform
single-ended to differential conversion. A PWM signal is typically generated using software, and many different
advanced haptic sensations can be produced by inputting different types of PWM signals into the DRV8601.
DRIVING LINEAR VIBRATORS USING THE DRV8601
Linear vibrators (also known as Linear Resonant Actuators or LRA in haptics terminology) vibrate only at their
resonant frequency. Usually, linear vibrators have a high-Q frequency response due to which there is a rapid
drop in vibration performance at offsets of 3-5 Hz from the resonant frequency. Therefore, while driving a linear
vibrator with the DRV8601, ensure that the commutation of the input PWM signal is within the prescribed
frequency range for the chosen linear vibrator. Vary the duty cycle of the PWM signal symmetrically above and
below 50% to vary the strength of the vibration. As in the case of DC motors, the PWM signal is typically
generated using software, and many different advanced haptic sensations can be produced by applying different
PWM signals into the DRV8601.
Duty Cycle = 25%
Duty Cycle = 75%
VPWM
0V
1/fRESONANCE
VOUT, Average
Figure 14. LRA Example for 1/2 Full-Scale Drive
Copyright © 2010–2012, Texas Instruments Incorporated
Product Folder Link(s): DRV8601
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