DRV8256: Speaker

Ray Vincent Aranzaso

Part Number: DRV8256

Hi,

Good Day.

The customer would like to ask a general question about the applications of DRV8256 Motor Driver or other parts of this series.

Have you evaluated the possibility to use a driver not to drive a motor winding but to drive a speaker?
The intended usage is an H-bridge and just a rectangular input audio signal of up to 20 kHz (siren tone).
Voltage, current, frequency/"dead time" etc. parameters should be OK. So, perhaps only the decay modes could have an impact on planned output.

Please advise. Thank you very much.

Best Regards,

Ray Vincent

over 1 year ago

0 Jacob Thompson over 1 year ago

TI__Mastermind 21980 points

Hey Ray,

Is it a Piezo speaker? Those are highly capacitive loads and I think it will depend on the capacitance of the speakers. If it's a Piezo I recommend a piezo driver: https://www.ti.com/product/DRV2700 or use this design tool to pick one: https://www.ti.com/tool/DRV8662-2665-2667_DESIGN_TOOL

TI also makes speaker amplifiers: https://www.ti.com/audio-ic/amplifiers/speaker-amplifiers/overview.html

As for your original question, if it's a standard 4Ω speaker I suspect it will work but recommend trying it out on an EVM. Typical brushed motor resistance is in the 2Ω-4Ω range, and the DRV8256 supports up to 100kHz PWM frequency. You might need to use Mixed Decay or Fast Decay as the Smart Tune decay modes might not work for a speaker instead of a motor.

If you do test it please let us know how it goes, I'm curious!

Regards,

Jacob

0 Jacob Thompson over 1 year ago in reply to Jacob Thompson

TI__Mastermind 21980 points

Hey Ray,

I tested it out with a spare car speaker (6" 30W RMS 4Ω) and the DRV8256E EVM board. I can confirm the motor driver can drive the speaker! There were some combinations of VREF, EN, and PH that made decent buzzing noises, but most settings just produced noise. The device never threw a fault or stopped working. I'm sure that using programming you would be able to generate nice tones or siren like you need.

Regards,

Jacob

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DRV8256: Speaker