DRV2605L: 5 or more LRAs into the 1 DRV2605L

tmatsuzawa

Part Number: DRV2605L
Hello. I am thinking to add vibration feedback to a touchscreen display, but the issue is that display was not specially designed for haptic motors. (i.e. I can see in TI example project LCD/touchpanel is floated so that vibration is effectively spread on its surface, but with ordinal monitors LCD panel is firmly attached to the sloid and relatively heavy background.) I learned that adding more haptic motors (instead of just one, maybe 5 or more) may help to vibrate the whole chassis and I want to try this. Then my question is is there recommended circuit connection and/or number of drivers. e.g.: - One DRV2605L chip connected to multiple motors? - Multiple DRV2605L chips each connected to a motor? I imagine motor power consumption or like may force some design restriction but I am new to electri circuit designs.

over 7 years ago

0 Kelly Griffin over 7 years ago

TI__Genius 10512 points

Hello.

Thank you for reaching out. We recommend 1 driver per LRA for optimum performance. Using 1 driver per LRA allows you to take advantage of our closed-loop algorithm that does 3 thing:
1. Decrease the acceleration rise time (overdrive feature)
2. Decrease the brake time (auto-brake feature)
3. Automatically tracks the LRA resonance frequency
The benefits from the algorithm are that short waveforms will feel be shorter and feel more crisp and also the LRA will be driven at the correct resonance frequency, which improves power consumption and provides the strongest acceleration.

You can drive multiple LRAs using a single driver if you configure the device to drive in "open-loop" mode. You will not get the benifits above.

0 Kelly Griffin over 7 years ago in reply to Kelly Griffin

TI__Genius 10512 points

Do you have any additional questions? If not, I will close this post.

0 tmatsuzawa over 7 years ago in reply to Kelly Griffin

Prodigy 190 points

Thanks.

Talking about how I wire the motors to the driver:

For 'open connection', what I need to do is to connect multiple LRAs in parallel to the driver's +/- outputs?

I imagine however there is a up-limit maybe due to the current supplied by driver chip?

0 Kelly Griffin over 7 years ago in reply to tmatsuzawa

TI__Genius 10512 points

Yes, you can connect the motors in parallel. After 2-3 LRAs are combined the resistance may drop below the threshold in the datasheet, 8Ohm.

0 tmatsuzawa over 7 years ago in reply to Kelly Griffin

Prodigy 190 points

That makes sense.
I think I may also try serial-parallel wiring.

Thanks.

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DRV2605L: 5 or more LRAs into the 1 DRV2605L