Light sequencer with motor driver 8834?

I have to illuminate one of 3 high-power LEDs in sequence (backyard stoplight project).

I was thinking I might be able to use a DRV8834 as both a current limiter and sequencer:

Would this work:

-Set the DRV8834 output current to the maximum current of the high power LEDs (1.4A, DRV8834 can supply 1.5A continuous)
-Connect LED1 to Coil A1-A2
-Connect LED2 to Coil A1-A2 in reverse
-Connect LED3 to Coil B1-B2

-Drive the 8834 in index mode, half step.
Pulling it out of sleep at the beginning of each sequence would start at a known state.
Half step mode, steps 1,3,5,7 seem to power the coils at full-on, full-off.
Its okay if two LEDs are powered briefly for steps 2,4,6,8 (or I may use nEnbl during these transitions).

(Or i may simply use enable/phase mode)

1)Is it safe to connect two LEDs head to head and have only one powered with that much current passing through one?
I know this is typical for tiny LEDs.
I assume the reverse voltage is usually the same as the forward voltage, even for high power LEDs? (I can verify with the specific LED)

2)Will the driver handle a high power LED?
The LED behaviour will be instantaneous in comparison to motor windings, so is there some chopping/hysteresis/? aspect that needs to be considered?

Thanks very much!

Well investigating this more, the high power 12V/8W LED bulbs I see, are not polarity sensitive,
so I think I may use: U3V50F12 (12V step up regulator, 5A) as power source, with 3 power mosfets.

Am I correct in thinking the 12v constant voltage output from the regulator safely drives the LEDs
without a need for current limiting?

Here’s more info for constant current vs constant voltage LED power supplies: … directed=1

If anyone’s interested I ended up getting 3 of these: … 1209/2834/

And contacted the company.
They informed me a 12V constant voltage source would be fine in this case.
I assume each bulb may or may not have some current limiting built in.


Hello, Rob.

Thanks for following up on your posts; glad you figured out how to work with your LEDs. In general, unless you have an LED with an integrated LED driver (like our WS281x-based addressable RGB LEDs), you would need to limit the current going into the LED. You can learn more about how to do that in this blog post about LED circuits.