Voltage droop - Teensy LC

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lalous

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Hi guys,

I Have a teensy LC connected to an RGB strip. The first time I tried connecting both of them to the same power supply (5V), the teensy LC fried the moment the RGB lit up. It was because there was a voltage droop, and the moment there was a load (RGB lit up), the voltage from the power supply fluctuated from 4.7 to 5.3 or even higher. Is there a simple circuit to stop that from happening ? When I power the teensy with my computer and my strip with the power supply everything is working perfectly. But it instantly fried when I played a sound on my first try when they were sharing the power supply. I already did a thread about it, asking what the problem was, but now I think this is the problem.

I already finished my PCB, do you know any simple circuit that I can add just before the Vin on the Teensy LC to try and reduce the voltage droop so I can use the same power supply with both RGB and Teensy LC.

Do you think adding a simple diode will drop the voltage enough so it never exceeds the maximum Vin voltage ?

Thank you !
 
Adding a diode won't do a lot, You can try Zeniers and inductive filters but main aim would be to make sure your power supply doesn't swing so much, if nothing else the LEDs won't like it either. Filtering the LED feeds with some reasonably Husky caps as close to the strips as possible and some inline inductance will help with the swing. A really basic test is to power a Teensy from USB and a strip from your chosen PSU and confirm it can in fact drive your target length at full white, and that the AC voltage measurment in that state isn't more than a hundred millivolts or so.
 
Do you think adding a Voltage Follower with an op-amp will isolate the load and stop the voltage droop ?

Here's what I have for my poject:
CircuitMic.PNG

the step-up module is a DC/DC boost converter, it was all I have to represent it. I don't think the problem is in the boost converter, because even when I powered the LED with a USB to my computer, the voltage droop still happened.
 
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There are 30 RGB LED, But I only use 2 colors, blue and green, and they never light up at the same time. Basicly when I play on a drum, it lights green on high frequencies and blue on low frequencies.
 
Let's assume a single LED can use up to 50mA. 0.05A * 30 = 1.5A

The is way too much for the poor USB (max 500mA) and i'm sure its too much for your boost convertor, too.

Solution is simple: Use a better powersupply.
 
I'd say Frank is spot on.

You could start by only illuminating the LEDs to a lower level (eg, 127 instead of 255 for full brightness). In combination with a bulk cap of a few hundred uF, that might rectify the issue somewhat, although the state of your battery will affect the reliability.
 
I don't use all three colors at the same time, I only use green or blue. So it would be the third of what Frank calculated no ?
 
Note that because the LEDs PWM a setting of 127 will consume half the average power, but while it's on, it's running the full current draw. So a collection of LEDs will for periods of time be drawing the full current for even G values of 1, even though on average on times will split apart you only need them all to be on together once to find if your PSU is a bit limp. Note also that even if the PSU is rated for 500mA and your worst case green LED only load is less than that if the PSU is a cheap one intended to feed 500mA to a static load like a battery charger it will fail under an oscillating load like the LEDs.

Proof is when you actually take some measurments with your PSU and LEDs.
 
Maybe post photos of how all this stuff is actually connected.

Sometime the problem is as simple as trying to use thin pre-made breadboard wires (which have incredibly thin wire inside) for 1 amp of current to the LEDs. But without a photo, we can't see what you're actually doing.
 
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