Hi people, I am just making a arduino clone and am using two voltage regulators AMS117 5.0 & 3.3. AM using the CH340G driver for programming this board. I believe that my circuit works good. When i connect the power supply, the regulators are getting over heated and burns out. I don't know the exact reason for this. Looking for your help!
How about a schematic?
Did you design a PCB or is it perfboard/breadboard?
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Believing is one thing, but how have you proved that?
In particular, that you have no shorts, and it's not drawing excessive current?
What power supply?
Are they properly rated for the current your "clone" is drawing?
Are they properly rated for the amount of power they need to dissipate, given your supply?
I'll help if you show our schematic.
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Assume nothing - always get the power supply working first.
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I can share the entire the entire schematic, I can share only this part if possible.
On a prototype you need to test as you build, and plan your build properly; so you SHOULD have tested the power supplies and current consumption in that process.
Clearly something is drawing too much current. it would help if you shared a schematic and a photo of your board.
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Not necessarily - it could be that he's trying to drop too much voltage across these regulators?
ie, it's the power dissipation that's excessive, rather than the current itself.
@aravind_0x7 - have you done the maths on this? You still haven't answered what power supply you're using.
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As you state "I can share the entire the entire schematic" sharing the whole thing would help. A partial would help as well. We know it does not work and since we cannot see or touch it you need to answer our questions if you want a viable answer.
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I didn't carryout any math on this. this is the case, there are two AMS (5 & 3.3 ). The 5v is to power the relay and 3.3 to power the controller. 5v connected to the atmega chipset and 3.3 connected to a nrf. I will share the schematic shortly. Thank you.
The input power for the board is 12 V and the AMS are used to step down that to 5 and 3.3
So do the maths now: you know how much the regulators are dropping, and what current is going through them - so work out the power dissipation. Is that within the capabilities of the chips?
What package AMS1117 are you using? I try to use sot89 when I can to save space, but dropping from 12V to 3.3V you can only draw a few mA before temps will sky rocket.
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am not directly droping from 12 to 3.3. Its like 12 to 5 and then 5 to 3.3. This is how the connection goes.
That's why we need to see your schematics!
Note that it's not necessarily a great idea - as that means the supply to the microcontroller will be affected by the relays operating.
Anyhow, have you done the sums yet?
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Another option, which I've done is use a dc/dc step down from 12V to 7V, and the feed this to the AMS1117-5.0, which in turn feeds the AMS1117-3.3
For my application this worked well. The 3.3V supplies an ESP32 and the 5V rail supplies a couple of other chips.
Cheers
Matt
Thanks,let me give it a try
Am using sot223
What load are you putting on the AMS1117-5.0?
Just for a laugh I just soldered a sot-89 AMS1117-5.0 onto a breakout board. Input and output caps 10uF ceramic soldered to the pins on the breakout. Then stuffed onto a breadboard.
With a 56ohm 2W resistor on the output for an 89mA load.
With an input of 7V from my power supply the output was 4.85V across the resistor.
Thermal camera measured the AMS1117-5.0 at around 76°C.
With 12V input the temp of the AMS1117-5.0 shot up to around 117°C. Not good.
I didn't use any heatsink. Just wanted to see what happened 
Anyway. Not sure of the relevance here, but thought that it was worth a mention.
I have some sot-223 also so might give one of those a try later under the same conditions to see the difference.
Cheers
Matt
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