Using 2 voltage regulators

I have a voltage source of a 2S LiPo (7.4 V). I will be using a AMS1117-3.3 as a voltage converter. In most of the sites its written that the maximum current output is around 1A. I will need a current of about 1.6 A. So will using 2 voltage regulators do the thing?

You can't just connect two in parallel, no.

But if you could segregate your loads into two (or more) where each one takes under 1A, that could be OK...

Hi,
You would be best to use a DC-DC voltage converter.
They are more efficient.
AMS1117-3.3 is a linear regulator.

If you have 7.4 volts on the input of the linear regulator, and 3.3 output, with 1.6A.
The power DISSIPATED in the regulator will be;

P = V x I = Voltdrop x current through device

P = ( 7.4 - 3.3 ) x 1.6 = 6.5W.
Which for a small regulator will need a heatsink.

Google;

DC-DC converter arduino

To see what is available.

Tom.. :smiley: :+1: :coffee: :australia:

Always best to look at the actual manufacturer's datasheet:

http://www.advanced-monolithic.com/pdf/ds1117.pdf

So that's a lot of voltage to drop!
Don't forget that power dissipation can be a limiting factor long before you hit the current limit:

Which package are you using?

You might consider a switch-mode "buck" regulator. They are a little more complicated (they require an inductor) but they can generally handle more current and they are nearly 100% efficient... i.e. They run cooler and if you are reducing the voltage in half, you can get about twice the current out as you feed-in... Your battery will last longer.

With a linear regulator going from 7.2v to 3.3v, the regulator has to dissipate more power (wasted as heat) than is going to your load.

You can buy an assembled board if you don't want to fool-around with the more complicated circuit.

+1

You can even get them in TO220-style packages; eg,

I am kind of constrained on space, so a buck converter would be really troublesome for me. How about I put a lm7805 (5V converter) and then use the 5v source on the ams1117. Will that resolve the heat issues?

I tried searching for them in the nearby stores and couldn't find the to220 package, online they are just too costly atleast in my region

my package is SOT-223, and it says thermal resistance is 90 C/W. So what temperature would be ideal?

Did you read the footnote:
With package soldering to copper area over backside
ground plane or internal power plane ϕ JA can vary from
46°C/W to >90°C/W depending on mounting technique and
the size of the copper area.

I was talking about the worst possible case

any temperature that doesn't exceed the stated maximum chip temperature of the device

"thermal resistance of 90 C/W" means that each watt of power dissipation will cause a 90 C rise in the chip temperature relative to ambient.

So, if your ambient is 25C, then 1W of dissipation will raise the chip to 90C above that - ie, to 115C

You are dissipating well over 4W - so the chip will burn.

So i changed the schematics and now i need only 40mA to power the ESP-32, I think the heat issues will be resolved if i use a 5v regulator alongside the ams1117

Don't just think - do the sums!

Thanks, now i have reverted to a 0.06C rise, that will work good

I did, I did, I am sorry i didnt state the values

Watts is Watts! You can put as many regulators in series as you like the wattage will be the same not counting the additional power required by the additional regulators. Linear regulators are nice, work very well but any voltage they drop is spend as heat via its internal series pass device.

Switching regulators turn on, store power in a reservoir, then turn off until more is needed within reason. With them being off part of the time no heat is generated so they are much cooler and efficient. I have seen 2A buck converters about the size of a postage stamp selling for under a buck or two.

For only 40mA you can just use the 1117 by itself

The thing is that, since my pcb is constrained on space, a postage stamp is still a lot, nevertheless, since i have already bought the regulators i dont plan on buying buck converters, but next time i need voltage regulation i will definitely buy a buck and reserve some space for it. Thanks for the info

Actually there are other components which have inbuilt regulators and i was planning on supplying 3.3 V to them, hence the 1.6A. But now I have changed some of them to 5V and some to 3.3V. Thats why I am using 2 regulators