Help with AMS1117

[dbrunod]

Hi Guys! I'm new here and learning. To give you some background, I have yet to have formal education in electronics. Most of my stuff is DIY, learning at forums, and so.

Recently I have been studying more in-depth circuits and PCBs on my own to create a PCB board for my use
with Arduino-like microcontrollers involving multiplexers, buffers, etc.

One crucial part is getting an onboard power regulator for 3v3 and 5V so I can power all the attached devices more efficiently, including the microcontroller board.

On all the schematics I find for AMS117, it shows the components values, but not things like forward voltage, power rating and so. Also, most of the projects are for regular size components, and I'm trying to learn and use SMD.

The board will be powered from a 1A 9V~12V power supply.

Therefore, I have adapted and reviewed the following schematics attached and the components listed.

ID	Designator	Name	Footprint	Quantity	Manufacturer Part	Manufacturer	Supplier	Supplier Part	Description
7​	C15,C24	10uF	CASE-B_3528	2​	T491B106K025AT	KEMET(基美)	LCSC	C110053	10uF 25V 2Ω@100kHz ±10% CASE-B-3528 Tantalum Capacitors ROHS
8​	C19,C22	10uF	CASE-A_3216	2​	TAJA106K010RNJ	Kyocera AVX	LCSC	C7177	10uF 10V 3Ω@100kHz ±10% CASE-A-3216 Tantalum Capacitors ROHS
10​	D2	S3A_C232835	SMC_L6.9-W5.9-LS8.0-RD	1​	S3A	onsemi(安森美)	LCSC	C232835	3A Single 50V [email protected] SMC(DO-214AB)
25​	R14	220Ω	R0805	1​	RC0805FR-07220RL	YAGEO(国巨)	LCSC	C114519	125mW Thick Film Resistors ±1% 220Ω 0805 Chip Resistor
28​	U3	AMS1117-3.3_C347222	SOT-223-4_L6.5-W3.5-P2.30-LS7.0-BR	1​	AMS1117-3.3	UMW(广东友台半导体)	LCSC	C347222	1A [email protected](120Hz) Fixed 5V~5V Positive 18V SOT-223
29​	U4	AMS1117-5.0_C347223	SOT-223_L6.7-W3.5-P2.30-BR	1​	AMS1117-5.0	UMW(广东友台半导体)	LCSC	C347223	1A [email protected](120Hz) Fixed 3.3V~3.3V Positive 18V SOT-223

I would like your expertise and opinions in evaluating if my choices are correct. Thanks a lot!

 

[Delta Prime]

Well... since you're here anyway.

https://maker.pro/arduino/projects/how-to-use-ams1117

 

[danadak]

PCB Thermal considerations :

https://www.ti.com/lit/an/snva183b/snva183b.pdf?ts=1682606805483&ref_url=https%253A%252F%252Fwww.google.com%252F

Regards, Dana.

 

[dbrunod]

Thanks, @Delta Prime, for sharing this project - https://maker.pro/arduino/projects/how-to-use-ams1117. This one didn't show up in my searches before.​

But at the same time, I have a few questions and considerations about the project above, as I think it's not suited for what I'm looking for for a few reasons:

1) It uses a 5V 1A power supply or battery to convert to 3.3V, which is the "safe" and most straightforward way to use this module, as the Source = Vin. So no need for a rectifier, diode, or PTC fuse, etc. Since the module has a 1.2V at 1A dropout voltage, heat is not an issue with 5V Vin as there is minimal input/output differential.

BUT it's strange that the project starts with a 5V 1A, and the testing sessions states : Then supply 12 V through the input terminals with connecting to the external power sources and you will see a 3.31 V to 3.35 V through the circuit so this how voltage is regulated by this AMS1117.

In this case, this circuit in the project will generate quite a bit of heat due to in/out diff , and the component sizes and values on the board do not account for it. Also, nowhere it's mentioned the necessity of a resistor for load, as the project mentions. (maybe it's being used to help with power dissipation / heat?)


2) On AMS117 datasheets, it usually specifies a 10uf(vin) and a 22uf (or 10uf) (vout) tantalum cap. ( The AMS1117 requires an output capacitor for device stability. Its value of 22F tantalum covers all cases of bypassing the adjustment terminal) .

I understand those are used for controlling noise (EMI etc.). So the project above might work, but the 4.7uf and non-tantalum caps can be inefficient in controlling those issues (Is this correct?)

And finally, I'm chaining the devices on my project - 12V >> 5.0 LDO >3.3V, so I can have the two voltages. I would like to understand if the sizes, forward voltage, specs, etc., are those or any other recommendations for the chosen components.

Thanks for your help!

 

[Bluejets]

so I can power all the attached devices more efficiently,

But...but...it's a linear regulator....

 

[dbrunod]

But...but...it's a linear regulator....

Yes I know… it delivers 5V and 3.3v… by efficient I mean have the voltage regulated and enough current for all devices. I’m sorry I don’t understand what you mean with your comment.

 

[Bluejets]

efficient

no they are not............that's the trouble these days, lack of understanding of the English language.

 

[dbrunod]

no they are not............that's the trouble these days, lack of understanding of the English language.

You’re so wrong. I can understand English, and three more languages … what about you? No contribution, useless comments … congratulations!

Yes any power regulator is not from an efficiency perspective 100% efficient. In my case, powering all my devices on the same integrated board is considered efficient, better designed, less wires.

And since you’re sooo good at English learn the meaning - efficient - achieving maximum productivity with minimum wasted effort or expense.

Thanks!

 

[Bluejets]

Well, in electrical or mechanical , it's the difference between input and output expressed as a percentage(normally).
Efficiency can be good or bad, but in the case of a linear regulator, considered bad in respect to other forms.
You apparently considered it to be of excellent design parameter, when it isn't.
Your whole idea seems a waste of time really given there are literally millions of already built and proven designs out there already.
Talk about reinvent the wheel.

 

[dbrunod]

Thanks.

 

[Bluejets]

And since you’re sooo good at English learn the meaning - efficient - achieving maximum productivity with minimum wasted effort or expense.

No, wrong again....that would be maximum efficiency.

 

[dbrunod]

Thanks! Love your contributions. Makers Pro Duolingo forum. Cheers!

 

[Harald Kapp]

Gentlemen or women, please calm down and continue the discussion on a technical basis.
No need to become personal. Otherwise I will delete this thread.

 

[kellys_eye]

what about you? No contribution, useless comments

If you hovver over the username a box pops up and you can put that user on 'ignore'. Worked for me...!