Voltage regulator and capacitor

Other Hardware General Electronics
1

Hi i have a question about voltage regulator and too low output voltage, to be specific AMS1117-3.3.

I explain quicly my setup: It is a PCB i design and made produced by a company (pcbway.com ... great pcb by the way) so I can't do any change to my design now. I post the image of the circuit (.png)

power source 120v AC wired on a HLK-5M05 power supply switcher (120v>5v) that is powering an arduino nano trough the 5v pin and also a AMS1117-3.3 voltage regulator breakout (so there is adequat capacitor on the little board). I also posted the photo of this unit. The 3.3v circuit power an NRF24l01+ radio.

I planed holes for capacitors in case i do not use this voltage breakout board.

It is not the first time I use the AMS1117-3.3 regulator breakout board and everything was ok. But the source was usualy a bit more than 5v (5.12v) The HLK5M05 psu give exactly 5.0v.

Now my NRF24l01 radio look to not working because i only have 3.25v, on another project PCB i have made(with no HLK-5M05 PSU) , my 1117-3.3 give me 3.29v and my radio is working properly if installed on this one.

My question: If I add other capacitor can it help me gain (or if you prefer, not loose) some 0.xx volt ?

1117.jpg

2

I just realize I have some spare LM1117-3.3 (TO220) I tested it with the HLK-5M05 5.0v and i got 3.32v

New question I have tested it (multimeter) with no capacitor because i had no more left. can the output voltage drop with capacitor ? (2x 10uf 25v capacitor)

thank again !

3

can the output voltage drop with capacitor

No.

The data sheet says for a nominal 3V3 output the voltage can range from 3.235V to 3.365V.
But without capacitors the whole system will not be stable.

4

Thank you I'll go buy some capacitor and unsolder the AMS1117 and try the LM1117 instead.

5

Low drop-out regulators can be quite fussy about their capacitors - read the datasheet to find out
if special requirements for value and ESR.

No linear regulator should be run without their capacitors, they can potentially oscillate and even destroy
components through over-voltage. However if the load itself has capacitors they may be enough, if
its close to the regulator.

6

Thank you. No worry i just stopped at my electronic store to buy some 10uf and .1 uf as wrote in the datasheet.