[SOLVED] 5v to 3.3v, around 70mA current at output.

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hi,

my application is to convert 5v to 3.3v and 70mA output.
i am looking for smd package.
i found AMS1117 3.3v voltage regulatorhttps://www.aliexpress.com/item/10pcs-AMS1117-3-3-AMS1117-LM1117-1117-3-3V-1A-Voltage-Regulator/32348815272.html?spm=2114.search0104.3.26.jxqdPm&ws_ab_test=searchweb0_0,searchweb201602_1_10152_10065_10151_10068_10326_10084_10083_10080_10307_10082_10081_10110_10137_10175_10111_10060_10112_10113_10155_10114_10154_143_10056_10055_10054_10312_10313_10059_10314_100031_10099_10078_10338_10079_10103_10073_10102_440_10052_10053_10142_10107_10050_10051,searchweb201603_19,ppcSwitch_4&btsid=f5eaf91d-dade-49c8-a836-5d89a5564f47&algo_expid=38aeccd1-5615-459f-8508-a8c4c473449a-3&algo_pvid=38aeccd1-5615-459f-8508-a8c4c473449a

i am confused in selected section shown in image.

is this sentence want to say that it will work when there is voltage difference of 1v? it will not work if 4v is input and output is 3.3v





thanks,
vraj
 

Vraj said:
is this sentence want to say that it will work when there is voltage difference of 1v? it will not work if 4v is input and output is 3.3v
Click to expand...

Right. For 3.3V output, the input must be greater than 4.3V.
 
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    Vraj

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i found another one XC6206 662k.
ams1117n was bigger in size.

am i in correct direction?
 

Vraj said:
am i in correct direction?
Click to expand...

You will find very few regulators that have lower drop than 1V; the regulator needs some space to work. Perhaps you can get one with a 0.9V dropout but then they are rare.

Anyway you will that 4V input cannot reliably produce 3.3V regulated output (most cases)
 
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    Vraj

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Hi,

but what´s the problem? You want to convert 5V to 3.3V.
And the 1117 operates with input voltages > 4.3V
5.0V > 4.3V. --> True. Everything is fine.

Klaus
 

Hi,

Why not use any of many preset or adjustable LDOs - maybe easily covering the 300 to 700-ish mV dropout headroom only?
 

KlausST said:
Hi,

but what´s the problem? You want to convert 5V to 3.3V.
And the 1117 operates with input voltages > 4.3V
5.0V > 4.3V. --> True. Everything is fine.

Klaus
Click to expand...

it was hard with another ics.
i was using qfn 4*4 packge and 0402 packages. 1117 was looking bigger.
XC6206 662k is available in sot23.
amazing thing of XC6206 662k[/URL] is that, it is ceramic capacitor compatible.
may be they are used for smoothing i/p and o/p waves.
my input is 5v from usb.

i don't have oscilloscope, can you say that i should go with mentioned value of capacitor (as datasheet)?

will capacitor rated with 10v will ok?

- - - Updated - - -

d123 said:
Hi,

Why not use any of many preset or adjustable LDOs -
Click to expand...

present LDOs? e.g.?
i need small smd package and cheaper one:thumbsup:

maybe easily covering the 300 to 700-ish mV dropout headroom only?
Click to expand...
means?
 

Hi,

amazing thing of XC6206 662k[/URL] is that, it is ceramic capacitor compatible.
Click to expand...
I don't see this as drawback, I see it as benefit

may be they are used for smoothing i/p and o/p waves.
Click to expand...
Every voltage regulator should have capacitors close at input and output to ensure stability.

my input is 5v from usb.
Click to expand...
So your input voltage is not exactly 5.0V.
Rather expect 4.2V ..... 5.5V (it is specified down to 4.5V, but I've seen many they go below this at the end of the cable)

i don't have oscilloscope, can you say that i should go with mentioned value of capacitor (as datasheet)?
Click to expand...
Keep on the datasheet recommendations.

will capacitor rated with 10v will ok?
Click to expand...
Yes.

present LDOs? e.g.?
Click to expand...
Almost any true LDO with 3.3V output will do the job.
There are hundreds of LDOs that can be used.

I'd go to a distributor's or a manufacturer's web site selection guide to choos the right one.
If you go to aliexpresss .... it's your way...

Klaus
 
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    Vraj

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hi,

My main MCU manufacturer has mentioned to add 4.7uF and 10nF capacitor to input 3.3v and ground.
i think they mentioned to smooth i/p.

my XC6206 662k is providing good o/p 3.3v with 1uF.

i think, i should continue with 1uf and parallel with 10nF, avoiding 4.7uF.

what's your opinion?

i also meant impressive(amazing)

thanks,
vraj
 

Hi,

you must not rely on any MCU manufacturer recommendation when you want stable XC6206 operation.

Rely on the XC6206 datasheet.
it clearely says to use 1uF ceramics each at input and output.
Additionally it says:
...
3. Please wire the input capacitor (C IN ) and the output capacitor (C L ) as close to the IC as possible.

4. Capacitances of these capacitors (C IN , C L ) are decreased by the influences of bias voltage and ambient temperature. Care
shall be taken for capacitor selection to ensure stability of phase compensation from the point of ESR influence.

Klaus
 

hi,

i think there is misunderstanding.
i mean my main ic is MCU. MCU is rated 3.3v input.
i need stable MCU operation.

if small capacitors like 10nF used to smooth remaining high frequency, then should i use?

thanks,
vraj
 

Hi,

for stable MCU operation you need to follow the recommendations in the MCU datasheet.

If they recommend to use 10nF capacitors then do so.
But read carefully. Usually they recommend one capacitor very close at each VCC pin of the IC....this has nothing to do with the capacitors close to the voltage regulator.

Klaus
 

Hi,

Read section:
■PRODUCT CLASSIFICATION

Klaus
 
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    Vraj

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You can find MANY regulators with less than 1V of dropout. But what is it you really want? You say you want 5V to 3.3V, that 1.7V of acceptable dropout
 

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