dc-dc converter help a noob AMS1117 and other stepdown ...

[voidptr]

hello,

here few questions for people used to use dcdc, 

I used in the past dcdc stepdown like the bottom module on the picture without problem, it can produce 5V with 1A and be not even too warm.

So for another thing I decide to buy the top module base on AMS1117 output 5V, I read the spec and it should be good from max around 800mA,
this is fine I need 200mA,  the problem tho is  if I try to draw more than 90mA  the module get really hot and the chip turn off (temp protection).

Well Im puzzle, do I got really crappy parts or those AMS1117 are junk I thought I would I have be able to get 250mA without heatsink... 

What do you think ?

any good suggestions I need to power a small 5 volt arduino clone from 12v ...

[DaveHardy]

You probably blew it up.   DC to DC converters are quite easy to damage.   You need a stable source and load.

[voidptr]

I tried with the same results from 2 different "new' one. 
source is converted PC power supply, kind of stable 12V
laod a big fat 25 watt ceramic resistor ....


humm I thought AMS1117 was a step down , is it more like a linear regulator so maybe it doesn't like to convert 12v to 5V without heat sink ...

You probably blew it up.   DC to DC converters are quite easy to damage.   You need a stable source and load.

[sleemanj]

The AMS1117 is a LINEAR regulator, not a DC-DC converter.

MASSIVE difference.

[DBecker]

The AMS1117 is a LINEAR regulator, not a DC-DC converter.

MASSIVE difference.

Linear regulators are often sold on eBay as "DC-DC converters".

In a broad sense they are, but not by the commonly accepted meaning of the phrase.

[voidptr]

Ya I guess Im a noob 

It was in the description sold has a dc-dc ...

and @sleemanj  I also found your datasheet about the Chinese version who max out at 10V.
(I read 12V and Max 15 on the none Chinese one)


so I will have to design this differently,  Im gonna put a step down in front
something like this who will give me 5V

http://www.ebay.com/itm/DC-DC-9V-12V-24V-to-5V-3A-Step-Down-Power-Module-Vehicle-Charger-Module-/142053321439?hash=item211309aadf:g:08cAAOSw5cNYbv3X

with noise like 300mV,  (I got an output variable here that I just measure)

Question tho is that stable enough to be seen like USB power for my arduino clone ?
or do I need filtering ?

or a step down variable with output like 7V plus ams1117 - 5V filtering ?...

 

The AMS1117 is a LINEAR regulator, not a DC-DC converter.
MASSIVE difference.

Linear regulators are often sold on eBay as "DC-DC converters".
In a broad sense they are, but not by the commonly accepted meaning of the phrase.