Can I use the LM317 to control output power of my 100W SMPS (12Vdc, 8.5A)?

[andrie_20]

can i use the LM317 to control output power of my 100W SMPS (12Vdc, 8.5A)?

 

[cameo_2007]

LM317

control the output power??

you can adjust the voltage, provided the current which you are going to draw is well within the chips capability, and I am sure that wont be 8.5A

 

[david_samtel]

Re: LM317

you can't use LM317 for your application since the output power current range of LM317 max is only 1.5A please check the data sheet. internal architecture of regulator not allow to increase the current behind 1.5A.so better you choose some other power regulator

 

[cameo_2007]

Re: LM317

you can't use LM317 for your application since the output power current range of LM317 max is only 1.5A

the thread starter has not mentioned whether he needs more than 1.5A at the output.

 

[pranam77]

Re: LM317

can i use the LM317 to control output power of my 100W SMPS (12Vdc, 8.5A)?

You may use LM317 TO3 package. But you need to confirm that to regulate the device will require a 3volts margin voltage. Mean if you need 12 volts, the device should be supplied with 15 volts minimum. Too the capacity of TO3 package is 3 amps maximum. If you need more power, you may use a current boost circuit mentioned in the datasheet of LM317. Cheers

 

[darKnight110588]

Re: LM317

i used lm317 as to create a 3.3V output... but instead of having 3.3V output it created a more or less 1.2V output. I'm pretty sure that i used the right value for r1(240ohms) and r2(400ohms). my input voltage is 12V. I tried to change the value of the resistor, still the output is 1..2V. what might be the problem?

 

[powerpratik]

LM317

if you are use LM317 for only to control the switching wavwform, it is usable.
But if you want 8.5 A from the LM317, don't imagine it because it's max rate of current is 1.5A...

 

[Tahmid]

LM317

Hi,
At 8.5A from LM317, impossible. At this power level, I wouldn't even think of going linear. I'd choose switching. Check out L4970 from ST. Amazing chip, man! The price is a tad high though.
Datasheet:
http://www.datasheetcatalog.org/datasheets/400/70035_DS.pdf
Application Note:
http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXxxyt.pdf

 

[peater]

LM317

you have choosed switching power.

 

[powerpratik]

Dear freind,

LM317 is used to control the total o/p current, but you cant take 8.5A from the LM317.
LM317 is used here in control circuit of the SMPS.