A way around to cheaper LM317K voltage regulator.

Thread Starter

Kuki Muki

Joined Apr 3, 2018
11
Hello there,i wanted to build an power supply,but LM317T specifications are under the requirements,because my supply can output 1.5A,but LM317T can only control up to 0.8,and there is another variation called LM317K which is just right for my requirements(1.5A),but costs 13$ more.
So i thought if we could use two LM317T as one shown in the circuit bellow:

So i though this maybe would get the job done,still i am not sure about those passive components values,and those are what i found on the internet.
And these two would get a heatsink and a fan.
Thanks you in advance!
 

dl324

Joined Mar 30, 2015
16,943
A more typical approach to increase current capacity would be to use an external pass transistor. Examples should be in the datasheet.
 

danadak

Joined Mar 10, 2018
4,057
Do NOT parallel regulators like that because they do not
have a current sharing mechanism (in circuit you posted).
Thats because their Vref error amp and reference are not
matched, device to device.

Regards, Dana.
 

Dodgydave

Joined Jun 22, 2012
11,306
You need a Pass Transistor like this circuit, make Rb 22 to 47 ohms, put power transistor on an heatsink, or use a TIP147.

lm317pass1.jpg
 
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