LR1084 at 5V:

Doing some testing to see which are the best heatsinks that I have on hand.

These thin black aluminium set up back to back get real hot at 300mA (2 per IC); 115C on VR front, 110 on HS back (bare, only held by screw/nut).
https://www.aliexpress.com/item/32882672963.html

(didn't take pics)


These mega aluminium get to 91C / 35C (bare, only held by screw).
https://www.amazon.ca/gp/product/B07H5GQVTD/?th=1
I would have expected much more "coloration" on the back, it's nearly like they entomb the heat in there.

(didn't take pics, gotta retest and take pics)


So I tried these on the front; 9x9 bare ALUM with installed tape:
https://www.aliexpress.com/item/1005004079109702.html

These on the back:
https://www.amazon.ca/gp/product/B0B68HPC65/

Along with Arctic MX-4 for improvement thermal exchange:
https://www.amazon.ca/gp/product/B07L9BDY3T


Setup looked like this (unit on the left was running at only 150mA or so):

Name: LM1084 1 setup.jpeg Views: 3106 Size: 162.7 KB


Front temps at 300mA:

Name: LM1084 4 300ma front.jpeg Views: 3088 Size: 142.5 KB

The front HS is at 50C, but the perimeter of the IC is at 128C. Is that adhesive tape holding back heat?


Rear temps at 300mA:

Name: LM1084 5 300ma back.jpeg Views: 3051 Size: 139.4 KB

Despite a relatively good thermal paste (I use it on CPUs), the center of the HS is only at 48C, but the screw is over 108C.


Is it common practice to use a fan to assist the heatsinks?

The LR1084 is rated at 5A; I'm not even running 1/2 amp at 5V...?

5.3 Recommended Operating conditions

Control section 125C max
Output section 150C max

I prefer not adding a fan if at all possible. I'm not seeing a lot of EXCELLENT rated tiny units.

I somehow expected the heatsinks to do "more", especially that last "tandem" setup (unless that chinesium adhesive tape is garbage).