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Pololu 5V, 5A Step-Down Voltage Regulator D24V50F5 sagging


#1

Hi,
I am hoping to use a Pololu 5V, 5A regulator to power 2 usb -> sata converters, a USB hub and a Raspberry Pi. My problem is that when I attach all 3 devices at the same time, the voltage out of the regulator is at 4.65v.

The sata devices are Anker usb 3.0 to SATA converters (via the hub)
The sata devices are also powered with 12v (I am using 3.5in disks)
The power supply is 12v @ 6a and is not sagging under load.
I milled a simple breakout board which contains no discrete components.
The breakout board contains a socket for the regulator, a 12v socket and a usb power socket.
None of the above sockets are at all warm.
The regulator was running at 50c. A fan reduced this to 32c. There was no change in the voltage.

What am I missing?

Thanks!


#2

What is the total current drawn by the load?


#3

With the sata-> usb and the hub (no RPi) it maxed out at 1.15A.


#4

How is that answer supposed to help with the stated problem?


#5

If your meaning is that I didn’t include the RPi, then the total with all three is 1.51A.


#6

Hi.

How are you measuring the current draw of your three devices and the temperature of the regulator? Where on the regulator’s VOUT line are you measuring the output voltage (e.g. at the solder joint on the regulator or at the connection to the sata device). Can you post pictures that show your breakout board and all of your connections?

-Claire


#7

Current draw: I am measuring them at the usb jack on my board.
Voltage: Same as above.
See the attached pictures of the board. It literally feeds 12v to two sets of pins (one for each sata device) and the regulator. The regulator (normally attached to the socket shown) then feeds ± on the usb port.

Is there anything obvious that I am missing?

Thanks!


#8

Those pictures are dark and blurry, so it is hard to see any details. Could you try again with more light? Could you also describe or post pictures of the connections you are making while measuring the current?

-Claire


#9

I measure the current directly out of the usb jack on my board with a modified cable. I cut the + wire of the cable and put the multimeter in line. Here are more pictures. I have included another of the regulator and how it would connect with my board (not pushed in obviously).




#10

It looks like the traces on your board might be a little small for handling 1-2A, so it is possible a significant voltage is being dropped over your board. Could you try measuring the output voltage directly on the regulator board and post a video that shows you doing that as well as measuring the current draw of your 3 devices?

-Claire