Getting 5V out of the MAX1675

Thread Starter

8dm7bz

Joined Jul 21, 2020
172
Hello everybody. I designed a circuit to boost the voltage from roughly 1.5V to 5V, with the help of the MAX1675. Unfortunately it only outputs 2.2V. I have the 8 pin package and connected it as in the picture attached. The actual battery gives me a reading of 1.6V.

I don't use the battery comparator, so I connected LBI and LBO to ground as stated on page 9:
If the low-battery comparator is not used, ground LBI and LBO.
The FB (feedback) pin is also grounded as indicated on page 6:
Connect to GND for +5.0V output.
For the inductor I use this one. And the battery is a AA Alkaline battery.


Any suggestions about what's wrong are appreciated.

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Thread Starter

8dm7bz

Joined Jul 21, 2020
172
I have indeed not tried it with those caps, because I thought it couldn't make that much of a difference. But what do I know, I will try this, thank you.
 

Thread Starter

8dm7bz

Joined Jul 21, 2020
172
Ok, yeah that didn't do anything. In fact now the output goes to 1.2V no matter the FB pin.

Maybe one thing that's weird is that the REF pin is stated to be 1.3V but I measure it to be 800mV.
Any ideas ?
 

Thread Starter

8dm7bz

Joined Jul 21, 2020
172
Oh well, I shouldn't do it on a breadboard then ^^. I will try it on a piece of perfboard and hope for better results.
 

Thread Starter

8dm7bz

Joined Jul 21, 2020
172
Thanks for the additional information eric. Despite the comments on breadboards, I got it to work on it ^^". I don't know why it doesn't work on the perfboard yet.

Thanks for the suggestions. Now I probably just wired something wrong.

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