Small, simple 5V to -4V converter

Thread Starter

RichardO

Joined May 4, 2013
2,271
I often need a low current negative voltage for prototyping on a solderless breadboard.

Here is a simple circuit to do that. This circuit can supply about 50 ma at -4 volts with +5 volt input. It uses a LT1054 but an ICL7660 or LT1044 could be used if lower output current is acceptable.

I used the 47uF, 6.3 volt ceramic caps because I had them and they have the required low ESR (less than 0.1 ohm). Being surface mount, I had to get a bit creative wiring them.

The entire circuit is built on a small piece of pad-per-hole prototyping board. My connector is a 0.1" spacing header with 0.025" diameter pins.

RO_+5V_to-5V_Converter_front_corr.jpg RO_+5V_to-5V_Converter_back_corr.jpg


upload_2017-4-9_15-29-5.png
+5V_to-5V_Converter_front.JPG +5V_to-5V_Converter_back.JPG
 

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bertus

Joined Apr 5, 2008
21,312
Hello,

I have added the datasheet.
I see that the chip can be used upto 15 Volts.
That may also be handy when you need to power circuits for RS232 or opamp circuits that require higher voltages.
For the higher voltage use, the capacitors must be adapted to the used voltage.

Bertus
 

Thread Starter

RichardO

Joined May 4, 2013
2,271
I made a PCB for the circuit using surface mount parts.

Some details:
The parts I actually used are 47uF in 1206 packages for C1 and C2.
The board is designed for a 1206 for C3 but I used a 10uf in an 0805 because that is what I had.
I have supplied the Gerber for the PCB. This site did not seem to recognize the .GBR file so I appended ".txt". You will have to remove the ".txt" from the file name.
The Gerber file is already backwards ready for toner transfer printing.
I used the program ViewMate to make the 8-board panel. It is free here:
https://www.pentalogix.com/t/software-products/viewmate
A couple of the boards on my panel did not print properly so I used a felt tip marker to "delete" them to save etchant.


Front.JPG

Panel.JPG
 

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