What is switchiing regulator for negative voltage (Same as Lm2576)

[nima_1981]

Hi , Friends
What is switching regulator for negative voltage
I need part number same as lm2576 but for negative Voltage also i need 3 ampere in output .
There is -48 VDc and i should , change to - 12 VDC.

thanks

 

[mtwieg]

The lm2576 could be made to work in a negative buck by referencing it to the -48V input, but it would require some external circuitry for shifting the output voltage sense and the gate drive.

 

[nima_1981]

The lm2576 could be made to work in a negative buck by referencing it to the -48V input, but it would require some external circuitry for shifting the output voltage sense and the gate drive.

did you have a sample for lm2576 in negative voltage ??

 

[BradtheRad]

I have not used such IC's...

But this simulation might illustrate what kind of clock pulses would control a negative buck converter.

It uses low side switching.

The output stage is referenced to 0V ground.

 

[nima_1981]

Thank you very much.
It was a great help.
How much current can deliver your circuit?
What do you suggest transistor
For the nearly 1.5 amps?

 

[BradtheRad]

How much current can deliver your circuit?
What do you suggest transistor
For the nearly 1.5 amps?

The scope traces tell the story.

Your initial spec was for 3A output. The transistor (or mosfet) should be rated to carry peaks of 2 times that.

As for voltage rating, it should be able to withstand 2 times your maximum expected voltage. Or greater, because switching off an inductor can generate high voltage spikes, if you're not careful.