+- 5V PSU with TPS5430

Rakshit Ramesh

Other Parts Discussed in Thread: LM2662, TPS5430

Hi ,

A while back i had made a design for a 5V PSU with TPS5430 .I had also connected the output of the TPS5430 to the input of an LM2662 Switched cap voltage inverter .Worked well with no load. As soon as i connected a load ,both + and -5 V dropped to 1 V and -1V.Then i came across a thread saying that TPS5430 isn't designed for current sharing .

Therefore ,is there any solution to obtaining +- 5V with TPS5430 ? Is there a way to avoid this current sharing problem i had with LM2662 at the o/p of TPS5430 ?

over 10 years ago

0 Jason Liu3 over 10 years ago

TI__Intellectual 1010 points

Hi,

More information is needed.
Could you provide the input voltage and, load condition and the waveform on switch node? Try to add load only on 5V output.

Regards,
Jason Liu

0 JohnTucker over 10 years ago in reply to Jason Liu3

TI__Guru**** 191445 points

You might want to look at a coupled inductor solution such as:

It should also work with TPS5430.

0 Rakshit Ramesh over 10 years ago in reply to JohnTucker

Intellectual 670 points

Thank you ,i shall look into it .
Also ,for my application ,i require 2.5 V which i would derive from the TPS5430's +5V out .
I thought of using the LM2662 swithced cap voltage converter . I'm most likely going to find the same current sharing problem as mentioned earlier .What other ways can i obtain 2.5 V (Apart from resistor divider )

0 JohnTucker over 10 years ago in reply to Rakshit Ramesh

TI__Guru**** 191445 points

LM2662 looks like it has the ability to divide 5V/2 to get 2.5V. As long as you don't need much current I don't see any particular issue with that.

0 Rakshit Ramesh over 10 years ago in reply to JohnTucker

Intellectual 670 points

The output of the TPS5430 going directly to the LM2662 won't cause a problem ? (Like it did for the voltage inverter as mentioned earlier )

0 JohnTucker over 10 years ago in reply to Rakshit Ramesh

TI__Guru**** 191445 points

I'm not sure what your issue was with the original design, but it was not "current sharing". Current sharing in this context refers to connecting two TPS5430 converter outputs together in parallel operation to double the available output current. You cannot generally do that with voltage mode control devices. It is very common to cascade converter stages where one converter output is used as the input to another converter.

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+- 5V PSU with TPS5430