Configuring Buck converter into Inverting Buck Boost

akash Sharma

Other Parts Discussed in Thread: LM46000, LM5017

Hi,

While configuring buck into IBB, it is generally suggested to keep one by-pass capacitor from input to output.

My concern is, if capacitor is connected from vin to vout, Line transient will be worsen. Because the transition of voltage will be passed to output due to bypass capacitor.

Could you please help me ?

Thanks,

Akash

over 7 years ago

0 Chris Glaser over 7 years ago

TI__Guru*** 146970 points

To receive the best support, it is best to ask a specific question about a specific application or part number. Do you have a part number, application, or power requirements? Will your application even have line transients?

0 akash Sharma over 7 years ago in reply to Chris Glaser

TI__Prodigy 60 points

Hello Glaser,

From the below document, I learnt how to configure buck into IBB.
"www.ti.com/.../slyt286.pdf"
On the second page of the document, it is written "A bypass capacitor from VIN to ground and from VIN to VOUT should be used on the input. The bypass from VIN to VOUT is across the device voltage input."

I used the concept on LM46000 pspice model in IBB config.
Pspice line transient simulation results were better (less overshoot and undershoot) when no bypass cap was used from VIN to VOUT.

Please let me know if anymore info is needed.

Thanks,
Akash

0 Chris Glaser over 7 years ago in reply to akash Sharma

TI__Guru*** 146970 points

We have many of these inverting buck boost app notes. The exact circuit is specific to each device. Please edit the title of your post to include the part number, if you want support for a specific device.

0 Vijay86929 over 7 years ago

TI__Genius 11490 points

This talks about inverting buck-boost design using LM5017
e2e.ti.com/.../lm5017-based-inverting-buck-boost-enables-negative-supply

This talks about layout and component placement in inverting buck-boost vs buck
e2e.ti.com/.../laying-out-an-inverting-buck-boost-converter-for-success

Regards

Power management

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Configuring Buck converter into Inverting Buck Boost