How to create negative power with buck ICs?

wenhe hou

Part Number: TPS54560

Tool/software:

Hi ,guys

As we all know, Buck and Buck-Boost are only different in the connection of the inductor and the diode or MOSFET, Buck-Boost can be used to generate negative voltage.

so can all Buck ICs be used to generate negative voltage? Or some specific Buck ICs?
How can I quickly determine if a Buck IC can be used to generate negative power?
When using Buck to generate negative pressure, I noticed that there are two connections, one is to connect the GND pin to ground, and the other is to connect the GND pin to Vout, what is the difference between the two?

over 1 year ago

0 David Baba over 1 year ago

TI__Mastermind 40040 points

Hello Wenhe,

There is nothing preventing any Buck IC to be configured as an IBB. there are limitations depending on the device selected. Recommend using current mode control or COT control architecture, please refer to the link below for more details, hope this helps.

Working with Inverting Buck-Boost Converters (Rev. B)

David

0 wenhe hou over 1 year ago in reply to David Baba

Prodigy 55 points

Hi David，

Thank you very much for your reply, but question 3 I don't seem to find the answer in the AN, can you help me with another answer?

0 David Baba over 1 year ago in reply to wenhe hou

TI__Mastermind 40040 points

Hello Wenhe,

the Gnd pin of the Device is tied to -VOUT. This is the reference voltage. the positive voltage of the negative supply is Gnd (0V).

Hope this helps.

David.

0 wenhe hou over 1 year ago in reply to David Baba

Prodigy 55 points

Hi David，

Thank you very much for your reply,I don't understand what you mean, can you give me a clearer description?

Will there be a difference in the working state of the circuits inside the ICs between the Pin tied GND and tied -VOUT, Are there any ICs that don't work?

wenhe

0 David Baba over 1 year ago in reply to wenhe hou

TI__Mastermind 40040 points

Hello Wenhe,

The Gnd nodes of the Device and its components all get tied to the -VOUT node. the actual ground which is 0V gets tied to VOUT of a traditional BUCK.

in the circuit diagram you posted above, please reference figure 2. -VOUT is depicted by a triangle shape. and 0V is depicted by the "earth" symbol.

please follow this diagram, there is no reason why any buck cannot be configured this way. hope this helps.

David.

0 wenhe hou over 1 year ago in reply to David Baba

Prodigy 55 points

Hi David，

OK，thank you so much! I got your point!

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How to create negative power with buck ICs?