TPS50601A-SP: Rad Hard negative supply with standard positve buck converter

Alessandro Schirmer

Part Number: TPS50601A-SP
Other Parts Discussed in Thread: UC1843B-SP

Hello,

I am searching for a negative supply in harsh environment (space). I read some articles of designing a negative boost converter from a standard positive buck converter (e.g. slyt516.pdf)

In the design I have +5V and +8V as supply voltages. It should be generated a voltage with at least -2V / 1A for the negative supply of some ADCs. The idea is to use a standard positive buck converter and to connect the output to GND, the GND connections of the buck converter become the negative supply voltage). I found a similar circuit here in the E2E.

There is used already a TPS50601A-SP in the design as Point of Load but this component has not enough margin (+5V + |-2V| = 7V, this is absolute maximum rating for this IC). I cannot find any other suitable TI ICs (buck converter). Are there any other possibilities to generate the negative voltage (-2V/1A)?

Thanks,

Regards, Alessandro

over 4 years ago

0 Daniel Hartung over 4 years ago

TI__Mastermind 28435 points

Hey Alessandro,

I would personally warn you against using the TPS50601A-SP as an inverting buck-boost.

I have personally tried it in the past and found issues inherent to the device that caused issues with the frequency response as well as drawing too much current.

This means your best bet would be to use one of our controllers like the UC1843B-SP and creating either a flyback or flybuck topology with it.

If you are unfamiliar with a flybuck an overview can be read here:

www.ti.com/.../snva674b.pdf

Thanks,

Daniel

0 Alessandro Schirmer over 4 years ago in reply to Daniel Hartung

Intellectual 290 points

Hello Daniel,

thanks for your reply and your advice.

The flyback topology is known. But it was not the preferred solution yet, because of the transformer. Do you have an advice for a transformer series or manufacturer?

I was already looking for transformers for a DC-DC converter. But everything was very large (for at least only 1A).

Thanks,

Alessandro

0 Daniel Hartung over 4 years ago in reply to Alessandro Schirmer

TI__Mastermind 28435 points

Hey Alessandro,

As far as space grade magnetics, I know of Flux A/S in Europe as well as Renco Electronics and Coilcraft for US.

Thanks,

Daniel

0 Alessandro Schirmer over 4 years ago in reply to Daniel Hartung

Intellectual 290 points

Hello Daniel,

thanks so far. I'm now looking for a flyback converter. Flux A/S has suitable products for my application.

Best Regards, Alessandro

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TPS50601A-SP: Rad Hard negative supply with standard positve buck converter