TPS54160: Will this dual rail configuration work&

Ilya Dontsov

Part Number: TPS54160
Other Parts Discussed in Thread: TPS7A47, LM317, TPS7A33

Could you please evaluate the following configuration and tell me if this will work?

I need clean +/-30V dual rail power supply for audio circuit. I have two unregulated 40V rails available. These rails power the system of several modules, each having its own point-of-load regulation. In the drawing below, +/-OUT1 powers first module, and +/-OUT2 powers second module. Ground and chassis should be common to all modules in the system. RAIL1 and RAIL2 are commont power supply lines for both modules. Will this configuration work?

Thanks!

over 6 years ago

0 Arief Hernadi over 6 years ago

TI__Mastermind 23845 points

Hi,

Rail 1 should be ok.

Rail 2, is the TPS54160 output will be negative voltage with respect to GND chasis?

If yes, you might want to use a negative LDO such as this one instead TPS7A47

http://www.ti.com/product/TPS7A33

Thanks

-Arief

0 JohnTucker over 6 years ago in reply to Arief Hernadi

TI__Guru**** 191445 points

Ilya and Arief,

Just FYI, 40 V input and -30 V output results in 70 V differential. TPS54160 is rated for 60 V.

0 Ilya Dontsov over 6 years ago in reply to JohnTucker

Prodigy 230 points

John,

This is exactly my concern. However, would the "negative" TPS54160 actually "see" the full 70V differential in this type of connection? To me it looks like the lower TPS54160 should see the same10V differential as the top one, no?

Arief,

Thanks for a suggestion. I'm aware of TPS7A33 chip. I was curious if TPS4A47 will work in that type of configuration (like, for example, LM317 does in the same setup, but in linear PSU).

0 Arief Hernadi over 6 years ago in reply to Ilya Dontsov

TI__Mastermind 23845 points

Hi Ilya,

I believe John is correct, you would see the total 70 V when you are converting from 40V to -30V because the IC will see a total of 70V.

As far as the configuration goes for the LDO, i would use the negative LDO because internally they designed to be operating with negative voltages and they are characterized to convert negative voltages.

Maybe this post will help

https://e2e.ti.com/support/power-management/f/196/p/772363/2858562

Thanks

-Arief

0 Ilya Dontsov over 6 years ago in reply to Arief Hernadi

Prodigy 230 points

Arief,

Thanks for explaining the subtle difference between the linear regs connection. I'll go with the TPS7A33 then.

However, I still can't figure out how the TPS54160 will see 70V, given the input voltage source is floating (see the sample schematic attached). If Vin is measured referenced to ground pin, it should see 45V max if connected like shown. I'm not planning to build an inverter circuit.

0 Arief Hernadi over 6 years ago in reply to Ilya Dontsov

TI__Mastermind 23845 points

Hi,

Yes, it depends where do you reference the 40V input.

If your 40V input is reference to earth GND then the IC will see VIN + VOUT between VIN pin and its GND pin which is 70V.

If your input is 40V in reference to the GND pin of the IC, then yes the IC will see 40V between VIN pin and its GND pin.

I hope that answers your question

Thanks

-Arief

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TPS54160: Will this dual rail configuration work&