TPS54386: dual channel with positive and negative outputs

Jingyuan Zhao1

Part Number: TPS54386

Hi team,

My customer is looking for a +10V 3A & -8V 3A dual channel power supply for OLED screen. I'm wondering is it possible to make it happen with dual channel buck like TPS54386. I've do tests on TPS54386 EVM and it's capable of providing 2A for each channel at the same time. Simplified schematics is illustrated as follow. Basically 2 channels with 18V & 8V outputs, using 8V as ground.

The one disadvantages I've think of is that +10V is easily affected when short or open circuit happens at -8V since it's the difference of 2 channels. Any other comments on this configuration? Has anyone actually do this in practical?

Thanks so much.

Best Regards,

Charles Zhao

over 4 years ago

0 JohnTucker over 4 years ago

TI__Guru**** 191445 points

Charles,

No that will not work. The buck side requires that the TPS54386 ground be at ground potential while the inverting buck-boost side requires the TPS54386 ground to be at the minus voltage potential. It cannot be both at once.

0 Jingyuan Zhao1 over 4 years ago in reply to JohnTucker

TI__Prodigy 440 points

Hi John,

Thanks for your reply.

Actually I've done tests on TPS54386 EVM and this works. Both channel is configured as Buck topology. You can think that as a dual channel buck with 18V and 8V outputs which use +8V potential as ground so that the it outputs +10V and -8V. Chip ground is connected to -8V potential.

Noted that the connection of electronic load 1 is between GND and -8V as illustrated in my previous question, so it displays +8V.

Thanks so much.

Best Regards,

Charles Zhao

0 JohnTucker over 4 years ago in reply to Jingyuan Zhao1

TI__Guru**** 191445 points

Charles,

I guess that is ok as long as you don't mind your 10 V output being regulated relative to the -8 V output instead of ground. One other thing to be careful of, the city cycle is right at 90 % at no load. Maximum duty cycle is 90 % for TPS54386.

0 Jingyuan Zhao1 over 4 years ago in reply to JohnTucker

TI__Prodigy 440 points

Hi John,

Thanks so much. I'll do more tests to see if it meets the requirements.

Best regards,

Charles Zhao

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TPS54386: dual channel with positive and negative outputs