TPS22990: Parallel connection

SteeVeeDee

Part Number: TPS22990
Other Parts Discussed in Thread: TPS22976

Do you see any issues with using TPS22990 in parallel as follows? I've seen this for other devices in this family of switches:

over 6 years ago

0 Alpha H over 6 years ago

TI__Genius 10855 points

Hi Steve,

Thanks for reaching out on E2E!

You are correct, you can use our load switches in parallel for higher current applications. Connecting both CT pins to the same capacitor shouldn't be an issue. We show a similar configuration on the TPS22976, in this app note.

For reference, can you comment on the application? 10A+ seems like a lot of current, this is a core rail or system rail?

Thanks,

Arthur Huang

0 SteeVeeDee over 6 years ago in reply to Alpha H

Intellectual 700 points

We are not switching 10A+ of current, rather we can not tolerate much drop across the switch. The max Rds,on of the TPS22990 is ~5.7 mOhm, and we are switching a 1.2V rail that requires +/- 3% tolerance (FPGA is part of the load). The load is ~4.5A, so you can see 4.5A * 0.0057 Ohm = 25.6 mV -> 2.1%. While we can margin up the supplies a little bit to accommodate this, the output accuracy of the 1.2V rail is ~1% as well, so we don't have a whole lot of room to play that game.

Obviously the TPS22990 Rds,on will typically be much lower than 5.7 mOhm, but this has to work on paper and it gives us about 1% more room in the design if we simply drop down the second, parallel switch... I'd prefer not to do it, but it will be easier to leave the extra part off the board later if we decide that we don't need it.

Thanks for your prompt response.

Best, Steve

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TPS22990: Parallel connection