TPS61088 Battery Voltage Leaks to Output in Shutdown Mode

Sergey Feingold

Other Parts Discussed in Thread: TPS61088, TPS61178

I'm having an issue with a recent board layout, and I'm not sure if I misunderstood the functionality of the IC or if something else is going on.

When battery voltage is applied to the board (single-cell LiPo), the battery voltage passes through to the output even when the EN pin is pulled low. My understanding from the datasheet was that the input/output are disconnected in shutdown mode.

Is this normal behavior or am I missing something? Pictures of the layout/schematic below.

over 9 years ago

0 Helen chen over 9 years ago

TI__Mastermind 40080 points

The TPS61088 doesn't has load disconnect function. The input side and the output side connet together through the upside FET's body diode.

If you want the load disconnect function, need to add an extra FET in the output side.

You can refer to the AN SLVA299A " Input to Output Isolation for the TPS6XXXX".

By the way, what is the load, is it a LED?

0 Sergey Feingold over 9 years ago in reply to Helen chen

Prodigy 220 points

The load is another buck converter (Actually an LED driver -> STMicro P/N LED2001) that feeds a small heater coil.

OK, understood there is no load disconnect I will look for that app note. Thank you!

0 Helen chen over 9 years ago in reply to Sergey Feingold

TI__Mastermind 40080 points

Get it, thanks for the update!

By the way, why do you need load disconnect function. Could you please share more application information with me? Like in what kind of equipment? Volume? Because we need to track the marketing trends for the new product design. My email address is helen-chen@ti.com

0 Helen chen over 9 years ago in reply to Sergey Feingold

TI__Mastermind 40080 points

we have another IC TPS61178 support Vo=20V, but it is still under development, it will be released on March’17. But we have samples and EVM boards now

You can ask for EVM board for test if the schedule is OK.

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TPS61088 Battery Voltage Leaks to Output in Shutdown Mode