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TPS61089EVM-742: Cannot reach even 2A of output current

Gabriele Rizzi
Prodigy 100 points
Part Number: TPS61089EVM-742
Other Parts Discussed in Thread: TPS61089, TPS61178, TPS61022

HI, I am just testing the TPS61089 using the EVM-742 evaluation board - as is.

Input voltage: 3.7V

With no load, the output voltage is 9.04V.

When I connect a 10ohm resistor as output load (i.e. <1A load), the output voltage drops immediately to just below the input voltage.

I tried increasing C7 to 1000uF with a low ESR cap but that did not help.

In addition, when the TPS61089 is disabled, the input voltage is appearing at the output, while I was expecting the IC to be disconnected from the load, but I guess this is structural and cannot be overcome.

Can I please get some hints on how to solve the problem?

In my target application, I need to boost the output of a 18650 LiPo battery (3.7V) to 5V 3A (abs. minimum); when the boost converter is disabled, no voltage should appear at the output. Is there a better choice than the TPS61089 ??

Thanks a lot!

  • 0
    TI__Mastermind 40080 points

    Dear Sir,

    TPS61089 should be OK for the 3.7Vin/9V1A Output. Please check the connection from the battery to the board, is it connect with a long and thin wire? Please check the on board Vin voltage, I guess it may drop to a very low value.

    It sounds you need load disconnect function, suggest you use TPS61022 or TPS61178.