TPS610985: Measure efficiency in TPS610985EVM

Niclas Samuelsson

Part Number: TPS610985

Hello. With such small currents, how should I go about getting accurate efficiency measurements of the TPS610985? I want to load it with 3uA, while supplying it with 1.5V.

Thank you!

over 3 years ago

0 Niclas Samuelsson over 3 years ago

Prodigy 70 points

In low power mode. So I want to verify that I am getting 80+% efficiency and 300nA quiscent current.

0 Niclas Samuelsson over 3 years ago in reply to Niclas Samuelsson

Prodigy 70 points

Measuring input current through a multimeter gives about 1uA with no load which seems incorrect.

0 EM over 3 years ago in reply to Niclas Samuelsson

TI__Genius 11215 points

Hello Niclas,

As specified in the datasheet, the quiescent current is measured in no load and no switching condition ( page 6 https://www.ti.com/lit/ds/symlink/tps610985.pdf?ts=1620409179898&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS610985 ) . Let me know if I can help you furthermore.

Kind regards.

0 Niclas Samuelsson over 3 years ago

Prodigy 70 points

I found the document SLVA828, "Calculating and Measuring the No Load Input Current of the Boost Converter" which helped me calculate the quiescent current to 0.5uA, which seems reasonable I guess. My efficiency is slightly lower than expected. I was expecting 85% at a load condition according to the graphs in the datasheets, but got 80% (with the eval board). What can I do to improve it to 85%?

0 Eric Yue over 3 years ago in reply to Niclas Samuelsson

TI__Expert 5180 points

Hi Niclas,

Input current can be measured by the same method introduced in SLVA828. In efficiency measurements, Kelvin four-wire test method is used for accurate input/output measurement. The impact of contact resistor can be reduced by four-wire test method using sense pins of the EVM.

Best Regards,

Eric Yue

Power management

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TPS610985: Measure efficiency in TPS610985EVM