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TPS62230: TPS62237 LDO mode

Prodigy 20 points

Replies: 2

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Part Number: TPS62230

Hello,

On the datasheet is written that the TPS62237 is able to keep the Ton at 100% in order to have Vout = Vin when Vin is close to the desired regulated output. This can help to use more capacity of a single cell Lithium battery.

On my board the current consumption is 87.3mAdc, when Vin = 3.737Vdc, and Vout = 3.329Vdc.

With the theoretical calculation, the Vout should stay at 3.329Vdc even if Vin is as low as 3.411Vdc :

Vin min = Vout max + Iout max * (RDSon max + RL) = 3,329 + 0,0873 * (0,850 + 0,095) = 3,411Vdc

But the measure is different from the theory :

Vin (batterie) [Vdc] Vout (3,3Vdc regulated) [Vdc]
4,31 3,325
3,741 3,329
3,64 3,329
3,61 3,302
3,5 3,188
3,314 2,997
3,005 2,679
2,71 2,37

Vout starts to decrease when Vin is around 3.6Vdc. Is there something wrong ?

I thank you in advance.

Fred

  • Hi Fred,

    Did you measure the voltages at the pins of the TPS62237? IR drop across PCB trace, connectors, etc. impacts the result.

    As well, did you measure the current to make sure it is really 87.3 mA when you performed this test?

    Chris Glaser

    Texas Instruments

    ________________________________

    TPSM82810 - new, 6Vin, 4A, high efficiency power module with clock synchronization Now sampling!

  • In reply to Chris Glaser:

    Hello Chris,

    There was indeed a problem with the instrumentation. Thank you for you advice.

    Fred

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