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LM5170-Q1: current monitor

K.Hamamoto
Guru 12155 points
Part Number: LM5170-Q1

Hi

I have some question about monitoring the current.

1. Is the internal current source of IOUTx disabled(open?) when it is disabled by ENx pin? 

    ( I am concerned that the reverse current does flow into IOUT pin if it is disable.)

2. The case of boost mode, should we compensate by duty to the IOUT voltage to calculate the output current ?

    Because in case of Buck mode , the average of sensed current by sense resistor is output current. However in the case of Boost mode, it is not.

Please let me know if you have any question.

Regards,

Koji Hamamoto

  • 0
    TI__Guru* 78060 points
    1. The IOUT source is not turned off by the EN pin. When EN pin is low, there is still 25uA sourcing.
    2. The IOUT monitors the inductor current. To obtain info of output current for boost operation, there are two ways: (1) correction by (1-D), where D is duty, or (2) correction by the ratio of Vin/Vout: the converter can achieve >97% efficiency thus the voltage ratio will not cause much error.