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TPS2590 input bias current for EN and RTRY inputs

Christopher Wilson
Prodigy 110 points
Other Parts Discussed in Thread: TPS2590

The datasheet for the TPS2590 specifies the input bias current for the RTRY input as MIN=50mA, TYP=25mA, and MAX=0mA.  EN is specified as MIN=2uA, TYP=1uA, and MAX=0.5uA.

1) Are the units correct? (i.e. is RTRY really mA vs. uA?)

2) Why is the MIN value less than the MAX value?  Does this have something to do with the direction of the current going into or out of the pin?

3) I'm trying to calculate the total quiescent current for the TPS2590 during sleep mode.  Is this the sum of the IN, EN, and RTRY input bias currents?  How do these relate to the sleep-mode supply current (figure 4)?  (In our circuit, RTRY is connected to GND)

4) How do I calculate the total quiescent current during enable mode?


Thanks,

Chris

  • 0
    TI__Mastermind 42795 points

    Chris, thank you for pointing out these errors within the datasheet. We will get these corrected as soon as possible.

    1) Are the units correct? (i.e. is RTRY really mA vs. uA?) The units are NOT correct and should be uA.

    2) Why is the MIN value less than the MAX value?  Does this have something to do with the direction of the current going into or out of the pin? The current flows out of the RTRY pin when RTRY = 0.2V and as such those currents should be -50uA, -25uA, 0uA.

    Note also that the currents for the EN = 0.2V (sourcing) should also be negative (-2uA, -1uA, -0.5uA).

    3) I'm trying to calculate the total quiescent current for the TPS2590 during sleep mode.  Is this the sum of the IN, EN, and RTRY input bias currents?  How do these relate to the sleep-mode supply current (figure 4)?  (In our circuit, RTRY is connected to GND) For the condition of Vin = 12V, you can use figure 4 for IN pin current (EN=2.4V and RTRY = open) and then add the RTRY = 0.2V currents (50uA, 25uA, 0uA flowing into IN and then out of RTRY).

    4) How do I calculate the total quiescent current during enable mode? This will be dominated by the IN pin bias current when EN = 0V. This is 3.9mA typical and 5mA maximum. This condition is specified with the RTRY pin open so, with RTRY = 0.2V some additional current will flow into IN (50uA maximum which is the current flowing out of the RTRY pin when RTRY = 0.2V).