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TPS3619-33 SPECIFICATION QUESTIONS

WhiteHorse
Genius 4430 points

e2e,

We have a customer that has questions about the TPS3619-33.

1)      VOUT Batt drop, the datasheet only specs

  1. Iout=.5mA, VBat=1.5 and Vout=Vbat-.05V
  2. Iout=7.5mA, VBat=3.3 and Vout=Vbat-.113V
  3. My specs are Iout=.1mA, VBAT=3, VDD=3.3V, -40C to 85C. What is Vout=Vbat-? For Battery Backup mode and Normal Mode

2)      Is there any droop when changing Vout from VCC to VBAT, aside from the voltage level change?

3)      What does the datasheet mean when referring to “High-level input”/ “High-level output” and “Low-level input”/ “Low-level output”? Is this VDD (high side) and VBAT (low side)?

4)      Why is the IDD (VDD Supply Current) listed at 40uA when VOUT=VBAT? Shouldn’t this be 0A?

5)      What is figure 11 on page 9  representing

Thanks for your help.

Regards,

John Wiemeyer

  • 0
    TI__Expert 8905 points

    Hi John,

    (1) For a 100uA load current, the drop will be extremely minimal. The closest case for you would be Iout of 500uA with Vin 1.5V, but I would expect the drop to be less than that as the 3.3V or 3V provides more voltage to drive the gate of the pass element.  In other words, during battery mode I wouldn't be surprised to see only a 10mV drop, and same in normal operation mode at 100uA of load current.

    (2) The may be some slight droop during the switchover, but your output capacitor should prevent any noticeable effect at low load currents.

    (3) The current ratings for that refer to the drive strength of the output of the MR/ pin. It tells you how much of a load you can drive with the MR/ pin, or in the case of a digital bus to how many different devices you can fanout the signal to.

    (4) This is for the case when Vin(min)  <= Vdd < Vit I believe, so the circuits on the Vdd pin are still drawing current and are powered, but the output is connected to Vbat

    (5) Figure 11 is the overdrive effect. This effect is in essence how hard you are driving the comparator. For example, the curve reads an overdrive of 0.25V at 1us pulse duration on Vdd - this means that if Vdd goes low by 0.25V for at least 1 us, the device will register that Vdd went below Vit and toggle the outputs. But now if your Vdd droops by 0.1V it will take at least a ~2.5us droop for the logic to assert that Vdd went below Vit.

    Regards,

    David