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TPS7A05: Dropout mode, low current behavior of TPS7A05

Dylan Jackson70
Prodigy 20 points
Part Number: TPS7A05


Have a few questions about the TPS7A05 that don't appear to be addressed in the datasheet and hoping they can be answered.

1) The datasheet describes how it reduces the Iq in dropout mode, but I couldn't find a graph or spec on what the Iq looks like in dropout mode. We use a CR2032 battery (full voltage is 3V, empty voltage is 2V), so we expect a significant amount of operation in dropout mode.
2) The datasheet indicates 10uA minimum is necessary to meet voltage accuracy specs, but our product spends most of its time in a deep sleep state with a current ~5uA. How inaccurate is the voltage output below 10uA?
3) It also mentions that when in dropout mode the voltage drop is just the drop over the PMOS transistor, but I can't find where it specifies what that is with respect to output current.
Finally, if the quantities were high enough, would it be possible to get this part trimmed to 2.7V?
Thank you!
  • 0
    TI__Expert 4435 points
    Hi Dylan,

    1) The Iq does not increase in dropout, so there is no graph to include in the datasheet. The Iq was the same in dropout and not in dropout. You can use Figure 1 in the datasheet for typical Iq.

    2) For typical performance, see figure 28 in the datasheet for change in Vout vs Iout. At Iout = 5 uA, you should see very similar performance to Iout = 10 uA. The output error started to increase below Iout = 2 uA and at +125°C. For Iout = 0 at temp = +125°C, Vout increased to +5% above the setpoint. I measured 0.842 V for a 0.8 V fixed output.

    3) Dropout voltage vs Iout (load current) typical performance is shown in figures 21 and 22.

    I'll pass on your request regarding 2.7 V and get back to you.
  • 0 in reply to Eric.Preiss
    TI__Expert 4435 points
    Hi Dylan,

    I haven’t heard back from you. I’m assuming you were able to resolve your issue. If not, just post a reply below or create a new thread if the thread has locked due to time-out.