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TLV743P: Drop out Voltage and Load Transient @ 2.5V

Part Number: TLV743P
Other Parts Discussed in Thread: MULTIPKGLDOEVM-823,

My customer is looking for an LDO, VIN = 3.3V, VOUT = 2.5V, IMAX = 300mA and the TLV7x3p looks to be a good fit.

Per the datasheet, it looks like the Drop out Voltage @ 2.5V should be 290mV (please confirm).

Do we have Load Transient information available @ 2.5V as well?

Best, Ishaan

  • Hi Ishaan,

    You are correct, per our Electrical Characteristics table, the maximum dropout over the full temperature range is 290 mV.

    Transient performance will depend on application specific conditions such as the output capacitor and the magnitude and slew rate of the transient itself.  We do provide load transient information for the 1 V and 3.3 V output to give an indication of the transient performance.  Please note that the scale for Vout (magenta) is different between the two curves.  The magnitude of the transient response is more similar than it appears at first glance.  Since the 2.5 V output is between the two voltages shown, the transient response will also be similar.

    We do always recommend prototyping so that you can see the performance under your application conditions.  MULTIPKGLDOEVM-823 can be used to assist in the early prototyping phases.

    Very Respectfully,

    Ryan

  • Hi Ryan,

    Thanks for the prompt reply.  We are looking to get more specific information on both fronts.

    For the VDO, can we provide curves similar to the below @ 2.5V?  Also, our assumption is that Figure 10 corresponds to the DQN package (but isn't listed).  Please confirm:

    Similarly, we are looking for the transient response @ 2.5V.  Per your comments, the 2.5V case should be similar (and I agree).  Can you comment on how similar?

    Best, Ishaan

  • Hi Ishaan,

    Yes the dropout curves will be similar for the 2.5 V device. The purpose of these curves is to show that dropout is linear with respect to output current. You can learn more about dropout in Chapter 1 of our LDO Basics E-book:

    www.ti.com/.../slyy151.pdf

    You are also correct that Figure 10 should state that it was taken on the DQN package.

    The magnitude of the load transient response will vary slightly with output voltage. During a load transient, the LDO feedback loop will first detect that the output voltage is too high or too low. TLV743P has a PMOS pass FET. When the output of the LDO is too low, the error amp will drive the gate of the FET towards its negative rail (GND). This allows more current to flow through the LDO to bring up the output voltage. Similarly, when the output voltage is too high, the error amp will drive the gate of the FET towards its positive rail (Vin) to stop the flow of current through the LDO until the load can discharge the output back to the regulated voltage.

    All of this is fixed for the TLV743P family by design. The only difference between the output voltages versions of the TLV743P family is the gain of the internal feedback resistor network. As such, if two output voltage versions were subjected to the same transient (magnitude/slew rate) with the same output capacitance, the transients will be extremely similar.

    Very Respectfully,
    Ryan