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TLV703: Designing with TLV70333DBVR

Vijay
Prodigy 170 points
Part Number: TLV703

Hello Team,
I am planning to use the LDO TLV70333DBVR in one of our projects.
The input is a 3.6V primary battery.
My required output is 3V at 100mA of current (The load is an MCU).
The minimum voltage of the battery is 1.65V and our MCU can operate to a voltage as low as 1.6V.
What happens if the battery voltage is dropped to a voltage lower than the fixed 3V output voltage of the LDO?
It seems the UVLO of the LDO is 1.9V.
What will be the voltage at the output of the LDO when the input voltage is between 2V and 3.22V (output voltage + dropout)?
In general, what will be the behavior of an LDO when its input voltage falls below its rated output voltage for a carrying load?
From the application note (Link), it seems the LDO will be in dropout region.


Looking for your reply.

  • 0
    TI__Mastermind 47415 points

    Hi Vijay,

    Once the input to the LDO has fallen below VOUT + VDO, the device is in dropout and the output is no longer regulated. For TLV703, the max dropout is 375mV at full load, so once the battery drops to about 3.6V - 375mV = 3.225V, the LDO is in dropout and is no longer regulating. In this case the output will follow the input minus the dropout voltage. 

    Regards,

    Nick

  • 0 in reply to Nick Butts
    Prodigy 170 points

    Hello Nick,
    Thank you for your reply.
    As I mentioned earlier, our load is an MCU and the current consumed will be different at different times.
    The MCU and other devices can operate at a voltage as low as 1.6V.
    I hope even when the input voltage is less than 3.6V - 375mV = 3.225V, the LDO can deliver current to the load. until it reaches the UVLO.
    Please correct me if I am wrong

  • +1 in reply to Vijay
    TI__Mastermind 47415 points

    Hi Vijay,

    Yes the device will still deliver current to the load when in dropout. However, when not in regulation the LDO does not have any PSRR and transient performance can be a lot worse.

    Regards,

    Nick