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LDO regulator for battery application

tablet23
Prodigy 40 points

Hello,
I am designing a wireless acquisition system with 3V3 VCC. I have two question:

1) I would like to have the greatest time of battery. Then, What is better? Use a LDO or Switching regulator. The battery is a 3.7V. If I use a LDO the system do not work with a Vin less than 3V3 but the LDO consumption is less than switching regulator.

2)If I use a 7.4V battery, What should I use? LDO or switching regulator. The power dissipation of the LDO is (7.4-3.3)*.25mA=1.025 W, but the TPS7201 , for example, accepts a input voltage range 3V-10V.

Thanks.
Regards.

  • 0
    TI__Guru 55940 points
    Hi ,

    While an LDO will not boost the battery voltage, the LDO will continue to power the load while it is in dropout. The load would see the input voltage minus Vdo rather than the regulated 3.3V. For the 3.7V battery, TPS78233 may be a good choice as Iq is typically 420nA.

    One of the things that you would need to decide is if your application can tolerate switching noise. An LDO will provide a low noise rail while the switcher will have some switching noise and associated losses.

    Very Respectfully,
    Ryan
  • 0 in reply to Ryan Eslinger
    Prodigy 40 points
    Hello,
    If I use a 7.4V battery wich is the best choice? LDO or or switching regulator? The LDO bears the 7.4V voltage.
    If I use a 3.7V battery and LDO with 3V3 output, How much autonomy can I lose?

    Thanks,
    Regards.
  • 0 in reply to tablet23
    TI__Guru 55940 points
    Hi ,

    The best choice for your application will depend on factors such as how much switching noise you can tolerate. One thing that you could do to help decide is to sample devices and/or use EVMs to test out your application.

    Very Respectfully,
    Ryan