Discussion in 'The Projects Forum' started by Philip Kristament, Oct 19, 2014.

  1. Philip Kristament

    Thread Starter New Member

    Oct 19, 2014
    I am a newbie at circuits trying to put a Bill of Materials together for a bit of kit which is a part of a much bigger system.
    My problem is as follows...
    I need the system to sense when the battery is getting low and needs recharging. I also want a buck/boost to provide a constant 3.3V to the power rail. So the supply voltage supervisor must sit behind the buck/boost otherwise it wouldn't work.
    The supply voltage supervisor I intend using is the TI TPS3800G27 which asserts a push-pull RESET signal whenVDD drops below a preset threshold. From what I have read push-pull uses two transistors to put either VDD or zero volts accross the load.

    1) Does "assert" imply a current or just a voltage? (told you I was a newbie).
    2) By being connected directly to the Lithium Ion battery VDD will be 3.7V and the microcontroller TI CC3200 is rated only up to 3.6V. Is that game over for this idea?

    Any input would be greatly appreciated.
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    You would want the voltage monitor in front of the buck boost converter, but the one you have only puts out a pulse so it's not a good choice. The buck boost will make sure the voltage to the mico is ok until the voltage monitor turns off the battery. In this case assert means a voltage. Usually current is controlled by the load.