I would like to use the S7V8F3/5 regulators with LiPo batteries and am wondering what happens when the battery voltage drops below 2.7 V (which I understand is fatal for these batteries). Do I need the extra low voltage shutoff for the battery or does the regulator chip shut itself off completely? If so, how accurate is the 2.7 V figure?
I looked for a data sheet on the regulator chip but it does not seem to be posted on the product page.
We do not release the datasheet for the IC on that regulator. However, the chip has undervoltage lockout that kicks in at an input voltage of around 2V. If the input voltage to the board falls below that point, it will go into shutdown mode. Above that, the chip will try to turn on, though the minimum recommended input voltage is 2.5V, and it might not turn on properly below that.
Thanks for that info, Claire. Can you confirm that I am correct in assuming that this regulator will NOT protect a LiPo from overdischarging and that a separate protection circuit is therefore required?
I ask because I saw a claim to the contrary on the Arduino forum.
That regulator has no built in protection to keep a single cell LiPo battery from over discharging. Since it does not enter shutdown mode until the input drops to around 2V, it is possible to continue draining your battery when the voltage drops below 2.7V.
Thank you for letting us know about that post on the Arduino forum. We have posted about this on that thread as well.
FYI I use a LiPo and Pololu voltage step-up regulator to power my Orangutan robot, and I monitor the LiPo voltage via a resistor network on one of the analog input channels. A simple routine cuts the motors and sounds an alarm if the voltage falls below a set threshold.
I have however trashed a LiPo by switching off the robot but leaving the LiPo connected overnight - the quiescent current can be sufficient to completely drain a partially depleted cell!
I am sorry to hear about your LiPo, but thanks for letting us know about your battery monitoring solution.