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What kind of IC can be used to drive the MOSFET, so that when the voltage drops below 6.2 V the battery disconnects from the load? That reverse protection MOSFET works fine for reverse protect...
Answer
#2: Post edited
by
Andy aka
·
2022-07-28T12:09:37Z (over 1 year ago)
- > _What kind of IC can be used to drive the MOSFET, so that when the voltage drops below 6.2 V the battery disconnects from the load?_
- That reverse protection MOSFET works fine for reverse protection but, it cannot be used to turn-off the load when the battery is correctly connected. Look closely at your diagram; can you see the little diode symbol associated with the MOSFET? That diode symbol tells you that there is an internal diode in every MOSFET that will conduct even if the MOSFET is supposedly deactivated.
- In other words it won't prevent over-discharge of the battery.
- > _Is it possible to use a low voltage detector, for example R311x or TPS3840 or other, with a simple voltage divider? Or is there a better solution to this problem?_
You'll need a separate MOSFET to your reverse protection MOSFET and, it will need to be in series with the load (like the reverse protection MOSFET) but, with drain and source positions swapped. You can then use a low-power comparator to deactivate that added MOSFET should your battery voltage drops below a prescribed threshold.
- > _What kind of IC can be used to drive the MOSFET, so that when the voltage drops below 6.2 V the battery disconnects from the load?_
- That reverse protection MOSFET works fine for reverse protection but, it cannot be used to turn-off the load when the battery is correctly connected. Look closely at your diagram; can you see the little diode symbol associated with the MOSFET? That diode symbol tells you that there is an internal diode in every MOSFET that will conduct even if the MOSFET is supposedly deactivated.
- In other words it won't prevent over-discharge of the battery.
- > _Is it possible to use a low voltage detector, for example R311x or TPS3840 or other, with a simple voltage divider? Or is there a better solution to this problem?_
- You'll need a separate MOSFET to your reverse protection MOSFET and, it will need to be in series with the load (like the reverse protection MOSFET) but, with drain and source positions swapped. You can then use a low-power comparator to deactivate the added MOSFET should your battery voltage drop below a prescribed threshold. There are some very low power comparators that barely take a microamp that can be used here.
#1: Initial revision
by
Andy aka
·
2022-07-28T12:03:32Z (over 1 year ago)
> _What kind of IC can be used to drive the MOSFET, so that when the voltage drops below 6.2 V the battery disconnects from the load?_ That reverse protection MOSFET works fine for reverse protection but, it cannot be used to turn-off the load when the battery is correctly connected. Look closely at your diagram; can you see the little diode symbol associated with the MOSFET? That diode symbol tells you that there is an internal diode in every MOSFET that will conduct even if the MOSFET is supposedly deactivated. In other words it won't prevent over-discharge of the battery. > _Is it possible to use a low voltage detector, for example R311x or TPS3840 or other, with a simple voltage divider? Or is there a better solution to this problem?_ You'll need a separate MOSFET to your reverse protection MOSFET and, it will need to be in series with the load (like the reverse protection MOSFET) but, with drain and source positions swapped. You can then use a low-power comparator to deactivate that added MOSFET should your battery voltage drops below a prescribed threshold.