common drain n-channel mosfet for charge and discharge battery cut off

[dcwebaccount]

please help, i have a question for control both n-channel mosfet to cut off discharge and charge for battery protection.

i already google this for a month without any solid solution, seem that none is care about control low side n channel for battery protection since it is mostly built-in protection IC ...

on controlling the discharge current, i just simply put the MDSG1 mosfet gate voltage Vgs high or low (to ground) for open or shutdown the path, however my problem is, when i want to close the MCHG1 mosfet for stop the Charge current (over voltage when charging my battery connected on left hand side), i don't know where to put my Vgs low enough to shutdown / turn off the MCHG1 mosfet !

last night i realized the potential between CHG(-) and BAT(-) were different that caused the Vgs of MCHG1 turn off automatically, unless i connect the Gate wire of MCHG1 to the CHG(-) point make Vgs = 0v, but the point is ... only single ground of the circuit can have right ? if the ground on CHG(-) as well that's mean the charge mosfet is disable function.

please help !!!!!

 

[FvM]

It's not clear what are PACK-, BAT-, CHG-, and how you want the current pathes to be switched.

 

[dcwebaccount]

It's not clear what are PACK-, BAT-, CHG-, and how you want the current pathes to be switched.

VIN and BAT(-) on the left hand side is connect to battery pack
PACK(+) and PACK(-) on the right hand side is connect to loading (discharge)
PACK(+) and CHG(-) on the right hand side is connect to battery charger (charge)

this is common battery protection circuit with common drain n-channel mosfet, mostly built-in in tiny battery protection IC for 2-4 cells li-ion battery, however i would like to built a bigger system for 20 cells of li-ion therefore i need to build such circuit myself.
i contacted T.I. engineer today, they have no idea and ask me to connect the emitter of Q0102 to the PACK(-), but i don't think it work.

 

[FvM]

Apart from the question if the connection of MOSFET switches is reasonable or not, to allow a swing below ground, the gate voltage can be controlled by PNP in common emitter circuit, you'll probably need another NPN as level converter to drive the PNP base.

I would usually expect a source-to-source tied pair of antiserial FETs with common gate control, disconnecting both charge and discharge.

 

[dcwebaccount]

Apart from the question if the connection of MOSFET switches is reasonable or not, to allow a swing below ground, the gate voltage can be controlled by PNP in common emitter circuit, you'll probably need another NPN as level converter to drive the PNP base.

I would usually expect a source-to-source tied pair of antiserial FETs with common gate control, disconnecting both charge and discharge.

hi, could you mind to hand draw a circuit for me, and i can do simulation tomorrow to see if it is feasible

 

[FvM]