Hello,

I have a PV charge controller which drives 4 50A mosfets to supply current to charge batteries in a small power station. I wish to modify it to handle larger current, by increasing the number of mosfets to 16.

Currently, the 4 mosfets are driven by a single emitter-follower circuit, through 10K resistors, one connected to each mosfet gate. eg, the emitter of the driver transistor is connected to 4 10k resistors, each resistor being connected to the gate of each mosfet.

My question is, can I simply connect the gates of the additional mosfets in the same way, to the same emitter-follower driver? So then I would have a single emitter-follow output connected to 16 10k resistors, each one connected to the gate of a mosfet. Or will I need to add additional emitter-follower driver circuits? It would seem to me that additional drivers should not be necessary, since the gate impedance of the mosfets are extremely high.

Also, I am curious what the purpose of the 10k resistors are.

(cross-posted on Electronics Point Forum)

 

Adding additional MOSFETs will be fine.

The 10kΩ resistor limits the current between the controller and the MOSFET and therefore provides a bit of protection to the controller in the event of a catastrophic failure of the MOSFET.

 

Great, thank you very much.

Kevin