I wonder, how many mosfets will be needed to handle 800-1500A current?

Ioannis

 

 

Well, with fig. 22 on the data sheet stating that max 100A are available with 100ms pulse and Vds 4 volts, this does not seem easy.

I would use at least 15 or better 20 in parallel... The cost of each is about 41 euros!

 

The switch on time (Ton) for the opamp MAX44251 is 25uS but would it be a good idea to have resistor of 100k which is 0.1mA bypass the BJT for an even better Ton ?

 

I have used this Constant Current under 30 mA This set up gives 3.27V 2.0280 mA
It would be a good to do this in LTspice. You can set R2 between 24 - 800 Ohms, maybe higher
you can see the meter arrangement it is basic but works ok.
Going from this to ultra precision reference does cost for a low ppm reference and high precision op amp.

 

The switch on time (Ton) for the opamp MAX44251 is 25uS

? i missed the context ? why you toggle the supply rails for the Op Amp in question
... the Op Amps may have considerable "Warm Up" times even for 10-s of minutes to gain their normal/stable operational mode

you better pull them up , down or on to a desired voltage level while they should be "disabled"

 

Since the mosfets are driven by the opamp i don't see a better way to toggle them.

 

? do you have a "high" level "logical" block diagram of your apparatus -- ( the initial-/startup timing is another design head ache ... one has to ... complete)

but the price is 3$

2.59€ for a single "high performance/reliability" "key" component is not "too high" is more like "relatively cheap"
considering the $ LF347

 

The schematic so far is attached in post15. Not completed yet. The idea is drive the mosfets to spot weld battery tabs for 18650 packs.

 

something type of
src :: Arc Welding Machine with Half-Bridge Forward Converter | Semantic Scholar

 

Those are arc welders. Mine falls in the category of RSW (Resistance Spot Welder).

 

(( just was curious about Fig.6 presented data Review of resistance spot welding of steel sheets Part 1 Modelling and control of weld nugget formation ))

 

1500 Amperes??