My apologies, I didn’t label them in the schematic, pin 1 is Normally Closed pin 2 is Normally Open pin 3 is Common pin 4 is LED cathode pin 5 is LED anode.
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This is why I would want an auto powerdown after like 8 hours of inactivity
I was gonna ask if it’s not a good idea to have a pull down resistors but it’s build in
Thanks for the diagram
do you think that 3 TPW1R306PLL1QCT would be enough for the 100A goal? price wise they are cheaper than the IRFS7530 and llower Rdson
Another challenge I"m looking at is finding the right fuse, ideally I would like to mount it on the PCB, but once we go to higher current the automotive fuses start to get too big
I remember Batman from @raphaelchang used tiny PCB fuses in parallel, I may go that route
They should be able to handle 100A but at those currents you also need to make sure the pcb traces can handle it as well. The entire PCB will need cooling if those currents are sustained. Cooling can be passive, like with a modest heatsink.
What I use for fuses is I inline an autolink fuse using ring terminals and bolts in my wiring. Trying to incorporate it on a pcb becomes too cumbersome.
I’m thinking is ditching the Toshibas since they are really small to work with
I’m really really space constrained that is hard to fit any of the common fuse types
So far I’ve found this one form Littlefuse that I really liked, but expensive
Spent a lot of time thinking about this after @b264 explained the issue. Ended up going with a mcu attiny85 to control everything.
https://easyeda.com/ninetailfox97/fused
https://www.electric-skateboard.builders/t/no-words-just-pictures-delete-words/2992/8860?u=deltazeta
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They have the same footprint as an SOIC-8, and unlike the DFN MOSFETs from ON Semi, they actually have leads, you shouldn’t have a problem working with them; I used a standard soldering iron to switch out the MOSFETs on a FSESC 4.20 with them a little while back.
Are you sure you wouldn’t be able to inline something like this? https://www.arrow.com/en/products/142.5631.6152/littelfuse It has almost the same profile as 10 gauge wire once everything is bolted together.
will upload once i’m back from class
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At least in my case it will be only peak, I doubt it will sustain anywhere near that
@deltazeta will take a look in what you did, thanks
Nice to hear that, I can use an SOIC-8 and just extend the pad to the bottom of it? Couldn’t manage to find any component in EasyEDA that has the same package
The Midi ones I may manage to fit, even more if I go with the Toshiba ones that are slim
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Oh, they’ll handle that no problem, then.
Actually, since the drain and source pins are contiguous on opposite sides (aside from the gate pin) simple rectangular pads should work with the right spacing. If not, they fit perfectly in the same footprint as the NTMFS5C628NL, which I believe is “DFN5 5x6mm” or “SO-8FL”. What you can do in easyEDA is place the NTMFS5C628NL and simply solder the TPW1R306Pl,L1Q in its place.
I know this because before I switched out the NTMFS5C628NL in my FSESC 4.20, I double checked the package drawings and soldered in the TPW1R306PL,L1Q. The FSESC 4.20 works better than ever xD.
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That’s a valuable tip, I was going to do the package from scratch
Design and testing tip, while adjusting fet gate timer, do all your tests with a single fet. That single fet must be able to take the inrush, to wich will be greatly reduced by the gate cap. While testing at the max voltage, use batteries, not a power supply.
Adding // fets will improve the reliability and reduce the Rdson
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Thanks Blasto, will see to it
I didn’t have much to work but was thinking, how does the LTC7004 current limiter is better than the Vedder implementation? Would’t we be also operating in the linear region as @b264 explained?
If yes, one way I thought to overcome that is to set the ramping time to a few seconds, but have another MOSFET with a current limiting resistor inline that turns immediately and a few seconds later it’s turned off by 555 timer, the majority of the current would pass by the limited current
Or maybe go back to my initial idea of using two 555 timers, one that turns the current limited MOSFET immediately and turn it off after a few seconds and then another 555 turn all the mains MOSFETs on after a few seconds
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I don’t think there is a problem operating in the linear region as long as you design the circuit correctly to not exceed the maximum ratings for the FET. Every product I have designed that uses a FET to switch power simply ramps the FET slowly enough to not exceed ratings. Don’t use 555 timers, they will make the problem worse, just use a resistor and capacitor on the gate and get the values right to not exceed the current rating of the FET.
Quickest way is to just do a spice simulation. Let me know if you need help with this.
Nice, would gladly accept some help, I have an idea how to do it but trust more in someone else
The LTC7004 datasheet has some formulas to calculate the rise time but I doesn’t take the current into account
On the spice we would just put a transistor being turned on by an RC network while powering a capacitance equal or greater than both VESC’s combined and watching how high the current gets?
My only suggestion for whole this project is not to put mosfet into linear mode they burn instantly doesn’t matter how many 2,3,4 you will put in parallel inrush currents are thousands of amps for few tens of ms you can check your mosfet SOA and will see that these inrush will kill it instantly.
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That part I understood, but wouldn’t the soft turn on of the LTC7004 with an adequate rise time make the current low enough? Or since an empty capacitor is almost a short, no matter how long the ramp up is the current would still be big?
LTC7004 by slowing down opening will put Mosfet into linear mode
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