This would just be to turn the FETs on and off. Shouldn’t really need to be high power specific?
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I thought you wanted to use that circuit to supply the ESC. driving gates makes more sense.
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At lunch, I will see with what I can come up with for integrating this logic into the DZ switch.
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Whatever you come up with, just make it work and keep two spares for me guys 
Let’s spread that thing. It’s been missing from DIY scene for waaaaaaay too long.
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The other problem is you will need two bits of memory, not just one bit like that circuit has.
- device on or off?
- precharging or discharging?
So at a minimum you’d need two of those wired up in a convoluted way. Likely with a couple comparators and a couple voltage dividers to get the signals under 5 volts.
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Yeah! I did see your design, it was really quite an ingenious way to leverage analog logic like that. I considered how to borrow your techniques for a momentary switch based design but never quite figured it out.
This is the 3rd iteration of the pcb, used to be a bit bigger 
. Needed to make it small to fit the eboosted vanguard enclosure, everything felt a bit too cramped.
I was on that page for so long when I was initially brainstorming 
. But as @b264 mentioned, it’s a bit weird trying to get a precharge circuit in there, but more of my lack of expertise than anything. I also give up due to the sheer number of components needed.
The guy from 3d servisas made it with i think less then 10 parts or something maybe take a look at his
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So what exactly is the drawback to having the microcontroller? It doesn’t have to be icp, except on debug boards. Once everything is tried and tested, there’s no reason not to omit the header. Sounds to be like attiny is the simplest solution. Maybe I misunderstood, I’m working under the assumption that you are trying to replace the microcontroller.
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nah, an mcu works for me. replacing it is more of a brain teaser at this point.
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Gotcha, I spent lunch thinking this over and the controller actually adds a ton of flexibility. Integration with other microcontrollers, choice of pretty much every type of switch. Temp sensor etc. All of it just a firmware patch away. The reason I’m so interested is I’d like to use a teensy controller to control various components via nfc. This makes it more interesting.
Thenet me ask this, any reason not to order a set of PCBs and components as per your design, right now?
haha, yeah possibly adding roll to start in the future (maybe @Gamer43 could help), and idle time out would be easy with the mcu. I’m mainly holding off on “production” to really make sure it works. With the vedder/fechter antispark known to last for anywhere from 1 min to several months before randomly dying, really want to be thorough. I’ve been overconfident with my design before
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555 Timer
Also, roll-to-start and auto turn off will require high side switching. This can be done using a photovoltaic optocoupler or the LTC700x series of MOSFET drivers. I use the LTC7004. The LTC7000 is a 150V version if you want higher voltage ratings. This solution will opt for dV/dt inrush current limiting instead of precharge, only two passive components as opposed to multiple active components and a dozen passive components. There are many datasheets and application notes from multiple big semiconductor manufacturers that recommend the dV/dt limiting method.
What really sucks though, is the STM32L0 has a maximum supply voltage of 3.6V, while the LTC700x VCC UVLO kicks in at ~3.5V D:<. Have to go with a crappy attiny85 or an expensive 5v low power MCU, or bite the bullet and add a 3.3V LDO (and another three components reeee).
The LTC700x is better to use than a photovoltaic optocoupler, more stock available and easier to design around.
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so a mosfet driver allows an n-channel fet to switch high-side?
Yes, it has an integrated charge pump to support 100% duty cycle.
The downside is that the chip is $4 in single quantity.
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well shit that changes everything…
but can’t i just have the fet driver go full on or off and keep the precharge circuit? Seems more reliable imo
Precharge has to move to high side along with the primary MOSFETs. It requires two transistors, a zener diode, and a bunch of passive components.
If an RC circuit works good enough, screw precharge. Details of the method can be found in the LTC7004 datasheet, page 9, no I lied, page 11.
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hmm, I’ll see what I can do…
I’m not too familiar with using fets as resistors, but the better the Rdson is, the worse the soa region.
If you really want precharge, use an appropriately sized P-channel MOSFET. It can be driven by an MCU using a level shifting N-channel MOSFET. Add zener diode and appropriate pullup and current limiting resistors accordingly.
The RC circuit controls the dV/dt slew rate and limits the inrush current to a constant value. The power dissipated in the MOSFETs is limited accordingly and decreases as the capacitors charge. Now the design consideration is to ensure power dissipation does not exceed the maximum rating of the MOSFET, i.e. SOA.
Rise time is now fixed and can be calculated (or user determined) easily.
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