3x Conn_01x16_Socket to switch output voltage between 2 input voltages
16x Screw_Terminal_01x02 to wire the consumers (the first 6 should be able to provide 10 amps)
2x Screw_Terminal_01x02 for power supply
2x Screw_Terminal_01x02 for use of the last 2 IO
1x Screw_Terminal_01x04 for alternate usw of the last 4 GPIO
1x Screw_Terminal_01x02 as power supply terminal
1x Screw_Terminal_01x02 for alternate usw of 2 GPIO for NTC
Currently i’m just trying to figure out, if i wired anything wrong, or forgot something, i would be very greatful, if you have a look as experienced KiCadders
Next step for me would be taking the right footsteps, maybe you could give me some hints, which parts you would pick for terminals, sockets…?
I’d change that node here. You currently have a voltage divider. While this is probably ok for the resistors chosen, it could be problematic if you later chose to use 10k for both for example.
Just to make sure: no resistor between IO and Gate?
Or the 1k after the node (between node and gate)?
currently, i’m trying to find the right footprints. I’d like to fully assemble the board in China, so i’d like to choose common parts.
What USB C connector would you choose? I wanna program via USB.
Currently, im planning with UJ20-C-H-G-MSMT-3-P16-TR but .- what footprint to choose in KiCad? I really have no idea…
depends on where you order. If you chose JLC (the part number I just gave you is from JLC), then you have to add that number as well. If you order somewhere else, I can’t help you with that
In IRLZ34N datasheet the minimum Vgs they specified Rdson is 4V.
When you look at Fig 1 and Fig 2 the first line that looks switching it on almost perfectly is for Vgs=6V.
And the figures are “Typical Characteristics”. As Vgson is between 1V and 2V than rationale is to assume that charts are for transistors with Vgson=1.5V. So for those having Vgson=2V I would expect the same lines for 0.5V higher Vgs voltages. So I would assume to have every piece switched almost perfectly 7.5V would be enough.
And you are using 3V3 * 10/11 = 3V.
No one forces you to get it switched on perfectly but…
Don’t be too focused on Vgson being between 1V and 2V. It is enough for 250uA only drain current. So it is not a voltage when transistor is switched on, but when it starts to switch on.
In past to drive some ST Omni-FETs from 3V3 microcontroller I used AHCT gates to drive it with 5V and not 3V3.
Why not assign a label to every pin and then sort them alphabetically to completely obfuscate the schematic? You alredy did a good job with the label “GND”
For the screw terminal/pwm-mosfet repeated circuits I believe there are ways in kicad to repeat the layout using a subsheet. In KiCad 9 there are is a new tool you can use for this: Post-V8 New Features and Development News - #64 by twl
The 10K on the gate should be there as it accounts for the gate capacitance, discharges it and the 1K was fine. Would work just fine, most people put a resistor to GND on the gate.
Wow, I didn’t expect such a useful response in such a short time.
Thank you very much for that! I love learning a lot in a short time – this platform seems to be exactly the right place for me. I only started yesterday morning and downloaded KiCad. I was aware that there would be many mistakes – that’s exactly why I signed up here.
@Piotr Thank you very much for your very constructive input regarding the MOSFET. I only checked whether it was suitable for logic level, and apparently, it might be good for switching low currents. However, the fact that it doesn’t fully switch on – which I could have simply taken from the datasheet – didn’t catch my attention. I will definitely use a converter. I quickly researched what options are available, and besides logic gates, I found a 3.3V to 5V converter. I will look into it in more detail and maybe find even better soultions, which switch 7V. Thanks again for the input – I probably wouldn’t have noticed this until later!
@joob Thank you for your comments! I will work through them step by step and do further research on each point. These are exactly the kind of comments I was looking for. You can probably also tell me why KiCad complains during the ERC check and tells me that some inputs have no connected outputs? Is there perhaps a thread that helps me understand the basic functionality of KiCad regarding the correct structure of a schematic?
It somehow sucks, that new members can only mark 2 people in the same post and are forced to split the reply into multiple messages…
@nickmBy & @jmk Thank you for your input as well. As you have correctly pointed out, I have almost no idea what I’m doing here. Maybe you could also kindly explain exactly what I did wrong, what effects this has, and how I can do it better? I think every forum benefits from constructive contributions rather than scattered Jigsaw puzzle pieces, which, when present in large numbers, only make it harder to find the key in the syringe pile.
You should know that this forum tries to be focused on problems with KiCad use only. With questions about electronic you should expect to be send to other forums (like EEVblog for example).
As it has nothing to do with KiCad I was wondering if someone would write to me that this is not the place for this.
If you know that your schematic is correct… I have never run ERC so no have a problems with its complains.
Some people (I think new age school) draw schematic like you just because they think it is the best way of drawing schematic. If you say them that for someone else it is very hard to understand it they don’t care and are often picky when someone draws their attention to it.
In my (and probably others) opinion it’s even rude to draw schematic to be almost impossible to understand and then ask other to help about it (assume you were looking to be such person).
When you see wire ending with label you (except being its author) don’t know where to search for it and even you will find the next end of this connection you don’t know if it is the only one as label can be used many times.
If you use bus (I use it without specifying wires inside - just as only graphic element (it was the only way for buses in earlier KiCad versions)) and end all such wires at bus than seeing one wire going into bus you know that only along that bus you should search for its other end - dramatically reduces the space you have to look through.
I have shown how my schematics looks like (without details). I use only one bus as I don’t have too many wires, but you can logically divide your wires into several buses.
Nothing much to add to my above comment that @Piotr has just written.
It may be easy for you to understand what you have drawn for a schematic, but for someone to look for the first time and comment requires much time and effort to hunt down joining labels and decipher their purpose.
If you had drawn the schematic as per Piotr’s example, anyone, at first glance could understand the circuit.
It took me much time (too much) to ensure myself that MOSFETs are driven here from 3V3 and not 5V (V_BUS) to be sure that what I write about IRLZ34N is rationale here. I didn’t bother to think about this schematic any deeper and don’t plan. For me it is absolutely ‘not for human’.
If we were here a set of AIs discussing about it than it would be probably not a problem to any one of us as on finding all labels and generating a netlist from them each of us would spend a time counted in ns. But unfortunately we are human here (unless I don’t know something about you).
