What value of fuses do you use?
The leas expensive can handle 3A, well above any thing I will connect.
I think they mean per pin.
- When you realize the card, check how the mosfets are heated both in continuous operation and in pwm to a current of 5A
How much is it suppose to handle? You know I want to get close to 10A but am satisfied with 7.5, without heatsink.
- What is the pwm frequency?
It looks like you can control the frequency, any recomendations, I am thinking 1Khz.
To contacts with 41A gives 82A rated current.
But they are very expensive, 15 Euro plus pcb connector.
Assuming a 30mOhm RDSon you would have a power of 1.7W with a current of 7.5A and 3W with 10A, you do not have a large dissipation surface for mosfets.
You have to do card tests designed to understand with this design the maximum current that you can have without exceeding the thermal limits of the components.
Or choose mosfets with a smaller RDSOn type 10mOhm.
With a frequency of 1KHz you shouldnât have any problems.
Post the component link.
https://www.mouser.se/ProductDetail/Phoenix-Contact/1716926?qs=u16ybLDytRZcgNBmr1gm4Q%3D%3D
https://www.phoenixcontact.com/en-in/products/pcb-plug-lpc-6-6-st-762-1716926
Also looked at:
But decided on using phoenix contact because then I can use from Aliexpress.
I dont know what standard is on ItsyBitsy M0 Express.
So ther is no mosfet for 3.3V that can handle 10 A with out heatsink.
NDrive Shiels say it can handel 20A per chanel in 60V?
Thats why I selected that mosfet.
I thought If I select that I will be on the safe side?
I was meaning protection for inputs, and if you by mistake put 28v, on the 5V side.
I dont want to burn the Isybisy or relays.
Buckconverter or Efuse or something?
Do a thermal test with this card using it at 7.5A and then at 10A .
1 Like
This can handle 700W with out heatsink, plus very protected.
Look ath this: Short circuit protection test - YouTube
The protection I suggested is for the polarity reversal.
You have to be careful when connecting the powers.
I donât see a simple solution to this problem.
I am imagineng I could put something like this:
https://www.electrokit.com/produkt/dc-dc-omvandlare-dubbel-9-36vdc-till-%c2%b15vdc-%c2%b1500ma/
To feed power to the ItsyBitsy M0 Express. The power is not enugh for relays but something similar.
But this is very expensive.
Also what would happen If I by mistake put + on the minus side.
[EDIT]
This could work:
TEN 6-2411WIN
[EDIT]
Sorry wrong input voltage.
[EDIT]
Or maybe something like this:
Realy good specifications:
Specifications:
- Model: MP1584
- Name: DC-DC Shutdown Module
- Input voltage: 4.5V ~ 28V
- Output voltage: 0.8V ~ 20V
- Output current: 3A (Max)
- Conversion efficiency: 96% (maximum)
- Output Ripple: <30mV
- Switching frequency: 1.5 MHz (highest) usually 1 MHz
- Operating temperature: -45°C ~ +85°C
- Size: 22mm * 17mm (L * W)
- Applications: DIY mobile power, surveillance power supply, power buggies, camera power supply, car power, communication equipment,
etc.
Or this:
Ali express bost buck converter
Or maybe create that on the board.
But will it ruin the analog signal or anything els?
Then technically if you want to dim something with hinger voltage and current you could do that with the powerful 5V trace/zone?
And no risk for burning the components.
I want to protect everything as good as possible.
Building an efficient buck/boost converter is not easy. You have to pay close attention to return paths. I would not suggest that. You have enough on your plate right now IMHO.
I have used the Aliexpress converters, they are ok. Not the best efficiency, but ok.
The MCU power supply does not come from the USB port?
Just as you designed the diagram, the supply voltages + 5V, + 12V and + 28V cannot cause damage to the MCU module.
A mosfet must be destroyed and the supply voltage enter the MCU through GPIO passing through the 1K R and from the circuit connected to the dim-channel connector.
Difficult but not impossible.
You could put on the GPIOs that control the mosfet of the optoisolated circuits.
It has not very good raising and descent times.
A test must be performed to check if PWM is used if excessive overheating occurs.
It can be improved with few discrete components anyway.
Different case for relay coils that can withstand 28V for a short time.
You should have a 5V AUX power supply for the relays from which you get the 3V3 for MCU so this problem resolves.
You are probably right.
I want one that is smal can handle about 2A, can bothe use voltage from 4-4.5 to about 30V
But most of them is boost or buck converter. I want bothe.
The plan is just when programing.
I have wrongly used GIPO in this thread, MCU (Microcontroller), is of course a better word. But what I was meant to say is. When the MCU will be programmed it will be plugged to USB. Then the dimmer will not be plugged in to usb more than if you have to re program it.
Thatâs why all the button and switches.
Otherwesi I could have skipped most of the electronics.
A dream would be If I could have bothe.
But then I need a good programer
God morning!
(Morning here in Sweden)
I mean if you accidently put 28 Volt plus on the 5v input. Then you can destroy both MCU and relays.
Thatâs why I was thinking of a âBoost Buck Converterâ that always keep the Voltage to 5V to MCU an Relays. Maybe feed that to Other components to.
In that case you could potentially use the 5Volt rail with higher Voltage, if you have a lot of 12 or 28 volt devices.
Would it be possible to connect one more chip to the ULN chip to control it with the on board MCU instead of external control?
I want in that case to be able to do both, not at the same time of course.
In that case I would save some outputs on the external MCU that controls the relays for the moment.
What I am asking is if I could ruin the CD74HC4067M chip if I externally send a signal to ULN?
Hard to explain.
Wild speculations:
The relay board seems like you can control it with shift register, but itâs not the same thing as multiplex, is it? Which I use.
But then you have to change a jumper?
What is it doing?
Could I have the same on my board even though I have a switch instead of a jumper, and that my board already has an MCU connected to it, which the relay board doesnât?
[From manual]
EK006 is a relay board with 8 SPDT relays which can be controlled serially via a shift register. The card gives one easy way to connect many relays to a microcontroller and requires only three connections (plus 5V and ground). The relays also go to control directly (parallel) by leaving JMP1 unbridged.
