Part requirements for a DC solenoid project

Perfect!

By the way I tried your suggestion of implementing the 1K pull-up to gate and it works. The ESP is powered first to have a LOW signal to gate ready and then when the 12 volt PSU is on, the motor waits until the gate receives the HIGH signal. NICE WORK on that one Mike. But as you say there is a slight latency on the switching but not very noticeable. Is there a risk for pin 23 since the diode is not blocking any reverse voltage to ESP? And the other concern is heat. With that method the MOSFET is generating a lot of heat, even if I keep the motor activated for less than a second and wait 5 seconds between HIGH's and LOW's. I didn't notice that when I was momentarily feeding the gate directly with 5 volts.

The heat is because the MOSFET isn't fully on. You could use a transistor to drive the gate but a driver chip is a much better solution.

Mike.

Mike, I'm about to order from my Canadian supplier the parts that I need for the gate driver. Can you please double-check my selection before I order?

1- Gate driver TC1427CPA-ND
2- Ceramic Capacitor 0.1µF MLC
3- Film Capacitor 1.5µF (1µF not available from the supplier. I hope 1.5 µF can do the work)

I also included the new diagram which is implementing the gate driver.

Thanks mate,
Justin

What is the purpose of R1?

ak

It is a pull-down resistor to shut 12 volts off until MOSFET gate is being activated by pin 23. Otherwise MOSFET would provide power continuously.

JJ2430 said:

It is a pull-down resistor to shut 12 volts off until MOSFET gate is being activated by pin 23. Otherwise MOSFET would provide power continuously.

Click to expand...

You would have to explain that one to me!!??
Max.

JJ2430 said:

It is a pull-down resistor to shut 12 volts off until MOSFET gate is being activated by pin 23. Otherwise MOSFET would provide power continuously.

Click to expand...

For that to work, the resistor has to be between source and GATE, not source and drain.

MaxHeadRoom78 said:

You would have to explain that one to me!!??
Max.

Click to expand...

Max, please refer to the following thread. I used it as a base example for my project since that is what I need to achieve. The problem is that I'm using a different board than the Arduino, the Wemos ESP 32 with Bluetooth. Arduino UNO provides more voltage (5 volts) on its digital pins than the ESP32 which is enough to activate a MOSFET gate while the ESP 32 isn't. My multimeter shows 2.7 volts for the ESP32's digital pin.

The logic level mosfet should turn on fine at 5V. Personally, I'd use a normal level mosfet and power the driver from 12V so the gate is driven high enough. I don't understand the purpose of R1 either.

Mike.

Your interpretation of that article is incorrect. In their images the 10 K resistor is from tha gate to GND, and can help with FET thru-off in some situations. But -

1. In your schematic the resistor is connected to the drain. It's only action is to continuously draw a small current through the motor when the FET is off.

2. It is not needed on the gate if the uC output pin is never in a high-impedance state such as tri-state or when the uC is unpowered. If the uC has continuous power, or is unpowered only when the motor also is unpowered, and its output is never in a tri-state mode, a gate pulldown resistor is not needed.

ak

I must apologize. You folks just pointed out a very obvious flaw in the diagram showing indeed the 10k going from source to drain while I was in fact meaning from source to gate. Sorry for the confusion everyone! I modified my diagram accordingly. Thank you for raising that mistake and for your inputs. I'll leave the resistor there to make sure that the gate stays off when the controller board is not powered or not connected (not sending LOW signal) while 12v psu for solenoid is running.



Getting back to the gate driver that I need for my N-Logic IRL540 MOSFET can I have your view on these parts before I order them? Thanks to all.

1- Gate driver TC1427CPA-ND
2- Ceramic Capacitor 0.1µF MLC
3- Film Capacitor 1.5µF (MKS2 1µF not available from the supplier. Only MKS02 1µF. I hope MKS2 1.5 µF can do the work)

The pulldown resistor on the gate is not needed. The driver chip will ensure the mosfet will turn on and off very fast (and override the pulldown). A safer way is to put the pulldown on IN_A so the mosfet will start in the off state. Your parts look fine.

Mike.

Great, thanks Mike. Do you think that the 1.5µf MKS2 film cap can work instead of the 1µf? Is there a big difference? On the TC1427 gate driver datasheet they state that a 1µf should be used but the supplier doesn't have that one in the MKS2 variant.

Edit: I also have an optoisolator that I plan to add between the board and gate driver to prevent any damage to the mc.

A bigger cap is fine. The cap is required to supply the 1.2A gate current to switch the mosfet quickly.

Mike.

Thanks a million!
Justin

JJ2430 said:

Edit: I also have an optoisolator that I plan to add between the board and gate driver to prevent any damage to the mc.

Click to expand...

An opto just adds another layer that can go wrong. The driver will not overload the uC.

Mike.

Ok noted, thx
Justin

Solenoid project is actually running on a 12V power supply plugged to an ac wall outlet. The next and final step is to provide the whole gig with battery power to render it entirely self-sustained and portable. After many researches and comparisons I decided to take the route of Li-Ion cells since once combined they will provide just the right amount of current and voltage (6A and 12V). I found a Canadian provider of "genuine"--so it is said on their website--18650 3.7V 3A Panasonic cells. But how could we be sure. The battery format would be perfect but with all 18650 fakes circulating on the market nowadays I tend to be prudent. An other solution would be to buy a genuine powerdrill battery pack of 20V 6A like Dewalt and I'll be 99.9% certain that enclosed batteries will be original Panasonic batteries, like the one mentioned in **broken link removed**. And I get more of the same exact battery model for the equivalent price of buying them separately. The problem with this new upgraded pack from Dewalt is that it is now equipped with 20700 battery format which is slightly more powerful than 18650 but I can't find any BMS protection PCB for the 20700 on the net. Does anyone on the forum have experience with Li-Ion BMS protection boards and do you think that 18650 BMS boards could comply with 20700 Li-Ion battery format?

Please see the latest schematic of the project now including 2 solenoids and autonomous power source. Thanks!

Be extremely careful with lithium cells.

There are two very different function "BMS" type boards sold on ebay and you need both functions when series connecting cells!

The commoner ones only provide undervoltage / overvoltage protection. With series cells you must also have a cell balance regulator, a "balance board", which maintains all the cells at equal voltage even if the capacities are not quite identical.
That also needs to have a reasonable current rating in proportion to the cell capacity and charge current involved.
eg. Some on ebay are only rated 1mA balance current while others are rated 100 - 200mA or more.

If you can find a cheap 12V or 16V power tool battery and charger, why not use that "as is" (or removed from its casing) as it's got all the protection circuitry already built in?

Do you get any strange glitches at power on. I.E. solenoids clicking? If so it maybe Digital Pin 23 gets driven high during bootup. GPIO4 and 5 seem to be always high impedance during startup so they might be a better choice. Also, R1 isn't needed between the output and input - connect it straight through and connect a 10k resistor from that connection to ground to keep the mosfet firmly off during boot.

Mike.
Edit, Agree with RJ re battery.