Author Topic: Is this Mosfet good for my peripherals?  (Read 603 times)

0 Members and 1 Guest are viewing this topic.

Offline shai

  • Contributor
  • Posts: 16
  • Country: us
Is this Mosfet good for my peripherals?
« on: January 21, 2019, 05:11:32 am »
Mosfets are confusing to me, but after doing extensive research, I found this one: https://www.digikey.com/product-detail/en/diodes-incorporated/DMN3404L-7/DMN3404LDICT-ND/2052805

However, I am still unsure if it fits my application or is the best one for me. I should note, I am trying to go with a SOT-23 package. Here it is: https://www.digikey.com/product-detail/en/diodes-incorporated/DMN3404L-7/DMN3404LDICT-ND/2052805

One person pointed out to me that 28mOhm at 10V gate for this Mosfet could mean that it will get too hot. Except, I have no idea how to calculate or figure out if this will be an issue for my case? I plan to use this on solenoids, LED ring and to turn on 5V vibrating motor for my OpenPNP build. Here are the specs:

Solenoid #1: 5V 1.1A
Solenoid #2: 5V 0.22A
LED ring (plan to use 6 of these) : https://www.digikey.com/product-detail/en/luminus-devices-inc/MP-3030-210H-40-95/1214-1604-2-ND/9593577
Vibrating motor: Not sure yet, but probably a 3V one like here: https://www.aliexpress.com/item/Best-Price-10x-4x8mm-DC-1-5-3V-Micro-Cell-Phone-Coreless-Vibration-Motor-Vibrator-For/32694004681.html?spm=a2g0s.9042311.0.0.27424c4d65RqfR

Will this Mosfet work for these peripherals/loads? If not, please provide a detailed explanation why so I can learn.
 

Offline blueskull

  • Supporter
  • ****
  • Posts: 12941
  • Country: cn
  • Power Electronics Guy
Re: Is this Mosfet good for my peripherals?
« Reply #1 on: January 21, 2019, 05:18:26 am »
Even if you are driving it with an MCU (5V), it still has 42mR Rdson, so for 0.64W dissipation (173K/W thermal resistance, rated worst case, 40C ambient+0.64*173K/W=150C max temperature), the MOSFET can allow a maximum 3.9A of RMS current.

Your maximum load would be 1.1A, so 1.1A*1.1A*0.042R=0.051W, 0.051W*173K/W=8.8K, 8.8K+40C=48.8C, well below maximum junction temperature.
 
The following users thanked this post: spec, shai

Offline shai

  • Contributor
  • Posts: 16
  • Country: us
Re: Is this Mosfet good for my peripherals?
« Reply #2 on: January 21, 2019, 05:25:03 am »
So based on that calculation, I should be ok using this Mosfet without issues?
 

Offline blueskull

  • Supporter
  • ****
  • Posts: 12941
  • Country: cn
  • Power Electronics Guy
Re: Is this Mosfet good for my peripherals?
« Reply #3 on: January 21, 2019, 05:31:13 am »
So based on that calculation, I should be ok using this Mosfet without issues?

Yes. Don't drive it too fast without a proper gate driver, don't overvolt the gate, and use reverse diode protection on the solenoids.
 

Offline rstofer

  • Super Contributor
  • ***
  • Posts: 6935
  • Country: us
Re: Is this Mosfet good for my peripherals?
« Reply #4 on: January 21, 2019, 08:22:33 pm »
How do you plan to drive the gate?  Vgs is EVERYTHING.  Until this number is nailed down, everything else is a guess.

At 3V on the gate, the device is only good for 2Amps - Maximum Rating, Page 2 - so somewhere less than that.
Look at Page 2 of the datasheet and pay attention to Note 7 for vias at the mounting pads.  2 Oz copper, etc.


 

Offline Kasper

  • Regular Contributor
  • *
  • Posts: 238
  • Country: ca
Re: Is this Mosfet good for my peripherals?
« Reply #5 on: January 21, 2019, 08:49:12 pm »
blueskull beat me to it, but it is worth repeating:

Include protection diodes.
 

Offline Doctorandus_P

  • Frequent Contributor
  • **
  • Posts: 592
  • Country: nl
Re: Is this Mosfet good for my peripherals?
« Reply #6 on: January 23, 2019, 01:27:05 am »
May I recommend to get some different fet's (and BJT's) in TO092 housing from Ali / Ebay / China?

These fit easily in a breadboard and are also handy for prototyping. Always handy to have some lying around.
I find it hard to imagine that price can be an arguing point for 80ct for a bag of 20.

Also:
I agree with BlueSkull & Kasper.
Remember a story about an EE practicum where the Students were given MOSfet's in TO220 for experiments.
Lot's of them got damaged untill they decided to solder (SMD) TVS diodes directly to the legs of the MOSfets before giving them to the students.
« Last Edit: January 25, 2019, 01:23:38 am by Doctorandus_P »
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf