0
\$\begingroup\$

I'm considering using some IRLZ44NS mosfets that I have with an ESP32 that runs at 3.3v. Looking at the datasheet it says:

VGS(th) - Gate Threshold Voltage - min: 1.0v, max: 2.0v

It seems like this will work, but I saw some other posts that refer to people using these mosfets unsuccessfully with 3.3v at the gate.

Here is the datasheet for the specific part that I purchased: https://static6.arrow.com/aropdfconversion/e4de403d6464383ac0f3e8f5420ce415f093cb18/irlz44nspbf.pdf

I want to use the mosfet as a switch to turn something on that also uses 3.3v (probably 1A max current). Figure 3 on the datasheet looks like I could pull up to ~10A with 3v.

Am I misinterpreting the datasheet? It looks like this part should be fine with 3.3v at the gate.

\$\endgroup\$
  • \$\begingroup\$ The 2.0 V max Vgs(th) spec is for a drain current of 250 uA. Is your application going to pull only a fraction of a milliamp? Or are you trying to get in to the 10's of A the FET is rated for (when driving the gate strongly above threshold)? \$\endgroup\$ – The Photon Dec 30 '19 at 18:53
  • \$\begingroup\$ @ThePhoton - I'm probably only going to be pulling like 1A max. I saw the 250 uA that you are referring to. Am I wrong to look at figure 3 to determine how many amps I can pull for 3v? It looks like at 3v it allows for up to ~10A (way more than I need). \$\endgroup\$ – kr4sh Dec 30 '19 at 19:51
1
\$\begingroup\$

No you are not misinterpreting the data sheet and, if your load is 1 amp max you should be fine. Also, if you look at the next figure that shows the drain current versus gate voltage, 3.3 volts is not in the danger zone for creating a thermal runaway situation.

But, remember that these graphs are “typical” figures and not maximums or minimums. Having said that, on balance I think you’ll be ok.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ I tested an IRLZ44N which had a measured threshold voltage of 1.6V. It needed 2.5V to turn fully on (0.05V D-S) at 1A. So it will probably work, but could be marginal if threshold voltage is at the upper limit. \$\endgroup\$ – Bruce Abbott Dec 30 '19 at 20:36
  • \$\begingroup\$ @BruceAbbott yes, I agree, it’s possibly marginal. \$\endgroup\$ – Andy aka Dec 30 '19 at 21:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.