Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Power MOSFET vrs TIP120

Status
Not open for further replies.

halloween_man

New Member
Hi,

I want to use a PIC pin to drive 500mA to 1A load.

I see many people recommend a TIP120 (many circuits on web for TIP), and others then say use power MOSFET like IRF540. From what I can see the MOSFET is about 2x the price but 25 cents extra per mosfet is no big deal if mosfets are really that much better.

Being a newbie I have a couple of questions.

1) Why MOSFET instead of TIP120?


2) How would MOSFET get connected to a PIC pin (can someone provide simple circuit please) when compared to a TIP120?


Thank you for your time, it is greatly appreciated.
 
Last edited:
Hello,

I am sorry if I have asked the same question more than once but I do not see where I asked questions regarding a TIP120 VRS MOSFET.

I just checked the threads where I posted and they are all regarding TIP120 connected to PIC, some conversation regarding ULN2803A, nothing with regards to why some people on this site prefer power MOSFET and others TIP120.

Again, I am sorry if I asked the exact same question twice.
 
A TIP120 darlington has a max saturation voltage loss of about 1.0V at a current of 0.5A.
It switches slowly.

An IRF3711Z logic-level Mosfet (there are hundreds of better ones) has a max saturation voltage loss of only 0.004V at a current of 0.5A.
It switches quickly.
 
Hello,

I am sorry if I have asked the same question more than once but I do not see where I asked questions regarding a TIP120 VRS MOSFET.

I just checked the threads where I posted and they are all regarding TIP120 connected to PIC, some conversation regarding ULN2803A, nothing with regards to why some people on this site prefer power MOSFET and others TIP120.

Again, I am sorry if I asked the exact same question twice.

Sorry about that, you didn't ask the same question more than once, I shouldn't have jumped on you.

It's just that your question relates to the other threads so it might have been better to simply add it to them.

As audioguru said a MOSFET is faster and has a lower loss but it also has a higher input impedance. The main disavantage is a MOSFET has a huge input capacitance so to get it to switch fast the circuit driving it needs to have a low inpedance.
 
halloween_man,
Sorry, I've tried to give you positive reputaion but accidentally clicked on the wrong button so I gave yo negative repiutation.

Could someone else please posative rep him and give him back his green square?
 
He had a red one before (I don't know why), so I suppose he's only back where he was before I cocked up so it's not too bad now.

Thank you.
 
Last edited:
For single target switching, or high current devices, FET's are really good, but I've always used the Darlington array ULN2003 for controlling upto 7 channels simultaneously

Keep in mind though, with FETs you need to use a P-Channel mosfet for switching supplies, and a N-Channel mosfet for switching earths.

If you use the wrong one for your circuit, then it will not fully turn on.

Although there are hundreds to choose from, I find myself using the **broken link removed** for N-Channel switching and the **broken link removed** for P-Channel

Its important to remember that mosfets are extremely sensitive to static damage, but that said, even with the cold weather and dry air here, I am yet to blow a mosfet because of static damage :eek:
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top