Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Mosfet heating up problem

Status
Not open for further replies.
A

amulya

Newbie level 5
Joined
May 7, 2007
Messages
8
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,337
mosfet heating

Hi all,
I am using Mosfet as switching device in Half-Hybrid design
load is taking ~70A current
Mosfet i am using is IRL3717
according to data sheet it can take upto 260A
but for 70A itself it is heating up a lot
i connected 4 Mosfets paralley even then problem occuring
Please give some suggestions for
Unequal sharing of current in Mosfet parallel connection



regards
amulya
 

mosfets parallel problem

Hi,
Is that heating effect usual or unusual? Have you connected the Sinks to your MOSFET.You first check in the data sheet as how much working temperature is given.I had used SCR (20A) at line frequency, they get around 100-125'C hot.First you confirm this it's very necessary, before you think about doing anything else.
 

irl3717 datasheet

I don't have a data sheet for that part, but it should be something like this:
(Rds=2.4mΩ@Vgs=10V)
Pd = Id²*Rds = 70²*2.4E-3=11.76W

Condidtions:Vgs=10V. If you drive gate with lower voltage, see data sheet for Rds!

You will need ~4K/W heatsink to keep junction at 100ºC @ ambient 40ºC
 

mosfet junction heating

Have you tried using a heat sink?
 

Re: irl3717 datasheet

Sinisa

how do you get 4K/W, can you show more details, .....will MOSFET's share current evenly? what about temerature effects?
 

What is the switching rate of the mosfer?
What kind of circuit drives the mosfet gate?

Alex
 

Re: irl3717 datasheet

nebo123 said:
Sinisa

how do you get 4K/W, can you show more details, .....will MOSFET's share current evenly? what about temerature effects?
Click to expand...

4K/W was approximate calculation for example given, based on static ON condition. Rth(h-a)= ΔT/Pd -Rth(j-c) -Rth(c-h), ΔT=Tjmax-Tamax

With insufficient data given on how MOSFET is driven and no data sheet I can't figure what problem might be. As FvM suggested, switching losses might be big part of problem.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top