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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
I have the TC4421 and TC4422 gate drive chips. They do get warm when I am driving high capacitance gates. I am cooling them by laying an aluminum bar across the top with some grease. The bar has forced air blowing over it.
What do the rest of you do to cool your gate drive chips?
Registered Member #2628
Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627
Arcstarter's method and yours have worked for me in the past too, but now days I just use those miniuture 45MM fans to cool down the chips, in most the drivers I use, the UCCs are just driving a mosfet push pull, so they really dont heat up too badly.
Registered Member #1617
Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139
There are a couple of other driver ICs the next size up from the TC4421, I cannot remember the exact number, but it is TC44xx something-or-other, they are in a TO-220 package, so you can easily put them on a heat sink.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
If I can keep the tc4421 below its maximum operating temperature, can I put a load on it that would exceed its 9A limit? If my supply voltage is 15v, what happens if I put a 1.5ohm load, but keep it cool? Will it still fry, or will it limit its current output to a maximum of 9A peak?
Does anyone know where I can get the IXDI514 and IXDN514? I may have to request samples if I can't find a source.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
If you are overheating TC4421 devices it is probably because you don't have enough series damping resistance between the driver chip and the MOSFET gate. It is in this resistor where the gate drive charge should be being dissipated.
In practice you will find it quite hard to exceed the 9A limit of the devices because it requires very low inductance to get peak currents this high at the switching instants.
Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
If I go higher on the resistance then I don't charge the gate fast enough when running parallel mosfets. Would it help if I put a diode across the resistor so it could discharge the gate through it?
Right now I am using 5ohm for my two mosfet modules. This would be 3A peak for each with my 15v supply. 5 ohms and 10 ohms work when I am just running one module per leg of the half-bridge. When I run 4 with 10 ohms there is a small timing issue with current sharing.
If I want to run 4 mosfets (two in parallel) then I would have 12A peak currents, which the TC4421 won't supply.
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Cooling gate drive chips
