Exceeding datasheet FET gate driver current with NCP1217?

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eem2am

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Hello,

NCP1217 PWM Controller has an on-chip FET gate driver, which , on page 1 of its datasheet, is said to be capable of 500mA.

-But is it safe to exceed this ever?
-after all, the FET gate drive current only flows for about 100ns.

For example, supposing i have a Vcc of 14V, and given the gate driver internal resistance of 20R.....suppose that i use no external series gate resistor...............then my FET gate drive peak current = 14/20 = 700mA....

...is this OK?


NCP1217 DATASHEET:
https://www.onsemi.com/pub_link/Collateral/NCP1217-D.PDF
 

I bet the 500ma is continuous as a rating. The short time frame for the 700 ma you mention is probably fine. Like most semiconductors have a time derating function. However you must take into account how the rest of the device is being used. How much power is is disipating and how hot is is getting. This will drive the derating in the wrong direction.

just my two cents

good luck
 
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    eem2am

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The current of 500mA in only shown in the schematic diagram for the output stage and
in the the first page (features) where it says 500 mA Peak Current Capability,
so when it says peak i don't think you can assume that it talks for the continuous current rating, this is after all a mosfet driver that will give very fast high current pulses so the specification is probably for that.
Maybe it can work with more current but there is also the possibility then this will overstress the chip and damage it after a period.
I wouldn't base a commercial product design on assumptions but on the actual data given by the designer of the chip.

Alex
 
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    eem2am

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you are right. Ask the applications engineer if you can get hold of him at the factory. Or contact a distributor and ask their FAE to look into it for you. He may have a better chance at getting the right answer.

dave
 
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