The unit I'm working on uses a 20kHz PWM signal (from a PIC - max supply 20mA) to drive a DC load. Input voltage could be either 12V or 24V, and the nature of the load to be driven is unknown - could be inductive or resistive. I'm using an Allegro AC8756 current sensor to monitor current and limit it (via duty cycle) to 30A for now.
The MOSFET I have been considering and playing with is the IRF1404ZGPBF. It's rated to 75A continuous which is more than enough, and has a pretty low on resistance of about 3 mΩ (at 75A). This is probably overkill, but I would like the capability to possibly run these same parts in a 50 or 60A configuration down the road.
I think I want to use the TI UCC37322 to drive this MOSFET since it can use my small PWM output signal and has a 9A max drive output which should be plenty of juice to turn the MOSFET on fast enough for my frequency range - even at 60A. The 37322, MOSFET, and necessary gate resistors will be immediately adjascent on the board and the MOSFET will be on a heat sink.
My concern is the continuous current output of the UCC37322 which is listed as 600mA. I want to be able to run this at a "true" 100% duty cycle which could conceivably see 30A running continuously from D to S. I have been unable to determine whether 600mA is enough to keep this MOSFET fully ON for an extended period of time. I suspect the answer is in the data sheet, but I'm unable to decipher it at this point and could use some direction.
I have been told on this forum by members whom I believe and respect that you typically want your gate current 1/10th of your drain current which would say I need 3A. I do not know if that rule-of-thumb was more for turning on fast or for keeping it on.
So, my questions:
1) Will the UCC37322 be able to keep up at 30A @ 100% duty cycle?
2) Same as #3, but at 60A?
3) Is this a robust combination of components for this type of load, or would you choose something(s) differently?
I appreciate any help or guidance - I'm sure the answers to 1 and 2 are in the documents I've been through, I'm just not seeing them. The answer to #3 is in wisdom that I do not yet possess.![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
The MOSFET I have been considering and playing with is the IRF1404ZGPBF. It's rated to 75A continuous which is more than enough, and has a pretty low on resistance of about 3 mΩ (at 75A). This is probably overkill, but I would like the capability to possibly run these same parts in a 50 or 60A configuration down the road.
I think I want to use the TI UCC37322 to drive this MOSFET since it can use my small PWM output signal and has a 9A max drive output which should be plenty of juice to turn the MOSFET on fast enough for my frequency range - even at 60A. The 37322, MOSFET, and necessary gate resistors will be immediately adjascent on the board and the MOSFET will be on a heat sink.
My concern is the continuous current output of the UCC37322 which is listed as 600mA. I want to be able to run this at a "true" 100% duty cycle which could conceivably see 30A running continuously from D to S. I have been unable to determine whether 600mA is enough to keep this MOSFET fully ON for an extended period of time. I suspect the answer is in the data sheet, but I'm unable to decipher it at this point and could use some direction.
I have been told on this forum by members whom I believe and respect that you typically want your gate current 1/10th of your drain current which would say I need 3A. I do not know if that rule-of-thumb was more for turning on fast or for keeping it on.
So, my questions:
1) Will the UCC37322 be able to keep up at 30A @ 100% duty cycle?
2) Same as #3, but at 60A?
3) Is this a robust combination of components for this type of load, or would you choose something(s) differently?
I appreciate any help or guidance - I'm sure the answers to 1 and 2 are in the documents I've been through, I'm just not seeing them. The answer to #3 is in wisdom that I do not yet possess.