Pro/Forums - View Single Post

Brians256 · 08-04-2003, 03:59 PM

I now have a much better idea what the Miller effect is (it helps having a PhD EE (focus in microwave frequency analysis) to answer questions) and I know what Qg is (gate charge in coulombs for saturation although it appears that Qsw is more relevant for timing calcs). I'm not stupid, if someone will take the time to point out where I need to learn. AoE is certainly a good reference tome, for instance.

Also, some of the timing issues are less troublesome when you have what appears to be an adaptive PWM source and an adaptive MOSFET driver such as the Intersil 6302 and 6602. At least the timing is not hardcoded to a specific impedance seen by the MOSFET driver (oh, and YES I know that the impedance is a complex value containing resistance and reactance and has frequency specific components).

The HIP6602BCB chip on the motherboard I'm currently examining has the ability to drive any MOSFET up to 3000pF gate capacitance at a decent speed, so lowering RDSon while leaving input capacitance below 3000pF should work.

I haven't read up on SOAR curves yet.

08-04-2003, 03:59 PM	#19
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	I now have a much better idea what the Miller effect is (it helps having a PhD EE (focus in microwave frequency analysis) to answer questions) and I know what Qg is (gate charge in coulombs for saturation although it appears that Qsw is more relevant for timing calcs). I'm not stupid, if someone will take the time to point out where I need to learn. AoE is certainly a good reference tome, for instance. Also, some of the timing issues are less troublesome when you have what appears to be an adaptive PWM source and an adaptive MOSFET driver such as the Intersil 6302 and 6602. At least the timing is not hardcoded to a specific impedance seen by the MOSFET driver (oh, and YES I know that the impedance is a complex value containing resistance and reactance and has frequency specific components). The HIP6602BCB chip on the motherboard I'm currently examining has the ability to drive any MOSFET up to 3000pF gate capacitance at a decent speed, so lowering RDSon while leaving input capacitance below 3000pF should work. I haven't read up on SOAR curves yet.