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THE AM BULLETIN BOARD => Class E Forum => Topic started by: VE3ELQ on October 17, 2016, 01:15:54 PM

Title: IXDN630CI Driver failure mystery solved
Post by: VE3ELQ on October 17, 2016, 01:15:54 PM
As reported in another thread, I was not able to achieve any gate drive using the IXDN630CI drivers at 15 volts.  I assumed they had failed and replaced them with IXDD614s which worked perfectly at 15V driving a pair of SIC FETS.
I obtained some replacements and installed one on one side of my new 6 FET 40 meter deck. It too would not provide any gate drive.  I disconnected the regulator and powered it directly from a variable DC power supply and dialing up the Vcc until past the Under Voltage Lockout (UVL) which turned out to be 19V well over the 13.5V specified. It then produced sporadic gate drive to the 3 parallel FETs and took 20 volts to achieve stable drive.  And yes they are very well bypassed with 3 caps in parallel. Drive current was a whopping 510ma just for one side and the slope of the pulses did not look any better than with the 614 drivers which draw 160ma per side driving 3 FETs each.  Also the drive amplitude was 20V well past the recommended FET gate specs.

Very disappointing, but at least I now know why they wouldn't function.  15V is insufficient to overcome the UVL on the CI variants.
They are available in a MCI variant with a UVL spec'd at 9V.  These may work at 15V and be good for driving the bigger FETs with high gate C if you can live with the high driver current.  But personally I'm done with them.

73s  Nigel
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