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L6480 cannot switch on my 170 nC transistors

Question asked by draganov.tom on Sep 6, 2014
Latest reply on Sep 8, 2014 by kenny.larry
I am doing a test series of stepper drivers with L6480 for furnace rotation control.
There seems to be a problem with the device.
The circuit is a copy of Eval 6480.
SPI is up and functional, every register is correctly set.
The problem is that L6480 cannot switch on all high-end transistors.
The transistors I use are IRFB4310ZPBF (hexfet power mosfet, Vdss-100V, Ids -120 A, Rds-5mOhm, Qg-170nC)
compared to the Eval 6480                        (stripfet power mosfet, Vdss-100V, Ids - 25 A, Rds-35mOhm, Qg- 14nC)
The device is running on 28 V DC, with Vboot-Vs=10,5 V, with GateConfig set to 96 mA / 3750 nS ( a total of over 330 nC).
But even if the OCD is disabled it is unable to switch on the upper transistors.
Could you help ?
Thanks in advance!
Eng. Tom Draganov , Alex Engineering Ltd.