Part Number:DRV8704
Hello,
My team and I are planning on using a DRV8704 in an electric vehicle running at 50V with a maximum current through each H-bridge of 20A using the CSD18535KCS MOSFETs and an ALLCELL HE-4820 battery. My question is regarding the DRIVE register. The MOSFETs' datasheet state a maximum gate charge of 80 nC so I calculated DRIVE settings using 100 nC. The settings I calculated are as follows:
Maximum source current: 100 mA
Maximum sink current: 200 mA
t_drive = 2.1 us
dead time = 670 ns
t_off = 16 us
t_blank = 5.880 us
Do these values seem okay for the FETs? We want to avoid excessive power dissipation and to have enough time for the gates to fully charge and fully discharge. My understanding is that t_blank should be at least longer than t_drive in order to avoid damaging the FETs when the DRV8704 goes into current limiting mode. Is that correct?
Another question:
How is the over current protection voltage calculated? My reasoning tells me that we should use the short circuit current of our battery times the ON resistance of the FETs. I'm unsure, however, about the over current protection deglitch time.
Thank you in advanced!