I found that in the data sheet of DRV8307, It is written that 'DRV8307 is a three half- bridge pre-driver that drives six N-type MOSFETs 30 mA with a single power supply.' While in this linked page(http://www.ti.com/product/drv8307/description), it is written that DRV8307 has 300mA GATE DRIVE current for six MOSFETS. So I am quite confused for the value of the GATE DRIVE Current. I wish this problem will be solved as soon as possible. If i am doing any mistake then kindly inform me. Thanks.
I have done this complaint at the error reporting page ([View:http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SLVSCK2A&partnum=DRV8307:1230:0]).
I get good reply also and thanks for reply and reply is given below:
Dear Dinesh,
Thanks for pointing out this error. The DRV8307 has a gate drive current of 30 mA, and the website has the error.
If you’re using large MOSFETs for a high current motor, and need more gate drive current, the DRV8308 allows up to 130 mA but requires SPI configuration.
For any other questions, I recommend using the E2E forum at https://e2e.ti.com/support/applications/motor_drivers/f/38
Best regards,
Ross
But after this reply, I get one more confusion. You said “If you’re using large MOSFETs for a high current motor, and need more gate drive current, the DRV8308 allows up to 130 mA but requires SPI configuration.”
Till now my understanding says that gate drive current is depended on gate charge of MOSFET and the switching Frequency (Normally PWM). So if MOSFET have high gate charge or if I want to switch MOFET at higher frequency then I required more gate current.
So for lower gate charge like 14nC and switching frequency 50kHz( For CSD88537ND N-Channel NexFET), required gate current is given by:
Igate= Qg * N(Number of MOSFET) * Fswitching
So for my example, GATE current is 4.2mA (Qg=14nC, N=6, Fs= 50kHz).
I also found out that this required gate current is depend on the GATE resistance because it controls charging time of the gate capacitance of MOSFET.
Now my confusion is ‘Which type of MOSFET can be called Large MOSFET for high current motor?’
MOSFET which have high output drain current capacity like (60A or 100A), Is this type of MOSFET can be called as ‘LARGE MOSFET’?
Is my understanding of required GATE current for MOSFET is right or wrong?
Kindly please tell me and correct my understanding.
Thank you.