MCF8329A: MCF8329A

Chirag Naik

Part Number: MCF8329A
Other Parts Discussed in Thread: MCT8329A, DRV8329

Tool/software:

Hello TI

I was in discussion with TI rep and he has suggested DRV816x standalone driver for driving high power BLDC (2.5KW, 45V) motor but during my search i found that MCF8329 requires no code and easily configured in

sensorless FOC control. Pls kindly advise is MCF8329 suitable for drone application? also as it generates gate drive voltage, can we drive a 320A mosfet with it.

11 months ago

0 Chirag Naik 11 months ago

Prodigy 30 points

Also if you have ref doc on mosfet selection for various applications pls do share with us.

0 Joshua Horlander Cruz 11 months ago in reply to Chirag Naik

TI__Mastermind 24080 points

Hi Chirag,

For drone applications, we mostly see customers use the MCT8329A due to the need for higher speed than what the MCF8329A can drive. The MCT8329A can support up to of 3kHz and the MCF8329A can support up to 1.8 kHz (electrical frequency).

To determine if the MCF8329A or MCT8329A can support the MOSFETs selected, you can use the BLDC Max Qg MOSFET Calculator (select DRV8329) to determine what is the max MOSFET Qg that can be supported by the MCx8329A given optional external capacitance, PWM frequency, control method, and PVDD voltage: BLDC-MAX-QG-MOSFET-CALCULATOR Calculation tool | TI.com.

For additional information you may find the following documents helpful:

System Design Considerations for High-Power Motor Driver Applications

Regards,

Joshua

0 Chirag Naik 11 months ago in reply to Joshua Horlander Cruz

Prodigy 30 points

Thank you

As per calculator the chip can drive mosfets which has Qg less than 304. Is my understanding correct?

We can also find with Q = CV (Ciss * VDS Typ) & I = Q / t ( where t = nsec).

Is this correct?

0 Joshua Horlander Cruz 11 months ago in reply to Chirag Naik

TI__Mastermind 24080 points

Your understanding is correct that given your inputs, the MCF8329A will be able to drive 6 MOSFETs if each of there Qg is less than 304 nC. This number is dependent on the output PWM frequency being 3 kHz though. I mention this because we typically see the output PWM be set to 20 kHz or greater which will change the result significantly.

Chirag Naik said:
We can also find with Q = CV (Ciss * VDS Typ) & I = Q / t ( where t = nsec).

Is this correct?

This equation would be good for determining an approximate answer, although, values like the number of MOSFETs switching (determined by the commutation type used), external pulldown resistance, and external capacitance are missing which can significantly affect the MOSFET able to be driven by the MCF8329A gate driver.

Below is a link to an E2E FAQ which covers the equations used to determine the gate current required to drive a half bridge MOSFET configuration: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1238968/faq-how-to-determine-which-mosfets-a-gate-driver-can-support

Regards,

Joshua

0 Chirag Naik 11 months ago in reply to Joshua Horlander Cruz

Prodigy 30 points

Thank you so very much. Its very helpful.

The only reason we are using MCF8329A (PWM= 1.8KHz) because it supports FOC control & MCT8329A (PWM = 3 KHz) is trapezoidal but as you said if we increase the PWM freq, the QG driving capability is reducing.

0 Joshua Horlander Cruz 11 months ago in reply to Chirag Naik

TI__Mastermind 24080 points

Hi Chirag,

Just incase there is a misunderstanding, I will clarify that the PWM values you mentioned for the MCT8329 and MCF8329 are the max electrical frequency which is the same as the max speed of the motor the MCF and MCT algorithms can support. This electrical frequency will not affect the QG driving capability of the motor driver.

The PWM value of the MCT8329 and MCF8329 which will affect the devices QG driving capability is the PWM_FREQ_OUT setting which will change the amount the half bridge MOSFETs are switched on and off when driving the motor. When using the max QG calculator please use the desired PWM_FREQ_OUT setting as the PWM input. We recommend using 20-30 kHz as a default value.

Regards,

Joshua

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MCF8329A: MCF8329A