• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 29 subscribers
  • Views 915 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV8305-Q1: DRV8302

Kamal Kant Pandey
Prodigy 10 points
Part Number: DRV8305-Q1
Other Parts Discussed in Thread: DRV8302,

Hello sir,

I am using DRV8305-Q1 and DRV8302 to drive same BLDC motor. N-channel MOSFETs that is being used to supply current is same for two designs. PWM frequency used in both the cases is same that is 40kHz. I am using 28V supply for both the designs.

MOSFET part number: STL160NS3LLH7

 But the problem is that my motor speed is slow with DRV8305-Q1 as compared to DRV8302.

I kept the IDRIVE to its maximum value that is 1.25A and 1A and observed that there is an improvement in slew rate (confirmed it by observing PWM signal at GHA i.e. pin 36 of DRV8305-Q1 and GH_A i.e pin 47 of DRV8302). I have also observed that slew rate for DRV8302 and DRV8305-Q1 is comparable when IDRIVE is max. But still I am getting poor response with DRV8305-Q1.

Ques1 : Is there anything that i should take into consideration to have a better response? If yes please enlighten me with all those factors that I should consider.

While comparing DRV8302 and DRV8305-Q1, I found that peak gate current for DRV8302 is 1.7A/2.3A while for DRV8305-Q1 is 1.25A/1A.

Ques2: Does this change in values of peak gate current will affect the motor performance? If yes please tell me the reason.

Quss3: Average gate current is same for both the devices right??

  • 0
    TI__Expert 4650 points
    Hi Kamal,

    Are you sure the Duty Cycle inputs are the same for the DRV8305-Q1 and DRV8302?
    Is there any type of external current limiting in your test? If so, is the threshold for current limiting different between the two devices?
    Is the DRV8305-Q1 reporting any time of FAULTS during operation?

    Q1: I would first try to determine if you have any external factors that are limiting the duty cycle, like cycle-by-cycle current limiting or other device FAULTs.

    Q2: It can affect motor performance if the slew rate is to slow, in which case the MOSFET will not turn on as quickly. We have an app note outling all of the IDRIVE / TDRIVE considerations in our devices, I would advise reading through this to learn more:

    www.ti.com/.../slva714a.pdf

    Q3: The DRV8302 has an average gate current of 30 mA, while theDRV8305-Q1 has an average gate current of 50 mA.