DRV8353: sampling resistance

Cherry Zhou

Part Number: DRV8353

Hi team,

In the application examples section of the DRV8353 note, as shown in the figure above, the phase currents are sampled with a single resistor and then output to the MCU through the SOA. Is the sampled value used to adjust the PWM duty cycle and then create a closed loop current control for BLDC?

The customer wants to connect only one sampling resistor as shown above, and the SP pin voltage is used as chip overcurrent protection, but does not output the SOA (SOB or SOC) to the MCU. The MCU gives a PWM signal with constant frequency and duty cycle to control the motor. Is it possible?

Could you help check this case? Thanks.

Best Regards,

Cherry

over 2 years ago

0 Anthony Lodi over 2 years ago

TI__Mastermind 26566 points

Hi Cherry,

It depends on what the customer is trying to achieve with the motor control. Is it a sensorless application? Or a sensored application with hall feedback? Are they using trapezoidal control? Are they needing speed control or torque tontrol for their application?

Regards,

Anthony Lodi

0 Cherry Zhou over 2 years ago in reply to Anthony Lodi

TI__Mastermind 22235 points

Hi Anthony Lodi,

Thank you for the support.

Anthony Lodi said:
Is it a sensorless application? Or a sensored application with hall feedback?

It's a sensored application with Hall feedback.

Anthony Lodi said:
Are they using trapezoidal control? Are they needing speed control or torque tontrol for their application?

Yes, they are using trapezoidal control, neither speed control nor torque control is required.

That is, it is equivalent to implementing an open-loop control, providing a fixed current, and providing a direction signal to control the motor rotation.

Thanks and regards,

Cherry

0 Anthony Lodi over 2 years ago in reply to Cherry Zhou

TI__Mastermind 26566 points

Hi Cherry,

The customer's implementation is possible if they are not concerned about current feedback. They can use the SP pin for overcurrent protection with a single resistor as shown in the application section.

The hall feedback will provide some speed information if speed control or speed monitoring is desired.

Regards,

Anthony Lodi

0 Cherry Zhou over 2 years ago in reply to Anthony Lodi

TI__Mastermind 22235 points

Hi Anthony Lodi,

If the VREF, SOA, SOB, SOC pins are not being used, is it okay to leave them floating?

Thanks and regards,

Cherry

0 Anthony Lodi over 2 years ago in reply to Cherry Zhou

TI__Mastermind 26566 points

Hi Cherry, yes it is ok to leave them floating if they are not being used.

Regards,

Anthony Lodi

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DRV8353: sampling resistance