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DRV10970: Reversing time in operation

Part Number: DRV10970

Hi Team,

The description in the data: Rotational direction can be changed while motor is spinning. The device takes t LOCK_EX time before reversing the direction.

The customer's understanding is that t LOCK_EX must be waited for commutation during movement (to ensure that the rotor stops rotating), and t LOCK_EX can be changed by changing the external capacitor.

However, after the customer test, it is found that when the duty cycle output is maintained, the FR pin is changed, and the waiting time is t LOCK_EN (typically 0.7S). Changing the size of the 22 pin external capacitor does not affect this time (the rotor lock detection time is changed when the motor is blocked ).

Customer would like to know:

1. If his test is wrong?

2. Is there any way to prevent the chip from going to sleep?

Thanks,

Annie

  • Hi Annie,

    Thanks for posting your question in MD forum. As explained in the datasheet, it takes t_LOCK_EX seconds before the device starts spinning the motor in reverse direction. This parameter can be changed by changing the C_RETRY cap. Can you check the device ground to see if there is any noise? The accuracy of this timing depends on the potential difference across C_RETRY capacitor. Any noise on GND pin will impact this timing.  Is there any reason why the customer wants the device not to enter sleep mode? Device enters sleep mode when PWM is driven low for t_SLEEP time. 

    Regards,

    Vishnu.