DRV8889-Q1: Itrip Ivalley of DRV8889 in smart tune ripple control mode

Scarlett Cao

Part Number: DRV8889-Q1

Hi team,

When customer set DRV8889-Q1 to smart tune ripple control mode, what is the Itrip and Ivalley as in below figures?

From datasheet description, Itrip seems to the full scale current set by below equation, right?

But I didnt find related description on Ivalley. Could you please share what is the Ivalley or ripple controlled( Itrip- Ivalley?)

Thank you

Scarlett

over 2 years ago

0 Pablo Armet over 2 years ago

TI__Mastermind 37683 points

Hi Scarlett,

The ITRIP is the maximum current for the specific step in the indexer table. The I_valley is the minimum current level. The current ripple is bounded by these two current levels as explained in the following section of the datasheet. I hope this answers your questions.

Regards,

Pablo Armet

0 Scarlett Cao over 2 years ago in reply to Pablo Armet

TI__Expert 4000 points

Hi Pablo,

The index table only have the % of full scale current, it is the average current? How to find the maximum and minimum current level for a specific step?

Thank you

Scarlett

0 Pablo Armet over 2 years ago in reply to Scarlett Cao

TI__Mastermind 37683 points

Scarlett,

The ITRIP for a specific step is a % of the full scale as you mentioned. The full scale is set by the user by using equation (1) of the datasheet.

As for calculating the IVALLEY (minimum threshold) this E2E thread answers this question: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/823040/drv8889-q1-toff-and-ivalley-about-smart-tune-ripple-control-mode

Regards,

Pablo Armet

0 Ryan Kehr over 2 years ago in reply to Scarlett Cao

TI__Guru 55605 points

Scarlett,

Please see this post for Ivalley.

https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/823040/drv8889-q1-toff-and-ivalley-about-smart-tune-ripple-control-mode

The current in the table is the Itrip point for each step.

Regards,

Ryan

0 Scarlett Cao over 2 years ago in reply to Ryan Kehr

TI__Expert 4000 points

Hi Ryan and Pablo,

Is the Ivalley value valid for all current range?

The Itrip align with calcul, but as current is low, I valley value is even higher than I trip from calculation.

I valley from calcul is (0.233+0.012）*0.99=0.24255。Actual measurement of Ivalley is around 0.213A.

Thank you

Scarlett

0 Pablo Armet over 2 years ago in reply to Scarlett Cao

TI__Mastermind 37683 points

Hi Scarlett,

Let me correct the E2E thread Ryan and I linked. The 12mA + 1% ITRIP equation is for the total current ripple. To find the Ivalley, subtract the ripple from ITRIP. In your case, the current ripple will be (.233*0.01 + 0.012 = 0.01433A) and the Ivalley is 0.233 - 0.01433 = 0.21867A which is closer to your measured value.

Regards,

Pablo Armet

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DRV8889-Q1: Itrip Ivalley of DRV8889 in smart tune ripple control mode