DRV8412 - Resistor for current limiting (OC-Threshold)

Xavier Queffelec

Other Parts Discussed in Thread: DRV8840, DRV8412

Hello,

I am making a design for our new project, where I need to drive a DC motor.

First I make my design with the DRV8840, because my DC motor need less than 1A and I can make it through the I control pin.
Then I change the design to be able to use 48V and be more flexible so I come to the DRV8412. My purpose was to have a board which can be used for further test in other project.
There I found on page 12 in the Table 2, that there is only resistor for limiting the current down to 1.4A
Is it possible to use a larger resistor than 200k, for example 300k for 0.7A?

I thank you for your answer.
Best Regards
Xavier

over 9 years ago

0 Rick Duncan over 9 years ago

TI__Guru** 114905 points

Hi Xavier,

The recommended upper limit of the OC_ADJ resistor is 200k. We cannot recommend increasing the resistance without additional study.

A few other items to note about the OC_ADJ:

From page 12 of the datasheet:

Assuming a fixed resistance on the OC_ADJ pin across multiple devices, a 20% device-to-device variation in OC threshold measurements is possible. Therefore, this feature is designed for system protection and not for precise current control.

Also, if you plan to use the current limit as cycle by cycle, please be aware that there is no fault indication when the cycle by cycle shutdown occurs. Also, both PWM_A/B or PWM_C/D must be toggled to recover. An example of this is discussed in the post:

http://e2e.ti.com/support/applications/motor_drivers/f/38/p/285252/1002518.aspx#1002518 Look for the discussion on August 28 and 29, 2013

0 Xavier Queffelec over 9 years ago in reply to Rick Duncan

Intellectual 310 points

Hi Rick,

Thank for your Feedback, so I will use the first design with the DRV8840.

I will reserved this one for application with at least 50W Motor

Thanks again.

Xavier

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DRV8412 - Resistor for current limiting (OC-Threshold)