DRV8833CEVM: Drv8833

Hi Jaquier,

As long as the voltage across the sense resistor remains within the absolute maximum specifications, increasing the sense resistor value should not cause any problems.

Yes, you can try changing the resistor on an EVM.

Dear Rick,

Thanks for your input.

1. Have you the same opinion for the DRV8832 which I am currently using in the design ?  Based on my tests, using sense resistor higher that 1 Ohms works too  but it is clearly stated in the datasheet "you must use a sense resistor lower than 1 Ohms". I need to limit the current in the 100-150 mA range. I am able to do it with a 1.5 to 2 Ohms resistor and works fine with DRV8832 (and DRV8833 too).

2. With the DRV8832, I also observed something "strange": In my application, I have  to go against a end stop (detected by a end switch), such that the motor reaches a stall condition and when the motor is in this stall condition (blocked), the VSET is changed to lower voltage (goal is to maintain a small force againt the end stop), the driver does not "update" the motor output. I have to move the motor, or release IN1 IN2 for a few ms such that the "update" applies. do you know why ? When the motor is in rotation, this features works perfectly. Is it due to a Fault condition ?

For the VSET, I use a filtered pwm output of a microcontroller. I had bad experience using the DRV8832 with PWM directly on the IN1 IN2 lines. Maybe the DRV8833 might be more appropriate for the point 2.

My application requires two drivers, one with a current limit of 100-150 mA with ideally a fault signal when limit is reached, exactly as the DRV8832 does (question in point 1) and the other has higher power, current limit is required, FLT signal on current limit is a wish (point 2).

Thanks for your answer.

Hi Jaquier,

One of the features of the DRV8832 is to maintain a constant motor speed as the voltage varies. This is useful in battery operations. Internal circuitry adjust the PWM duty cycle to achieve the proper speed.

The DRV8833 is more appropriate if you intend to PWM the inputs.

What is the system voltage? There may be other options available, but not with a fault signal.

1. Have you the same opinion for the DRV8832 which I am currently using in the design ? Based on my tests, using sense resistor higher that 1 Ohms works too but it is clearly stated in the datasheet "you must use a sense resistor lower than 1 Ohms". I need to limit the current in the 100-150 mA range. I am able to do it with a 1.5 to 2 Ohms resistor and works fine with DRV8832 (and DRV8833 too).

We will check with the design team.

2. With the DRV8832, I also observed something "strange": In my application, I have to go against a end stop (detected by a end switch), such that the motor reaches a stall condition and when the motor is in this stall condition (blocked), the VSET is changed to lower voltage (goal is to maintain a small force againt the end stop), the driver does not "update" the motor output. I have to move the motor, or release IN1 IN2 for a few ms such that the "update" applies. do you know why ? When the motor is in rotation, this features works perfectly. Is it due to a Fault condition ?

Has the FAULTn signal asserted before VSET is changed?

Hello Rick,

Design voltage is 5V for both motor. This fault signal on the current limit (and not only on the general overcurrent) is very useful for the application. I will need to reproduce this signal if I use another IC, especially for the motor where I need to limit current to 100-150 mA

1. We will check with the design team.

Thank you in advance for checking this. it's important.
It appears that the blanking time is shorter for the DRV8832 (3us) than DRV8833 (3.75us).

2. Has the FAULTn signal asserted before VSET is changed?

I will check it. But I expect to get the end switch signal and VSET adjustment before the 275ms delay of the FLT signal. I will test it.

Hi Jaquier,

The designer said that using a 2 Ohm with 150mA should work.

We will still have to look into the change in VSET.