drv8832 schematic

In 8832 the output voltage is determined by the voltage at the pin : VSET. You cannot PWM the input pins IN1 and IN2 very fast. 

You could PWM the voltage at the VSET pin (using a RC filter). 

For constant speed applications, you can set VSET with resp. to VREF. If you want to change the speed, you'd have to drive the VSET using a DAC. (or use DRV8830 & I2C to set VSET).

I am assuming its a constant speed application, here's a rough schematic (using 8832):

Vref output voltage  = 1.285V (typical)

This implies: Vset  = 0.825 and the Voltage difference between OUT1 and OUT2 will be 0.825*4 = 3.3V

The output state of the OUT1 and OUT2 will be given by table 2 here: http://focus.ti.com/lit/ds/symlink/drv8832.pdf

Vivek Shankar

If you really have to PWM (and cannot use the DAC in the MCU), you can use this configuration: MCU -> PWM -> RC Filter -> VSET

RC value will depends on PWM frequency, normally, above audible frequency (20k) is recommended, higher frequency will be easy to select RC filter to filter PWM. This frequency will not affect DRV8832 and external circuit efficiency. 

Motor Speed (8832 output voltage) will depends on PWM duty cycle. Keep in mind DRV8832 output voltage is equal with 4 times Vset value.

Here's a sample schematic with 5V PWM output:

The resistor divider will ensure that a 5V signal gets transformed into a 1.25V signal. RC filter time constant for this particular combination would be 1.13 ms. If you need the Vset voltage to change faster than that, you could play with the R and C values. Make sure the ripple is very less (<20 mV) at the filter output.

Thanks

Vivek

Akos Odry said:

Hi,

 

I have a request with DRV8832 motor drivers. Can someone publish a typical application (schematic) of DRV8832 motor driver for 3.3V DC motors?

I am working on a robot project where i would like to control dc motors with pulses with modulation (through MSP430 MCU).

 

Thanks,

Akos

 

Hi.

I have the same problem. I want to control the speed of a DC motor with just a chip and a PWM signal from a microcontroller (VCC = 3.3v)

Do you have any chip with this parameters?

thanks a lot

Hi Raul,

Do you mean low voltage? If so, we have a few devices being developed that will accept a PWM input and transform the duty cycle information into DC motor speed.

If it is for larger voltage applications, you can look at any of our devices such as the DRV8800/01/02/13/14/40/41/42, etc. They will all accept PWM inputs to control DC motors.

The low voltage version (DRV8833 http://focus.ti.com/docs/prod/folders/print/drv8833.html) should be available in the June/July time frame.

Hope the info helps. Best regards,

Jose Quinones

Hi.

I have both options low voltage 3.3v, or larger 7.4v. but I prefer low voltage.

I will wait for DRV8833 and meanwhile I will try DRV8800.

Thanks a lot

Hi Raul,

None of the higher voltage devices that I mentioned before, including the DRV8800, will work at 7V. At the bare minimum, they all work at 8V or more (some of them are 8.2V).

Definitely, DRV8833 will be the way to go!

Best regards,

Jose Quinones

I will wait for DRV8833

Thanks