DRV8703-Q1: DRV8703-Q1 PWM mode

Celso Silva

Part Number: DRV8703-Q1

How to achieve the following PWM control mode? Mode=Hi-Z?

Ti response

There are two ways to achieve PWM control mode.

1) Leave the MODE pin floating. There is an internal pullup and pulldown that will set the internal voltage at ~1.05V to enter PWM mode

2) If using a GPIO on a mcu, set the GPIO as an input with no pullup or pulldown enabled.

Best Regards,
Rick Duncan
Motor Applications Team

My question:

I want to use PWM control on IN_1 and IN_2 (similar to DRV8701P i used before)

Leaving Mode pin floating or connect to a mcu input without pullup or pulldown the mode vref will be 2.35V and not 1.05V please see pictures from datashhet.

Vef = 2.35V = DVDD(3.3v)*65K/(65K+26K)

Can i use a resistor with 14k in parallel with 65K to be equivalent to 12K. Vref will be DVDD(3.3)*12k/(12k+26k) = 1.04 V ?

Best Regards

Celso Silva

Flexidoor SA

over 5 years ago

0 Wang5577 over 5 years ago

TI__Guru 56650 points

Celso,

No. Please don't put an external resistor in parallel with the internal 65kohm. Input pin HiZ means floating. I would think 1.05V is a typo.

I agree with mode pin voltage = 2.35V = DVDD(3.3v)*65K/(65K+26K) when it is floating.

0 Celso Silva over 5 years ago in reply to Wang5577

Prodigy 70 points

I know that Hiz means floating. But if you see the picture from datasheet, is mode is floating Vef = 2.35V = DVDD(3.3v)*65K/(65K+26K) and the two comparators that make the logic for the Digital core will make the same combination if we apply "1" to the mode pin.

0 Wang5577 over 5 years ago in reply to Celso Silva

TI__Guru 56650 points

Celso,

I checked it on an EVM, MODE pin voltage is about 1.05V at HiZ mode. That is doesn't match the pullup and pulldown resistor value.

I am checking it with our senior engineer to see if we can get the answer.

0 Wang5577 over 5 years ago in reply to Wang5577

TI__Guru 56650 points

Hello,

I don't have the answer right now. Let me try to get it tomorrow.

0 Wang5577 over 5 years ago in reply to Wang5577

TI__Guru 56650 points

Celso,

Our senior engineer found a comment from design team.

The internal diode drop between DVDD and the internal resistor divider makes the HiZ mode pin floating voltage is between 0.75~1.35V, instead of 2.35V.

So, you don't need extra resistor for HiZ mode.

0 Celso Silva over 5 years ago in reply to Wang5577

Prodigy 70 points

Wang Li,

Thanks for your attention and cooperation.

Best regards

Celso Silva

Motor drivers

Motor drivers forum

DRV8703-Q1: DRV8703-Q1 PWM mode