DRV8306: Hall comparator threshold

Takashi Onawa

Genius 13200 points

Part Number: DRV8306

On the datasheet, the high and low thresholds for Hall comparator are very unclear…

I understand that as following though, could you double check if my understanding is correct or not?

VIT+ : No spec in datasheet, estimated Vhys/2 from following figure?

VIT- : No spec in datasheet, estimated ‐Vhys/2 from following figure?

Delta threshold : VIT+ - VIT- = Vhys

I can understand this comparator has much tolerant against noise but actual positive and negative threshold is unclear on the datasheet description.

Could you tell me the reason why VIT are not specified on the datasheet also? I need to explain that to my customer.

Regards,

Takashi Onawa

over 5 years ago

0 Adam Sidelsky over 5 years ago

TI__Guru 65320 points

Onawa-San,

I am not sure why this is not specified, let me see if we have information for this.

I will get back to you this week.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

Can I have any update on this?

Then, I got additional one questions from them today regarding Vcm.

According to the datasheet, Vcm range is specified as 1.5V to 3.5V. But The hall output's common mode voltage is set to DVDD/2 in the motor. DVDD min voltage is specified as 2.9V, so hall output can not met Vcm spec of DRV8306 in worst case.

Can you tell me about the configuration for shifting up the common mode voltage?

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65320 points

Onawa-San,

Has the customer seen the DVDD reduce to 2.9V?

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

No, yet. However, since it has been listed in the datasheet, their rules require that it be designed with worst values.

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65320 points

Onawa-San,

I need more time to check this with my team, I can get back to you by end of Monday of that's okay.

Regards,

-Adam

0 Takashi Onawa over 5 years ago in reply to Adam Sidelsky

TI__Genius 13200 points

Hi Adam-san,

OK, i understood. I will ask them to wait on these questions.

Please don't forget their 1st question about threshold as well.

Regards,

Takashi Onawa

0 Takashi Onawa over 5 years ago in reply to Takashi Onawa

TI__Genius 13200 points

Hi Adam-san,

Would you be able to respond within today?

Regards,

Takashi Onawa

0 Adam Sidelsky over 5 years ago in reply to Takashi Onawa

TI__Guru 65320 points

Onawa-San,

I have a meeting with design this week to discuss the hysteresis level.

For the other question, Figure 5 and 6 in the datasheet show the DVDD output expected vs. DVDD current and temperature. We do not expect the DVDD output on any device to be 2.9V unless DVDD is loaded more than 30mA.

Can you check with the customer what load they expect to have on DVDD in their system?

If they are concerned about this they can adjust RH and RI so that the ratio is not 1 to 1 and therefore the Vcom will be shifted up slightly. I recommend adjusting RI to be higher than RH so that the Vcom is 2.5V (half way between 1.5V and 3.5V) when DVDD is at the nominal 3.3V.

What is their RH and RI value at the moment?

Regards,

-Adam

0 Adam Sidelsky over 5 years ago in reply to Adam Sidelsky

TI__Guru 65320 points

Onawa-San,

I spoke with design and they have confirmed that the Vhys is 15 to 35mV.

Regards,

-Adam

Motor drivers

Motor drivers forum

DRV8306: Hall comparator threshold