DRV8320: Pullup resistor at SDO pin

Shunsuke Nagata

Part Number: DRV8320

Hi,

My customer found the phenomenon which the rising wave of SDO become slow when he use 10K ohms pullup resistor. Once he use 1K ohms resistor, it would be improved. His application has 18pF in SDO line. Unfortunately, there is no information to show the resistor value. Customer would like to realize the square wave in SDO and work it faster.

- Do you have recommend resistor value?
- Do you have any idea to realize square waveform in SDO?
- Could you please measure the waveform of SDO in TI environments?

Regards,
Nagata.

over 4 years ago

0 Adam Sidelsky over 4 years ago

TI__Guru 61380 points

Nagata-San,

Thanks for posting on the MD forum!

The EVM uses a 1.5k ohm resistor but 1k ohm would be fine as well. The datasheet does show 10k ohm in the application schematic but this is likely for lower speed SPI.

This should fix your issue and provide square edges.

Regards,

-Adam

0 Shunsuke Nagata over 4 years ago in reply to Adam Sidelsky

TI__Genius 12240 points

Hi, Adam -san,

Thank you very much for your support. Could you please give your supports for below additional question?

- What is the highest speed in SPI of DRV8320? Is it 10Mbps?
- What is the recommend pull-up resistor value in the case of highest SPI speed?

Regards,
Nagata.

0 Adam Sidelsky over 4 years ago in reply to Shunsuke Nagata

TI__Guru 61380 points

Nagata-San,

This is highly dependent on your system PCB, MCU, and software. Please check it on your board.

That being said we expect theoretical maximum SCLK speed of 10MHz per the datasheet.

Regards,

-Adam

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DRV8320: Pullup resistor at SDO pin