USB-8452 Pull-ups

[Jo-Jo]

I'm not sure if this is the right place for 8452 questions, but I couldn't find a better forum.

One of the EEs I'm working with wants to know the value of the pull-ups in the USB-8452. Strangely, I can't find this information in the datasheet.

Can someone tell me the strength of the internal pull-ups of the USB-8452?

[crossrulz]

Page 50 under DIO, there is a line that goes "If disabled, these lines are tri-stated with weak pull-down resistors (40 kΩ)."  If configured as output, you have a push-pull setup.  As input, they should be in the tri-stated mode with the 40k pull-down.

[Jo-Jo]

I guess my question wasn't clear. When the USB-8452 is configured to use I2C there are internal pull-ups that can be enabled if there aren't any external pull-ups in the circuit.

What value are the internal pull-ups?

[AlexanderEgg]

Hi Jo-Jo,

I was searching every NI side for a information to this, and havent found it so far. 

So I was wondering if you found out what the values for the internal pull ups are. I am using the USB-8452 as an I2C-Master to communicate with a PCBA, which has no pull up resistors. At the moment the communication is no stable, dropping information, not answering etc.

I might just add external pull ups because to me the current setup with USB-8452 and internal pull up does not work. And NI hid this information for internal pull ups really well. Next time I will use USB-8451 and go for external pull ups right away.

Thanks for your reply!

best regards,

Alexander Egg