CDCM9102: Which of the assigned pins is "LVCMOS INOUTS" erelctrical characteristics specified?

Tamio Yokokura

Part Number: CDCM9102

Hi, CDCM9102 supprot team,

I understood that the TYPE of OE / OS1 / OS0 pin in the following Pin Functions table is a typo so that it is explained in other thread. And also, not only 25MHz X-tal clock but also AC-coupled 2.5V LVCMOS and DC-coulpled 3.3V LVCMOS signal applied to the XIN.

By the way, which of the assigned pins is the following "LVCMOS INOUTS" erelctrical characteristics specified? Is it only for XIN pin?

If OE pin is LVCMOS input, is 150kohm pull-uped resstor presence?

Thanks

Tamio

over 4 years ago

0 Adam Siismets over 4 years ago

TI__Intellectual 950 points

Hi Tamio,

Only the XIN pin is LVCMOS input.

The OE pin does not have an internal pullup resistor.

Regards,

Adam

0 Tamio Yokokura over 4 years ago in reply to Adam Siismets

TI__Expert 3670 points

Hi, Adam,

Their evaluation indicates that the OE pin is pulled up to 3.3V via 150kohm.

The below is their evaluation result.

When OE pin is opened, the voltage of OE pin is 3.241V
When OE pin is pulled-down to ground via 100kohm, the voltage of OE pin is 1.348V

It looks like that there is a 150kohm pull-up resistor.

Please confirm the internal design of OE pin to design team again.

Thanks

Tamio

0 Adam Siismets over 4 years ago in reply to Tamio Yokokura

TI__Intellectual 950 points

Apologies, the datasheet did not indicate that this pullup resistor is there but your test results are conclusive evidence. Given that though, there is probably a 20% variation of the 150 kOhms over PVT.

Regards,

Adam

0 Tamio Yokokura over 4 years ago in reply to Adam Siismets

TI__Expert 3670 points

Hi, Adam,

I will explain to my customer that there is an internal resistor (150kohm) on OE pin.

Please check if there are the internal resistor on OS1 and OS0 in your site.

If there are the internal resistor, please revise the datasheet about the internal resistor of not only OE pin but also OS1 and OS0.

Thanks

Tamio

0 Hao Z over 4 years ago in reply to Tamio Yokokura

TI__Mastermind 18070 points

Hello Tamio,

I couldn't find the exact pullup resistance value from internal documentation but I believe that OS1 and OS0 indeed have pullup resistors. This is deducted by looking at the EVM schematic. The external pullup resistors for both pins are not installed:

Attaching a clearer copy of schematic: 0714.CDCM9102EVM_schematic.pdf

Regards,
Hao

0 Tamio Yokokura over 4 years ago in reply to Hao Z

TI__Expert 3670 points

Hi, Hao,

Thank you for your reply.

If possible, I would like you to check the voltage of OS0 pin and OS1 pin when both pins is pulled-down by 100kohm or 150kohm for understanding the internal pull-up resistor.

Thanks

Tamio

0 Adam Siismets over 4 years ago in reply to Tamio Yokokura

TI__Intellectual 950 points

Hi Tamio,

Unfortunately, we are unable to support these measurements at this time. We hope you understand.

Best,

Adam

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CDCM9102: Which of the assigned pins is "LVCMOS INOUTS" erelctrical characteristics specified?