CDCVF25081 16pin connection

Takumi Suzuki1

Mastermind 8490 points

Other Parts Discussed in Thread: CDCVF25081

Hi,

I would like to ask you 2 questions about CDCVF25081 16pin connection.

Q1) Must 16pin be connected one of 8 outputs (1Y0 - 1Y3, 2Y0 - 2Y3)?

If yes, for example, 1Y3(15pin) is very useful to connect due to next pin, I think.

What do you think of 15pin connect?

Q2) Is it necessary to use "capacitor" (for example, 10pF) between 16pin and GND to prevent signal overshoot/undershoot from occuurring?

Thank you very much in advance for your support!

Best Regards,

over 10 years ago

0 Gabe Ayala over 10 years ago

TI__Genius 10320 points

Hi Takumi-san,

FBIN must be connected to an output to complete the feedback loop if the PLL is to be used in zero delay mode. If the PLL is bypassed (S2/S1 1/0 mode in Functiona table), then this is not necessary.

This capacitor is not necessary as the output drivers can interface with the feedback input natively. If no input is detected, the device will force the outputs to a low state.

Gabe

0 Takumi Suzuki1 over 10 years ago in reply to Gabe Ayala

Mastermind 8490 points

Gabe-san,

Thank you very much for your reply!

I understood well.

Best Regards,

0 Takumi Suzuki1 over 10 years ago in reply to Takumi Suzuki1

Mastermind 8490 points

Gabe-san,

I'm sorry can I ask you one more basic question?

Q) How much capacitor should we use for driver line(pin 1Yx, 2Yx)?

I think I would like to connect FBIN with 1Y3. If 1Y3 is necessary capacitor (Ex. 10pF) to drive, is there anything problem to feedback to PLL via FBIN? Or if 1Y3 is used for FBIN feedback, we should not use it to drive? (Just only connect to FBIN?)

Best Regards,

0 Gabe Ayala over 10 years ago in reply to Takumi Suzuki1

TI__Genius 10320 points

HI Takumi-san,

The internal capacitance of FBIN should be OK for the LVCMOS output driver as this is how it was intended to be used. A nonpopulated capacitor footprint could be added if the customer is concerned about this issue however.

Gabe

0 Takumi Suzuki1 over 10 years ago in reply to Gabe Ayala

Mastermind 8490 points

Hi Gabe-san,

Thank you for your support! I understood.

Best Regards,

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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CDCVF25081 16pin connection