ADS4245: ADC digital CMOS outputs driving traces > 2"

Nicholas Schaub

Part Number: ADS4245
Other Parts Discussed in Thread: SN74AVC16T245

Dear Friends at TI:

I have selected the ADS4245 for use in my application. In this scenario, the CMOS outputs on the ADC will drive a board-to-board connector and several inches of PCB traces. Section 10.2.2.3 Digital Interface in the ADS4245 datasheet recommends using a CMOS buffer when driving distances greater than a few inches. This seems like one of those instances. My questions:

(1) Do I need a buffer?

(2) Can you recommend a buffer/driver and/or reference design?

(3) What risk do I assume by omitting a buffer under these circumstances?

(4) Is there any risk to timing or other implications of inserting a buffer in the path?

Thank you so much for your assistance.

Nick

over 4 years ago

0 jim s over 4 years ago

TI__Guru* 91947 points

Nick,

(1) Do I need a buffer? Yes

(2) Can you recommend a buffer/driver and/or reference design? SN74AVC16T245

(3) What risk do I assume by omitting a buffer under these circumstances? Depending on clock speed, the data signal integrity may be degraded resulting in bad data captures.

(4) Is there any risk to timing or other implications of inserting a buffer in the path? Make sure to send the ADC output clock through the buffer as well so that all data lines and clocks have the same added delay. You may also want to add some dampening series resistors at the output of the buffer to minimize reflections. See attached TI EVM schematic for an example.

Regards,

Jim

5466.ADS42XX_58C28EVM-SCH_C.pdf

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ADS4245: ADC digital CMOS outputs driving traces > 2"