ADC12D800RF: Latest datasheet and schematic of the evaluation board

Lingmei Ma

Part Number: ADC12D800RF
Other Parts Discussed in Thread: ADC12D500RF, LM3880

We are currently designing a data acquisition board using ADS12D500/800RF. We found different versions of the datasheet and the schematic of its evaluation board and we noticed that there are some inconsistencies. So I have got some questions about this:

1. Is the datasheet updated on March 2013 the latest version?

2. Is the schematic for the reference board updated on Jan 30, 2013 the latest version?

3. Is pin C6 a power supply? In another version it was a test pin.

4. According to the datasheet, pin CalDly is recommended to be connected to GND or VA by a 1k ohm resistor, but in the schematic of the reference board, a 49.9 ohm resistor is used, should we follow the datasheet or the reference design?

5. There is a powering up sequence in the reference design (using LM3880), is it recommended that we do the same? Any reason why?

Thanks a lot.

Lingmei

over 7 years ago

0 Jim Brinkhurst1 over 7 years ago

TI__Mastermind 44550 points

Hi Lingmei

Regarding your questions.

Yes, that datasheet is the most recent revision published.
The schematic for the board currently in production is ADC1xDxxxx(RF)RB Rev. B. /cfs-file/__key/communityserver-discussions-components-files/73/5428.4743.ADC12D1X00RF_5F00_RB_2D00_SCH_5F00_B.pdf
Pin C6 should be connected to the VA supply net. It was used for other functions on some pre-production test versions of the IC, that is why the earlier document should the alternate usage as a test pin.
Either 1k or 49.9 ohm values are acceptable to tie CalDly high or low. I recommend following the datasheet guidance.
The power-up sequence resulting from the LM3880 operation ensures the FPGA is powered up first (but not configured until later), followed by the ADC and then the clock circuitry. The goal is to prevent driving any of the FPGA or ADC pins until it those devices have been powered up.

Best regards,

Jim B

0 Lingmei Ma over 7 years ago in reply to Jim Brinkhurst1

Intellectual 330 points

Thank you Jim!

Lingmei

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ADC12D800RF: Latest datasheet and schematic of the evaluation board