Interfacing the LTC2440 24bit ADC with the Arduino

in Arduino by DP | 3 comments

Jbeale shows how to interface the LTC2440 24bit analog to digital converter with the Arduino. He provided the pin connections, a small sketch, as well as some advice to get it up and running.

I should add: to reach the specified noise performance of this part (200 nV RMS) you must have an absolutely clean layout, heavy ground copper and the grounds must be connected in the right way. At first I had > 1 uV RMS, then I removed some bypass caps (dumping current into a sensitive ground area?) and it got quite a bit better to 250 nV but even after some effort, I could not quite reach the spec level with my SSOP->DIP adaptor board. At this level the “excess noise” of resistors (1/f noise) becomes relevant. Physically large metal-film resistors are generally good (low noise). Small cheap SMT resistors are usually noisy.

Via the forum.

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Comments

  1. JBeale says:

    Always kind of a shock to come to DP and see one of my posts make the front page :-). That part has good resolution; I wish it came in some easier form factor than the SSOP-16, but that’s the only choice. I guess the casual experimenter is not supposed to want this level of performance.

  2. willemite says:

    cool! I’ve been trying to get my prototype up and running for my LTC2440 board that I’ve been working on all year (1 hour here and there type of on-off job). Got first version of board made only to find I put the wrong opamp footprint on it, and grounded something I should not have…

    I found it to be quite straightforward to solder it to a board, and luckily I had some SSOP to DIP breakouts.

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