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ADS1602: ADS1602 analog to digital Numerical value question

James Chiu
Prodigy 115 points
Part Number: ADS1602

Hi

I use ADS1602 to translate voltage to numerical value.

I use external vref, Vrefp=4V, Vrefn=1V, Vmid=2.5V, so I know my input can be differential Vin=3V.

But I read data, when Vin=0.5V, the numerical value=230xx(2V), Vin=0.3V, the numerical value=138xx(1.2V).

There's always a 4-times than it should be. Is there a times-adjustment at ADS1602?

If yes, how to adjust times?

Thanks.

  • +1
    TI__Mastermind 39380 points

    Hello James,

    There is no multiplication factor inside the ADC.  My guess is that you are not reading the data at the correct time, causing a 2 bit shift in the data, resulting in a 4x multiplication.

    Referring to Figure 2, you should read the MSB on the first falling edge of SCLK following the falling edge of FSO, and then the remaining 15b.

    Also, you must assert the SYNC pin after power up, per figure 1, for proper operation of the ADS1602.

    If possible, please provide a logic analyzer capture or scope capture of the waveforms.

    Regards,
    Keith Nicholas
    Precision ADC Applications