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ADS8689: Current Accuracy

GARETH OU
Guru 12780 points

Part Number: ADS8689

Hi

Customers using ADC: ADS8689 found that when reading current (0~20ma), the current error will become larger when it is above 5ma, and the other set of control gears is plus or minus 10V, and the accuracy can be within 0.1 of our expected accuracy. %FSR.

1. A 120.24 ohm resistor will be added to the circuit design of the customer’s current measurement. The gear selected by the software is plus or minus 6.144v. Would you recommend reducing it to plus or minus 2.56?

2. What is the function of Reference 4.096 inside the ADC?

  • 0
    TI__Guru 69266 points

    Hi Gareth,

    1. Can you try restating your first question? I'm not sure I understand what you're asking. In general, the ADC's full-scale range (FSR) should be selected such that it is slightly larger than the expected input voltage range in your application. 

    2. The ADS8689 features an internal reference voltage = 4.096 V. This reference is trimmed for precision and is used to convert the analog input voltage to a binary digital output. Alternatively, the REFIO pin allows you to provide an external reference voltage. Note that the ADC's FSR will scale by a factor of VREF_ext / 4.096 V.

    Regards,

    Ryan