LTC2496 is generating zero as output data

Hi RevathiB ,

For your question, this error may be caused by an over range condition. Bit 20 in conjunction with Bit 21 also provides under range and over range indication. If both Bit 21 and Bit 20 are HIGH, the differential input voltage is above the positive full-scale range (+FS) or over range. Furthermore, when both Bit 21 and Bit 20 are LOW, the differential input voltage is below the negative full-scale range (-FS) or under range. You may also refer to Table 1 in the datasheet.

In your case, both Bit 21 and Bit 20 are HIGH which indicates an over range condition. The allowable input voltage range (IN+ - IN-) must be within 0.5Vref as specified in the datasheet.

Regards,

JC

Hi JCCillion ,

In our application we have configured channel no 11 as single ended and the input voltage is 2.5V. The reference voltage for the ADC is 5V. In case of single ended the input range of ADC is 0.5ref?

Thanks,

Revathi

Hi RevathiB ,

Yes, you are correct. For single ended, the input range is 0.5ref. Referring to Table 2 in the datasheet, since you have an input of 2.5V which is FS+, the value you are reading is correct.

One thing to note, the output data format of LTC2496 is at 2's complement. To convert the code to actual values, you must check the MSB first before multiplying the decimal code by the LSB. When MSB is 0 you can just multiply decimal code directly by LSB but if the MSB is 1 you need to subtract 2^n from the code, then multiply by LSB size, where n is the number of bits.

Regards,

JC

Hi JCCillion ,

Thanks for you assistance ,it is working as expected .

Regards,

Revathi

Hi RevathiB ,

Good to know that it is finally working. Feel free to post a thread if you have any more concerns. I will be closing this thread.

Regards,

JC

Hi RevathiB ,

Good to know that it is finally working. Feel free to post a thread if you have any more concerns. I will be closing this thread.

Regards,

JC