TMS320F28377S: ADC question

Hello Rain,

Rain Wang said:

The customer is interested in evaluating the F28377S, but the description of ADC has questions: The customer ADC needs 16bit, single-channel sampling, can the 176pin package be up to 20 channels?

Or if need 16bit, must use differential mode，not use single mode?

Rain Wang said:

 The customer's demand for the 176pin 283777S chip ADC is; 16bit, single channel sampling, 18 to 20 channels；

The 16-bit resolution cannot be used in single-ended mode. Although they cannot reach 16-bit resolution with single-ended mode, they can use oversampling in their software to increase the precision of their results from 12-bit mode.

Rain Wang said:

 Another question is why 20 pins only support 9 differential circuits instead of 10?

According to the Channel Selection section of the ADC in the device manual, for differential mode the ADC inputs must be numerically adjacent (i.e. 0 and 1, 2 and 3, etc.). If you look at the Analog Subsystem Block Diagram in the datasheet (figure 7-28 on page 95), you'll see that ADCINC4 and ADCIND4 do not have an adjacent pair (ADCINC5 and ADCIND5), which is why there is one less differential input. This is essentially a constrain by the number of pins on the package, and the way they were broken out to be accessible (other required pins may be taking their place instead, although I'm not sure the exact details of how this was chosen).

Best regards,

Omer Amir