AFE5816: AFE5816 output data format

Koo SeongWoo

Part Number: AFE5816

Tool/software:

Hi, everyone

In the previous thread, a TI expert mentioned that the default ADC output format is in two's complement form and advised that to change the output format, one should set register 4, bit 3 to 1.

I have three questions about this

I'm curious about what the output format changes to when this is done.
Given that there is an internally 1V offset on the INP pin and the maximum analog input is 1Vpp, I believe there will be no negative values for the input. Therefore, when using two's complement, I assume the most significant bit (MSB) will always be 0. Is this correct?
Does two's complement use 1V as the reference point for distinguishing between positive and negative values, instead of 0V?

Thank you

7 months ago

0 Sachin H K 7 months ago

TI__Expert 5955 points

I am giving an example of this with 4 bit . When you write register 4 bit 3 to 1 it changes to offset binary format from twos complement .

Decimal	Offset binary, K = 8	Two's complement
7	1111	0111
6	1110	0110
5	1101	0101
4	1100	0100
3	1011	0011
2	1010	0010
1	1001	0001
0	1000	0000
−1	0111	1111
−2	0110	1110
−3	0101	1101
−4	0100	1100
−5	0011	1011
−6	0010	1010
−7	0001	1001
−8	0000	1000

This device takes single ended input with common mode of 1V . If the signal is swinging from 0.9V to 1.1V it is effectively the signal from -0.1V to 0.1V.

So 1V is the reference point always . Now the output format can be chosen accordingly based on user convivence