Hi

Please let me know about these fundamental questions of AD5259.

Datasheet says

RWA(D)={(256-D)/256}XRAB + 2 X Rw (2)

Total wipe resistance Rwb is 75 ohm typ @ Code 0x00

What is the relation between these specs and Zero scale Error?

2X Rw = Rwb @code0x00 in ideal?

The typical of Zero scale error means Rwb ?

Figure 39 looks 2XRw.

INL means difference from (2) ? or only (256-D)/256 ?

Your guide (The essential guide say to the Data conversion) says (256-D)/256 is ideal curve, I think.

And the typ full scale error is minus value.

Does it mean RWA(256) < RAB ?

Figure 39 looks Rs remain.

Regards

moto

Hi Moto-san,

Ideally at code 0x00, Rwb = 2 x Rw. RW is the wiper resistance contributed by the ON resistance of each internal switch.

To measure zero-scale error, write all zeroes to the part and measure the output. The difference of that output and the ideal zero-scale measurement (0 ohm ideally) is the zero-scale error.

To measure the full-scale error, write all ones to the part and measure the output. The difference of that output and the ideal full-scale measurement (ideally Rab-1LSB) is the full-scale error.

INL has typical values of +/- 0.1 to +/-0.4LSB. However, according to the data sheet, it can go as low as -4LSB to as high as 4LSB.

For a more detailed explanation on Linearities you may refer to this link.

Regards,

Mark