Rainbow Electronics MAX5123 - Manual (Page 15)

MAX5122/MAX5123
+5V/+3V, 12-Bit, Serial, Force/Sense DACs
with 10ppm/°C Internal Reference
______________________________________________________________________________________ 15
__________Applications Information
Definitions
Integral Nonlinearity (INL)
Integral nonlinearity (Figure 8a) is the deviation of the
values on an actual transfer function from a straight
line. This straight line can be either a best-straight-line
fit (closest approximation to the actual transfer curve)
or a line drawn between the endpoints of the transfer
function, once offset and gain errors have been nulli-
fied. For a DAC, the deviations are measured at every
single step.
Differential Nonlinearity (DNL)
Differential nonlinearity (Figure 8b) is the difference
between an actual step height and the ideal value of
1LSB. If the magnitude of the DNL is less than or equal
to 1LSB, the DAC guarantees no missing codes and is
monotonic.
Offset Error
The offset error (Figure 8c) is the difference between
the ideal and the actual offset point. For a DAC, the off-
set point is the step value when the digital input is zero.
This error affects all codes by the same amount and
can usually be compensated for by trimming.
Gain Error
Gain error (Figure 8d) is the difference between the
ideal and the actual full-scale output voltage on the
transfer curve, after nullifying the offset error. This error
alters the slope of the transfer function and corre-
sponds to the same percentage error in each step.
0
2
1
4
3
7
6
5
000 010 001 011 100 101 110
AT STEP
O11 (1/2 LSB )
AT STEP
001 (1/4 LSB )
111
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE (LSB)
Figure 8a. Integral Nonlinearity
Figure 8b. Differential Nonlinearity
0
2
1
4
3
6
5
000 010 001 011 100 101
DIFFERENTIAL LINEARITY
ERROR (-1/4 LSB)
DIFFERENTIAL
LINEARITY ERROR (+1/4 LSB)
1 LSB
1 LSB
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE (LSB)
0
2
1
3
000 010 001 011
ACTUAL
DIAGRAM
IDEAL DIAGRAM
ACTUAL
OFFSET POINT
OFFSET ERROR
(+1 1/4 LSB)
IDEAL OFFSET
POINT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE (LSB)
Figure 8c. Offset Error
Figure 8d. Gain Error
0
5
4
6
7
000 101 100 110 111
IDEAL DIAGRAM
GAIN ERROR
(-1 1/4 LSB)
IDEAL FULL-SCALE OUTPUT
ACTUAL
FULL-SCALE
OUTPUT
DIGITAL INPUT CODE
ANALOG OUTPUT VALUE (LSB)