Datasheet

AD5398
Rev. B | Page 10 of 16
TERMINOLOGY
Relative Accuracy
For the DAC, relative accuracy or integral nonlinearity is a
measurement of the maximum deviation, in LSB, from a
straight line passing through the endpoints of the DAC transfer
function. A typical INL vs. code plot is shown in
Figure 6.
Differential Nonlinearity (DNL)
Differential nonlinearity is the difference between the measured
change and the ideal 1 LSB change between any two adjacent
codes. A specified differential nonlinearity of ±1 LSB maximum
ensures monotonicity. This DAC is guaranteed monotonic by
design. A typical DNL vs. code plot is shown in
Figure 7.
Zero-Code Error
Zero-code error is a measurement of the output error when
zero code (0x0000) is loaded to the DAC register. Ideally, the
output is 0 mA. The zero-code error is always positive in the
AD5398 because the output of the DAC cannot go below 0 mA.
This is due to a combination of the offset errors in the DAC and
output amplifier. Zero-code error is expressed in mA.
Gain Error
This is a measurement of the span error of the DAC. It is the
deviation in slope of the DAC transfer characteristic from the
ideal, expressed as a percent of the full-scale range.
Gain Error Drift
This is a measurement of the change in gain error with changes
in temperature. It is expressed in LSB/°C.
Digital-to-Analog Glitch Impulse
Digital-to-analog glitch impulse is the impulse injected into the
analog output when the input code in the DAC register changes
state. It is normally specified as the area of the glitch in nA-s
and is measured when the digital input code is changed by
1 LSB at the major carry transition.
Digital Feedthrough
Digital feedthrough is a measurement of the impulse injected
into the analog output of the DAC from the digital inputs of the
DAC, but is measured when the DAC output is not updated. It
is specified in nA-s and measured with a full-scale code change
on the data bus, that is, from all 0s to all 1s and vice versa.
Offset Error
Offset error is a measurement of the difference between I
SINK
(actual) and I
OUT
(ideal) in the linear region of the transfer
function, expressed in mA. Offset error is measured on the
AD5398 with Code 16 loaded into the DAC register.
Offset Error Drift
This is a measurement of the change in offset error with a
change in temperature. It is expressed in µV/°C.