ADT7518
Rev. A | Page 11 of 40
DAC-to-DAC Crosstalk
This is the glitch impulse transferred to the output of one DAC
due to a digital code change and subsequent output change of
another DAC. This includes both digital and analog crosstalk. It
is measured by loading one of the DACs with a full-scale code
change (all 0s to all 1s and vice versa) with
LDAC
low and
monitoring the output of another DAC. The energy of the glitch
is expressed in nV-s.
Multiplying Bandwidth
The amplifiers within the DAC have a finite bandwidth. The
multiplying bandwidth is a measure of this. A sine wave on the
reference (with full-scale code loaded to the DAC) appears on
the output. The multiplying bandwidth is the frequency at
which the output amplitude falls to 3 dB below the input.
Total Harmonic Distortion
This is the difference between an ideal sine wave and its atten-
uated version using the DAC. The sine wave is used as the
reference for the DAC, and the THD is a measure of the
harmonics present on the DAC output, expressed in dB.
Round Robin
This term is used to describe the ADT7518 cycling through the
available measurement channels in sequence, taking a measure-
ment on each channel.
DAC Output Settling Time
This is the time required, following a prescribed data change, for
the output of a DAC to reach and remain within ?.5 LSB of the
final value. A typical prescribed change is from 1/4 scale to
3/4 scale.
AMPLIFIER
FOOTROOM
LOWER
DEADBAND
CODES
NEGATIVE
OFFSET
ERROR
GAIN ERROR
+
OFFSET ERROR
ACTUAL
OUTPUT
VOLTAGE
NEGATIVE
OFFSET
ERROR
DAC CODE
IDEAL
Figure 8. DAC Transfer Function with Negative Offset
ACTUAL
GAIN ERROR
+
OFFSET ERROR
UPPER
DEADBAND
CODES
OUTPUT
VOLTAGE
POSITIVE
OFFSET
ERROR
DAC CODE
FULL SCALE
IDEAL
Figure 9. DAC Transfer Function with Positive Offset (V
REF
= V
DD
)