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AD5721 Datasheet PDF : 31 Pages
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AD5761/AD5721
Data Sheet
TERMINOLOGY
Total Unadjusted Error (TUE)
Total unadjusted error is a measure of the output error taking
all the various errors into account, namely INL error, offset
error, gain error, and output drift over supplies, temperature,
and time. TUE is expressed in % FSR.
Relative Accuracy or Integral Nonlinearity (INL)
For the DAC, relative accuracy, or integral nonlinearity, is a
measure of the maximum deviation, in LSB, from a straight line
passing through the endpoints of the DAC transfer function. A
typical INL error vs. DAC code plot is shown in Figure 7.
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. A
typical DNL error vs. code plot is shown in Figure 11.
Monotonicity
A DAC is monotonic if the output either increases or remains
constant for increasing digital input code. The AD5761/AD5721
are monotonic over their full operating temperature range.
Bipolar Zero Error
Bipolar zero error is the deviation of the analog output from the
ideal half-scale output of 0 V when the DAC register is loaded
with 0x8000 (straight binary coding) or 0x0000 (twos complement
coding) for the AD5761/AD5721.
Bipolar Zero Temperature Coefficient (TC)
Bipolar zero TC is a measure of the change in the bipolar zero
error with a change in temperature. It is expressed in µV/°C.
Zero-Scale Error
Zero-scale error is the error in the DAC output voltage when
0x0000 (straight binary coding) or 0x8000 (twos complement
coding) is loaded to the DAC register. Ideally, the output voltage
is negative full scale. A plot of zero-scale error vs. temperature is
shown in Figure 21.
Gain Error Temperature Coefficient (TC)
Gain error TC is a measure of the change in gain error with
changes in temperature. It is expressed in ppm FSR/°C.
DC Power Supply Rejection Ratio (DC PSRR)
DC power supply rejection ratio is a measure of the rejection of
the output voltage to dc changes in the power supplies applied
to the DAC. It is measured for a given dc change in power supply
voltage and is expressed in mV/V.
AC Power Supply Rejection Ratio (AC PSRR)
AC power supply rejection ratio is a measure of the rejection of
the output voltage to ac changes in the power supplies applied
to the DAC. It is measured for a given amplitude and frequency
change in power supply voltage and is expressed in decibels.
Output Voltage Settling Time
Output voltage settling time is the amount of time it takes for
the output to settle to a specified level for a full-scale input
change. Full-scale settling time is shown in Figure 39 to Figure 42.
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 nV-sec
and is measured when the digital input code is changed by 1 LSB at
the major carry transition (see Figure 47 and Figure 48).
Glitch Impulse Peak Amplitude
Glitch impulse peak amplitude is the peak amplitude of the
impulse injected into the analog output when the input code in
the DAC register changes state. It is specified as the amplitude
of the glitch in mV and is measured when the digital input code
is changed by 1 LSB at the major carry transition.
Digital Feedthrough
Digital feedthrough is a measure 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
nV-sec and measured with a full-scale code change on the data bus.
Zero-Scale Error Temperature Coefficient (TC)
Noise Spectral Density
Zero-scale error TC is a measure of the change in zero-scale
Noise spectral density is a measurement of the internally generated
error with a change in temperature. It is expressed in µV/°C.
random noise characterized as a spectral density (nV/√Hz). It is
Offset Error
Offset error is a measure of the difference between VOUT (actual)
and VOUT (ideal) expressed in mV in the linear region of the
measured by loading the DAC to full scale and measuring noise
at the output. It is measured in nV/√Hz. A plot of noise spectral
density is shown in Figure 60.
transfer function.
Total Harmonic Distortion (THD)
Offset Error Temperature Coefficient (TC)
THD is the ratio of the rms sum of harmonics to the fundamental.
Offset error TC is a measurement of the change in offset error
For the AD5761/AD5721, it is defined as
with a change in temperature. It is expressed in µV/°C.
Gain Error
Gain error is a measure of the span error of the DAC. It is the
deviation in slope of the DAC transfer characteristic from the
THD (dB) = 20 × log V22 + V32 + V42 + V52 + V62
V1
where:
ideal expressed in % FSR. A plot of gain error vs. temperature is
V1 is the rms amplitude of the fundamental.
shown in Figure 24.
V2, V3, V4, V5, and V6 are the rms amplitudes of the second
through the sixth harmonics.
Rev. C | Page 20 of 31
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