Datasheet

DAC8311
DAC8411
SBAS439B –AUGUST 2008–REVISED MAY 2013 www.ti.com
PARAMETER DEFINITIONS
With the increased complexity of many different
Full-Scale Error
specifications listed in product data sheets, this
section summarizes selected specifications related to
Full-scale error is defined as the deviation of the real
digital-to-analog converters.
full-scale output voltage from the ideal output voltage
while the DAC register is loaded with the full-scale
STATIC PERFORMANCE
code (0xFFFF). Ideally, the output should be V
DD
– 1
LSB. The full-scale error is expressed in percent of
Static performance parameters are specifications
full-scale range (%FSR).
such as differential nonlinearity (DNL) or integral
nonlinearity (INL). These are dc specifications and
Offset Error
provide information on the accuracy of the DAC. They
are most important in applications where the signal
Offset error is defined as the difference between
changes slowly and accuracy is required.
actual output voltage and the ideal output voltage in
the linear region of the transfer function. This
Resolution
difference is calculated by using a straight line
defined by two codes (for example, for 16-bit
Generally, the DAC resolution can be expressed in
resolution, codes 485 and 64714). Since the offset
different forms. Specifications such as IEC 60748-4
error is defined by a straight line, it can have a
recognize the numerical, analog, and relative
negative or positve value. Offset error is measured in
resolution. The numerical resolution is defined as the
mV.
number of digits in the chosen numbering system
necessary to express the total number of steps of the
Zero-Code Error
transfer characteristic, where a step represents both
a digital input code and the corresponding discrete
Zero-code error is defined as the DAC output voltage,
analogue output value. The most commonly-used
when all '0's are loaded into the DAC register. Zero-
definition of resolution provided in data sheets is the
scale error is a measure of the difference between
numerical resolution expressed in bits.
actual output voltage and ideal output voltage (0V). It
is expressed in mV. It is primarily caused by offsets in
Least Significant Bit (LSB)
the output amplifier.
The least significant bit (LSB) is defined as the
Gain Error
smallest value in a binary coded system. The value of
the LSB can be calculated by dividing the full-scale
Gain error is defined as the deviation in the slope of
output voltage by 2
n
, where n is the resolution of the
the real DAC transfer characteristic from the ideal
converter.
transfer function. Gain error is expressed as a
percentage of full-scale range (%FSR).
Most Significant Bit (MSB)
Full-Scale Error Drift
The most significant bit (MSB) is defined as the
largest value in a binary coded system. The value of
Full-scale error drift is defined as the change in full-
the MSB can be calculated by dividing the full-scale
scale error with a change in temperature. Full-scale
output voltage by 2. Its value is one-half of full-scale.
error drift is expressed in units of %FSR/°C.
Relative Accuracy or Integral Nonlinearity (INL)
Offset Error Drift
Relative accuracy or integral nonlinearity (INL) is
Offset error drift is defined as the change in offset
defined as the maximum deviation between the real
error with a change in temperature. Offset error drift
transfer function and a straight line passing through
is expressed in μV/°C.
the endpoints of the ideal DAC transfer function. INL
is measured in LSBs.
Zero-Code Error Drift
Zero-code error drift is defined as the change in zero-
Differential Nonlinearity (DNL)
code error with a change in temperature. Zero-code
Differential nonlinearity (DNL) is defined as the
error drift is expressed in μV/°C.
maximum deviation of the real LSB step from the
ideal 1LSB step. Ideally, any two adjacent digital
codes correspond to output analog voltages that are
exactly one LSB apart. If the DNL is within ±1LSB,
the DAC is said to be monotonic.
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