DAC8564 Datasheet, PDF (39/46 Pages) Texas Instruments – 16-Bit, Quad Channel, Ultra-Low Glitch, Voltage Output DIGITAL-TO-ANALOG CONVERTER with 2.5V, 2ppm/°C Internal Reference

DAC8564
www.ti.com
SBAS403A – JUNE 2007 – REVISED NOVEMBER 2007
PARAMETER DEFINITIONS
With the increased complexity of many different specifications listed in product data sheets, this section
summarizes selected specifications related to digital-to-analog converters.
STATIC PERFORMANCE
Static performance parameters are specifications such as differential nonlinearity (DNL) or integral nonlinearity
(INL). Those are dc specifications and provide information on the accuracy of the DAC. They are most important
in applications where the signal is slowly changing and accuracy is required.
Resolution
Full-Scale Error
Generally, the DAC resolution can be expressed in
different forms. Specifications such as IEC 60748-4
recognize the numerical, analog, and relative
resolution. The numerical resolution is defined as the
number of digits in the chosen numbering system
necessary to express the total number of steps of the
transfer characteristic, where a step represents both
a digital input code and the corresponding discrete
analogue output value. The most commonly-used
definition of resolution provided in data sheets is the
numerical resolution expressed in bits.
Least Significant Bit (LSB)
The least significant bit (LSB) is defined as the
smallest value in a binary coded system. The value of
the LSB can be calculated by dividing the full-scale
output voltage by 2ⁿ, where n is the resolution of the
converter.
Full-scale error is defined as the deviation of the real
full-scale output voltage from the ideal output voltage
while the DAC register is loaded with the full-scale
code (0xFFFF). Ideally, the output should be V_DD – 1
LSB. The full-scale error is expressed in percent of
full-scale range (%FSR).
Offset Error
The offset error is defined as the difference between
actual output voltage and the ideal output voltage in
the linear region of the transfer function. This
difference is calculated by using a straight line
defined by two codes (code 485 and 64714). Since
the offset error is defined by a straight line, it can
have a negative or positve value. Offset error is
measured in mV.
Zero-Code Error
Most Significant Bit (MSB)
The most significant bit (MSB) is defined as the
largest value in a binary coded system. The value of
the MSB can be calculated by dividing the full-scale
output voltage by 2. Its value is one-half of full-scale.
The zero-code error is defined as the DAC output
voltage, when all '0's are loaded into the DAC
register. Zero-scale error is a measure of the
difference between actual output voltage and ideal
output voltage (0V). It is expressed in mV. It is
primarily caused by offsets in the output amplifier.
Relative Accuracy or Integral Nonlinearity (INL)
Relative accuracy or integral nonlinearity (INL) is
defined as the maximum deviation between the real
transfer function and a straight line passing through
the endpoints of the ideal DAC transfer function. DNL
is measured in LSBs.
Differential Nonlinearity (DNL)
Differential nonlinearity (DNL) is defined as the
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 less than 1LSB,
the DAC is said to be monotonic.
Gain Error
Gain error is defined as the deviation in the slope of
the real DAC transfer characteristic from the ideal
transfer function. Gain error is expressed as a
percentage of full-scale range (%FSR).
Full-Scale Error Drift
Full-scale error drift is defined as the change in
full-scale error with a change in temperature.
Full-scale error drift is expressed in units of
%FSR/°C.
Offset Error Drift
Offset error drift is defined as the change in offset
error with a change in temperature. Offset error drift
is expressed in µV/°C.
Copyright © 2007, Texas Instruments Incorporated
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