DAC8564 datasheet(39/46 Pages) TI

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PARAMETER DEFINITIONS

Full-Scale Error

STATIC PERFORMANCE

Offset Error

Resolution

Zero-Code Error

Gain Error

Least Significant Bit (LSB)

Full-Scale Error Drift

Most Significant Bit (MSB)

Offset Error Drift

Relative Accuracy or Integral Nonlinearity (INL)

Zero-Code Error Drift

Differential Nonlinearity (DNL)

Gain Temperature Coefficient

DAC7565

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With the increased complexity of many different

specifications listed in product data sheets, this

Full-scale error is defined as the deviation of the real

section summarizes selected specifications related to

full-scale output voltage from the ideal output voltage

digital-to-analog converters.

while the DAC register is loaded with the full-scale

code. Ideally, the output should be VDD – 1 LSB. The

full-scale error is expressed in percent of full-scale

Static performance parameters are specifications

range (%FSR).

such as differential nonlinearity (DNL) or integral

nonlinearity (INL). These are dc specifications and

provide information on the accuracy of the DAC. They

The offset error is defined as the difference between

are most important in applications where the signal

actual output voltage and the ideal output voltage in

changes slowly and accuracy is required.

the linear region of the transfer function. This

difference is calculated by using a straight line

defined by two codes. Since the offset error is defined

Generally, the DAC resolution can be expressed in

by a straight line, it can have a negative or positve

different forms. Specifications such as IEC 60748-4

value. Offset error is measured in mV.

recognize

the

numerical,

analog,

and

relative

resolution. The numerical resolution is defined as the

number of digits in the chosen numbering system

The zero-code error is defined as the DAC output

necessary to express the total number of steps of the

voltage, when all '0's are loaded into the DAC

transfer characteristic, where a step represents both

a digital input code and the corresponding discrete

difference between actual output voltage and ideal

analogue output value. The most commonly-used

output voltage (0V). It is expressed in mV. It is

definition of resolution provided in data sheets is the

primarily caused by offsets in the output amplifier.

numerical resolution expressed in bits.

Gain error is defined as the deviation in the slope of

The least significant bit (LSB) is defined as the

the real DAC transfer characteristic from the ideal

smallest value in a binary coded system. The value of

transfer function. Gain error is expressed as a

the LSB can be calculated by dividing the full-scale

percentage of full-scale range (%FSR).

output voltage by 2n, where n is the resolution of the

converter.

Full-scale error drift is defined as the change in

full-scale

error

with

change

temperature.

The most significant bit (MSB) is defined as the

Full-scale

error

drift

expressed

units

largest value in a binary coded system. The value of

%FSR/

°C.

the MSB can be calculated by dividing the full-scale

output voltage by 2. Its value is one-half of full-scale.

Offset error drift is defined as the change in offset

error with a change in temperature. Offset error drift

Relative accuracy or integral nonlinearity (INL) is

is expressed in

µV/°C.

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.

Zero-code error drift is defined as the change in

zero-code error with a change in temperature.

Zero-code error drift is expressed in

µV/°C.

Differential nonlinearity (DNL) is defined as the

maximum deviation of the real LSB step from the

ideal 1LSB step. Ideally, any two adjacent digital

The gain temperature coefficient is defined as the

codes correspond to output analog voltages that are

change in gain error with changes in temperature.

exactly one LSB apart. If the DNL is less than 1LSB,

The gain temperature coefficient is expressed in ppm

the DAC is said to be monotonic.

of FSR/

°C.

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