AD5671R datasheet(21/32 Pages) AD

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Data Sheet

AD5674/AD5674R/AD5679/AD5679R

Rev. B | Page 21 of 32

TERMINOLOGY

Relative Accuracy or Integral Nonlinearity (INL)

For the DAC, relative accuracy or integral nonlinearity is a

measurement of the maximum deviation, in LSBs, from a straight

line passing through the endpoints of the DAC transfer function.

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. These DACs are guaranteed monotonic

by design.

Zero Code Error

Zero code error is a measurement of the output error when zero

code (0x0000) is loaded to the DAC register. The ideal output is

0 V. The zero code error is always positive because the output of

the DAC cannot go below 0 V due to a combination of the offset

errors in the DAC and the output amplifier. Zero code error is

expressed in mV.

Full-Scale Error

Full-scale error is a measurement of the output error when full-

scale code (0xFFFF) is loaded to the DAC register. The ideal

output is VDD − 1 LSB. Full-scale error is expressed in percent of

full-scale range (% of FSR).

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

ideal expressed as % of FSR.

Offset Error Drift

Offset error drift is a measurement of the change in offset error

with a change in temperature. Offset error drift is expressed in

µV/°C.

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

transfer function. Offset error is measured with Code 256 loaded

in the DAC register. Offset error can be negative or positive.

DC Power Supply Rejection Ratio (PSRR)

The dc PSRR indicates how the output of the DAC is affected by

changes in the supply voltage. PSRR is the ratio of the change in

VOUT to a change in VDD for full-scale output of the DAC. PSRR

is measured in mV/V. VREF is held at 2 V, and VDD is varied by

±10%.

Output Voltage Settling Time

The output voltage settling time is the amount of time it takes for

the output of a DAC to settle to a specified level for a ¼ to ¾ full-

scale input change and is measured from the rising edge of SYNC.

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. Digital-to-analog glitch impulse 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

(0x7FFF to 0x8000).

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. Digital

feedthrough is specified in nV-sec and measured with a full-

scale code change on the data bus, that is, from all 0s to all 1s

and vice versa.

Reference Feedthrough

Reference feedthrough is the ratio of the amplitude of the signal

at the DAC output to the reference input when the DAC output

is not being updated. Reference feedthrough is expressed in dB.

Noise Spectral Density

Noise spectral density is a measurement of the internally generated

random noise. Random noise is characterized as a spectral density

(nV/√Hz). Noise spectral density is measured by loading the DAC

to midscale and measuring noise at the output. Noise spectral

density is measured in nV/√Hz.

DC Crosstalk

DC crosstalk is the dc change in the output level of one DAC in

response to a change in the output of another DAC. DC crosstalk

is measured with a full-scale output change on one DAC (or soft

power-down and power-up) when monitoring another DAC

kept at midscale. DC crosstalk is expressed in μV.

DC crosstalk due to load current change is a measure of the impact

that a change in load current on one DAC has on another DAC

kept at midscale. DC crosstalk due to load current change is

expressed in μV/mA.

Digital Crosstalk

Digital crosstalk is the glitch impulse transferred to the output

of one DAC at midscale in response to a full-scale code change

(all 0s to all 1s and vice versa) in the input register of another

DAC. Digital crosstalk is measured in standalone mode and is

expressed in nV-sec.

Analog Crosstalk

Analog crosstalk is the glitch impulse transferred to the output

of one DAC due to a change in the output of another DAC.

Analog crosstalk is measured by first loading one of the input

registers with a full-scale code change (all 0s to all 1s and vice

versa). Then, execute a software LDAC and monitor the output

of the DAC whose digital code was not changed. The area of the

glitch is expressed in nV-sec.

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