AD5663

Rev. 0 | Page 12 of 24

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. A typical INL vs. code plot is shown in Figure 4.

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 by

design. A typical DNL vs. code plot is shown in Figure 5.

Zero-Scale Error

Zero-scale error is a measurement of the output error when

zero code (0x0000) is loaded to the DAC register. Ideally, the

output should be 0 V. The zero-scale error is always positive in

the AD5663 because the output of the DAC cannot go below

0 V. It is due to a combination of the offset errors in the DAC

and the output amplifier. Zero-scale error is expressed in mV.

A plot of zero-scale error vs. temperature is shown in Figure 10.

Full-Scale Error

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

scale code (0xFFFF) is loaded to the DAC register. Ideally, the

percent of full-scale range. A plot of full-scale error vs. tempera-

ture is shown in Figure 9.

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 ideal

expressed as a percent of the full-scale range.

Zero-Scale Error Drift

Zero-scale error drift is a measurement of the change in zero-

scale error with a change in temperature. It is expressed in μV/°C.

Gain Temperature Coefficient

Gain temperature coefficient is a measurement of the change in

gain error with changes in temperature. It is expressed in (ppm

of full-scale range)/°C.

Offset Error

fer function. Offset error is measured on the AD5663 with

positive.

DC Power Supply Rejection Ratio (PSRR)

PSRR indicates how the output of the DAC is affected by changes

Output Voltage Settling Time

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 1/4 to 3/4 full-

scale input change and is measured from the 24th falling edge of

SCLK.

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-s,

and is measured when the digital input code is changed by

1 LSB at the major carry transition (0x7FFF to 0x8000). See

Figure 19.

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 it is measured when the DAC output is not updated.

It is specified in nV-s and measured with a full-scale code change

on the data bus, that is, from all 0s to all 1s and vice versa.

Total Harmonic Distortion (THD)

Total harmonic distortion is the difference between an ideal

sine wave and its attenuated version using the DAC. The sine

wave is used as the reference for the DAC, and the THD is a

measurement of the harmonics present on the DAC output.

It is measured 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 (voltage per √Hz). It is measured by loading the

DAC to midscale and measuring noise at the output. It is

measured in nV/√Hz. Figure 24 shows a plot of noise spectral

density.

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. It is measured

with a full-scale output change on one DAC (or soft power-down

and power-up) while monitoring another DAC kept at midscale.

It 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 to another

DAC kept at midscale. It 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. It is measured in standalone mode and is expressed

in nV-s.