AD5541/AD5542

–6–

REV. A

TERMINOLOGY

Relative Accuracy

For the DAC, relative accuracy or integral nonlinearity (INL)

is a measure of the maximum deviation, in LSBs, from a straight

line passing through the endpoints of the DAC transfer function.

A typical INL versus code plot can be seen in Figure 2.

Differential Nonlinearity

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. Figure 3 illustrates a typical DNL versus

code plot.

Gain Error

Gain error is the difference between the actual and ideal analog

output range, expressed as a percent of the full-scale range.

It is the deviation in slope of the DAC transfer characteristic

from ideal.

Gain Error Temperature Coefficient

This is a measure of the change in gain error with changes in

temperature. It is expressed in ppm/

°C.

Zero Code Error

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

is loaded to the DAC register.

Zero Code Temperature Coefficient

This is a measure of the change in zero code error with a change

in temperature. It is expressed in mV/

°C.

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. A plot of the glitch impulse is shown

in Figure 15.

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. CS is

held high, while the CLK and DIN signals are toggled. It is

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

on the data bus, i.e., from all 0s to all 1s and vice versa. A typi-

cal plot of digital feedthrough is shown in Figure 14.

Power Supply Rejection Ratio

This specification indicates how the output of the DAC is affected

by changes in the power supply voltage. Power-supply rejection

ratio is quoted in terms of % change in output per % change in

Reference Feedthrough

DAC output when the DAC is loaded with all 0s. A 100 kHz,

in mV p-p.