AD5821

Rev. 0 | Page 10 of 16

TERMINOLOGY

Relative Accuracy

For the DAC, relative accuracy or integral nonlinearity is a

measurement of the maximum deviation, in LSB, from a

straight line passing through the endpoints of the DAC transfer

function. A typical INL vs. code plot is shown in Figure 5.

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 6.

Zero-Code Error

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

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

is 0 mA. The zero-code error is always positive in the AD5821

because the output of the DAC cannot go below 0 mA. This is

due to a combination of the offset errors in the DAC and output

amplifier. Zero-code error is expressed in milliamperes (mA).

Gain Error

Gain error is a measurement of the span error of the DAC. It is

the deviation in slope of the DAC transfer characteristic from

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

Gain Error Drift

Gain error drift is a measurement of the change in gain error

with changes in temperature. It is expressed in LSB/°C.

Digital-to-Analog Glitch Impulse

This 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 nanoamperes per second

(nA-s) and is measured when the digital input code is changed

by 1 LSB at the major carry transition.

Digital Feedthrough

Digital feedthrough is a measurement 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 nanoamperes per second (nA-s) and measured

with a full-scale code change on the data bus, that is, from all 0s

to all 1s and vice versa.

Offset Error

function, expressed in milliamperes (mA). Offset error is

measured on the AD5821 with Code 16 loaded into the DAC

register.

Offset Error Drift

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

with a change in temperature. It is expressed in microvolts per

degree Celsius (μV/°C).