AD5686 datasheet(14/24 Pages) AD

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AD5696/AD5694

Data Sheet

Rev. A | Page 14 of 24

TERMINOLOGY

Relative Accuracy or Integral Nonlinearity (INL)

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. Figure 5

and Figure 6 show typical INL vs. code plots.

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. The AD5696/AD5694 are guaranteed monotonic

by design. Figure 7 and Figure 8 show typical DNL vs. code plots.

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

the AD5696/AD5694 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.

Figure 13 shows a plot of zero-code error vs. temperature.

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

output should be VDD − 1 LSB. Full-scale error is expressed as a

percentage of the full-scale range (% of FSR). Figure 12 shows a

plot of full-scale error vs. temperature.

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 in % of FSR.

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 FSR/°C.

Offset Error

Offset error is a measurement of the difference between VOUT

(actual) and VOUT (ideal) expressed in mV in the linear region

of the transfer function. It can be negative or positive.

Offset Error Drift

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

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

DC Power Supply Rejection Ratio (PSRR)

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 midscale output of the DAC. It is mea-

sured in mV/V. VREF is held at 2.5 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.

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-sec

and is measured when the digital input code is changed by 1 LSB

at the major carry transition (0x7FFF to 0x8000) (see Figure 27).

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 is measured when the DAC output is not updated. It 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.

Noise Spectral Density (NSD)

Noise spectral density is a measurement of the internally gener-

ated random noise. Random noise is characterized as a spectral

density (nV/√Hz) and is measured by loading the DAC to mid-

scale and measuring noise at the output. It 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. 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 measurement

of the impact that a change in load current on one DAC has

on 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 expressed in nV-sec.

Analog Crosstalk

Analog crosstalk is the glitch impulse transferred to the output

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

To measure analog crosstalk, load one of the input registers with

a full-scale code change (all 0s to all 1s and vice versa), and 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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