AD3552R datasheet(24/59 Pages) AD

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Data Sheet

AD3541R

TERMINOLOGY

analog.com

Rev. A | 24 of 59

Relative Accuracy or Integral Nonlinearity (INL)

For the DAC, relative accuracy or integral nonlinearity is a meas-

urement 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.

Offset Error

Offset error is the vertical deviation from the ideal transfer func-

tion after the gain error has been compensated. Offset error is

expressed in mV. In the AD3541R, offset error is measured at

midscale. The comparison between the ideal output and the actual

output is performed at midscale.

Offset Error Drift

The offset error drift is a measurement of the relative variation of

the offset with temperature. It is expressed in ppm/°C. Total offset at

a given temperature is calculated as

OffsetT=Offset25°C+TC×T−25×VRANGE

106

Full-Scale and Zero-Scale Error

These errors measure the deviation from the ideal value at full

scale and zero scale, at 25°C. The error is expressed as % of

full-scale range (FSR). In the case of the AD3541R, the ideal

value is calculated as the average of a sufficiently high number of

samples.

Full-Scale and Zero-Scale Error Drift

These parameters measure the variation of the zero-scale and

full-scale voltage as a function of the temperature, relative to the

ideal zero-scale and full-scale voltages. They are expressed in

ppm/°C. The total deviation over temperature is calculated using

the same formula used for the offset.

DC PSRR and AC PSRR

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 the supplies for midscale output of the DAC. DC PSRR is

measured in mV/V, and AC PSRR is measured in dB. VREF is held

at 2.5 V, and the supplies are varied by ±200 mV p-p.

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 within a given accuracy

for a given step change. Typically, it is evaluated for a small step

and a large step to account for the effect of amplifier slewing.

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.

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. Digital feedthrough

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

on the data bus, which means from all 0s to all 1s and vice versa.

Output Noise Spectral Density

Noise spectral density is a measurement of the internally generat-

ed random noise. Noise is measured at the DAC output when

it is loaded with the midscale code and using an ideal external

reference. Noise is also measured at the output of the internal

reference, if available. Noise density is expressed in nV/

Hz.

Figure 30 depicts the spectral density of the noise in the 1/f region

and the flat (broadband) region, whereas the specification quoted in

Table 2 pertains to the flat region.

Total Harmonic Distortion (THD)

THD is the difference between the sine wave played by the DAC

and an ideal sine wave of the same frequency and amplitude. The

deviation from an ideal sine wave is due to time and amplitude

discretization and nonlinear distortion. THD is measured as the

power ratio of the sum of harmonic components to the fundamental

component. It is expressed in dB.

Voltage Reference Temperature Coefficient

(TC)

Voltage reference TC is a measure of the change in the reference

output voltage with a change in temperature. The reference TC

is calculated using the box method, which defines the TC as the

maximum change in the reference output over a given temperature

range expressed in ppm/°C, as shown in the following equation:

TC = VREF_MAX − VREF_MIN

VREF_NOM × TEMP_RANGE

×106 (1)

where:

VREF_MAX is the maximum reference output measured over the total

temperature range.

VREF_MIN is the minimum reference output measured over the total

temperature range.

VREF_NOM is the nominal reference output voltage, 2.5 V.

TEMP_RANGE is the specified temperature range, −40°C to

+105°C.

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