AD5044 datasheet(16/28 Pages) AD

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AD5024/AD5044/AD5064

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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.

Figure 4, Figure 5, and Figure 6 show plots of typical INL vs. code.

Differential Nonlinearity (DNL)

DNL 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 monoto-

nicity. This DAC is guaranteed monotonic by design. Figure 7,

Figure 8 and Figure 9 show plots of typical DNL vs. code.

Offset Error

Offset error is a measure of the difference between the actual

VOUT and the ideal VOUT, expressed in millivolts in the linear

region of the transfer function. Offset error is measured on the

part with Code 512 (AD5064), Code 128 (AD5044), and Code 32

(AD5024) loaded into the DAC register. It can be negative or

positive and is expressed in millivolts.

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 the

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

Offset Error Drift

Offset error drift is a measure of the change in offset error with

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

Celsius.

Gain Temperature Coefficient

Gain error drift is a measure of the change in gain error with

changes in temperature. It is expressed in parts per million of

full-scale range per degree Celsius.

Full-Scale Error

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

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

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

percentage of the full-scale range. Measured with VREF < VDD.

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 nanovolt-

seconds and is measured when the digital input code is changed

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

Figure 27.

DC Power Supply Rejection Ratio (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 VDD for full-scale output of the DAC. It is measured

in decibels. VREF is held at 2.5 V, and VDD is varied by ±10%.

Measured with VREF < VDD.

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 microvolts.

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 microvolts per milliamp.

Reference Feedthrough

Reference feedthrough is the ratio of the amplitude of the signal

at the DAC output to the reference input when the DAC output

is not being updated (that is, LDAC is high). It is expressed in

decibels.

Digital Feedthrough

Digital feedthrough is a measure of the impulse injected into

the analog output of a DAC from the digital input pins of the

device, but it is measured when the DAC is not being written

to (SYNC held high). It is specified in nanovolt-seconds and

measured with one simultaneous data and clock pulse loaded

to the DAC.

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 or vice versa) in the input register of another

DAC. It is measured in standalone mode and is expressed in

nanovolt-seconds.

Analog Crosstalk

Analog crosstalk is the glitch impulse transferred to the output

of one DAC due to a change in the output of another DAC. It is

measured by loading one of the input registers with a full-scale

code change (all 0s to all 1s or vice versa) while keeping LDAC

high, and then pulsing LDAC low and monitoring the output of

the DAC whose digital code has not changed. The area of the

glitch is expressed in nanovolt-seconds.

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