AD7225 データシートの表示（PDF） - Analog Devices

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AD7225

LC2MOS Quad 8-Bit DAC with Separate Reference Inputs

Analog Devices 

AD7225

TERMINOLOGY

Total Unadjusted Error

Total unadjusted error is a comprehensive specification that

includes full-scale error, relative accuracy, and zero code error.

Maximum output voltage is VREF − 1 LSB (ideal), where 1 LSB

(ideal) is VREF/256. The LSB size varies over the VREF range.

Therefore, the zero code error, relative to the LSB size, increases

as VREF decreases. Accordingly, the total unadjusted error, which

includes the zero code error, also varies in terms of LSB over the

VREF range. As a result, total unadjusted error is specified for a

fixed reference voltage of 10 V.

Relative Accuracy

Relative accuracy or endpoint nonlinearity is a measure of the

maximum deviation from a straight line passing through the

endpoints of the DAC transfer function. It is measured after

allowing for zero code error and full-scale error and is normally

expressed in LSB or as a percentage of full-scale reading.

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

over the operating temperature range ensures monotonicity.

Digital Feedthrough

Digital feedthrough is the glitch impulse transferred to the

output of the DAC due to a change in its digital input code. It is

specified in nV sec and is measured at VREF = 0 V.

Digital Crosstalk

Digital crosstalk is the glitch impulse transferred to the output

of one converter (not addressed) due to a change in the digital

input code to another addressed converter. It is specified in nV

sec and is measured at VREF = 0 V.

AC Feedthrough

AC feedthrough is the proportion of reference input signal that

appears at the output of a converter when that DAC is loaded

with all 0s.

Channel-to-Channel Isolation

Channel-to-channel isolation is the proportion of input signal

from the reference of one DAC (loaded with all 1s) that appears

at the output of one of the other three DACs (loaded with all 0s)

The figure given is the worst case for the three other outputs

and is expressed as a ratio in dB.

Full-Scale Error

Full-scale error is defined as

FSE = Measured Value − Zero Code Error − Ideal Value

Rev. C | Page 8 of 24

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