AD7923BRUZ-REEL7(RevD) データシートの表示（PDF） - Analog Devices

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AD7923BRUZ-REEL7
(Rev.:RevD)

4-Channel, 200 kSPS 12-Bit ADC with Sequencer in 16-Lead TSSOP

Analog Devices 

AD7923

TERMINOLOGY

Integral Nonlinearity

This is the maximum deviation from a straight line passing

through the endpoints of the ADC transfer function. The

endpoints of the transfer function are zero scale, a point 1 LSB

below the first code transition, and full scale, a point 1 LSB

above the last code transition.

Differential Nonlinearity

This is the difference between the measured and the ideal 1 LSB

change between any two adjacent codes in the ADC.

Offset Error

This is the deviation of the first code transition (00 ... 000) to

(00 ... 001) from the ideal, that is, AGND + 1 LSB.

Offset Error Match

This is the difference in offset error between any two channels.

Gain Error

This is the deviation of the last code transition (111 ... 110) to

(111 ... 111) from the ideal (that is, REFIN – 1 LSB) after the

offset error has been adjusted.

Gain Error Match

This is the difference in gain error between any two channels.

Zero-Code Error

This applies when using the twos complement output coding

option, in particular, with the 2 × REFIN input range when

−REFIN to +REFIN is biased around the REFIN point. It defined

as the deviation of the midscale transition (all 0s to all 1s) from

the ideal VIN voltage, that is, REFIN – 1 LSB.

Zero-Code Error Match

This is the difference in zero-code error between any two

channels.

Positive Gain Error

This applies when using the twos complement output coding

option, in particular, with the 2 × REFIN input range when

−REFIN to +REFIN is biased around the REFIN point. It is the

deviation of the last code transition (011 ... 110) to (011 ... 111)

from the ideal (that is, +REFIN – 1 LSB) after the zero-code

error has been adjusted.

Data Sheet

Positive Gain Error Match

This is the difference in positive gain error between any two

channels.

Negative Gain Error

This applies when using the twos complement output coding

option, in particular, with the 2 × REFIN input range when

−REFIN to +REFIN is biased around the REFIN point. It is the

deviation of the first code transition (100 ... 000) to (100 ... 001)

from the ideal (that is, −REFIN + 1 LSB) after the zero-code

error has been adjusted.

Negative Gain Error Match

This is the difference in negative gain error between any two

channels.

Channel-to-Channel Isolation

Channel-to-channel isolation is a measure of the level of cross-

talk between channels. It is measured by applying a full-scale

400 kHz sine wave signal to all three nonselected input channels

and determining how much that signal is attenuated in the

selected channel with a 50 kHz signal. The figure is given in the

worst-case across all four channels for the AD7923.

Power Supply Rejection (PSR)

Variations in power supply affect the full-scale transition, but

not the converter’s linearity. Power supply rejection is the maxi-

mum change in the full-scale transition point from a change in

power supply voltage from the nominal value.

Figure 6 shows the power supply rejection ratio vs. supply ripple

frequency for the AD7923 with no decoupling. The power sup-

ply rejection ratio is defined as the ratio of the power in the

ADC output at full-scale frequency, f, to the power of a 200 mV

p-p sine wave applied to the ADC AVDD supply of frequency fS:

PSSR (dB) = 10log(Pf/PfS)

Pf is equal to the power at frequency f in the ADC output; PfS is

equal to the power at frequency fS coupled onto the ADC AVDD

supply.

Track-and-Hold Acquisition Time

The track-and-hold amplifier returns into track mode at the

end of conversion. Track-and-hold acquisition time is the time

required for the output of the track-and-hold amplifier to reach

its final value, within ±1 LSB, after the end of conversion.

Rev. D | Page 10 of 24

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