AD9240EB データシートの表示（PDF） - Analog Devices

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AD9240EB

Complete 14-Bit, 10 MSPS Monolithic A/D Converter

Analog Devices 

AD9240

Table I. Analog Input Configuration Summary

Input

Connection

Single-Ended

Input

Coupling Span (V)

DC

2

Input Range (V)

VINA1

VINB1

0 to 2

1

Figure

#

32, 33

Comments

Best for stepped input response applications, suboptimum THD

and noise performance, requires ± 5 V op amp.

2 × VREF 0 to

2 × VREF

VREF

32, 33

Same as above but with improved noise performance due to

increase in dynamic range. Headroom/settling time requirements

of ± 5 V op amp should be evaluated.

5

0 to 5

2.5

32, 33 Optimum noise performance, excellent THD performance. Requires

op amp with VCC > +5 V due to insufficient headroom @ 5 V.

2 × VREF 2.5 – VREF 2.5

to

2.5 + VREF

39

Optimum THD performance with VREF = 1, noise performance

improves while THD performance degrades as VREF increases

to 2.5 V. Single supply operation (i.e., +5 V) for many op amps.

Single-Ended AC

2 or

0 to 1 or

1 or VREF 34

2 × VREF 0 to 2 × VREF

Suboptimum ac performance due to input common-mode level

not biased at optimum midsupply level (i.e., 2.5 V).

5

0 to 5

2.5

2 × VREF 2.5 – VREF 2.5

to

2.5 + VREF

34

Optimum noise performance, excellent THD performance.

35

Flexible input range, Optimum THD performance with VREF = 1.

Noise performance improves while THD performance degrades as

VREF increases to 2.5 V.

Differential

AC or 2

DC

2 to 3

3 to 2

29–31 Optimum full-scale THD and SFDR performance well beyond the

A/Ds Nyquist frequency.

2 × VREF

2.5 – VREF/2 2.5 + VREF/2 29–31

to

to

2.5 + VREF/2 2.5 – VREF/2

Same as 2 V to 3 V input range with the exception that full-scale

THD and SFDR performance can be traded off for better noise

performance.

5

1.25 to 3.75 3.75 to 1.25

1VINA and VINB can be interchanged if signal inversion is required.

29–31 Widest dynamic range (i.e., ENOBs) due to optimum noise

performance.

Reference

Operating Mode

INTERNAL

INTERNAL

INTERNAL

EXTERNAL

(NONDYNAMIC)

EXTERNAL

(DYNAMIC)

Table II. Reference Configuration Summary

Input Span (VINA–VINB)

(V p-p)

2

5

2 ≤ SPAN ≤ 5 AND

SPAN = 2 × VREF

2 ≤ SPAN ≤ 5

2 ≤ SPAN ≤ 5

Required VREF (V)

1

2.5

1 ≤ VREF ≤ 2.5 AND

VREF = (1 + R1/R2)

1 ≤ VREF ≤ 2.5

CAPT and CAPB

Externally Driven

Connect

SENSE

SENSE

R1

R2

SENSE

VREF

SENSE

VREF

EXT. REF. 1

EXT. REF. 2

To

VREF

REFCOM

VREF AND SENSE

SENSE AND REFCOM

AVDD

EXT. REF.

AVDD

REFCOM

CAPT

CAPB

REV. A

–11–

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