ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329

FN8273 Rev 1.00

Page 13 of 23

September 5, 2013

Analog Inputs

Some members of the ISL26320, ISL26321, ISL26322,

ISL26323, ISL26324, ISL26325 and ISL26329 family feature a

fully differential input with a nominal full-scale range equal to

inputs have a nominal full scale range equal to twice the applied

out of phase from one another for a total differential input of

Differential signaling offers several benefits over a single-ended

input, such as:

• Doubling of the full-scale input range (and therefore the

dynamic range)

• Improved even order harmonic distortion

• Better noise immunity due to common mode rejection

Figure 24 shows the relationship between the reference voltage

and the full-scale differential input range for two different values

of VREF. Note that the common-mode input voltage must be

Those devices with singled-ended inputs have a ground-referenced

peak-to-peak input voltage span equal to the reference voltage.

FIGURE 21. IDEAL TRANSFER CHARACTERISTICS, DIFFERENTIAL INPUT

FIGURE 22. IDEAL TRANSFER CHARACTERISTICS, SINGLE-ENDED INPUT

100...000

100...001

100...010

111...111

000...000

000...001

011...110

011...111

ANALOG INPUT

AIN+ – (AIN–)

+ ½LSB

– 1½LSB

0V

– 1LSB

000...000

000...001

000...010

011...111

100...000

100...001

111...110

111...111

ANALOG INPUT

0 = + ½LSB

FIGURE 23. DIFFERENTIAL INPUT SIGNALING

ISL2631X/32X

AIN+

AIN-

FIGURE 24. RELATIONSHIP BETWEEN VREF AND FULL-SCALE

RANGE FOR DIFFERENTIAL INPUTS

3.0

5.0

2.0

1.0

4.0

AIN+

AIN–

2.5Vp-p

3.0

5.0

2.0

1.0

4.0

AIN+

AIN–

VCM

5Vp-p

t

V

t

V

ALLOWABLE VCM RANGE

ALLOWABLE VCM RANGE