ADS8364

11

SBAS219B

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When the input is differential, the amplitude of the input is the

difference between the +IN and –IN input, or: (+IN) – (–IN).

The peak-to-peak amplitude of each input is

±1/2V

this common voltage. However, since the inputs are 180

°

out-of-phase, the peak-to-peak amplitude of the differential

the range of the voltage that may be common to both inputs,

as shown in Figure 4.

FIGURE 2. Using the ADS8364 in the Single-Ended and Differential Input Modes.

FIGURE 3. Single-Ended Input: Common-Mode Voltage

FIGURE 4. Differential Input: Common-Mode Voltage

Range vs V

In each case, care should be taken to ensure that the output

impedance of the sources driving the +IN and –IN inputs are

matched. Often, a small capacitor (20pF) between the posi-

tive and negative input helps to match their impedance.

Otherwise, this may result in offset error, which will change

with both temperature and input voltage.

The input current on the analog inputs depends on a number

of factors as sample rate or input voltage. Essentially, the

CM + V

REF

+V

REF

–V

REF

Single-Ended Inputs

t

+IN

CM Voltage

CM – V

REF

CM + 1/2V

REF

Differential Inputs

NOTES: Common-Mode Voltage (Differential Mode) =

, Common-Mode Voltage (Single-Ended Mode) = IN–.

(+IN) + (–IN)

2

The maximum differential voltage between +IN and –IN of the ADS8364 is V

explanation of the common voltage range for single-ended and differential inputs.

t

+IN

–IN

CM Voltage

CM – 1/2V

REF

–IN = CM Voltage

+V

REF

–V

REF

1.0

1.5

2.0

2.5

2.6

3.0

V

–1

0

1

2

3

4

5

2.7

2.3

3.8

1.2

AV

Single-Ended Input

1.0

1.5

2.0

2.5

2.6

3.0

V

–1

0

1

2

3

4

5

4.55

0.45

AV

4.0

1.0

Differential Input