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OPA689

57.6

Ω

6

I VH

V H = 3.7V

V

O

V

L = 1.3V

V IN

I VL

806

Ω

3

2

4

7

8

5

806

Ω

523

Ω

976

Ω

523

Ω

R G

402

Ω

R

F

402

Ω

500

Ω

0.1 µ F

0.1 µ F

0.1 µ F

2.2 µ F

0.1 µ F

V S = +5V

0.1 µ F

0.1 µ F

Limited Output, ADC Input Driver

O P A 6 8 9

V S = + 5 V

V

S =

+ 5 V

4

3

2

7

5

8

6

V

S =

+ 5 V

V IN

4 . 0 p F

7 5 0 Ω

0 . 1 µ F

R E F B

R E F T

I N

I NT /E X T

R S E L

+ V S

GND

0 . 1 µ F

1 8 p F

1 0 0 p F

V

H =

+ 3 . 6 V

V L = + 1 . 4 V

+ 2 . 5 V

3 7 4 Ω

1 . 4 0 k Ω

2 4 . 9 Ω

1 . 4 0 k Ω

0 . 1 µ F

0 . 1 µ F

7 8 7 Ω

1 0 0 Ω

1 0 0 Ω

7 8 7 Ω

A D S 8 2 2

1 0 −B i t

4 0 M S P S

1 0 −B i t

D a t a

+ 1 . 5 V

+ 3 . 5 V

OPA689M

GAIN +4 STABLE WIDEBAND

VOLTAGE-LIMITING AMPLIFIER

SGLS146B – MARCH 2003 – REVISED DECEMBER 2006

APPLICATION INFORMATION (continued)

Figure 31. AC-Coupled, Single Supply Amplifier

The circuit in Figure 32 shows an inverting, low distortion ADC driver that operates on a single supply. The

converter's internal references bias the op amp input. The 4.0-pF and 18-pF capacitors form a compensation

network that allows the OPA689 to have a flat frequency response at a gain of –2. This increases the loop gain

of the op amp feedback network, which reduces the distortion products below their specified values.

Figure 32. Low Distortion, Limiting ADC Input Driver

13

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