AD8615/AD8616/AD8618

Rev. E | Page 12 of 20

OVERLOAD RECOVERY TIME

Overload recovery time is the time it takes the output of the

amplifier to come out of saturation and recover to its linear region.

Overload recovery is particularly important in applications where

small signals must be amplified in the presence of large transients.

Figure 40 and Figure 41 show the positive and negative overload

recovery times of the AD8616. In both cases, the time elapsed

before the AD8616 comes out of saturation is less than 1 μs. In

addition, the symmetry between the positive and negative recovery

times allows excellent signal rectification without distortion to the

output signal.

TIME (1µs/DIV)

–50mV

+2.5V

0V

0V

Figure 40. Positive Overload Recovery

TIME (1µs/DIV)

+50mV

–

2.5V

0V

0V

Figure 41. Negative Overload Recovery

D/A CONVERSION

The AD8616 can be used at the output of high resolution DACs.

The low offset voltage, fast slew rate, and fast settling time make

the part suitable to buffer voltage output or current output

DACs.

Figure 42 shows an example of the AD8616 at the output of the

AD5542. The AD8616’s rail-to-rail output and low distortion

help maintain the accuracy needed in data acquisition systems

and automated test equipment.

AD5542

UNIPOLAR

OUTPUT

AGND

DGND

REFS

1/2

AD8616

REFF

SERIAL

INTERFACE

0.1

µF

0.1µF

10µF

5V

2.5V

+

CS

DIN

SCLK

LDAC

Figure 42. Buffering DAC Output

LOW NOISE APPLICATIONS

Although the AD8618 typically has less than 8 nV/√Hz of voltage

noise density at 1 kHz, it is possible to reduce it further. A simple

method is to connect the amplifiers in parallel, as shown in

Figure 43. The total noise at the output is divided by the square

root of the number of amplifiers. In this case, the total noise is

approximately 4 nV/√Hz at room temperature. The 100 Ω

resistor limits the current and provides an effective output

resistance of 50 Ω.

V–

R3

100Ω

R1

10Ω

V+

3

2

1

R2

1kΩ

V–

R6

100Ω

R4

10Ω

V+

3

2

1

R5

1kΩ

V–

R9

100Ω

R7

10Ω

V+

3

2

1

R8

1kΩ

V–

R12

100Ω

R10

10Ω

V+

3

2

1

R11

1kΩ

Figure 43. Noise Reduction