Data Sheet

ADA4522-1/ADA4522-

2/ADA4522-4

analog.com

Rev I 31 of 48

Figure 73.Input and Output Waveforms, No Phase Reversal

Large Signal Transient Response

When the ADA4522-1/ADA4522-2/ADA4522-4 are configured in a closed-loop configuration with a large input

transient (for example, a step input voltage), the internal back to back diodes may turn on. Consider a case where

the amplifier is in unity-gain configuration with a step input waveform. This case is shown in Figure 74.

The noninverting input is driven by an input signal source and the inverting input is driven by the output of the

amplifier. The maximum amplifier output current depends on the input step function and the external source

resistance at the input terminals of the amplifier.

Case 1

If the external source resistance is low (for example, 100 Ω in Figure 75

) or if the input step function is large, the

maximum amplifier output current is limited to the output short-circuit current as specified in the Specifications

section. The maximum differential voltage between the input signal and the amplifier output is then limited by the

maximum amplifier output current multiplied by the total input resistance (internal and external) and the turn-on

voltage of the back to back diode (see Figure 72 for the input EMI filter and clamp circuit architecture).

When the noninverting input voltage changes with a step signal, the inverting input voltage (and, therefore, the

output voltage) follows the change quickly until it reaches the maximum differential voltage between the input

signal and amplifier output possible. The inverting input voltage then starts slewing with the slew rate specified in

the Specifications section until it reaches its desired output. Therefore, as seen in Figure 74, there are two

distinctive sections of the rising and falling edge of the output waveform. With this test condition, the amount and

duration of the input/output current is limited and, therefore, does not damage the amplifier.

20

0

–20

10

–10

20

0

–20

10

–10

TIME (400s/DIV)

VSY = ±15V

AV = 1

VIN

VOUT