AD8024

–10–

REV. C

Overload Recovery

The most important overload conditions are:

Input Common-Mode Voltage Overdrive

Output Voltage Overdrive

Input Current Overdrive.

When configured for a low closed-loop gain, the AD8024

recovers quickly from an input common-mode voltage over-

drive; typically in <25 ns.

When configured for a higher gain and overloaded at the output,

recovery from an output voltage overdrive is also short; approxi-

mately 55 ns (see Figure 5). For higher overdrive, the response

is somewhat slower. For 100% overdrive, the recovery time is

substantially longer.

When configured for a high noninverting gain, a high input over-

drive can result in a large current into the input stage. Although

this current is internally limited to approximately 30 mA, its

effect on the total power dissipation may be significant. See also

the warning under Maximum Power Dissipation.

1V

5V

50ns

Figure 5. 15% Overload Recovery, Gain = +10

Disable Mode Operation

When the Disable pin is tied to DGND, all amplifiers are opera-

tional, in the enabled state.

When the voltage on the Disable pin is raised to 1.6 V or more

above DGND, all amplifiers are in the disabled, powered-down

state. In this condition, the DISABLE pin sources approximately

0.1

µA, the total quiescent current is reduced to approximately

500

µA, all outputs are in a high impedance state, and there is a

high level of isolation from inputs to outputs.

The output impedance in the disabled mode is the equivalent of all

external resistors, seen from the output pin, in parallel with the

total disabled output impedance of the amplifier, typically 20 pF.

The input stages of the AD8024 include protection from large

differential input voltages that may be present in the disabled

mode. Internal clamps limit this voltage to 1.5 V. The high input-

to-output isolation is maintained for voltages below this limit.