Data Sheet

ADA4500-2

Rev. B | Page 21 of 24

POWER-ON CURRENT PROFILE

The ADA4500-2 powers up with a smooth current profile, with

no supply current overshoot (see Figure 63). When powering up

a system, spikes in the power-up current are undesirable (see

Figure 64). The overshoot requires a designer to source a large

enough power supply (such as a voltage regulator) to supply the

peak current, even though a heavier supply is not necessary once

the system is powered up. If multiple amplifiers are pulling a

spike in current, the system can go into a current limit state and

not power up. This is all avoided with the smooth power up of

the ADA4500-2.

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Figure 63. ISY and VSY vs. Time for ADA4500-2 with No Spike

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Figure 64. ISY and VSY vs. Time with a Power-Up Spike

For systems that are frequently switching off and on, the power-

up overshoot results in excess power use. As the amplifier switches

off and on, the power consumed by the large spike is repeated

on each power-up, increasing the total power consumption by

magnitudes. As an example, if a battery-powered sensor system

periodically powers up the sensor and signal path, takes a reading,

and shuts down until the next reading, the ADA4500-2 enables

much longer battery life because there is no excess charge being

consumed at each power-up.