ADG46+1/ADG46+3
Power Supply Sequencing
protection diodes. The VDD supply normally gets pulled up to
the input voltage level minus a diode drop, VDD ~VS, VD − VDIODE
This voltage can be high enough to power up other chips that
are connected to this supply rail in a system, potentially damaging
other components in that system.
.
Another benefit of the ADG4612/ADG4613 is it eliminates
concerns about the power supply sequence. The part can be
powered up in any sequence without damage. For devices with
conventional CMOS switches, it is recommend that power supplies
are powered up before analog or digital inputs are present. The
ADG4612/ADG4613 do not have any power supply sequencing
requirements, thereby making them a very robust design. However,
a ground must first be present for the device to function in isolation
mode and normal mode.
The ADG4612/ADG4613 architecture ensures that the VDD supply
is isolated from the analog inputs, thereby preventing the supplies
from being pulled to a higher potential when a signal is present
on the inputs without any power having been applied.
V
DD Supply
Another area of concern with conventional CMOS switches that
have analog signals present before the part is powered up is that
the VDD supply can be pulled up through the internal ESD
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