ADUM2401: Common mode voltage

Document created by analog-archivist Employee on Feb 23, 2016
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I have some questions about the ADuM140x, ADuM240x and other ADuM ICs.

(A) The ADuM1401 and ADuM2401, for example, have three direct and one reverse
channels.

Questions:
(1) What channels, direct or reverse, may be under high common voltage (with
their supply source)? Is it independently?
(2) May be three direct and one reverse channels of these ADuM1401 and ADuM2401
used conversely as three reverse and one direct channels?

(B) The Common-Mode Transient Immunity (min) is 25 kV/us for the ADuM1401 and
ADuM2401.
What is a real value for these ICs that is permitted?

 

Before I answer I want to explain the concept of common mode voltage as it
applies to iCouplers (and other isolation devices as well).  The term Common
Mode Voltage (CMV) refers to the voltage that can appear across the "isolation
barrier", or between any input and output side pin of the device.  This is
different concept than Common Mode range of an opamp, or instrumentation
amplifier where voltages are referenced to the same ground.

(A):
(1) What channels, direct or reverse, may be under high common voltage (with
their supply source)? Is it independently?

The supply voltage, and channel direction have no bearing on the common mode
voltage specification for the device (see above explanation).    

(2) May be three direct and one reverse channels of these ADuM1401 and ADuM2401
used conversely as three reverse and one direct channels?

The channels are uni directional, but you can use the ADuM1401 or 2401 in
either direction by hooking channel up in the other direction.

(B) The Common-Mode Transient Immunity (min) is 25 kV/us for the ADuM1401 and
ADuM2401.
What is a real value for these ICs that is permitted?

Common-Mode Transient Immunity is the rate of change of CMV that will not cause
digital data to be in error.  25kV/uS is min spec, so any rate of change <
25kV/uS is guaranteed.  Note absolute max spec is 100kV/uS, above this rate may
damage the device.

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