Data Sheet ADuM240D/ADuM240E/ADuM241D/ADuM241E/ADuM242D/ADuM242E
Rev. A | Page 21 of 26
THEORY OF OPERATIONS
The ADuM240D/ADuM240E/ADuM241D/ADuM241E/
ADuM242D/ADuM242E use a high frequency carrier to
transmit data across the isolation barrier using iCoupler chip
scale transformer coils separated by layers of polyimide isolation.
Using an on/off keying (OOK) technique and the differential
architecture shown in Figure 19 and Figure 20, the ADuM240D/
ADuM240E/ADuM241D/ADuM241E/ADuM242D/ADuM242E
have very low propagation delay and high speed. Internal regulators
and input/output design techniques allow logic and supply
voltages over a wide range from 1.7 V to 5.5 V, offering voltage
translation of 1.8 V, 2.5 V, 3.3 V, and 5 V logic. The architecture
is designed for high common-mode transient immunity and
high immunity to electrical noise and magnetic interference.
Radiated emissions are minimized with a spread spectrum
OOK carrier and other techniques.
Figure 19 illustrates the waveforms for models of the ADuM240D/
ADuM240E/ADuM241D/ADuM241E/ADuM242D/ADuM242E
that have the condition of the fail-safe output state equal to low,
where the carrier waveform is off when the input state is low.
If the input side is off or not operating, the low fail-safe output
state (ADuM240D0/ADuM240E0/ADuM241D0/ADuM241E0/
ADuM242D0/ADuM242E0) sets the output to low. For the
ADuM240D/ADuM240E/ADuM241D/ADuM241E/ADuM242D/
ADuM242E that have a high fail-safe output state, Figure 20
illustrates the conditions where the carrier waveform is off
when the input state is high. When the input side is off or not
operating, the high fail-safe output state (ADuM240D1/
ADuM240E1/ADuM241D1/ADuM241E1/ADuM242D1/
ADuM242E1) sets the output to high. See the Ordering Guide
for the model numbers that have the fail-safe output state of low
or the fail-safe output state of high.
Figure 19. Operational Block Diagram of a Single Channel with a Low Fail-Safe Output State
Figure 20. Operational Block Diagram of a Single Channel with a High Fail-Safe Output State
TRANSMITTER
GND
1
GND
2
IN
V
OUT
RECEIVER
REGULATOR REGULATOR
13576-014
TRANSMITTER
GND
1
GND
2
IN
V
OUT
RECEIVER
REGULATOR REGULATOR
13576-015
