Datasheet

ADM3054 Data Sheet
Rev. D | Page 16 of 20
ELECTRICAL ISOLATION
In the ADM3054, electrical isolation is implemented on the
logic side of the interface. Therefore, the device has two main
sections: a digital isolation section and a transceiver section
(see Figure 29). The driver input signal, which is applied to the
TxD pin and referenced to the logic ground (GND
1
), is coupled
across an isolation barrier to appear at the transceiver section
referenced to the isolated ground (GND
2
). Similarly, the receiver
input, which is referenced to the isolated ground in the tran-
sceiver section, is coupled across the isolation barrier to appear
at the RxD pin referenced to the logic ground.
iCoupler Technology
The digital signals transmit across the isolation barrier using
iCoupler technology. This technique uses chip scale transformer
windings to couple the digital signals magnetically from one
side of the barrier to the other. Digital inputs are encoded into
waveforms that are capable of exciting the primary transformer
winding. At the secondary winding, the induced waveforms are
decoded into the binary value that was originally transmitted.
Positive and negative logic transitions at the input cause narrow
(~1 ns) pulses to be sent to the decoder via the transformer. The
decoder is bistable and is, therefore, set or reset by the pulses,
indicating input logic transitions. In the absence of logic transitions
at the input for more than ~1 μs, a periodic set of refresh pulses,
indicative of the correct input state, are sent to ensure dc correct-
ness at the output. If the decoder receives no internal pulses for
more than about 5 μs, the input side is assumed to be unpowered
or nonfunctional, in which case the output is forced to a default
state (see Table 9).
Figure 29. Digital Isolation and Transceiver Sections
T
xD
RxD
ISOL
ATION
BARRIER
GND
1
DECODE
DECODE
DECODE
V
DD2SENSE
ENCODE
ENCODE
ENCODE
V
REF
V
DD1
ADM3054
VOLTAGE
REFERENCE
CAN TRANSCEIVER
LOGIC SIDE BUS SIDE
V
DD2
CANL
CANH
DIGITAL ISOLATION
iCoupler
®
R
D
V
DD2
VOLTAGE
SENSE
THERMAL
SHUTDOWN
GND
2
10274-029
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