ADN4691E/ADN4693E/ADN4696E/ADN4697E Data Sheet
Rev. B | Page 14 of 20
THEORY OF OPERATION
The ADN4691E/ADN4693E/ADN4696E/ADN4697E are trans-
ceivers for transmitting and receiving multipoint, low voltage
differential signaling (M-LVDS) at high speed (data rates up
to 200 Mbps). Each device has a differential line driver and a
differential line receiver, allowing each device to send and
receive data.
Multipoint LVDS expands on the established LVDS low voltage
differential signaling method by allowing bidirectional commu-
nication between more than two nodes. Up to 32 nodes can
connect on an M-LVDS bus.
HALF-DUPLEX/FULL-DUPLEX OPERATION
Half-duplex operation allows a transceiver to transmit or
receive, but not both at the same time. However, with full-
duplex operation, a transceiver can transmit and receive
simultaneously. The ADN4691E/ADN4696E are half-duplex
devices in which the driver and the receiver share differential
bus terminals. The ADN4693E/ADN4697E are full-duplex
devices that have dedicated driver output and receiver input
pins. Figure 37 and Figure 38 show typical half- and full-duplex
bus topologies, respectively, for M-LVDS.
THREE-STATE BUS CONNECTION
The outputs of the device can be placed in a high impedance
state by disabling the driver or receiver. This allows several
driver outputs to connect to a single M-LVDS bus. Note that, on
each bus line, only one driver can be enabled at a time, but
many receivers can be enabled at the same time.
The driver can be enabled or disabled using the driver enable
pin (DE). DE enables the driver outputs when taken high; when
taken low, DE puts the driver outputs into a high impedance state.
Similarly, an active low receiver enable pin (
RE
) controls the
receiver. Taking
RE
low enables the receiver, whereas taking it
high puts the receiver outputs into a high impedance state.
Truth tables for driver and receiver output states under various
conditions are shown in Table 10, Table 11, Table 12, and Table 13.
TRUTH TABLES
Table 9. Truth Table Abbreviations
Abbreviation Description
H High level
X Don’t care
I Indeterminate
Z High impedance (off)
NC Disconnected
Driver, Half-Duplex (ADN4691E/ADN4696E)
Table 10. Transmitting (See Table 9 for Abbreviations)
Power
Inputs Outputs
DE DI A B
Yes H H H L
Yes H L L H
Yes H NC L H
Yes L X Z Z
Yes NC X Z Z
≤1.5 V X X Z Z
Driver, Full-Duplex (ADN4693E/ADN4697E)
Table 11. Transmitting (See Table 9 for Abbreviations)
Power
Inputs Outputs
DE DI Y Z
Yes H H H L
Yes H L L H
Yes H NC L H
Yes L X Z Z
Yes NC X Z Z
≤1.5 V X X Z Z
Type 1 Receiver (ADN4691E/ADN4693E)
Table 12. Receiving (see Table 9 for Abbreviations)
Power
Inputs Output
A − B
RE
RO
Yes ≥50 mV L H
Yes ≤−50 mV L L
Yes −50 mV < A − B < 50 mV L
I
Yes NC L I
Yes X H
Z
Yes X NC Z
No X X Z
Type 2 Receiver (ADN4696E/ADN4697E)
Table 13. Receiving (See Table 9 for Abbreviations)
Power
A − B
RE
RO
Yes ≥150 mV L
H
Yes ≤50 mV L L
Yes 50 mV < A − B < 150 mV L
I
Yes NC L L
Yes X H
Z
Yes X NC Z
No X X Z
