ADN4690E/ADN4692E/ADN4694E/ADN4695E Data Sheet
Rev. B | Page 14 of 20
THEORY OF OPERATION
The ADN4690E/ADN4692E/ADN4694E/ADN4695E are
transceivers for transmitting and receiving multipoint, low
voltage differential signaling (M-LVDS) at high speed (data
rates up to 100 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 be
connected 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 ADN4690E/ADN4694E are half-duplex
devices in which the driver and the receiver share differential
bus terminals. The ADN4692E/ADN4695E are full-duplex
devices that have dedicated driver output and receiver input
pins. Figure 36 and Figure 37 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 be connected 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 this pin 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
L Low level
X Don’t care
I Indeterminate
Z High impedance (off)
NC Disconnected
Driver, Half Duplex (ADN4690E/ADN4694E)
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 (ADN4692E/ADN4695E)
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 (ADN4690E/ADN4692E)
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 (ADN4694E/ADN4695E)
Table 13. Receiving (see Table 9 for Abbreviations)
Power
Inputs Output
RE
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
