Datasheet

ADM3070E/ADM3071E/ADM3072E/ADM3073E/ADM3074E/ADM3075E/ADM3076E/ADM3077E/ADM3078E
Rev. E | Page 17 of 20
LOW POWER SHUTDOWN MODE
(ALL EXCEPT ADM3071E/ADM3074E/ADM3077E)
Low power shutdown mode is initiated by bringing both
RE
high and DE low. In shutdown mode, the device draws less
than 1 μA of supply current.
RE
and DE can be driven simulta-
neously, but the parts are guaranteed not to enter shutdown if
RE
is high and DE is low for fewer than 50 ns. If the inputs are
in this state for 600 ns or more, the parts are guaranteed to enter
shutdown. Enable times t
ZH
and t
ZL
assume that the part was not
originally in a low power shutdown state (see the
section). Enable times (t
ZH(SHDN)
and t
ZL(SHDN)
) assume that the part was originally shut down. It
takes drivers and receivers longer to become enabled from low
power shutdown mode (t
ZH(SHDN)
, t
ZL(SHDN)
) than from driver/
receiver disable mode (t
ZH
, t
ZL
).
Test C i rcuits
and Switching Characteristics
DRIVER OUTPUT PROTECTION
The ADM307xE family features two methods to prevent
excessive output current and power dissipation caused by
faults or by bus contention. Current limit protection on the
output stage provides immediate protection against short
circuits over the whole common-mode voltage range (see
Figure 22 and Figure 23). In addition, a thermal shutdown
circuit forces the driver outputs into a high impedance state
if the die temperature rises excessively.
TYPICAL APPLICATIONS
The ADM3072E/ADM3075E/ADM3078E transceivers are
designed for bidirectional data communications on multipoint
bus transmission lines. Figure 34 shows a typical network
applications circuit. The ADM3071E/ADM3074E/ADM3077E
transceivers are designed for point-to-point transmission lines
(see Figure 35). The ADM3070E/ADM3073E/ADM3076E
transceivers are designed for full-duplex RS-485 networks
(see Figure 36).
To minimize reflections, terminate the line at both ends with
a termination resistor (the value of the termination resistor
should be equal to the characteristic impedance of the cable
used) and keep stub lengths off the main line as short as
possible.
B
A
R
D
RO
DI
DE
ADM3072E/
ADM3075E/
ADM3078E
ADM3072E/
ADM3075E/
ADM3078E
ADM3072E/
ADM3075E/
ADM3078E
ADM3072E/
ADM3075E/
ADM3078E
B
A
R
D
RO
DI
DE
B
A
R
D
RO
RE DI
DE
B
A
R
D
RO
RE
DI
DE
R
T
R
T
06285-016
NOTES
1. MAXIMUM NUMBER OF NODES: 256.
2.
R
T
IS EQUAL TO THE CHARACTERISTIC IMPEDANCE OF THE CABLE USED.
RE
RE
Figure 34. ADM3072E/ADM3075E/ADM3078E Typical Half-Duplex RS-485 Network
B
A
R
D
RO
DI
RO
DI
Y
Z
B
A
Y
Z
MASTER
R
D
SLAVE
ADM3071E/
ADM3074E/
ADM3077E
ADM3071E/
ADM3074E/
ADM3077E
06285-017
Figure 35. ADM3071E/ADM3074E/ADM3077E Full-Duplex Point-to-Point Applications