1 µA S u p p ly Cu rre n t , 1 Mb p s , 3 .0 V t o 5 .5 V,
RS -2 3 2 Tra n s c e ive rs w it h Au t o S h u t d o w n P lu s
–7/MAX3245
RECEIVER
INPUTS
INVALID
REGION
}
TRANSMITTER
INPUTS
TRANSMITTER
OUTPUTS
V
INVALID
OUTPUT
CC
t
INVL
t
INVH
t
0
AUTOSHDN
t
AUTOSHDN
t
t
WU
WU
*V
CC
OUTPUT
0
V+
V
CC
0
V-
*MAX3224–MAX3227
Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram
when a valid receiver level is detected (same function-
ality as AutoShutdown feature on MAX3221/MAX3223/
MAX3243).
POWER-
MANAGEMENT
UNIT
MASTER SHDN LINE
0.1µF
1M
A mouse or other system with AutoShutdown Plus may
need time to wake up. Figure 5 shows a circuit that
forces the transmitters on for 100ms, allowing enough
time for the other system to realize that the MAX3244/
MAX3245 is awake. If the other system outputs valid
RS-232 signal transitions within that time, the RS-232
ports on both systems remain enabled.
FORCEOFF FORCEON
MAX3224
MAX3225
MAX3226
MAX3227
MAX3244
MAX3245
S o ft w a re -Co n t ro lle d S h u t d o w n
If direct software control is desired, use INVALID to
indicate DTR or Ring Indicator signal. Tie FORCEOFF
and FORCEON together to bypass the AutoShutdown
Plus so the line acts like a SHDN input.
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
______________________________________________________________________________________ 11
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
