Datasheet

±15kV ESD-Protected, 1µA, 1Mbps 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
By connecting FORCEON and FORCEOFF to INVALID,
the MAX3224E–MAX3227E/MAX3244E/MAX3245E shut
down when no valid receiver level is detected and
wake up when a valid receiver level is detected (same
functionality as AutoShutdown feature on MAX3221E/
MAX3223E/MAX3243E).
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 MAX3244E/
MAX3245E is awake. If the other system outputs valid
RS-232 signal transitions within that time, the RS-232
ports on both systems remain enabled.
Software-Controlled Shutdown
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.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against electrostatic
discharges encountered during handling and assembly.
The driver outputs and receiver inputs of the
MAX3224E–MAX3227E/MAX3244E/MAX3245E have extra
protection against static electricity. Maxim’s engineers
have developed state-of-the-art structures to protect
V
CC
0
0
V+
V-
V
CC
0
INVALID
OUTPUT
READY
TRANSMITTER
INPUTS
RECEIVER
INPUTS
}
INVALID
REGION
*MAX3224E–MAX3227E
TRANSMITTER
OUTPUTS
*V
CC
t
AUTOSHDN
t
WU
t
WU
t
INVL
t
INVH
t
AUTOSHDN
Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram
FORCEON
MASTER SHDN LINE
0.1μF1MΩ
FORCEOFF
MAX3224E
MAX3225E
MAX3226E
MAX3227E
MAX3244E
MAX3245E
POWER-
MANAGEMENT
UNIT
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
12
Maxim Integrated
MAX3224E/MAX3225E/
MAX3226E/MAX3227E/MAX3244E/MAX3245E