MAX3224E Maxim, MAX3224E Datasheet - Page 11

• Manufacturer Part Number: MAX3224E
• Description: 15kV ESD-Protected / 1A / 1Mbps / 3.0V to 5.5V / RS-232 Transceivers with AutoShutdown Plus
• Manufacturer: Maxim

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.
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.
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
Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram
±15kV ESD-Protected, 1µA, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
OUTPUT
OUTPUT
INVALID
*MAX3224E–MAX3227E
TRANSMITTER
TRANSMITTER
RECEIVER
OUTPUTS
INPUTS
INPUTS
*V
V
V
CC
CC
V+
CC
V-
0
0
0
Software-Controlled Shutdown
t
INVL
______________________________________________________________________________________
±15kV ESD Protection
t
INVH
t
AUTOSHDN
have developed state-of-the-art structures to protect
these pins against ESD of ±15kV without damage. The
ESD structures withstand high ESD in all states: normal
operation, shutdown, and powered down. After an ESD
event, Maxim’s E versions keep working without
latchup, whereas competing RS-232 products can
latch and must be powered down to remove latchup.
Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
t
WU
MANAGEMENT
POWER-
UNIT
t
AUTOSHDN
MASTER SHDN LINE
FORCEOFF
MAX3224E
MAX3225E
MAX3226E
MAX3227E
MAX3244E
MAX3245E
0.1µF
t
WU
FORCEON
1M
}
INVALID
REGION
11