Datasheet

MAX3387E
3V, ±15kV ESD-Protected, AutoShutdown Plus
RS-232 Transceiver for PDAs and Cell Phones
_______________________________________________________________________________________ 9
V
CC
0
V+
V-
V
CC
0
INVALID
OUTPUT
TRANSMITTER
INPUTS
RECEIVER
INPUTS
}
INVALID
REGION
TRANSMITTER
OUTPUTS
t
AUTOSHDN
t
WU
t
WU
t
INVL
t
INVH
t
AUTOSHDN
Figure 3b. AutoShutdown Plus/INVALID Timing Diagram
Software-Controlled Shutdown
If direct software control is desired, INVALID can be
used to indicate a DTR or ring indicator signal. Connect
FORCEOFF and FORCEON together to bypass
AutoShutdown 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 electro-
static discharges (ESDs) encountered during handling
and assembly. The MAX3387E driver outputs and
receiver inputs have extra protection against static
electricity. Maxim has developed state-of-the-art struc-
tures to protect these pins against ESD of ±15kV with-
out damage. The ESD structures withstand high ESD in
all states: normal operation, shutdown, and powered
down. After an ESD event, Maxim’s “E” version devices
keep working without latchup, whereas competing RS-
232 products can latch and must be powered down to
remove latchup. ESD protection can be tested in vari-
ous ways. The transmitter outputs and receiver inputs
of this product family are characterized for protection to
the following limits:
1) ±15kV using the Human Body Model
2) ±8kV using the Contact-Discharge method specified
in IEC 1000-4-2
3) ±15kV using IEC 1000-4-2’s Air-Gap method
FORCEON
MASTER SHDN LINE
0.1μF1M
FORCEOFF
MAX3387E
POWER-
MANAGEMENT
UNIT
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
System