Datasheet

MAX3187
±15kV ESD-Protected, EMC-Compliant, 230kbps,
Dual RS-232 Serial Port for Motherboards/Desktops
_______________________________________________________________________________________ 7
TRANSISTOR COUNT: 419
___________________Chip Information
Machine Model
The Machine Model for ESD testing uses a 200pF stor-
age capacitor and zero-discharge resistance. It mimics
the stress caused by handling during manufacturing
and assembly. Of course, all pins (not just RS-232
inputs and outputs) require this protection during man-
ufacturing. Therefore, the Machine Model is less rele-
vant to the I/O ports than are the Human Body Model
and IEC 1000-4-2.
Applications Information
Use proper layout to ensure other devices on your
board are not damaged in an ESD strike. Currents as
high as 60A can instantaneously pass into ground, so
be sure to minimize the ground-lead return path to the
power supply. A separate return path to the power sup-
ply is recommend. Trace widths should be greater than
40 mils. Bypass V
CC
, V
DD
, and V
SS
with 0.1µF capaci-
tors as close to the part as possible to ensure maxi-
mum ESD protection.
Connect any unused transmitter inputs to GND or V
CC
.
The MAX3187 is not sensitive to power-supply
sequencing, and therefore requires no external protec-
tion diodes.
RS-232
INTERCONNECTING
CABLE
T1
T2
T3
T4
T5
R1
R2
T3
T4
T5
R3
R4
R5
R8
R9
R10
R2
R1
R3
T1
T2
TTL/CMOS
LOGIC
I/O
TTL/CMOS
LOGIC
I/O
MOUSE
V+
GND V
SS
GND V
SS
0.1µF
0.1µF
-12V
V+
V-
TX
T6
R6
-12V
0.1µF
0.1µF0.1µF
+5V
V
CC
V
DD
MAX3186MAX3187
V
CC
V
DD
+12V +5V +12V
0.1µF
R7
__________Typical Operating Circuit