MAX3209E Maxim, MAX3209E Datasheet - Page 6

• Manufacturer Part Number: MAX3209E
• Description: 15kV ESD-Protected / 12V / Dual RS-232 Serial Port with Low-Power Standby for Motherboards/Desktops
• Manufacturer: Maxim

±15kV ESD-Protected, 12V, Dual RS-232 Serial Port
with Low-Power Standby for Motherboards/Desktops
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.
The MAX3209E is placed in standby mode when V
not present, provided that V
+5.5V. In standby mode, receivers R5 and R10 remain
active, consuming 100µA max while unloaded. Standby
mode allows activity to be sensed on the serial ports so
that main power can be restored by the power-man-
agement unit, as shown in Figure 4.
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
as close to the part as possible to ensure maximum
ESD protection.
The MAX3209E is not sensitive to power-supply
sequencing, and therefore requires no external protec-
tion diodes.
6
Figure 3b. IEC 1000-4-2 ESD-Generator Current Waveform
t
_______________________________________________________________________________________
R
= 0.7ns to 1ns
R5 and R10 Active in Standby Mode
100%
90%
10%
I
Applications Information
DD
Layout Considerations
30ns
and V
STBY
60ns
STBY
with 0.1µF capacitors
remains at +3V to
Machine Model
DD
t
is
The MAX3209E can directly interface with various 3V
and 5V logic families, including ACT and HCT CMOS.
See Table 1 for more information on possible combina-
tions of interconnections.
The MAX3209E has been specifically designed to
power serial mice while operating from low-voltage
power supplies. It has been tested with leading mouse
brands from manufacturers such as Microsoft and
Logitech. The MAX3209E successfully drove all serial
mice tested and met their respective current and volt-
age requirements.
Figure 4. MAX3209E in Standby Mode
Table 1. Logic Family Compatibility with
Various Supply Voltages
SUPPLY VOLTAGE
SYSTEM POWER-
Interconnection with 3V and 5V Logic
3.3
(V)
5
5
SUPER
I/O
+12V
VOLTAGE
SUPPLY
V
STBY
(V)
3.3
3.3
5
POWER-MANAGEMENT UNIT
Mouse Driveability
T_
R10
V
R5
R_
Compatible with all
CMOS families.
Compatible with all
TTL and CMOS fami-
lies.
Compatible with ACT
and HCT CMOS, and
with AC, HC, or
CD4000 CMOS.
STBY
COMPATIBILITY
ALL OTHER
RECEIVERS
INACTIVE
ALL TRANSMITTERS
INACTIVE
MAX3209E
GND
V
DD