MAX3209E
±15kV ESD-Protected, 12V, Dual RS-232 Serial Port
with Low-Power Standby for Motherboards/Desktops
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digital oscilloscope according to the specifications in
IEC 1000-4-4 sec. 6.1.1 and 6.1.2. A simplified diagram
of the EFT/B generator is shown in Figure 4. The burst
stresses were applied to R1IN–R10IN and T1OUT–
T6OUT simultaneously.
IEC 1000-4-4 provides several levels of test severity
(see Table 1). The MAX3209E passes the 4000V stress,
a special category “X” the beyond the highest level for
severe (transient) industrial environments for telecom-
munication lines.
The stresses are applied while the MAX3209E is pow-
ered up. Test results are reported as:
1) Normal performance within the specification limits.
2) Temporary degradation or loss of function or perfor-
mance which is self-recoverable.
3) Temporary degradation, loss of function or perfor-
mance requiring operator intervention, such as sys-
tem reset.
4) Degradation or loss of function not recoverable due
to damage.
The MAX3209E meets classification 2 listed above.
Additionally, the MAX3209E will not latchup during the
IEC burst stress events.
Applications Information
R5 and R10 Active in Standby Mode
The MAX3209E is placed in standby mode when V
DD
is
not present, provided that V
STBY
remains at +3V to
+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 6.
Layout Considerations
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
DD
and V
STBY
with 0.1µF capacitors
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.
Interconnection with 3V and 5V Logic
The MAX3209E can directly interface with various 3V
and 5V logic families, including ACT and HCT CMOS.
See Table 2 for more information on possible combina-
tions of interconnections.
Mouse Driveability
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.
