MAX3209EEUU Просмотр технического описания (PDF) - Maxim Integrated

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MAX3209EEUU

±15kV ESD-Protected, 12V, Dual RS-232 Serial Port with Low-Power Standby for Motherboards/Desktops

Maxim Integrated 

±15kV ESD-Protected, 12V, Dual RS-232 Serial Port

with Low-Power Standby for Motherboards/Desktops

I

100%

90%

POWER-MANAGEMENT UNIT

+12V

10%

tR = 0.7ns to 1ns

30ns

t

60ns

Figure 3b. IEC 1000-4-2 ESD-Generator Current Waveform

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

R5 and R10 Active in Standby Mode

The MAX3209E is placed in standby mode when VDD is

not present, provided that VSTBY 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 4.

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 VDD and VSTBY 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.

SUPER

I/O

VSTBY

VDD

MAX3209E

R5

R10

R_

T_

ALL OTHER

RECEIVERS

INACTIVE

ALL TRANSMITTERS

INACTIVE

GND

Figure 4. MAX3209E in Standby Mode

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 1 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.

Table 1. Logic Family Compatibility with

Various Supply Voltages

SYSTEM POWER-

SUPPLY VOLTAGE

(V)

VSTBY

SUPPLY

VOLTAGE

(V)

3.3

3.3

5

5

5

3.3

COMPATIBILITY

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.

6 _______________________________________________________________________________________

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