MAX3224ECTP datasheet(12/21 Pages) MAXIM

12 / 21 page

±15kV ESD-Protected, 1µA, 1Mbps 3.0V to 5.5V,

RS-232 Transceivers with AutoShutdown Plus

By connecting FORCEON and FORCEOFF to INVALID,

the MAX3224E–MAX3227E/MAX3244E/MAX3245E shut

down when no valid receiver level is detected and

wake up when a valid receiver level is detected (same

functionality as AutoShutdown feature on MAX3221E/

MAX3223E/MAX3243E).

A mouse or other system with AutoShutdown Plus may

need time to wake up. Figure 5 shows a circuit that

forces the transmitters on for 100ms, allowing enough

time for the other system to realize that the MAX3244E/

MAX3245E is awake. If the other system outputs valid

RS-232 signal transitions within that time, the RS-232

ports on both systems remain enabled.

Software-Controlled Shutdown

If direct software control is desired, use INVALID to

indicate DTR or ring indicator signal. Tie FORCEOFF

and FORCEON together to bypass the AutoShutdown

Plus 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 electrostatic

discharges encountered during handling and assembly.

The driver outputs and receiver inputs of the

MAX3224E–MAX3227E/MAX3244E/MAX3245E have extra

protection against static electricity. Maxim’s engineers

have developed state-of-the-art structures to protect

VCC

V+

V-

VCC

INVALID

OUTPUT

READY

TRANSMITTER

INPUTS

RECEIVER

INPUTS

}

INVALID

REGION

*MAX3224E–MAX3227E

TRANSMITTER

OUTPUTS

*VCC

tAUTOSHDN

tWU

tINVL

tINVH

tAUTOSHDN

Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram

FORCEON

MASTER SHDN LINE

0.1

μF1MΩ

FORCEOFF

MAX3224E

MAX3225E

MAX3226E

MAX3227E

MAX3244E

MAX3245E

POWER-

MANAGEMENT

UNIT

Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a

Mouse or Another System

Maxim Integrated

MAX3224E/MAX3225E/

MAX3226E/MAX3227E/MAX3244E/MAX3245E

MAX3224ECTP Datasheet(PDF) 12 Page - Maxim Integrated Products

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