MAX3381E Просмотр технического описания (PDF) - Maxim Integrated

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MAX3381E

+2.35V to +5.5V, 1µA, 2Tx/2Rx RS-232 Transceivers with ±15kV ESD-Protected I/O and Logic Pins

Maxim Integrated 

+2.35V to +5.5V, 1µA, 2Tx/2Rx RS-232 Transceivers

with ±15kV ESD-Protected I/O and Logic Pins

T_IN

EDGE

DETECT

R_IN

EDGE

DETECT

FORCEOFF

S

30s

TIMER

R

AUTOSHDN

FORCEON

Figure 2c. AutoShutdown Plus Logic

+2.7V

+0.3V

0

-0.3V

-2.7V

TRANSMITTERS ENABLED, INVALID HIGH

INDETERMINATE

AutoShutdown, TRANSMITTERS DISABLED,

1µA SUPPLY CURRENT INVALID LOW

INDETERMINATE

TRANSMITTERS ENABLED, INVALID HIGH

Figure 3. AutoShutdown Trip Levels

RECEIVER

INPUTS

TRANSMITTER

INPUTS

TRANSMITTER

OUTPUTS

INVALID

OUTPUT

VL tINVL

0

tINVH

tAUTOSHDN

FORCEOFF

FORCEON

AUTOSHDN

* POWERDOWN IS ONLY AN INTERNAL SIGNAL.

IT CONTROLS THE OPERATIONAL STATUS OF

THE TRANSMITTERS AND THE POWER SUPPLIES.

POWERDOWN*

Figure 2d. Power-Down Logic

By connecting FORCEON and FORCEOFF to INVALID,

the MAX3380E/MAX3381E are shut down when no valid

receiver level is detected.

VL Logic Supply Input

Unlike other RS-232 interface devices where the receiv-

er outputs swing between 0 and VCC, the MAX3380E/

MAX3381E feature a separate logic supply input (VL)

that sets VOH for the receiver and INVALID outputs. VL

also sets the threshold for the transmitter inputs,

FORCEON and FORCEOFF. This feature allows a great

deal of flexibility in interfacing to many different types of

systems with different logic levels. Connect this input to

} INVALID

REGION

tAUTOSHDN

tWU

tWU

V+

VCC

0

V-

Figure 4. AutoShutdown Plus/INVALID Timing Diagram

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