MAX221CUE データシートの表示（PDF） - Maxim Integrated
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MAX221CUE Datasheet PDF : 8 Pages
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+5V, 1µA, Single RS-232 Transceiver
with AutoShutdown
Table 1. Output Control Truth Table
OPERATION
STATUS
FORCEON
FORCEOFF
EN
VALID
RECEIVER
LEVEL
TOUT
ROUT
Shutdown
X
0
0
X
High-Z
Active
(Forced Off)
X
0
1
X
High-Z
High-Z
Normal Operation
1
1
0
X
Active
Active
(Forced On)
1
1
1
X
Active
High-Z
Normal Operation
0
1
0
Yes
Active
Active
(AutoShutdown)
0
1
1
Yes
Active
High-Z
Shutdown
0
1
0
No
High-Z
Active
(AutoShutdown)
0
1
1
No
High-Z
High-Z
X = Don’t care
+0.3V
RIN
-0.3V
30µs
COUNTER
R
TO MAX221
POWER SUPPLY
AND TRANSMITTER
INVALID
* TRANSMITTER IS DISABLED, REDUCING SUPPLY CURRENT TO 1µA IF
RECEIVER INPUT IS BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs.
Figure 2a. Entering 1µA Supply Mode via AutoShutdown
FORCEOFF
FORCEON
INVALID
POWER DOWN
INVALID IS AN INTERNALLY GENERATED SIGNAL USED BY
THE AUTOSHUTDOWN LOGIC AND APPEARS AS AN OUTPUT.
POWER DOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE
OPERATIONAL STATUS OF THE TRANSMITTER AND POWER SUPPLIES.
Figure 2c. AutoShutdown Logic
+2.7V
TO MAX221
RIN
30µs POWER SUPPLY
COUNTER INVALID
-2.7V
R
* TRANSMITTER IS ENABLED IF:
RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V;
RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30µs.
Figure 2b. Transmitter Enabled Using AutoShutdown
Table 2. INVALID Truth Table
RS-232 SIGNAL PRESENT
AT RECEIVER INPUT
INVALID OUTPUT
Yes
High
No
Low
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