max221e Maxim Integrated Products, Inc., max221e Datasheet - Page 6

• Manufacturer Part Number: max221e
• Description: Max221e ?15kv Esd-protected, +5v, 1?a, Single Rs-232 Transceiver With Autoshutdown
• Manufacturer: Maxim Integrated Products, Inc.

±15kV ESD-Protected, +5V, 1µA, Single RS-232
Transceiver with AutoShutdown
Table 1. Output Control Truth Table
x = Don’t care
Figure 2a. Entering 1µA Supply Mode via AutoShutdown
Figure 2b. Transmitter Enabled Using AutoShutdown
6
+0.3V
-0.3V
Shutdown
(Forced Off)
Normal Operation
(Forced On)
Normal Operation
(AutoShutdown)
Shutdown
(AutoShutdown)
RIN
* TRANSMITTER IS DISABLED, REDUCING SUPPLY CURRENT TO 1 A IF
+2.7V
-2.7V
* TRANSMITTER IS ENABLED IF:
_______________________________________________________________________________________
RECEIVER INPUT IS BETWEEN +0.3V AND -0.3V FOR AT LEAST 30 s.
OPERATION
RIN
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 30 s.
STATUS
FORCEON
X
X
1
1
0
0
0
0
COUNTER
30µs
COUNTER
R
FORCEOFF
30µs
R
TO MAX221E
POWER SUPPLY
AND TRANSMITTER
0
0
1
1
1
1
1
1
TO MAX221E
POWER SUPPLY
INVALID
INVALID
EN
0
1
0
1
0
1
0
1
Figure 2c. AutoShutdown Logic
Table 2. INVALID Truth Table
RS-232 SIGNAL PRESENT
AT RECEIVER INPUT
INVALID IS AN INTERNALLY GENERATED SIGNAL USED BY
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.
FORCEOFF
FORCEON
INVALID
RECEIVER
Yes
VALID
No
Yes
Yes
No
No
X
X
X
X
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
TOUT
INVALID OUTPUT
POWER DOWN
High
Low
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
ROUT