+5V-Powered, Multichannel RS-232
Drivers/Receivers
0–MAX249
Test Circuits/Timing Diagrams
+3V
0V*
50%
50%
50%
INPUT
+3V
INPUT
0V
V
CC
OUTPUT
50%
GND
V+
0V
V-
OUTPUT
t
t
t
PLHR
PHLR
PHLS
t
PLHS
t
t
PHLT
PLHT
*EXCEPT FOR R2 ON THE MAX243
WHERE -3V IS USED.
ꢁigure ±. Transmitter Propagation-Delay Timing
ꢁigure 2. Receiver Propagation-Delay Timing
EN
1kΩ
R OUT
X
R
V
CC
- 2V
X
R IN
X
+3V
SHDN
a) TEST CIRCUIT
0V
150pF
0V
OUTPUT DISABLE TIME (t
)
DT
+3V
EN INPUT
V+
+5V
EN
OUTPUT ENABLE TIME (t
)
ER
0V
-5V
+3.5V
V-
RECEIVER
OUTPUTS
+0.8V
a) TIMING DIAGRAM
b) ENABLE TIMING
+3V
EN
0V
T
X
1 OR 0
EN INPUT
OUTPUT DISABLE TIME (t
)
DR
50pF
3kΩ
V
OH
V
OH
- 0.5V
RECEIVER
OUTPUTS
V
- 2V
CC
V
OL
+ 0.5V
b) TEST CIRCUIT
V
OL
c) DISABLE TIMING
ꢁigure 3. Receiver-Output Enable and Disable Timing
ꢁigure 4. Transmitter-Output Disable Timing
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
