+5V-Powered, Multichannel RS-232
Drivers/Receivers
INPUT
OUTPUT
+3V
V+
0V
V-
0V
tPLHT
tPHLT
tPHLR
tPHLS
tPLHR
tPLHS
50%
VCC
50%
+3V
50%
INPUT
OUTPUT
*EXCEPT FOR R2 ON THE MAX243
WHERE -3V IS USED.
0V*
50%
GND
Figure 1. Transmitter Propagation-Delay Timing
Figure 2. Receiver Propagation-Delay Timing
EN
RX IN
a) TEST CIRCUIT
b) ENABLE TIMING
c) DISABLE TIMING
EN INPUT
RECEIVER
OUTPUTS
RX OUT
RX
1k
Ω
0V
+3V
EN
+0.8V
+3.5V
OUTPUT ENABLE TIME (tER)
VCC - 2V
VOL + 0.5V
VOH - 0.5V
OUTPUT DISABLE TIME (tDR)
VCC - 2V
+3V
0V
150pF
EN INPUT
VOH
RECEIVER
OUTPUTS
VOL
1 OR 0
TX
3k
Ω
50pF
-5V
+5V
OUTPUT DISABLE TIME (tDT)
V+
SHDN
+3V
0V
V-
0V
a) TIMING DIAGRAM
b) TEST CIRCUIT
Figure 3. Receiver-Output Enable and Disable Timing
Figure 4. Transmitter-Output Disable Timing
Test Circuits/Timing Diagrams
Maxim Integrated
11
MAX220–MAX249