Datasheet

When using the minimum required capacitor values,
make sure the capacitor value does not degrade
excessively with temperature. If in doubt, use capaci-
tors with a larger nominal value. The capacitor’s equiv-
alent series resistance (ESR), which usually rises at low
temperatures, influences the amount of ripple on V+
and V-.
MAX3238
+3.0V to +5.5V, 1µA, up to 250kbps, True
RS-232 Transceiver with AutoShutdown Plus
8 _______________________________________________________________________________________
Table 3. Required Minimum Capacitance
Values
RECEIVER INPUT LEVELS
-2.7V
-0.3V
+2.7V
+0.3V
0V
INDETERMINATE
INVALID HIGH
INVALID LOW
INVALID HIGH
INDETERMINATE
Figure 4a. Receiver Positive/Negative Thresholds for INVALID
V
CC
0
V+
V-
V
CC
0
INVALID
OUTPUT
* ALL RECEIVERS/TRANSMITTERS INACTIVE
** ANY ONE RECEIVER/TRANSMITTER BECOMES ACTIVE FORCEON = GND, FORCEOFF = V
CC
TRANSMITTER
INPUTS
VOLTAGE
RECEIVER
INPUTS
VOLTAGE
TRANSMITTER
OUTPUTS
VOLTAGE
t
AUTOSHDN
INVALID
REGION
***
t
WU
t
WU
I
NVL
t
AUTOSHDN
Figure 4b. AutoShutdown Plus and INVALID Timing Diagram
10.223.0 to 5.5
0.330.0474.5 to 5.5
C2, C3, C4, C
BYPASS
(µF)
0.22
0.10.13.15 to 3.6
0.223.0 to 3.6
C1
(µF)
V
CC
(V)