Datasheet

______________________________________________________________Pin Description
7.5
-5.0
-7.5
0 1000 3000 5000
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
-2.5
5.0
MAX3238 TOC-01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2000 4000
2.5
0
V
OUT
+
V
OUT
–
FOR DATA RATES UP TO 250kbps
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
LOADED 3kΩ + C
L
14
4
2
0
0 1000 3000 5000
SLEW RATE
vs. LOAD CAPACITANCE
6
12
MAX3238-02
SLEW RATE (V/µs)
LOAD CAPACITANCE (pF)
2000 4000
10
8
+SLEW
–SLEW
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
LOADED 3kΩ + C
L
70
20
10
0
0 1000 3000 5000
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
30
60
MAX3238 TOC-03
SUPPLY CURRENT (mA)
LOAD CAPACITANCE (pF)
2000 4000
50
40
250kbps
120kbps
20kbps
__________________________________________Typical Operating Characteristics
(V
CC
= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, T
A
= +25°C, unless otherwise noted.)
MAX3238
+3.0V to +5.5V, 1µA, up to 250kbps, True
RS-232 Transceiver with AutoShutdown Plus
4 _______________________________________________________________________________________
Positive Terminal of Voltage-Doubler Charge-Pump CapacitorC1+28
+5.5V Generated by the Charge PumpV+27
+3.0V to +5.5V Supply VoltageV
CC
26
NAME FUNCTION
1
C2+ Positive Terminal of Inverting Charge-Pump Capacitor
2 GND Ground
PIN
3 C2- Negative Terminal of Inverting Charge-Pump Capacitor
4 V- -5.5V Generated by the Charge Pump
14
FORCEOFF
Force-Off Input. Drive low to shut down transmitters, receivers (except R1OUTB), and on-
board supply. This overrides AutoShutdown Plus and FORCEON (Table 1).
13 FORCEON
Force-Off Input. Drive high to override AutoShutdown Plus, keeping transmitters and
receivers on (FORCEOFF must be high) (Table 1).
8, 9, 11 R_IN RS-232 Receiver Inputs (R1IN–R3IN)
5, 6, 7, 10, 12 T_OUT RS-232 Transmitter Outputs (T1OUT–T5OUT)
25 C1- Negative Terminal of Voltage-Doubler Charge-Pump Capacitor
18, 20, 21 R_OUT TTL/CMOS Receiver Outputs (R3OUT–R1OUT)
17, 19, 22, 23, 24 T_IN TTL/CMOS Transmitter Inputs (T5IN–T1IN)
16 R1OUTB Noninverting Complementary Receiver Output. Always active.
15
INVALID
Output of the Valid Signal Detector. A logic “1” indicates if a valid RS-232 level is present
on receiver inputs.