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