5 V-Powered
CMOS RS-232 Drivers/Receivers
ADM231L–ADM234L/ADM236L–ADM241L
Rev. C
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FEATURES
Single 5 V power supply
Meets all EIA-232-E and V.28 specifications
120 kbps data rate
On-board dc-to-dc converters
±9 V output swing with 5 V supply
Small 1 µF capacitors
Low power shutdown ≤1 µA
±30 V receiver input levels
Latch-up free
APPLICATIONS
Computers
Peripherals
Modems
Printers
Instruments
GENERAL DESCRIPTION
The ADM2xx family of line drivers/receivers is intended for all
EIA-232-E and V.28 communications interfaces, especially in
applications in which 12 V is not available. The ADM236L and
ADM241L feature a low power shutdown mode that reduces
power dissipation to less than 5 µW, making them ideally suited
for battery-powered equipment. The ADM233L does not
require any external components and is particularly useful in
applications where printed circuit board space is critical.
All members of the ADM2xxL family, except the ADM231L and
ADM239L, include two internal charge pump voltage converters
that allow operation from a single 5 V supply. These parts convert
the 5 V input power to the ±10 V required for RS-232 output
ADM236L TYPICAL OPERATING CIRCUIT
T1
IN
T1
OUT
T2
IN
T2
OUT
RS-232
OUTPUTS
T3
IN
T4
IN
R1
OUT
R1
IN
R2
OUT
R2
IN
TTL/CMOS
OUTPUTS
R3
IN
R3
OUT
T3
OUT
T4
OUT
1µF
+6.3V
1µF
+16V
C1+
C1–
C2–
C2+
V–
1µF
+16V
+10V TO –10V
VOLTAGE
INVERTER
1µF
+6.3V
1µF
+6.3V
+5V INPUT
V
CC
+5V TO +10V
VOLTAGE
DOUBLER
T1
T2
T3
T4
R1
R2
R3
V+
SD
ADM236L
GND
00070-0-015
TL/CMOS
INPUTS
1
RS-232
INPUTS
2
1
INTERNAL 400kΩ PULL-UP RESISTOR ON EACH TTL/CMOS INPUT.
2
INTERNAL 5kΩ PULL-DOWN RESISTOR ON EACH RS-232 INPUT.
EN
Figure 1.
levels. The ADM231L and ADM239L are designed to operate
from 5 V and 12 V supplies. An internal +12 V to −12 V charge
pump voltage converter generates the −12 V supply.
The ADM2xxL is an enhanced upgrade to the AD2xx family. It
features lower power consumption, faster slew rate, and the
ability to operate with smaller (1 µF) capacitors.
Table 1. Selection Table
Part
Number
Power Supply Voltage
No. of RS-232
Drivers
No. of RS-232
Receivers
External
Capacitors
Low Power
Shutdown (SD)
TTL
Three-State
EN
No. of
Pins
ADM231L 5 V and 7.5 V to 13.2 V 2 2 2 No No 14
ADM232L 5 V 2 2 4 No No 16
ADM233L 5 V 2 2 None No No 20
ADM234L 5 V 4 0 4 No No 16
ADM236L 5 V 4 3 4 Yes Yes 24
ADM237L 5 V 5 3 4 No No 24
ADM238L 5 V 4 4 4 No No 24
ADM239L 5 V and 7.5 V to 13.2 V 3 5 2 No Yes 24
ADM241L 5 V 4 5 4 Yes Yes 28
