a
FEATURES
200 kB/s Transmission Rate
Small (0.1 F) Charge Pump Capacitors
Single 5 V Power Supply
Meets All EIA-232-E and V.28 Specifications
Two Drivers and Two Receivers
On-Board DC-DC Converters
9 V Output Swing with 5 V Supply
30 V Receiver Input Levels
Pin Compatible with MAX222/MAX232A/MAX242
APPLICATIONS
Computers
Peripherals
Modems
Printers
Instruments
High-Speed, 5 V, 0.1 F
CMOS RS-232 Drivers/Receivers
ADM222/ADM232A/ADM242
FUNCTIONAL BLOCK DIAGRAM
5V INPUT
0.1 F
V
CC
+5V TO +10V
V+
VOLTAGE DOUBLER
+5V TO –10V
VOLTAGE INVERTER V–
0.1 F
0.1 F
C1+
0.1 F
C1–
C2+
0.1 F
C2–
T1
IN
TTL/CMOS
INPUTS
*
T2
IN
R1
OUT
TTL/CMOS
OUTPUTS
R2
OUT
T1
T2
R1
R2
T1
OUT
T2
OUT
R1
IN
R2
IN
EN
SHDN
RS-232
INPUTS
**
RS-232
OUTPUTS
ADM2xx
(ADM242)
(ADM222, ADM242)
GENERAL DESCRIPTION
GND
The ADM222, ADM232A, ADM242 are a family of high-speed
RS-232 line drivers/receivers offering transmission rates up to
200 kB/s. Operating from a single 5 V power supply, a highly
efficient on-chip charge pump using small (0.1
µF)
external
capacitors allows RS-232 bipolar levels to be developed. Two
RS-232 drivers and two RS-232 receivers are provided on
each device.
The devices are fabricated on BiCMOS, an advanced mixed
technology process that combines low power CMOS with high-
speed bipolar circuitry. This allows for transmission rates up to
200 kB/s, yet minimizes the quiescent power supply current to
under 5 mA.
The ADM232A is a pin-compatible, high-speed upgrade for the
AD232 and for the ADM232L. It is available in 16-lead DIP
and in both narrow and wide surface-mount (SOIC) packages.
The ADM222 contains an additional shutdown (SHDN) func-
tion that may be used to disable the device, thereby reducing the
supply current to 0.1
µA.
During shutdown, all transmit/receive
PULL-UP RESISTOR
ON EACH TTL/CMOS INPUT
**
INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
*
INTERNAL 400k
functions are disabled. The ADM222 is available in 18-lead
DIP and in a wide surface-mount (SOIC) package.
The ADM242 combines both shutdown (SHDN) and enable
(EN) functions. The shutdown function reduces the supply
current to 0.1 mA. During shutdown, the transmitters are dis-
abled but the receivers continue to operate normally. The
enable function allows the receiver outputs to be disabled
thereby facilitating sharing a common bus. The ADM242 is
available in 18-lead DIP and in a wide surface-mount (SOIC)
package.
REV.
B
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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Fax:
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© Analog Devices, Inc.,
2010
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