Low Power, 3.3 V, RS-232
Line Drivers/Receivers
ADM3202/ADM3222/ADM1385
FEATURES
FUNCTIONAL BLOCK DIAGRAMS
+3.3V INPUT
0.1µF +
10V
T1
T1IN
T1OUT
T2
T2IN
R2
ADM3202
Figure 1.
+3.3V INPUT
T2IN
T1OUT
T2
R1IN
R2
R2OUT
C5
0.1µF
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
R2IN
EN
SD
*INTERNAL 5kΩ PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
00071-002
ADM3222
GND
Four external 0.1 μF charge pump capacitors are used for the
voltage doubler/inverter, permitting operation from a single
3.3 V supply.
Figure 2.
+3.3V INPUT
T1IN
V–
+
CMOS
OUTPUTS
C2+ +6.6V TO –6.6V
VOLTAGE
C2–
INVERTER
C4
0.1µF
10V
T1
T2IN
T1OUT
T2
T2OUT
R1
R1OUT
R1IN
R2
R2OUT
DD
GND
ADM1385
R2IN
C3
0.1µF
10V
C5
0.1µF
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
SD
*INTERNAL 5kΩ PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
00071-003
0.1µF +
10V
CMOS
INPUTS
C1+ +3.3V TO +6.6V VCC
VOLTAGE
C1–
V+
DOUBLER
+
0.1µF +
10V
+
The ADM3202 is available in a 16-lead PDIP, SOIC_W, and
SOIC_N, as well as a space-saving 16-lead TSSOP. The ADM3222
is available in 18-lead PDIP and SOIC_W and in 20-lead SSOP
and TSSOP. The ADM1385 is available in a 20-lead SSOP,
which is pin-compatible with the LTC1385 CG.
T2OUT
R1
R1OUT
The ADM3202/ADM3222/ADM1385 parts conform to the
EIA-232E and CCITT V.28 specifications and operate at data
rates up to 460 kbps.
C4
0.1µF
10V
V–
T1
T1IN
C3
0.1µF
6.3V
+
CMOS
OUTPUTS
C2+ +6.6V TO –6.6V
VOLTAGE
C2–
INVERTER
+
0.1µF +
10V
CMOS
INPUTS
C1+ +3.3V TO +6.6V VCC
VOLTAGE
C1–
V+
DOUBLER
+
0.1µF +
10V
GENERAL DESCRIPTION
The ADM1385 contains a driver disable mode and a complete
shutdown mode.
EIA/TIA-232
INPUTS*
R2IN
*INTERNAL 5kΩ PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
General-purpose RS-232 data link
Portable instruments
Printers, palmtop computers, PDAs
The ADM3222 contains additional enable and shutdown
circuitry. The EN input can be used to three-state the receiver
outputs. The SD input is used to power down the charge pump
and transmitter outputs, reducing the quiescent current to less
than 0.5 μA. The receivers remain enabled during shutdown
unless disabled using EN.
R1IN
R2OUT
APPLICATIONS
The ADM3202/ADM3222/ADM1385 transceivers are high
speed, 2-channel RS-232/V.28 interface devices that operate
from a single 3.3 V power supply. Low power consumption and
a shutdown facility (ADM3222/ADM1385) make them ideal for
battery-powered portable instruments.
EIA/TIA-232
OUTPUTS
T2OUT
R1
R1OUT
GND
C4
0.1µF
10V
V–
C5
0.1µF
00071-001
CMOS
OUTPUTS
C2+ +6.6V TO –6.6V
VOLTAGE
C2–
INVERTER
C3
0.1µF
6.3V
+
CMOS
INPUTS
C1+ +3.3V TO +6.6V VCC
VOLTAGE
C1–
V+
DOUBLER
+
0.1µF +
10V
+
460 kbps data rate
Specified at 3.3 V
Meets EIA-232E specifications
0.1 μF charge pump capacitors
Low power shutdown (ADM3222 and ADM1385)
PDIP, SOIC_N, SOIC_W, SSOP, and TSSOP options
Upgrade for MAX3222/MAX3232 and LTC1385
ESD protection to IEC 1000-4-2 (801.2)
on RS-232 pins (ADM3202 only)
±8 kV: contact discharge
±15 kV: air gap discharge
Figure 3.
Rev. E
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