FEATURES
460 kbps Data Rate
Specified at +3.3 V
Meets EIA-232E Specifications
0.1 F Charge Pump Capacitors
Low Power Shutdown (ADM3222E and ADM1385)
DIP, SO, SOIC, SSOP and TSSOP Package Options
Upgrade for MAX3222/32 and LTC1385
APPLICATIONS
General Purpose RS-232 Data Link
Portable Instruments
Printers
Palmtop Computers
PDAs
GENERAL DESCRIPTION
The ADM3202/ADM3222/ADM1385 transceivers are high
speed, 2-channel RS-232/V.28 interface devices which operate
from a single +3.3 V power supply.
Low power consumption and a shutdown facility (ADM3222/
ADM1385) makes them ideal for battery powered portable
instruments.
The ADM3202/ADM3222/ADM1385 conforms to the EIA232E and CCITT V.28 specifications and operates at data rates
up to 460 kbps.
Four external 0.1 µF charge pump capacitors are used for the
voltage doubler/inverter permitting operation from a single
+3.3 V supply.
The ADM3222 contains additional enable and shutdown circuitry. The EN input may 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.
The ADM1385 contains a driver disable mode and a complete
shutdown mode.
The ADM3202 is available in a 16-lead DIP, narrow and wide
SOIC as well as a space saving 20-lead TSSOP package. The
ADM3222 is available in 18-lead DIP, SO and in 20-lead SSOP
and TSSOP. The ADM1385 is available in a 20-lead SSOP
package, which is pin compatible with the LTC1385 CG.
Line Drivers/Receivers
ADM3202/ADM3222/ADM1385
FUNCTIONAL BLOCK DIAGRAMS
+3.3V INPUT
CMOS
INPUTS
CMOS
OUTPUTS
CMOS
INPUTS
CMOS
OUTPUTS
CMOS
INPUTS
CMOS
OUTPUTS
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
+
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
ENSD
+
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
DD
C1–
+6.6V TO –6.6V
C2+
C2–
+3.3V TO +6.6V
C1+
C1–
+6.6V TO –6.6V
C2+
C2–
+3.3V TO +6.6V
C1+
C1–
+6.6V TO –6.6V
C2+
C2–
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
GND
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
GND
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
GND
+3.3V TO +6.6V
C1+
+
V
CC
V+
V–
ADM3202
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
+3.3V INPUT
V
CC
V+
V–
ADM3222
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
+3.3V INPUT
V
CC
V+
V–
C4
+
0.1F
10V
ADM1385
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
SD
+
+
T1
T2
R1
R2
+
+
T1
T2
R1
R2
T1
T2
R1
R2
C3
0.1F
6.3V
C4
0.1F
10V
OUT
OUT
IN
IN
C3
0.1F
6.3V
C4
0.1F
10V
OUT
OUT
IN
IN
OUT
OUT
IN
IN
+
C3
0.1F
6.3V
+
C5
0.1F
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
+
C5
0.1F
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
+
C5
0.1F
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
REV. A
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.
Output Voltage Swing (RS-562)± 3.7VV
Transmitter Output Resistance300ΩV
RS-232 Output Short Circuit Current± 15mA
Output Leakage Current± 25µASD = Low, V
TIMING CHARACTERISTICS
Maximum Data Rate460kbpsVCC = 3.3 V, RL = 3 kΩ to 7 kΩ, CL = 50 pF to
Receiver Propagation Delay1000 pF. One Tx Switching
TPHL0.41µs
TPLH0.41µs
Transmitter Propagation Delay300750nsR
Receiver Output Enable Time200ns
Receiver Output Disable Time200ns
Transmitter Skew30ns
Receiver Skew300ns
Transition Region Slew RateMeasured from +3 V to –3 V or –3 V to +3 V,
61030V/µsR
41030V/µsR
*ADM1385: Input leakage current typically –10 µA when TIN = GND.
Specifications subject to change without notice.
to T
MIN
unless otherwise noted.)
MAX
810 mAR
0.8VT
0.4VI
L
IN
IN
OUT
OUT
IN
CC
with 3 kΩ to Ground
CC
CC
L
V
CC
L
L
= 3 kΩ to GND
= 1.6 mA
= –1 mA
= GND to VCC*
= 3.3 V. All Transmitter Outputs Loaded
= 3.0 V
= 0 V, V
OUT
OUT
= ± 2 V
= 12 V
= 3 kΩ, CL = 1000 pF
= +3.3 V
= 3 kΩ, CL = 1000 pF, TA = +25°C
= 3 kΩ, CL = 2500 pF, TA = +25°C
*This is a stress rating only; functional operation of the device at these or any other
conditions above those indicated in the operation sections of this specification
is not implied. Exposure to absolute maximum rating conditions for extended
periods of time may affect reliability.
ORDERING GUIDE
ModelTemperature RangePackage Options*
ADM3202AN–40°C to +85°CN-16
ADM3202ARN–40°C to +85°CR-16A
ADM3202ARW–40°C to +85°CR-16
ADM3202ARU–40°C to +85°CRU-16
ADM3222AN–40°C to +85°CN-18
ADM3222ARW–40°C to +85°CR-18
ADM3222ARS–40°C to +85°CRS-20
ADM3222ARU–40°C to +85°CRU-20
ADM1385ARS–40°C to +85°CRS-20
*N = Plastic DIP; R = Small Outline; RS = Shrink Small Outline; RU = Thin
Shrink Small Outline.
–3–REV. A
Page 4
ADM3202/ADM3222/ADM1385
PIN FUNCTION DESCRIPTIONS
MnemonicFunction
V
CC
Power Supply Input: +3.3 V ± 0.3 V.
V+Internally Generated Positive Supply
(+6 V Nominal).
V–Internally Generated Negative Supply
(–6 V Nominal).
GNDGround Pin. Must be connected to 0 V.
C1+, C1–External Capacitor 1 is connected between these
pins. 0.1 µF capacitor is recommended but larger
capacitors up to 47 µF may be used.
C2+, C2–External Capacitor 2 is connected between these
pins. 0.1 µF capacitor is recommended but larger
capacitors up to 47 µF may be used.
Tx
IN
Transmitter (Driver) Inputs. These inputs accept
TTL/CMOS levels.
Tx
OUT
Transmitter (Driver) Outputs. These are RS-232
signal levels (typically ±9 V).
Rx
IN
Receiver Inputs. These inputs accept RS-232
signal levels. An internal 5 kΩ pull-down resistor
to GND is connected on each input.
Rx
OUT
Receiver Outputs. These are CMOS output logic
levels.
EN(ADM3222) Receiver Enable, Active Low. When
low, the receiver outputs are enabled. When high,
they are three-stated.
SD(ADM3222) Shutdown Control. Active Low.
When low, the charge pump is shut down and
the transmitter outputs are disabled.
SD(ADM1385) Shutdown Control. When low, the
charge pump is shut down and all transmitters
and receivers are disabled.
DD(ADM1385) Driver Disable. When low, the
charge pump is turned off and the transmitters
are disabled. The receivers remain active.
PIN CONNECTIONS DIP (N, R Packages)
1
T2
C1+
V+
C1–
C2+
C2–
V–
OUT
R2
1
2
3
4
5
6
7
8
IN
ADM3202
TOP VIEW
(Not to Scale)
V
16
CC
GND
15
T1
14
OUT
R1
13
IN
R1
12
OUT
T1
11
IN
T2
10
IN
R2
9
OUT
T2
EN
C1+
V+
C1–
C2+
C2–
V–
OUT
R2
2
3
4
5
6
7
8
9
IN
ADM3222
TOP VIEW
(Not to Scale)
PIN CONNECTIONS DIP (RS, RU Packages)
1
EN
2
C1+
3
V+
4
C1–
5
C2+
6
C2–
7
V–
T2
8
OUT
9
R2
IN
R2
10
OUT
NC = NO CONNECT
ADM3222
(SSOP
TSSOP)
TOP VIEW
(Not to Scale)
20
SD
V
19
CC
GND
18
T1
17
OUT
16
R1
IN
15
R1
OUT
14
NC
T1
13
IN
T2
12
IN
NC
11
1
DD
2
C1+
3
V+
4
C1–
5
C2+
6
C2–
7
V–
8
T2
OUT
9
R2
IN
10
NC
NC = NO CONNECT
ADM1385
(SSOP)
TOP VIEW
(Not to Scale)
18
SD
V
17
CC
GND
16
T1
15
OUT
R1
14
IN
R1
13
OUT
T1
12
IN
T2
11
IN
R2
10
OUT
20
SD
19
V
CC
18
GND
17
T1
OUT
16
R1
IN
15
R1
OUT
14
T1
IN
13
T2
IN
12
R2
OUT
11
NC
–4–
REV. A
Page 5
Typical Performance Characteristics
LOAD CAPACITANCE – pF
25
20
0
050001000200030004000
15
10
5
IDD (mA) @ 250kbps
IDD (mA) @ 160kbps
IDD (mA) @ 80kbps
ADM3202/ADM3222/ADM1385
6
T
(HIGH)
4
2
0
–2
–4
–6
050001000200030004000
OUT
T
(LOW)
OUT
LOAD CAPACITANCE – pF
Figure 1. Transmitter Output Voltage High/Low vs. Load
Capacitance @ 230 kbps
12
10
8
6
4
8
6
4
2
0
–2
–4
–6
–8
0 10203040
V+ (V)
V– (V)
CURRENT – mA
Figure 4. Charge Pump V+, V– vs. Current
250
200
V– IMPEDANCE
150
V+ IMPEDANCE
100
2
0
35.53.54.04.55.0
Figure 2. Transmitter Output Voltage High vs. V
8
6
4
2
0
–2
–4
–6
–8
0102468
VCC – V
T1
(HIGH) – V
OUT
T1
(LOW) – V
OUT
CURRENT – mA
CC
Figure 3. Transmitter Output Voltage Low/High vs. Load
Current
50
0
3.05.53.54.04.55.0
Figure 5. Charge Pump Impedance vs. V
VCC – V
CC
Figure 6. Power Supply Current vs. Load Capacitance
–5–REV. A
Page 6
ADM3202/ADM3222/ADM1385
T1
IN
2V/DIV
T1
OUT
5V/DIV
1s/DIV
Figure 7. 230 kbps Data Transmission
GENERAL DESCRIPTION
The ADM3202/ADM3222/ADM1385 are RS-232 line drivers/
receivers. Step-up voltage converters coupled with level shifting
transmitters and receivers allow RS-232 levels to be developed
while operating from a single +3.3 V supply.
CMOS technology is used to keep the power dissipation to an
absolute minimum, allowing maximum battery life in portable
applications.
The ADM3202/ADM3222/ADM1385 is a modification, enhancement and improvement to the AD230–AD241 family and
its derivatives. It is essentially plug-in compatible and does not
have materially different applications.
CIRCUIT DESCRIPTION
The internal circuitry consists of three main sections. These are:
1. A charge pump voltage converter
2. 3.3 V logic to EIA-232 transmitters
3. EIA-232 to 5 V logic receivers.
Charge Pump DC-DC Voltage Converter
The charge pump voltage converter consists of a 200 kHz oscillator and a switching matrix. The converter generates a ±6.6 V
supply from the input +3.3 V level. This is done in two stages
using a switched capacitor technique as illustrated below. First,
the +3.3 V input supply is doubled to +6.6 V using capacitor
C1 as the charge storage element. The +6.6 V level is then
inverted to generate –6.6 V using C2 as the storage element. C3
is shown connected between V+ and V
tive if connected between V+ and GND.
Capacitors C3 and C4 are used to reduce the output ripple.
Their values are not critical and can be increased if desired.
Capacitor C3 is shown connected between V+ and V
also acceptable to connect this capacitor between V+ and GND.
If desired, larger capacitors (up to 10 µF) can be used for
capacitors C1–C4.
, but is equally effec-
CC
. It is
CC
CMOS
INPUTS
CMOS
OUTPUTS
CMOS
INPUTS
CMOS
OUTPUTS
CMOS
INPUTS
CMOS
OUTPUTS
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
+
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
ENSD
+
0.1F
10V
+
0.1F
10V
T1
IN
T2
IN
R1
OUT
R2
OUT
DD
C1–
+6.6V TO –6.6V
C2+
C2–
+3.3V TO +6.6V
C1+
C1–
+6.6V TO –6.6V
C2+
C2–
+3.3V TO +6.6V
C1+
C1–
+6.6V TO –6.6V
C2+
C2–
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
GND
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
ADM3222
GND
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
VOLTAGE
DOUBLER
VOLTAGE
INVERTER
T1
T2
R1
R2
ADM1385
GND
*INTERNAL 5k PULL-DOWN RESISTOR
ON EACH RS-232 INPUT
+3.3V TO +6.6V
C1+
+
V
ADM3202
V
V
+3.3V INPUT
CC
V+
V–
+3.3V INPUT
CC
V+
V–
+3.3V INPUT
CC
V+
V–
SD
+
C3
+
0.1F
6.3V
C4
+
0.1F
10V
T1
T2
R1
R2
C3
+
0.1F
6.3V
C4
+
0.1F
10V
T1
T2
R1
R2
C4
0.1F
10V
T1
T2
R1
R2
OUT
OUT
IN
IN
OUT
OUT
IN
IN
+
OUT
OUT
IN
IN
+
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
+
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
+
C3
0.1F
6.3V
EIA/TIA-232
OUTPUTS
EIA/TIA-232
INPUTS*
C5
0.1F
C5
0.1F
C5
0.1F
–6–
Figure 8. Typical Operating Circuits
REV. A
Page 7
ADM3202/ADM3222/ADM1385
0.2992 (7.60)
0.2914 (7.40)
169
81
0.4133 (10.50)
0.3977 (10.00)
0.4193 (10.65)
0.3937 (10.00)
PIN 1
SEATING
PLANE
0.0118 (0.30)
0.0040 (0.10)
0.0192 (0.49)
0.0138 (0.35)
0.1043 (2.65)
0.0926 (2.35)
0.0500
(1.27)
BSC
0.0125 (0.32)
0.0091 (0.23)
0.0500 (1.27)
0.0157 (0.40)
0.0291 (0.74)
0.0098 (0.25)
x 45
8
0
V
CC
GND
INTERNAL
OSCILLATOR
S1
S2
S3
+
C1
C3
S4
V+ = 2V
+
CC
V
CC
Figure 9. Charge Pump Voltage Doubler
S3
+
C2
C4
S4
+
GND
V– = –(V+)
FROM
VOLTAGE
DOUBLER
V
+
GND
INTERNAL
OSCILLATOR
S1
S2
Figure 10. Charge Pump Voltage Inverter
Transmitter (Driver) Section
The drivers convert 3.3 V logic input levels into RS-232 output
levels. With V
= +3.3 V and driving an RS-232 load, the
CC
output voltage swing is typically ±6 V.
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Receiver Section
The receivers are inverting level-shifters that accept RS-232
input levels and translate them into 3 V logic output levels.
The inputs have internal 5 kΩ pull-down resistors to ground and
are also protected against overvoltages of up to ±30 V. Unconnected inputs are pulled to 0 V by the internal 5 kΩ pull-down
resistor. This, therefore, results in a Logic 1 output level for
unconnected inputs or for inputs connected to GND.
The receivers have Schmitt trigger inputs with a hysteresis level
of 0.4 V. This ensures error-free reception for both noisy inputs
and for inputs with slow transition times.
HIGH BAUD RATE
The ADM3202E/ADM3222E feature high slew rates permitting
data transmission at rates well in excess of the EIA/RS-232E
specifications. RS-232 voltage levels are maintained at data rates
up to 460 kbps even under worst case loading conditions. This
allows for high speed data links between two terminals or indeed
it is suitable for the new generation I
modem standards which
SDN
requires data rates of 230 kbps. The slew rate is internally controlled to less than 30 V/µs in order to minimize EMI interference.
0.210 (5.33)
MAX
0.160 (4.06)
0.115 (2.93)
16-Lead Plastic DIP
(N-16)
0.840 (21.34)
0.745 (18.92)
16
18
PIN 1
0.022 (0.558)
0.014 (0.356)
0.100
(2.54)
BSC
9
0.280 (7.11)
0.240 (6.10)
0.060 (1.52)
0.015 (0.38)
0.070 (1.77)
0.045 (1.15)
0.130
(3.30)
MIN
SEATING
PLANE
0.325 (8.26)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.195 (4.95)
0.115 (2.93)
16-Lead Thin Shrink Small Outline (TSSOP)
(RU-16)
0.201 (5.10)
0.193 (4.90)
16
0.177 (4.50)
0.169 (4.30)
1
9
8
0.256 (6.50)
0.246 (6.25)
0.1574 (4.00)
0.1497 (3.80)
0.0098 (0.25)
0.0040 (0.10)
SEATING
PLANE
16-Lead Narrow Body SOIC
(R-16A)
0.3937 (10.00)
0.3859 (9.80)
169
PIN 1
0.0192 (0.49)
0.0500
(1.27)
0.0138 (0.35)
BSC
0.2440 (6.20)
81
0.2284 (5.80)
0.0688 (1.75)
0.0532 (1.35)
0.0099 (0.25)
0.0075 (0.19)
16-Lead Wide Body SOIC
(R-16)
0.0196 (0.50)
0.0099 (0.25)
8
0
0.0500 (1.27)
0.0160 (0.41)
x 45
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
PIN 1
0.0256
(0.65)
BSC
0.0118 (0.30)
0.0075 (0.19)
0.0433
(1.10)
MAX
0.0079 (0.20)
0.0035 (0.090)
8°
0°
0.028 (0.70)
0.020 (0.50)
–7–REV. A
Page 8
ADM3202/ADM3222/ADM1385
18-Lead Plastic DIP
(N-18)
0.925 (23.49)
0.845 (21.47)
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.93)
18
19
PIN 1
0.022 (0.558)
0.014 (0.356)
0.100
(2.54)
BSC
10
0.070 (1.77)
0.045 (1.15)
0.280 (7.11)
0.240 (6.10)
0.060 (1.52)
0.015 (0.38)
0.130
(3.30)
MIN
SEATING
PLANE
20-Lead Thin Shrink Small Outline (TSSOP)
(RU-20)
0.260 (6.60)
0.252 (6.40)
2011
0.325 (8.25)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.195 (4.95)
0.115 (2.93)
1810
PIN 1
0.0118 (0.30)
0.0040 (0.10)
2011
18-Lead Wide Body SOIC
(R-18)
0.4625 (11.75)
0.4469 (11.35)
0.2992 (7.60)
0.2914 (7.40)
0.0500
(1.27)
BSC
91
0.1043 (2.65)
0.0926 (2.35)
0.0192 (0.49)
0.0138 (0.35)
0.4193 (10.65)
SEATING
PLANE
0.3937 (10.00)
0.0125 (0.32)
0.0091 (0.23)
0.0291 (0.74)
0.0098 (0.25)
0.0500 (1.27)
8
0
0.0157 (0.40)
20-Lead Shrink Small Outline (SSOP)
(RS-20)
0.295 (7.50)
0.271 (6.90)
x 45
C00071–0–8/00 (rev. A)
0.177 (4.50)
0.006 (0.15)
0.002 (0.05)
SEATING
PLANE
0.169 (4.30)
1
PIN 1
0.0256 (0.65)
BSC
10
0.0118 (0.30)
0.0075 (0.19)
0.256 (6.50)
0.246 (6.25)
0.0433
(1.10)
MAX
0.0079 (0.20)
0.0035 (0.090)
8
0
0.028 (0.70)
0.020 (0.50)
0.311 (7.9)
0.301 (7.64)
0.078 (1.98)
0.068 (1.73)
0.008 (0.203)
0.002 (0.050)
PIN 1
0.0256
(0.65)
BSC
101
0.07 (1.78)
0.066 (1.67)
SEATING
PLANE
0.212 (5.38)
0.205 (5.21)
0.009 (0.229)
0.005 (0.127)
8
0
0.037 (0.94)
0.022 (0.559)
PRINTED IN U.S.A.
–8–
REV. A
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