Page 1
Craft Port
TM
Tiny RS-232 Transceiver for
a
FEATURES
460 kbit/s Transmission Rate
Single +5 V Power Supply
Compatible with RS-232 Input/Output Levels
0.1 F Charge Pump Capacitors
One Driver and One Receiver
On-Board DC-DC Converter
ⴞ4.2 V Output Swing with +5 V Supply
Low Power BiCMOS: 500 A I
Ultralow Power (1 A) Shutdown Mode
10-Lead SOIC Package
APPLICATIONS
Mobile Telephones
Palmtop Computers
PDAs
Portable Instrumentation
GPS Receivers
CC
Portable Applications
ADM101E
FUNCTIONAL BLOCK DIAGRAM
0.1mF
+
0.1mF
+
V
CC
10
C1+
9
8
SD
T
7
OUT
R
R1
6
IN
0.1mF
GND
C1–
+
R
OUT
+5V TO –5V
1
VOLTAGE
INVERTER
2
V–
ADM101E
3
T
IN
T1
4
5
+5V
GENERAL DESCRIPTION
The ADM101E is a single channel RS-232 driver and receiver in
the Analog Devices Craft Port
series, designed to operate from a
single, +5 V supply. A highly efficient charge-pump voltage
inverter generates an on-chip –5 V supply, which eliminates the
need for a negative power supply for the driver and permits
RS-232 compatible output levels to be developed using charge
pump capacitors as small as 0.1 µF.
A shutdown input disables the charge pump and puts the device
into a low power shutdown mode, in which the current con-
sumption is typically less than 1 µA. The transmitter is disabled
during shutdown but the receiver remains functional.
Craft Port is a trademark of Analog Devices, Inc.
An epitaxial BiCMOS construction minimizes power consumption to 3 mW and also guards against latch-up. Overvoltage
protection is provided allowing the receiver inputs to withstand
continuous voltages in excess of ±30 V. In addition, all I-O pins
have ESD protection to levels greater than 15 kV.
The ADM101E is available in a 10-lead µSOIC package, which
makes it ideal for serial communications in small, portable applications such as palmtop computers and mobile telephones,
where a full, RS-232 serial interface is not required, but compact size and low power drain are paramount.
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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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
Page 2
ADM101E–SPECIFICATIONS
(VCC = +5 V ⴞ 10%, C1 = C2 = 0.1 F. All specifications T
otherwise noted.)
MIN
Parameter Min Typ Max Units Test Conditions/Comments
Output Voltage Swing ±3.5 ±4.2 V V
±3.25 ±4.2 V V
= 5 V ±5%, T
CC
= 5 V ±10%, T
CC
Loaded with 3 kΩ to GND
OUT
Loaded with 3 kΩ to
OUT
GND
Power Supply Current (Unloaded) 0.5 1 mA No Load, TIN = VCC or GND
V
CC
V
Power Supply Current (Loaded) 1.85 2.5 mA T
CC
Power Supply Current (Shutdown) 1 µA SD Input = V
V
CC
Input Logic Threshold Low, V
Input Logic Threshold High, V
INL
INH
2.4 V
0.8 V
Loaded with 3 kΩ to GND
OUT
CC
Input Leakage Current ±1 µA
RS-232 Input Voltage Range –15 +15 V
RS-232 Input Threshold Low 0.8 2.2 V
RS-232 Input Threshold High 2.4 2.6 V
RS-232 Input Hysteresis 0.2 V
RS-232 Input Resistance 357kΩ
TTL/CMOS Output Voltage Low, V
TTL/CMOS Output Voltage High, V
Propagation Delay 0.25 µs RS-232 to TTL
Instantaneous Slew Rate
1
OL
OH
3.5 V I
25 V/µsC
0.4 V I
Transition Region Slew Rate 11 V/µsR
= 1.6 mA
OUT
= –1.0 mA
OUT
= 10 pF, R
L
= 3 kΩ, C
L
= 3 kΩ–7 kΩ, TA = +25°C
L
= 1000 pF
L
Measured from +3 V to –3 V or Vice Versa
Baud Rate 460 kB R
Output Resistance 300 Ω V
= 3 kΩ, C
L
= 0 V, V
CC
= 1 nF
L
= ±2 V
OUT
RS-232 Output Short Circuit Current ±25 ±60 mA
NOTES
1
Sample tested to ensure compliance.
Specifications subject to change without notice.
to T
MAX
unless
ABSOLUTE MAXIMUM RATINGS*
(T
= +25°C unless otherwise noted)
A
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6 V
V– . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to –6 V
Input Voltages
Driver Input T
Receiver Input R
. . . . . . . . . . . . . . –0.3 V to (VCC, +0.3 V)
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . ±30 V
IN
Output Voltages
Driver Output T
Receiver Output R
. . . . . . . . (VCC, +0.3 V) to (V–, –0.3 V)
OUT
. . . . . . . . . . . –0.3 V to (VCC +0.3 V)
OUT
Short Circuit Duration
T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
OUT
Power Dissipation
RM-10 (Derate 12 mW/°C Above +70°C) . . . . . . . 1488 mW
Thermal Impedance . . . . . . . . . . . . . . . . . . . . . . . +135°C/W
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Soldering
Vapor Phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . .+215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . .+220°C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >2000 V
ESD Rating (I-O Pins) . . . . . . . . . . . . . . . . . . . . . . . . . 15 kV
*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
Temperature Package Package
Model Range Description Option
ADM101EARM –40°C to +85°C µSOIC RM-10
–2–
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ADM101E
GND
V– SD
T
IN
1
2
3
4
10
9
8
7
ADM101E
TOP VIEW
(Not to Scale)
C1– C1+
T
OUT
5
6
R
OUT
R
IN
V
CC
LOAD CAPACITANCE – pF
14
12
0
0 3500500
I
DD
– mA
1000 1500 2000
10
8
6
4
2500 3000
2
PIN FUNCTION DESCRIPTION
Pin
No. Mnemonic Function
1 GND Ground Pin. Must be connected to 0 V.
2 C1– Negative Terminal of C1 (if C1 is Polarized
Capacitor).
3 V– Internally Generated Negative Supply Voltage.
4T
IN
Driver Input (3 V to 5 V TTL/CMOS
Logic Levels).
5R
OUT
Receiver Output (3 V to 5 V TTL/CMOS
Logic Levels).
6R
7T
IN
OUT
Receiver Input (EIA-232 Signal Levels).
Driver Output (EIA-232 Signal Levels).
8 SD Shutdown Input. Logic 1 on this input puts
the ADM101E into low power shutdown mode.
9 C1+ Positive Terminal of Charge Pump Capacitor
(if C1 is Polarized Capacitor).
10 V
CC
Positive Power Supply, Nominally +5 V.
Typical Performance Characteristics
0
PIN CONFIGURATION
–1
–2
–3
–4
CHARGE PUMP VOLTAGE – Volts
–5
–6
0
10 15 20
CURRENT – mA
Figure 1. Charge Pump Voltage vs. Current
255
Figure 2. IDD vs. Load Capacitance @ 460 kbps
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–3–
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ADM101E
6
5
4
3
2
1
0
O/P – Volts
X
T
–1
–2
–3
–4
–5
0 500
1000 1500 2000
LOAD CAPACITANCE – pF
TX HI
T
LO
X
2500
Figure 3. Transmitter Output Voltage vs. Load Capacitance
@ 460 kbps
6
HI
T
4
2
0
O/P HI & LO
X
T
–2
–4
–6
01
234
VCC – Volts
5
X
T
LO
X
67
Figure 4. Tx Output Voltage vs. Supply
40
30
20
10
0
–10
SLEW RATE – Volts/ms
–20
–30
–40
0 100
200 300 400
DATA RATE – kbps
SERIES 1
SERIES 2
500 600
Figure 5. Slew Rate vs. Data Rate
5
4
3
2
1
0
–1
OUTPUT VOLTAGE
X
–2
T
–3
–4
–5
02
468
LOAD CURRENT – mA
TX HI
TX LO
10 12
14
Figure 6. Transmitter Output Voltage vs. Load Current
–4–
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Page 5
ADM101E
GENERAL DESCRIPTION
The ADM101E is an RS-232 compatible line driver/receiver in
the Analog Devices Craft Port
series, containing one driver (transmitter) and one receiver. It is ideal for serial communication in
small portable devices such as mobile telephones, palmtop personal computers and personal digital assistants, where a full,
RS-232 serial interface is not required, and only Tx and Rx lines
are required for low speed communication between devices. The
ADM101E operates from a single, +5 V supply, and generates
its own, on-chip, –5 V power supply, thus removing the need for
a negative power supply for the driver.
CIRCUIT DESCRIPTION
The internal circuitry consists of three main sections. These are:
1. A charge pump dc-to-dc converter.
2. 5 V logic to EIA-232 driver.
3. EIA-232 to 5 V logic receiver.
Charge Pump DC-DC Converter
The dc-dc converter generates a negative supply voltage from
the +5 V supply, thus removing the need for a separate –5 V
rail. It consists of an on-chip 200 kHz oscillator, switching matrix and two external capacitors, as shown in Figure 7.
V
CC
GND
INTERNAL
OSCILLATOR
S1
S2
S3
+
C1
S4
GND
+
C2
V– = –V
CC
Figure 7. Charge Pump DC–DC Converter
When S1 and S2 are closed, S3 and S4 are open, and C1
charges to +V
. S1 and S2 are then opened, while S3 and S4
CC
are closed to connect C1 across C2, dumping charge into C2.
Since the positive terminal of C2 is at ground, a negative voltage
will be built up on its negative terminal with each cycle of the
oscillator. This voltage depends on the current drawn from C2.
If the current is small, the voltage will be close to –V
, but will
CC
fall as the current drawn increases.
Charge Pump Capacitors And Supply Decoupling
For proper operation of the charge pump, the capacitors should
have an equivalent series resistance (ESR) less than 1 Ω. As the
charge pump draws current pulses from V
pling capacitor should also have low ESR. The V
, the VCC decou-
CC
decoupling
CC
capacitor and V– reservoir capacitor should also have low ESR
because they determine how effectively ESD pulses are clamped
or V– by the on-chip clamp diodes. Tantalum or mono-
to V
CC
lithic ceramic capacitors are suitable for these components. If
using tantalum capacitors, do not forget to observe polarity.
Transmitter (Driver) Section
The driver converts 5 V logic input levels into RS-232 compatible output levels. With V
= +5 V and driving an EIA-232
CC
load, the output voltage swing is typically ±4.2 V.
Receiver Section
The receivers are inverting level-shifters that accept EIA-232
input levels and translate them into 5 V logic output levels.
The inputs have internal 5 kΩ pull-down resistors to ground and
are also protected against overvoltages of up to ±25 V. The
guaranteed switching thresholds are 0.8 V minimum and 2.8 V
maximum. An unconnected receiver input is 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 input with a hysteresis level
of 0.25 V. This ensures error-free reception for both noisy inputs and for inputs with slow transition times.
SHUTDOWN INPUT
The shutdown input allows the ADM101E to be put into an
ultralow power mode where the dc-dc converter is switched off
and the transmitter is disabled. The receiver remains active
during shutdown. Logic 0 at this input enables the ADM101E,
while a Logic 1 at this input shuts down the ADM101E.
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–5–
Page 6
ADM101E
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
10-Lead SOIC
(RM-10)
0.124 (3.15)
0.112 (2.84)
0.124 (3.15)
0.112 (2.84)
0.038 (0.97)
0.030 (0.76)
10 6
PIN 1
0.0197 (0.50) BSC
0.122 (3.10)
0.110 (2.79)
0.006 (0.15)
0.002 (0.05)
51
0.016 (0.41)
0.006 (0.15)
0.199 (5.05)
0.187 (4.75)
0.043 (1.09)
0.037 (0.94)
SEATING
PLANE
0.011 (0.28)
0.003 (0.08)
0.120 (3.05)
0.112 (2.84)
6
8
0
8
C3444–2–3/99
0.022 (0.56)
0.021 (0.53)
–6–
PRINTED IN U.S.A.
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