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.
a
ADM101E
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., 2001
Craft Port
TM
Tiny RS-232 Transceiver for
Portable Applications
FUNCTIONAL BLOCK DIAGRAM
VCC
GND
V– SD
TIN
1
2
3
4
10
9
8
7
C1– C1+
TOUT
56
ROUT RIN
R1
T1
+5V TO –5V
VOLTAGE
INVERTER
0.1F
0.1F
5V
0.1F
+
+
+
ADM101E
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
4.2 V Output Swing with 5 V Supply
Low Power BiCMOS: 500 A ICC
Ultralow Power (1 A) Shutdown Mode
10-Lead SOIC Package
APPLICATIONS
Mobile Telephones
Palmtop Computers
PDAs
Portable Instrumentation
GPS Receivers
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 consump-
tion 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 com-
pact size and low power drain are paramount.
REV. A
–2–
ADM101E–SPECIFICATIONS
(VCC = 5 V 10%, C1 = C2 = 0.1 F. All specifications TMIN to TMAX unless
otherwise noted.)
Parameter Min Typ Max Unit Test Conditions/Comments
Output Voltage Swing ±3.5 ±4.2 V V
CC
= 5 V ±5%, T
OUT
Loaded with 3 kΩ to GND
±3.25 ±4.2 V V
CC
= 5 V ±10%, T
OUT
Loaded with 3 kΩ to
GND
V
CC
Power Supply Current (Unloaded) 0.5 1 mA No Load, T
IN
= V
CC
or GND
V
CC
Power Supply Current (Loaded) 1.85 2.5 mA T
OUT
Loaded with 3 kΩ to GND
V
CC
Power Supply Current (Shutdown) 1 µA SD Input = V
CC
Input Logic Threshold Low, V
INL
0.8 V
Input Logic Threshold High, V
INH
2.4 V
Input Leakage Current ±1µA
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
OL
0.4 V I
OUT
= 1.6 mA
TTL/CMOS Output Voltage High, V
OH
3.5 V I
OUT
= –1.0 mA
Propagation Delay 0.25 µs RS-232 to TTL
Instantaneous Slew Rate
1
25 V/µsC
L
= 10 pF, R
L
= 3 kΩ–7 kΩ, T
A
= 25°C
Transition Region Slew Rate 11 V/µsR
L
= 3 kΩ, C
L
= 1000 pF
Measured from +3 V to –3 V or Vice Versa
Baud Rate 460 kB R
L
= 3 kΩ, C
L
= 1 nF
Output Resistance 300 ΩV
CC
= 0 V, V
OUT
= ±2 V
RS-232 Output Short Circuit Current ±25 ±60 mA
NOTES
1
Sample tested to ensure compliance.
Specifications subject to change without notice.
ABSOLUTE MAXIMUM RATINGS*
(T
A
= 25°C unless otherwise noted)
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
V– . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to –6 V
Input Voltages
Driver Input T
IN
. . . . . . . . . . . . . . –0.3 V to (V
CC
, +0.3 V)
Receiver Input R
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . ±30 V
Output Voltages
Driver Output T
OUT
. . . . . . . (V
CC
, +0.3 V) to (V–, –0.3 V)
Receiver Output R
OUT
. . . . . . . . . . –0.3 V to (V
CC
+0.3 V)
Short Circuit Duration
T
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
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°CµSOIC RM-10
REV. A
ADM101E
–3–
PIN FUNCTION DESCRIPTIONS
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
IN
Receiver Input (EIA-232 Signal Levels).
7T
OUT
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.
PIN CONFIGURATION
GND
V–SD
TIN
1
2
3
4
10
9
8
7
ADM101E
TOP VIEW
(Not to Scale)
C1–C1+
TOUT
56
ROUT RIN
VCC
Typical Performance Characteristics
CURRENT – mA
0
–1
–60255
CHARGE PUMP VOLTAGE – Volts
10 15 20
–2
–3
–4
–5
TPC 1. Charge Pump Voltage vs. Current
LOAD CAPACITANCE – pF
14
12
00 3500500
I
DD
– mA
1000 1500 2000
10
8
6
4
2500 3000
2
TPC 2. I
DD
vs. Load Capacitance @ 460 kbps
REV. A
ADM101E
–4–
LOAD CAPACITANCE – pF
6
5
–5
0 500
T
X
O/P – Volts
1000 1500 2000
4
3
2
1
2500
0
–1
–2
–3
–4
T
X
HI
T
X
LO
TPC 3. Transmitter Output Voltage vs. Load Capacitance @
460 kbps
VCC – Volts
6
–6
01
TXO/P HI & LO
23 4
4
2
5
0
–2
–4
TX HI
TX LO
67
TPC 4. Tx Output Voltage vs. Supply
DATA RATE – kb
p
s
40
–40
0 100
SLEW RATE – Volts/s
200 300 400
30
20
10
0
–10
500 600
–20
–30
SERIES 1
SERIES 2
TPC 5. Slew Rate vs. Data Rate
LOAD CURRENT – mA
5
–502
T
X
OUTPUT VOLTAGE
468
4
3
2
1
0
10 12
–1
–2
T
X
LO
–3
–4
14
T
X
HI
TPC 6. Transmitter Output Voltage vs. Load Current
REV. A
ADM101E
–5–
GENERAL DESCRIPTION
The ADM101E is an RS-232 compatible line driver/receiver in
the Analog Devices Craft Port
series, containing one driver (trans-
mitter) and one receiver. It is ideal for serial communication in
small portable devices such as mobile telephones, palmtop per-
sonal 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 1.
INTERNAL
OSCILLATOR
GND
C2
C1
S1
S2
S3
S4
VCC GND
V– = –VCC
+
+
Figure 1. Charge Pump DC–DC Converter
When S1 and S2 are closed, S3 and S4 are open, and C1
charges to +V
CC
. S1 and S2 are then opened, while S3 and S4
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
CC
, but will
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
CC
, the V
CC
decou-
pling capacitor should also have low ESR. The V
CC
decoupling
capacitor and V– reservoir capacitor should also have low ESR
because they determine how effectively ESD pulses are clamped
to V
CC
or V– by the on-chip clamp diodes. Tantalum or mono-
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 compat-
ible output levels. With V
CC
= 5 V and driving an EIA-232 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 con-
nected 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.
REV. A
ADM101E
–6–
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
C00053–0–2/01 (rev. A)
PRINTED IN U.S.A.
10-Lead SOIC
(RM-10)
0.120 (3.05)
0.112 (2.85)
6
00.028 (0.70)
0.016 (0.40)
0.009 (0.23)
0.005 (0.13)
10 6
51
0.0197 (0.50) BSC
0.122 (3.10)
0.114 (2.90)
0.199 (5.05)
0.187 (4.75)
PIN 1
0.122 (3.10)
0.114 (2.90)
0.012 (0.30)
0.006 (0.15)
0.037 (0.94)
0.031 (0.78)
SEATING
PLANE
0.120 (3.05)
0.112 (2.85)
0.043 (1.10)
MAX
0.006 (0.15)
0.002 (0.05)
ADM101E–Revision History
Location Page
Data sheet changed from REV. 0 to REV. A.
Changes made to Outline Dimensions (RM-10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
