Datenblatt-pdf.com


ADM202E Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADM202E
Beschreibung RS-232 Line Drivers/Receivers
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 16 Seiten
ADM202E Datasheet, Funktion
EMI/EMC-Compliant, ±15 kV, ESD-Protected
RS-232 Line Drivers/Receivers
ADM202E/ADM1181A
FEATURES
Complies with 89/336/EEC EMC directive
ESD protection to IEC1000-4-2 (801.2)
±8 kV: contact discharge
±15 kV: air-gap discharge
±15 kV: human body model
EFT fast transient/burst immunity (IEC1000-4-4)
Low EMI emissions (EN55022)
230 kbits/s data rate guaranteed
TSSOP package option
Upgrade for MAX202E, 232E, LT1181A
APPLICATIONS
General-purpose RS-232 data link
Portable instruments
PDAs
GENERAL DESCRIPTION
The ADM202E and ADM1181A are robust, high speed,
2-channel RS-232/V.28 interface devices that operate from a
single 5 V power supply. Both products are suitable for operation
in harsh electrical environments and are compliant with the EU
directive on EMC (89/336/EEC). Both the level of electromagnetic
emissions and immunity are in compliance. EM immunity
includes ESD protection in excess of ±15 kV on all I/O lines,
fast transient/burst protection (1000-4-4), and radiated
immunity (1000-4-3). EM emissions include radiated and
conducted emissions as required by Information Technology
Equipment EN55022, CISPR22.
The ADM202E and ADM1181A conform to the EIA-232E
and CCITT V.28 specifications and operate at data rates up
to 230 kbps.
Four external 0.1 µF charge-pump capacitors are used for the
voltage doubler/inverter, permitting operation from a single
5 V supply.
FUNCTIONAL BLOCK DIAGRAMS
5V INPUT
0.1µF
10V
0.1µF
10V
C1+ +5V TO +10V VCC
VOLTAGE
C1– DOUBLER V+
C2+ +10V TO –10V V–
VOLTAGE
C2– INVERTER
C3
0.1µF
6.3V
C4
0.1µF
10V
C5
0.1µF
CMOS
INPUTS
T1IN
T2IN
T1
T2
T1OUT
T2OUT
EIA/TIA-232
OUTPUTS
CMOS
OUTPUTS
R1OUT
R2OUT
R1
R2
R1IN
R2IN
EIA/TIA-232
INPUTS*
GND ADM202E
*INTERNAL 5kPULL-DOWN RESISTOR ON EACH RS-232 INPUT
Figure 1.
5V INPUT
0.1µF
10V
0.1µF
10V
CMOS
INPUTS
T1IN
T2IN
C1+
+5V TO +10V
VOLTAGE
VCC
C1– DOUBLER V+
C2+ +10V TO –10V V–
VOLTAGE
C2– INVERTER
T1
T2
C5
0.1µF
C3
0.1µF
10V
C4 10V
0.1µF
10V
T1OUT
T2OUT
EIA/TIA-232
OUTPUTS
CMOS
OUTPUTS
R1OUT
R2OUT
R1
R2
GND ADM1181A
R1IN
R2IN
EIA/TIA-232
INPUTS*
*INTERNAL 5kPULL-DOWN RESISTOR ON EACH RS-232 INPUT
Figure 2.
The ADM202E provides a robust pin-compatible upgrade for
existing ADM202, ADM232L, or MAX202E/MAX232E sockets.
It is available in a 16-lead PDIP, a wide SOIC, a narrow SOIC,
and a space-saving TSSOP package that is 44% smaller than the
SOIC package.
The ADM1181A provides a robust pin-compatible upgrade for
the LTC1181A, and it is available in a 16-lead PDIP package
and a wide 16-lead SOIC package.
Rev. C
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 that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703 © 2005 Analog Devices, Inc. All rights reserved.






ADM202E Datasheet, Funktion
ADM202E/ADM1181A
GENERAL DESCRIPTION
The ADM202E/ADM1181E are rugged 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 5 V supply.
Features include low power consumption, high transmission
rates, and compliance with the EU directive on electromagnetic
compatibility. EM compatibility includes protection against
radiated and conducted interference, including high levels of
electrostatic discharge.
All inputs and outputs contain protection against electrostatic
discharges of up to ±15 kV and electrical fast transients of up
to ±2 kV. This ensures compliance to IEC1000-4-2 and
IEC1000-4-4 requirements.
The devices are ideally suited for operation in electrically harsh
environments or where RS-232 cables are frequently being
plugged/unplugged. They are also immune to high RF field
strengths without special shielding precautions.
CMOS technology is used to minimize the power dissipation,
allowing maximum battery life in portable applications.
The ADM202E/ADM1181A serve as a modification,
enhancement, and improvement to the ADM230–ADM241
family and its derivatives. It is essentially plug-in compatible
and do not have materially different applications.
CIRCUIT DESCRIPTION
The internal circuitry consists of four main sections:
A charge-pump voltage converter
5 V logic to EIA-232 transmitters
EIA-232 to 5 V logic receivers.
Transient protection circuit on all I/O lines
Charge-Pump DC-to-DC Voltage Converter
The charge-pump voltage converter consists of a 200 kHz
oscillator and a switching matrix. The converter generates a
±10 V supply from the input 5 V level. This is done in two stages,
using a switched capacitor technique, as illustrated in Figure 6
and Figure 7. First, the 5 V input supply is doubled to 10 V, using
Capacitor C1 as the charge storage element. The 10 V level is
then inverted to generate −10 V, using C2 as the storage element.
Capacitor C3 and Capacitor C4 are used to reduce the output
ripple. Their values are not critical and can be increased if
desired. On the ADM202E, Capacitor C3 is shown connected
between V+ and VCC, whereas it is connected between V+ and
GND on the ADM1181A. It is acceptable to use either
configuration with both the ADM202E and ADM1181A. If
desired, larger capacitors (up to 47 µF) can be used for
Capacitor C1 to Capacitor C4. This facilitates direct substitution
with older generation charge-pump RS-232 transceivers.
VCC
S1
GND
C1
S2
S3
C3
S4
V+ = 2VCC
VCC
INTERNAL
OSCILLATOR
NOTE: C3 CONNECTS BETWEEN V+ AND GND ON THE ADM1181A
Figure 6. Charge-Pump Voltage Doubler
V+
FROM
VOLTAGE
DOUBLER
GND
S1
C2
S2
S3
C4
S4
INTERNAL
OSCILLATOR
Figure 7. Charge-Pump Voltage Inverter
GND
V– = –(V+)
Transmitter (Driver) Section
The drivers convert 5 V logic input levels into RS-232 output
levels. When driving an RS-232 load with VCC = 5 V, the output
voltage swing is typically ±9 V.
Receiver Section
The receivers are inverting level shifters that accept RS-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 ±30 V. Unconnected
inputs are pulled to 0 V by the internal 5 kΩ pull-down resistor.
Therefore, unconnected inputs and those connected to GND
have a Logic 1 output level.
The receivers have Schmitt-trigger inputs with a hysteresis level
of 0.65 V. This ensures error-free reception for both noisy
inputs and inputs with slow transition times.
HIGH BAUD RATE
The ADM202E/ADM1181A feature high slew rates, permitting
data transmission at rates well in excess of the EIA/RS-232-E
specifications. RS-232 voltage levels are maintained at data rates
of up to 230 kbps, even under worst case loading conditions.
This allows for high speed data links between two terminals and
is also suitable for the new generation ISDN modem standards,
which require data rates of 230 kbps. The slew rate is internally
controlled to less than 30 V/µs to minimize EMI interference.
Rev. C | Page 6 of 16

6 Page









ADM202E pdf, datenblatt
ADM202E/ADM1181A
IEC1000-4-3 RADIATED IMMUNITY
IEC1000-4-3 (previously IEC801-3) describes the measure-
ment method and defines the levels of immunity to radiated
electromagnetic fields. It was originally intended to simulate the
electromagnetic fields generated by portable radio transceivers
and other devices that generate continuous wave-radiated
electromagnetic energy. Its scope has since been broadened to
include spurious EM energy, which can be radiated from
fluorescent lights, thyristor drives, inductive loads, and
other sources.
Testing for immunity involves irradiating the device with an
EM field. There are various methods of achieving this, including
use of anechoic chamber, stripline cell, TEM cell, and GTEM
cell. A stripline cell consists of two parallel plates with an electric
field developed between them. The device being tested is placed
within the cell and exposed to the electric field. There are three
severity levels that have field strengths ranging from 1 V to
10 V/m. Results are classified in a similar fashion to those for
IEC1000-4-2.
Classification 1: Normal operation
Classification 2: Temporary degradation or loss of
function that is self-recoverable when the interfering
signal is removed
Classification 3: Temporary degradation or loss of function
that requires operator intervention or system reset when
the interfering signal is removed
Classification 4: Degradation or loss of function that is not
recoverable due to damage
The ADM202E/ADM1181A products easily meet Classification 1
at the most stringent (Level 3) requirement. In fact, field strengths
of up to 30 V/m showed no performance degradation, and error-
free data transmission continued even during irradiation.
Table 6. Test Severity Levels (IEC1000-4-3)
Level
Field Strength V/m
11
23
3 10
CONDUCTED EMISSIONS
Conducted emissions is a measure of noise conducted onto the
mains power supply. Switching transients from the charge pump
that are 20 V in magnitude and that contain significant energy
can lead to conducted emissions. Another source of conducted
emissions is the overlap in switch-on times in the charge-pump
voltage converter. In the voltage doubler shown in Figure 23, if
S2 is not fully turned off before S4 turns on, a transient current
glitch occurs between VCC and GND that results in conducted
emissions. Therefore, it is important that the switches in the
charge pump guarantee break-before-make switching under all
conditions to prevent instantaneous short-circuit conditions.
The ADM202E is designed to minimize the switching transients
and ensure break-before-make switching, thereby minimizing
conducted emissions. This results in emission levels well below
the specified limits. No additional filtering or decoupling, other
than the recommended 0.1 µF capacitor, is required.
Conducted emissions are measured by monitoring the mains
line. The equipment used consists of a spectrum analyzer and a
LISN (line impedance stabilizing network) that essentially
presents a fixed impedance at RF. The spectrum analyzer scans
for emissions of up to 30 MHz; a plot for the ADM202E is
shown in Figure 25.
VCC
S1
GND
C1
S2
S3
C3
S4
V+ = 2VCC
VCC
INTERNAL
OSCILLATOR
Figure 23. Charge-Pump Voltage Doubler
1
2
SWITCHING GLITCHES
EMISSIONS/INTERFERENCE
EN55 022 and CISPR22 define the permitted limits of radiated
and conducted interference from information technology (IT)
equipment. The objective of the standard is to minimize the
level of emissions, both conducted and radiated. For ease of
measurement and analysis, conducted emissions are assumed to
predominate below 30 MHz, and radiated emissions are
assumed to predominate above 30 MHz.
Rev. C | Page 12 of 16
Figure 24. Switching Glitches

12 Page





SeitenGesamt 16 Seiten
PDF Download[ ADM202E Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
ADM202CMOS RS-232 Driver/ReceiverAnalog Devices
Analog Devices
ADM202ERS-232 Line Drivers/ReceiversAnalog Devices
Analog Devices

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche