AD202 Datasheet PDF - Analog Devices
| Part Number | AD202 | |
| Description | Low Cost / Miniature Isolation Amplifiers | |
| Manufacturers | Analog Devices | |
| Logo |  |
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a
Low Cost, Miniature
Isolation Amplifiers
AD202/AD204
FEATURES
Small Size: 4 Channels/lnch
Low Power: 35 mW (AD204)
High Accuracy: ؎0.025% Max Nonlinearity (K Grade)
High CMR: 130 dB (Gain = 100 V/V)
Wide Bandwidth: 5 kHz Full-Power (AD204)
High CMV Isolation: ؎2000 V pk Continuous (K Grade)
(Signal and Power)
Isolated Power Outputs
Uncommitted Input Amplifier
APPLICATIONS
Multichannel Data Acquisition
Current Shunt Measurements
Motor Controls
Process Signal Isolation
High Voltage Instrumentation Amplifier
GENERAL DESCRIPTION
The AD202 and AD204 are general purpose, two-port, trans-
former-coupled isolation amplifiers that may be used in a broad
range of applications where input signals must be measured,
processed, and/or transmitted without a galvanic connection.
These industry standard isolation amplifiers offer a complete
isolation function, with both signal and power isolation provided
for in a single compact plastic SIP or DIP style package. The
primary distinction between the AD202 and the AD204 is that
the AD202 is powered directly from a 15 V dc supply while the
AD204 is powered by an externally supplied clock, such as the
recommended AD246 Clock Driver.
The AD202 and AD204 provide total galvanic isolation between
the input and output stages of the isolation amplifier through
the use of internal transformer-coupling. The functionally com-
plete AD202 and AD204 eliminate the need for an external,
user-supplied dc-to-dc converter. This permits the designer
to minimize the necessary circuit overhead and consequently
reduce the overall design and component costs.
The design of the AD202 and AD204 emphasizes maximum
flexibility and ease of use, including the availability of an
uncommitted op amp on the input stage. They feature a bipolar
± 5 V output range, an adjustable gain range of from 1V/V to
100 V/V, ± 0.025% max nonlinearity (K grade), 130 dB of
CMR, and the AD204 consumes a low 35 mW of power.
The functional block diagrams can be seen in Figures 1a and 1b.
PRODUCT HIGHLIGHTS
The AD202 and AD204 are full-featured isolators offering
numerous benefits to the user:
Small Size: The AD202 and AD204 are available in SIP and
DIP form packages. The SIP package is just 0.25" wide, giving
the user a channel density of four channels per inch. The isolation
barrier is positioned to maximize input to output spacing. For
applications requiring a low profile, the DIP package provides a
height of just 0.350".
High Accuracy: With a maximum nonlinearity of ± 0.025%
for the AD202K/AD204K (± 0.05% for the AD202J/AD204J)
and low drift over temperature, the AD202 and AD204 provide
high isolation without loss of signal integrity.
Low Power: Power consumption of 35 mW (AD204) and
75 mW (AD202) over the full signal range makes these isolators
ideal for use in applications with large channel counts or tight
power budgets.
Wide Bandwidth: The AD204’s full-power bandwidth of 5 kHz
makes it useful for wideband signals. It is also effective in appli-
cations like control loops, where limited bandwidth could result
in instability.
Excellent Common-Mode Performance: The AD202K/
AD204K provide ± 2000 V pk continuous common-mode isola-
tion, while the AD202J/AD204J provide ± 1000 V pk continuous
common-mode isolation. All models have a total common-mode
input capacitance of less than 5 pF inclusive of power isolation.
This results in CMR ranging from 130 dB at a gain of 100 dB to
104 dB (minimum at unity gain) and very low leakage current
(2 mA maximum).
Flexible Input: An uncommitted op amp is provided at the
input of all models. This provides buffering and gain as required,
and facilitates many alternative input functions including filtering,
summing, high voltage ranges, and current (transimpedance) input.
Isolated Power: The AD204 can supply isolated power of
± 7.5 V at 2 mA. This is sufficient to operate a low-drift input
preamp, provide excitation to a semiconductor strain gage, or
power any of a wide range of user-supplied ancillary circuits.
The AD202 can supply ± 7.5 V at 0.4 mA, which is sufficient to
operate adjustment networks or low power references and op
amps, or to provide an open-input alarm.
REV. D
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. 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
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
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AD202/AD204
AD246 Clock Driver. The AD246 is a compact, inexpensive
clock driver that can be used to obtain the required clock from a
single 15 V supply. Alternatively, the circuit shown in Figure 4
(essentially an AD246) can be used. In either case, one clock
circuit can operate at least 32 AD204s at the rated minimum
supply voltage of 14.25 V and one additional isolator can be
operated for each 40 mV increase in supply voltage up to 15 V.
A supply bypass capacitor is included in the AD246, but if many
AD204s are operated from a single AD246, an external bypass
capacitor should be used with a value of at least 1 mF for every
five isolators used. Place the capacitor as close as possible to the
clock driver.
14 6 5
6
180pF
1C
3 RC
2
R
49.9k⍀
CD
4047B
TELEDYNE 1N914
TSC426
10 2
Q
7
45
12 9 8 7 4
1N914
3
15V
CLK
OUT
+ 1F
35V
CLK AND
PWR COM
Figure 4. Clock Driver
Input Configurations. The AD202 and AD204 have been
designed to be very easy to use in a wide range of applications.
The basic connection for standard unity gain applications, useful
for signals up to ± 5 V, is shown in Figure 5; some of the possible
variations are described below. When smaller signals must be
handled, Figure 6 shows how to achieve gain while preserving a
very high input resistance. The value of feedback resistor RF
should be kept above 20 kW for best results. Whenever a gain of
more than five is taken, a 100 pF capacitor from FB to IN COM
is required. At lower gains this capacitor is unnecessary, but it
will not adversely affect performance if used.
2k⍀
(SEE TEXT)
VSIG
(؎5V)
FB
IN–
IN+
IN COM
OUT
HI
OUT
LO
AD202
OR
AD204
VOUT
؎5V
15V OR
CLOCK
100pF
2k⍀
VSIG
RF
RG
AD202
OR
AD204
VO
( )VO = V SIG ؋ 1 + –RR–GF–
RF 20k⍀
Figure 6. Input Connections for Gain > 1
The noninverting circuit of Figures 5 and 6 can also be used to
your advantage when a signal inversion is needed: just interchange
either the input leads or the output leads to get inversion. This
approach retains the high input resistance of the noninverting
circuit, and at unity gain no gain-setting resistors are needed.
When the isolator is not powered, a negative input voltage of
more than about 2 V will cause an input current to flow. If the
signal source can supply more than a few mA under such con-
ditions, the 2 kW resistor shown in series with IN+ should be
used to limit current to a safe value. This is particularly impor-
tant with the AD202, which may not start if a large input current
is present.
Figure 7 shows how to accommodate current inputs or sum
currents or voltages. This circuit can also be used when the
input signal is larger than the ± 5 V input range of the isolator;
for example, a ± 50 V input span can be accommodated with
RF = 20 kW and RS = 200 kW. Once again, a capacitor from FB
to IN COM is required for gains above five.
IS
RS2
VS2 RS1
VS1
RF
AD202
OR
AD204
V
( )V = – VS1 –RR–SF–1 + V S2 –RR–SF–2 + IS RF + ...
RF 20k⍀
Figure 7. Connections for Summing or Current Inputs
Figure 5. Basic Unity-Gain Application
REV. D
(NOTE: Circuit figures shown on this page are for SIP-style packages. Refer to
Page 3 for proper DIP package pinout.)
–5–
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for AD202 electronic component. |
| Information | Total 12 Pages | |
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