AD202JN ,Low Cost, Miniature Isolation AmplifiersSPECIFICATIONS SModel AD204J AD204K AD202J AD202KGAINRange 1 V/V–100 V/V * * *Error ±0.5% typ (±4% ..
AD202JY ,Low Cost, Miniature Isolation AmplifiersGENERAL DESCRIPTIONand low drift over temperature, the AD202 and AD204 provideThe AD202 and AD204 a ..
AD202KN ,Low Cost, Miniature Isolation AmplifiersGENERAL DESCRIPTIONand low drift over temperature, the AD202 and AD204 provideThe AD202 and AD204 a ..
AD202KY ,Low Cost, Miniature Isolation AmplifiersSpecifications same as AD204J.1Nonlinearity is specified as a % deviation from a best straight line ..
AD203SN ,Rugged, Military Temperature Range, 10 kHz Bandwidth Isolation AmplifierSPECIFICATIONS (typical @ +NT, ll, = +15 ll d/ses, 5therwise noted)
GAIN
Range
Error
vs. Temp ..
AD204JN ,Low Cost, Miniature Isolation AmplifiersSpecifications subject to change without notice.1 +INPUTAD246 Pin Designations2 INPUT/V COMMONISO3 ..
AD8403AN10 ,1-/2-/4-Channel Digital PotentiometersSpecifications Apply to All VRsResolution N 8 Bits4Integral Nonlinearity INL –4 ±1 +4 LSB4Different ..
AD8403AN100 ,1-/2-/4-Channel Digital PotentiometersSpecifications Apply to All VRs2Resistor Differential NL R-DNL R , V = NC –1 ±1/4 +1 LSBWB A2Resist ..
AD8403AN50 ,1-/2-/4-Channel Digital PotentiometersSpecifications Apply to All VRs2Resistor Differential NL R-DNL R , V = NC –1 ±1/4 +1 LSBWB A2Resist ..
AD8403AR1 ,1-/2-/4-Channel Digital PotentiometersCHARACTERISTICSBandwidth –3 dB BW_10K R = 10 kΩ 600 kHzTotal Harmonic Distortion THD V = 1 V rms + ..
AD8403AR1 ,1-/2-/4-Channel Digital PotentiometersFEATURES FUNCTIONAL BLOCK DIAGRAM256 PositionReplaces 1, 2 or 4 PotentiometersRDAC11 kV, 10 kV, 50 ..
AD8403AR-1 ,1-/2-/4-Channel Digital PotentiometersSpecifications Apply to All VRsResolution N 8 Bits4Integral Nonlinearity INL –4 ±1 +4 LSB4Different ..
AD202JN-AD202JY-AD202KN-AD202KY-AD204JN-AD204JY-AD204KN-AD204KN ..-AD204KY-AD246JY
Low Cost, Miniature Isolation Amplifiers
FUNCTIONAL BLOCK DIAGRAMLow Cost, Miniature
Isolation AmplifiersREV.B
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 DESCRIPTIONThe 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/dc converter. This permits the designer to
minimize the necessary circuit overhead and consequently re-
duce 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 un-
committed op amp on the input stage. They feature a bipolar
±5 V output range, an adjustable gain range of from 1 to 100 V/V,0.025% max nonlinearity (K grade), 130 dB of CMR and the
AD204 consumes a low 35 mW of power.
PRODUCT HIGHLIGHTSThe AD202 and AD204 are full-featured isolators offering
numerous benefits to the user:
Small Size: The AD202 and AD204 are available in SIP andDIP 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 spac-
ing. 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
applications 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 μA 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 filter-
ing, summing, high-voltage ranges, and current (transimped-
ance) 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 to
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.
VSIG
IN COMPOWER
RETURN
+15V DC
VOUT–VISO OUT
+VISO OUT
(typical @ + 25°C & VS = +15 V unless otherwise noted)AD202/AD204–SPECIFICATIONSFREQUENCY RESPONSE
TEMPERATURE RANGE
PIN DESIGNATIONS
AD202/AD204 SIP Package
Pin
AD202/AD204 DIP Package
Pin
AD246–SPECIFICATIONS
(typical @ +25°C & VS = +15 V unless otherwise noted)NOTES
*Specifications the same as the AD246JY.The high current drive output will not support a short to ground.
Specifications subject to change without notice.
AD246 Pin Designations
Pin (Y)
ORDERING GUIDE
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
accumulate on the human body and test equipment and can discharge without detection.
Although the AD202/AD204 features proprietary ESD protection circuitry, permanent damage
AD202/AD204
DIFFERENCES BETWEEN THE AD202 AND AD204The primary distinction between the AD202 and AD204 is in
the method by which they are powered: the AD202 operates
directly from +15 V dc while the AD204 is powered by a non-
isolated externally-supplied clock (AD246) which can drive up
to 32 AD204s. The main advantages of using the externally-
clocked AD204 over the AD202 are reduced cost in multichannel
applications, lower power consumption, and higher bandwidth.
In addition, the AD204 can supply substantially more isolated
power than the AD202.
Of course, in a great many situations, especially where only one
or a few isolators are used, the convenience of stand-alone op-
eration provided by the AD202 will be more significant than any
of the AD204’s advantages. There may also be cases where it is
desirable to accommodate either device interchangeably, so the
pinouts of the two products have been designed to make that
easy to do.
VSIG
IN COMPOWER
RETURN
+15V DC
VOUT–VISO OUT
+VISO OUTFigure 1a.AD202 Functional Block Diagram
VSIG
IN COMPOWER
RETURN
(15V
p-p/25kHz)
VOUT–VISO OUT
+VISO OUT
CLOCKFigure 1b.AD204 Functional Block Diagram
(Pin Designations Apply to the DIP-Style Package)
INSIDE THE AD202 AND AD204The AD202 and AD204 use an amplitude modulation technique
to permit transformer coupling of signals down to dc (Figure 1a
and 1b). Both models also contain an uncommitted input op
amp and a power transformer which provides isolated power to
the op amp, the modulator, and any external load. The power
transformer primary is driven by a 25 kHz, 15 V p-p square
wave which is generated internally in the case of the AD202, or
supplied externally for the AD204.
Within the signal swing limits of approximately ±5 V, the output
voltage of the isolator is equal to the output voltage of the op
amp; that is, the isolation barrier has unity gain. The output sig-
nal is not internally buffered, so the user is free to interchange
output resistance of the isolator is typically 3 kΩ for the AD204
(7 kΩ for AD202) and varies with signal level and temperature,
so it should not be loaded (see Figure 2 for the effects of load
upon nonlinearity and gain drift). In many cases a high-imped-
ance load will be present or a following circuit such as an output
filter can serve as a buffer, so that a separate buffer function will
not often be needed.
Figure 2.Effects of Output Loading
USING THE AD202 AND AD204
Powering the AD202. The AD202 requires only a single +15 Vpower supply connected as shown in Figure 3a. A bypass ca-
pacitor is provided in the module.
Figure 3a.
Powering the AD204. The AD204 gets its power from an ex-ternally supplied clock signal (a 15 V p-p square wave with a
nominal frequency of 25 kHz) as shown in Figure 3b.
Figure 3b.
AD246 Clock Driver. The AD246 is a compact, inexpensiveclock 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.
The “noninverting” circuit of Figures 5 and 6 can also be used
to 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 condi-
tions, the 2 kΩ resistor shown in series with IN+ should be used
to limit current to a safe value. This is particularly important
with the AD202, which may not start if a large input current is
present.
Figure 7 shows how to accommodate current inputs or sum cur-
rents 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 k and RS = 200 k. Once again, a capacitor from FB to IN
COM is required for gains above five.
Figure 7.Connections for Summing or Current Inputs
Adjustments. When gain and zero adjustments are needed, thecircuit details will depend on whether adjustments are to be
made at the isolator input or output, and (for input adjust-
ments) on the input circuit used. Adjustments are usually best
done on the input side, because it is better to null the zero
ahead of the gain, and because gain adjustment is most easily
done as part of the gain-setting network. Input adjustments are
also to be preferred when the pots will be near the input end of
the isolator (to minimize common-mode strays). Adjustments
on the output side might be used if pots on the input side would
represent a hazard due to the presence of large common-mode
voltages during adjustment.
Figure 8a shows the input-side adjustment connections for use
with the “noninverting” connection of the input amplifier. The
zero adjustment circuit injects a small adjustment voltage in
series with the low side of the signal source. (This will not work
if the source has another current path to input common or if
current flows in the signal source LO lead). Since the adjust-
ment voltage is injected ahead of the gain, the values shown will
AD204s are operated from a single AD246, an external bypass
capacitor should be used with a value of at least 1 μF for every
five isolators used. Place the capacitor as close as possible to the
clock driver.
Figure 4.Clock Driver
Input Configurations. The AD202 and AD204 have been de-signed 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
Figure 5.Basic Unity-Gain Application
handled, Figure 6 shows how to get gain while preserving a very
high input resistance. The value of feedback resistor RF should
be kept above 20 kΩ 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.
