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Low-Cost, Miniature |
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Isolation Amplifiers |
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AD202/AD204 |
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FEATURES
Small Size: Four 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
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 complete 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 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 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.
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
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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
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AD202 |
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IN– |
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SIGNAL |
DEMOD |
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HI |
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MOD |
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IN+ |
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5V |
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5V |
VOUT |
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VSIG |
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IN COM |
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+VISO OUT |
+7.5V |
RECT |
POWER |
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OSCILLATOR |
15V DC |
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–7.5V |
AND |
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–VISO OUT |
FILTER |
25kHz |
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25kHz |
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POWER |
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RETURN |
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 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 isolation, 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 A 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 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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 |
World Wide Web Site: www.analog.com |
Fax: 781/326-8703 |
© Analog Devices, Inc., 2001 |
AD202/AD204–SPECIFICATIONS(Typical @ 25 C and VS = 15 V unless otherwise noted.)
Model |
AD204J |
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AD204K |
AD202J |
AD202K |
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GAIN |
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Range |
1 V/V–100 V/V |
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Error |
± 0.5% typ (± 4% max) |
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vs. Temperature |
± 20 ppm/°C typ (± 45 ppm/°C max) |
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vs. Time |
± 50 ppm/1000 Hours |
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vs. Supply Voltage |
± 0.01%/V |
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± 0.01%/V |
± 0.01%/V |
± 0.01%/V |
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Nonlinearity (G = 1 V/V)1 |
± 0.05% max |
± 0.025% max |
± 0.05% max |
± 0.025% max |
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Nonlinearity vs. Isolated Supply Load |
± 0.0015%/mA |
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INPUT VOLTAGE RATINGS |
± 5 V |
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Input Voltage Range |
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Max lsolation Voltage (Input to Output) |
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AC, 60 Hz, Continuous |
750 V rms |
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1500 V rms |
750 V rms |
1500 V rms |
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Continuous (AC and DC) |
± 1000 V Peak |
± 2000 V Peak |
± 1000 V Peak |
± 2000 V Peak |
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Isolation-Mode Rejection Ratio (IMRR) @ 60 Hz |
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RS ≤ 100 Ω (HI & LO Inputs) G = 1 V/V |
110 dB |
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110 dB |
105 dB |
105 dB |
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G = 100 V/V |
130 dB |
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RS ≤ l kΩ (Input HI, LO, or Both) G = 1 V/V |
104 dB min |
104 dB min |
100 dB min |
100 dB min |
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G = 100 V/V |
110 dB min |
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Leakage Current Input to Output @ 240 V rms, 60 Hz |
2 µA rms max |
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INPUT IMPEDANCE |
1012 Ω |
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Differential (G = 1 V/V) |
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Common-Mode |
2 GΩ 4.5 pF |
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INPUT BIAS CURRENT |
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Initial, @ 25°C |
± 30 pA |
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vs. Temperature (0°C to 70°C) |
± 10 nA |
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INPUT DIFFERENCE CURRENT |
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Initial, @ 25°C |
± 5 pA |
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vs. Temperature (0°C to 70°C) |
± 2 nA |
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INPUT NOISE |
4 µV p-p |
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Voltage, 0.1 Hz to 100 Hz |
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f > 200 Hz |
50 nV/√Hz |
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FREQUENCY RESPONSE |
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Bandwidth (VO ≤ 10 V p-p, G = 1 V–50 V/V) |
5 kHz |
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5 kHz |
2 kHz |
2 kHz |
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Settling Time, to ± 10 mV (10 V Step) |
1 ms |
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OFFSET VOLTAGE (RTI) |
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Initial, @ 25°C Adjustable to Zero |
(± 15 ± 15/G)mV max |
(± 5 ± 5/G)mV max |
(± 15 ± 15/G)mV max |
(± 5 ± 5/G)mV max |
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vs. Temperature (0°C to 70°C) |
±10 |
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RATED OUTPUT |
± 5 V |
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Voltage (Out HI to Out LO) |
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Voltage at Out HI or Out LO (Ref. Pin 32) |
± 6.5 V |
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Output Resistance |
3 kΩ |
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3 kΩ |
7 kΩ |
7 kΩ |
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Output Ripple, 100 kHz Bandwidth |
10 mV p-p |
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5 kHz Bandwidth |
0.5 mV rms |
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ISOLATED POWER OUTPUT2 |
± 7.5 V |
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Voltage, No Load |
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Accuracy |
± 10% |
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Current |
2 mA (Either Output)3 |
2 mA (Either Output)3 |
400 µA Total |
400 µA Total |
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Regulation, No Load to Full Load |
5% |
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Ripple |
100 mV p-p |
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OSCILLATOR DRIVE INPUT |
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Input Voltage |
15 V p-p Nominal |
15 V p-p Nominal |
N/A |
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Input Frequency |
25 kHz Nominal |
25 kHz Nominal |
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N/A |
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POWER SUPPLY (AD202 Only) |
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15 V ± 5% |
15 V ± 5% |
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Voltage, Rated Performance |
N/A |
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Voltage, Operating |
N/A |
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N/A |
15 V ± 10% |
15 V ± 10% |
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Current, No Load (VS = 15 V) |
N/A |
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N/A |
5 mA |
5 mA |
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TEMPERATURE RANGE |
0°C to 70°C |
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Rated Performance |
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Operating |
–40°C to +85°C |
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Storage |
–40°C to +85°C |
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PACKAGE DIMENSIONS4 |
2.08" × 0.250" × 0.625" |
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SIP Package (Y) |
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DlP Package (N) |
2.10" × 0.700" × 0.350" |
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NOTES
*Specifications same as AD204J.
1Nonlinearity is specified as a % deviation from a best straight line. 21.0 F min decoupling required (see text).
33 mA with one supply loaded.
4Width is 0.25" typ, 0.26" max.
Specifications subject to change without notice.
–2– |
REV. C |
AD202/AD204
AD246–SPECIFICATIONS
(Typical @ 25°C and VS = 15 V unless otherwise noted.)
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AD246JY |
AD246JN |
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25 kHz Nominal |
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15 V p-p Nominal |
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32 Max |
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POWER SUPPLY |
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REQUIREMENTS |
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15 V ± 5% |
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Input Voltage |
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Supply Current |
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Unloaded |
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Each AD204 Adds |
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2.2 mA |
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Each 1 mA Load on AD204 |
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+VISO or –VISO Adds |
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0.7 mA |
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*Specifications the same as the AD246JY. |
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1The high current drive output will not support a short to ground. |
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Specifications subject to change without notice. |
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AD246 Pin Designations |
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Pin (Y) |
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Pin (N) |
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15 V POWER IN |
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CLOCK OUTPUT |
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COMMON |
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PIN DESIGNATIONS
AD202/AD204 SIP Package
Pin Function
1+INPUT
2INPUT/VISO COMMON
3–INPUT
4INPUT FEEDBACK
5–VISO OUTPUT
6+VISO OUTPUT
3115 V POWER IN (AD202 ONLY)
32CLOCK/POWER COMMON
33CLOCK INPUT (AD204 ONLY)
37OUTPUT LO
38OUTPUT HI
AD202/AD204 DIP Package
Pin Function
1+INPUT
2INPUT/VISO COMMON
3–INPUT
18OUTPUT LO
19OUTPUT HI
2015 V POWER IN (AD202 ONLY)
21CLOCK INPUT (AD204 ONLY)
22CLOCK/POWER COMMON
36+VISO OUTPUT
37–VISO OUTPUT
38INPUT FEEDBACK
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Max Common-Mode |
Max |
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Option |
Voltage (Peak) |
Linearity |
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AD202JY |
SIP |
1000 V |
±0.05% |
AD202KY |
SIP |
2000 V |
±0.025% |
AD202JN |
DIP |
1000 V |
±0.05% |
AD202KN |
DIP |
2000 V |
±0.025% |
AD204JY |
SIP |
1000 V |
±0.05% |
AD204KY |
SIP |
2000 V |
±0.025% |
AD204JN |
DIP |
1000 V |
±0.05% |
AD204KN |
DIP |
2000 V |
±0.025% |
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V 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 may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING! |
ESD SENSITIVE DEVICE |
REV. C |
–3– |
AD202/AD204
The 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 nonisolated externally-supplied clock (AD246) which can drive up to 32 AD204s. The main advantages of using the externallyclocked 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 operation 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.
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SIGNAL |
DEMOD |
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MOD |
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IN+ |
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5V |
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5V |
VOUT |
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VSIG |
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LO |
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IN COM |
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+VISO OUT |
+7.5V |
RECT |
POWER |
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OSCILLATOR |
15V DC |
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–7.5V |
AND |
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–VISO OUT |
FILTER |
25kHz |
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25kHz |
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Figure 1a. AD202 Functional Block Diagram
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AD204 |
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IN– |
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SIGNAL |
DEMOD |
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HI |
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MOD |
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IN+ |
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5V |
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5V |
VOUT |
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VSIG |
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LO |
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IN COM |
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+VISO OUT |
+7.5V |
RECT |
POWER |
POWER |
CLOCK |
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AND |
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15V p-p |
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–7.5V |
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CONV. |
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–VISO OUT |
FILTER |
25kHz |
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25kHz |
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25kHz |
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Figure 1b. AD204 Functional Block Diagram
(Pin Designations Apply to the DIP-Style Package)
The 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 signal is not internally buffered, so the user is free to interchange
the output leads to get signal inversion. Additionally, in multichannel applications, the unbuffered outputs can be multiplexed with one buffer following the mux. This technique minimizes offset errors while reducing power consumption and cost. The 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.
NON- |
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GAIN |
GAIN TC |
LINEARITY |
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CHANGE |
CHANGE |
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(ppm/ C) |
0.25 |
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–10 |
–500 |
0.20 |
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–400 |
0.15 |
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AD202 GAIN AND GAIN TC |
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–6 |
–300 |
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AD202 NONLINEARITY |
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0.10 |
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AD204 GAIN AND GAIN TC |
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–4 |
–200 |
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0.05 |
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–2 |
–100 |
0 |
AD204 NONLINEARITY |
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0 |
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0 |
0.1 |
0.2 |
0.3 |
0.4 |
0.5 |
0.6 |
0.7 |
0.8 |
0.9 |
1.0 |
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OUTPUT LOAD – M |
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Figure 2. Effects of Output Loading
Powering the AD202. The AD202 requires only a single 15 V power supply connected as shown in Figure 3a. A bypass capacitor is provided in the module.
AD202
15V 5%
15V RETURN
Figure 3a.
Powering the AD204. The AD204 gets its power from an externally supplied clock signal (a 15 V p-p square wave with a nominal frequency of 25 kHz) as shown in Figure 3b.
AD246
AD204 AD204 AD204
15V
+
15V RETURN
Figure 3b.
(NOTE: Circuit figures shown on this page are for SIP-style packages. Refer to Page 3 for proper DIP package pinout.)
–4– |
REV. C |