Analog Devices AD204, AD202 Datasheet

Low Cost, Miniature

a

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, trans­former-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.

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 spac-

REV. B

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.

Isolation Amplifiers

AD202/AD204

FUNCTIONAL BLOCK DIAGRAM

FB

4

V

+V
–V

SIG

IN COM

ISO
ISO

IN–
IN+

OUT
OUT

3

1

2

6
5

+7.5V
–7.5V

±5V

FS

RECT &

FILTER

SIGNAL

MOD

POWER

25kHz

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 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 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 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: [phone] Fax: [phone]

AD202

DEMOD

OSCILLATOR

25kHz

© Analog Devices, Inc., 1994

±5V
F.S.

38

37

31

32

HI

LO

+15V DC

POWER
RETURN

V

OUT

AD202/AD204–SPECIFICATIONS

(typical @ + 25°C & VS = +15 V unless otherwise noted)

Model AD204J AD204K AD202J AD202K

GAIN

Range 1 V/V–100 V/V * * *
Error ±0.5% typ (±4% max) * * *
vs. Temperature ±20 ppm/°C typ (±45 ppm/°C max) * * *
vs. Time ±50 ppm/1000 Hours * * *
vs. Supply Voltage ±0.01%/V ±0.01%/V ±0.01%/V ±0.01%/V
Nonlinearity (G = 1 V/V)

1

±0.05% max ±0.025% max ±0.05% max ±0.025% max

Nonlinearity vs. Isolated Supply Load ±0.0015%/mA * * *

INPUT VOLTAGE RATINGS

Input Voltage Range ±5 V * * *
Max lsolation Voltage (Input to Output)

AC, 60 Hz, Continuous 750 V rms 1500 V rms 750 V rms 1500 V rms

Continuous (AC and DC) ±1000 V Peak ±2000 V Peak ±1000 V Peak ±2000 V Peak

Isolation-Mode Rejection Ratio (IMRR) @ 60 Hz

≤ 100 Ω (HI & LO lnputs) G = 1 V/V 110 dB 110 dB 105 dB 105 dB

R

S

G = 100 V/V 130 dB * * *

≤ l kΩ (Input HI, LO, or Both) G = 1 V/V 104 dB min 104 dB min 100 dB min 100 dB min

R

S

G = 100 V/V 110 dB min * * *

Leakage Current Input to Output @ (240 V rms, 60 Hz 2 µA rms max * * *
INPUT IMPEDANCE

Differential (G = 1 V/V) 10

12

Ω ***

Common Mode 2 GΩi4.5 pF * * *

INPUT BIAS CURRENT

Initial, @ +25°C ±30 pA * * *
vs. Temperature (0°C to +70°C) ±10 nA * * *

INPUT DIFFERENCE CURRENT

Initial, @ +25°C ±5 pA * * *
vs. Temperature (0°C to +70°C) ±2 nA * * *

INPUT NOISE

Voltage, 0.1 Hz to 100 Hz 4 µV p-p * * *

f > 200 Hz 50 nV/√Hz ***

FREQUENCY RESPONSE

Bandwidth (V
Settling Time, to ±10 mV (10 V Step) 1 ms * * *

≤ 10 V p-p, G = 1 V–50 V/V) 5 kHz 5 kHz 2 kHz 2 kHz

O

OFFSET VOLTAGE (RTI)

Initial, @ +25°C Adjustable to Zero ( ±15 ±15/G)mV max (±5 ±5/G)mVmax (±15 ±15/G)mVmax (±5 ±5/G)mVmax

vs . Temperature (0°C to +70°C)






±10 ±

10



µV/°C



G



RATED OUTPUT

Voltage (Out HI to Out LO) ± 5 V * * *
Voltage at Out HI or Out LO (Ref. Pin 32) ±6.5 V * * *
Output Resistance 3 kΩ 3 kΩ 7 kΩ 7 kΩ
Output Ripple, 100 kHz Bandwidth 10 mV pk-pk * * *

5 kHz Bandwidth 0.5 mV rms * * *

ISOLATED POWER OUTPUT

2

Voltage, No Load ±7.5 V * * *
Accuracy ±10% * * *
Current 2 mA (Either Output)

3

2 mA (Either Output)3400 µA Total 400 µA Total
Regulation, No Load to Full Load 5% * * *
Ripple 100 mV pk-pk * * *

OSCILLATOR DRIVE INPUT

Input Voltage 15 V pk-pk Nominal 15 V pk-pk Nominal N/A N/A
Input Frequency 25 kHz Nominal 25 kHz Nominal N/A N/A

POWER SUPPLY (AD202 Only)

Voltage, Rated Performance N/A N/A +15 V ± 5% +15 V ± 5%
Voltage, Operating N/A N/A +15 V ± 10% +15 V ± 10%
Current, No Load (VS = +15 V) N/A N/A 5 mA 5 mA

TEMPERATURE RANGE

Rated Performance 0°C to +70°C***
Operating –40°C to +85°C* * *
Storage –40°C to +85°C* * *

PACKAGE DIMENSIONS

4

SIP Package (Y) 2.08" × 0.250" × 0.625" * * *
DlP Package

NOTES
Specifications same as AD204J.

1

Nonlinearity is specified as a % deviation from a best straight line.

2

1.0 µF min decoupling required (see text).

3

3 mA with one supply loaded.

4

Width is 0.25" typ, o.26" max.

Specifications subject to change without notice .

(N)

2.10" × 0.700" × 0.350" * * *

–2–

REV. B

AD202/AD204

WARNING!

ESD SENSITIVE DEVICE

PIN DESIGNATIONS

AD202/AD204 SIP Package

Pin Function

1 +INPUT
2 INPUT/V

COMMON

ISO

3 –INPUT
4 INPUT FEEDBACK
5–V
6+V

OUTPUT

ISO

OUTPUT

ISO

31 +15 V POWER IN (AD202 ONLY)
32 CLOCK/POWER COMMON
33 CLOCK INPUT (AD204 ONLY)
37 OUTPUT LO
38 OUTPUT HI

AD202/AD204 DIP Package

Pin Function

1 +INPUT
2 INPUT/V

COMMON

ISO

3 –INPUT
18 OUTPUT LO
19 OUTPUT HI
20 +15 V POWER IN (AD202 ONLY)
21 CLOCK INPUT (AD204 ONLY)
22 CLOCK/POWER COMMON
36 +V
37 –V

OUTPUT

ISO

OUTPUT

ISO

38 INPUT FEEDBACK

AD246–SPECIFICATIONS

(typical @ +25°C & VS = +15 V unless otherwise noted)

Model AD246JY AD246JN

OUTPUT

Frequency 25 kHz Nominal *
Voltage 15 V p-p Nominal *
Fan-Out 32 max *

POWER SUPPLY
REQUIREMENTS

Input Voltage +15 V ± 5% *
Supply Current

NOTES
*Specifications the same as the AD246JY.

1

The high current drive output will not support a short to ground.

Specifications subject to change without notice.

l

Unloaded 35 mA *
Each AD204 Adds 2.2 mA *
Each 1 mA Load on AD204

+V

ISO

or –V

Adds 0.7 mA *

ISO

AD246 Pin Designations

Pin (Y) Pin (N) Function

1 12 +15 V POWER IN

2 1 CLOCK OUTPUT
12 14 COMMON
13 24 COMMON

CAUTION

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.

REV. B

ORDERING GUIDE

Package Max Common- Max

Model Option Mode Voltage (Peak) Linearity

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%

–3–

AD202/AD204

DIFFERENCES BETWEEN THE AD202 AND 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.

V

+V
–V

SIG

IN COM

ISO
ISO

IN–
IN+

OUT
OUT

FB

4

3

1

2

6
5

+7.5V
–7.5V

±5V

FS

RECT &

FILTER

SIGNAL

MOD

POWER

25kHz

25kHz

AD202

DEMOD

OSCILLATOR

±5V
F.S.

38

37

31

32

HI

V

OUT

LO

+15V DC

POWER
RETURN

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-imped­ance 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 V

power supply connected as shown in Figure 3a. A bypass ca­pacitor is provided in the module.

Figure 1a. AD202 Functional Block Diagram

V

+V
–V

SIG

IN COM

ISO
ISO

IN–

IN+

OUT
OUT

FB

4

3

1

2

6
5

+7.5V
–7.5V

±5V

FS

RECT &

FILTER

SIGNAL

MOD

POWER

25kHz

25kHz

AD204

DEMOD

POWER

CONV.

±5V
F.S.

HI

38

LO

37

CLOCK

(15V

33

p-p/25kHz)

POWER

32

RETURN

V

OUT

Figure 1b. AD204 Functional Block Diagram
(Pin Designations Apply to the DIP-Style Package)

INSIDE THE AD202 AND AD204

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

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.

Figure 3b.

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

(Circuit figures shown on this page are for SIP style pack­ages. Refer to page 3 for proper DIP package pinout.)

–4–

REV. B