Analog Devices AD204, AD202 Datasheet

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 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.

		FUNCTIONAL BLOCK DIAGRAM
FB	4					AD202
IN–	3			SIGNAL		DEMOD		HI
			MOD
IN+							38
	1		±5V				±5V	VOUT
VSIG	2		FS				F.S.	LO
							37
IN COM
+VISO OUT	6	+7.5V	RECT &	POWER
		–7.5V				OSCILLATOR	31	+15V DC
–VISO OUT	5		FILTER
			25kHz		25kHz
							32	POWER
								RETURN

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.

© Analog Devices, Inc., 1994

One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: [phone] Fax: [phone]

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	± 5 V
Input Voltage Range						*	*	*
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
RS £ 100 W (HI & LO lnputs) G = 1 V/V	110 dB					110 dB	105 dB	105 dB
G = 100 V/V	130 dB					*	*	*
RS £ l kW (Input HI, LO, or Both) G = 1 V/V	104 dB min					104 dB min	100 dB min	100 dB min
G = 100 V/V	110 dB min					*	*	*
Leakage Current Input to Output @ (240 V rms, 60 Hz	2 mA rms max					*	*	*
INPUT IMPEDANCE	1012 W
Differential (G = 1 V/V)						*	*	*
Common Mode	2 GWi4.5 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	4 mV p-p
Voltage, 0.1 Hz to 100 Hz						*	*	*
f > 200 Hz	50 nV/Ö		Hz			*	*	*
FREQUENCY RESPONSE
Bandwidth (VO £ 10 V p-p, G = 1 V–50 V/V)	5 kHz					5 kHz	2 kHz	2 kHz
Settling Time, to ± 10 mV (10 V Step)	1 ms					*	*	*
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
	æ	10 ö
vs . Temperature (0°C to +70°C)	ç ±10 ±			÷ mV/°C
	è		G ø
RATED OUTPUT	± 5 V
Voltage (Out HI to Out LO)						*	*	*
Voltage at Out HI or Out LO (Ref. Pin 32)	± 6.5 V					*	*	*
Output Resistance	3 kW					3 kW	7 kW	7 kW
Output Ripple, 100 kHz Bandwidth	10 mV pk-pk					*	*	*
5 kHz Bandwidth	0.5 mV rms					*	*	*
ISOLATED POWER OUTPUT2	± 7.5 V
Voltage, No Load						*	*	*
Accuracy	± 10%					*	*	*
Current	2 mA (Either Output)3					2 mA (Either Output)3	400 mA Total	400 mA 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)							+15 V ± 5%	+15 V ± 5%
Voltage, Rated Performance	N/A					N/A
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	0°C to +70°C
Rated Performance						*	*	*
Operating	–40°C to +85°C					*	*	*
Storage	–40°C to +85°C					*	*	*
PACKAGE DIMENSIONS4	2.08" ´ 0.250" ´ 0.625"
SIP Package (Y)						*	*	*
DlP Package (N)	2.10" ´ 0.700" ´ 0.350"					*	*	*

NOTES

Specifications same as AD204J.

1Nonlinearity is specified as a % deviation from a best straight line. 21.0 μF min decoupling required (see text).

33 mA with one supply loaded.

4Width is 0.25" typ, o.26" max.

Specifications subject to change without notice .

–2–

REV. B

AD202/AD204

PIN DESIGNATIONS

AD202/AD204 SIP Package

Pin Function

1+INPUT

2INPUT/VISO COMMON

3–INPUT

4INPUT FEEDBACK

5–VISO OUTPUT

6+VISO OUTPUT

31+15 V POWER IN (AD202 ONLY)

32CLOCK/POWER COMMON

33CLOCK INPUT (AD204 ONLY)

37OUTPUT LO

38OUTPUT HI

AD246–SPECIFICATIONS

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

Model	AD246JY	AD246JN
OUTPUTl
Frequency	25 kHz Nominal	*
Voltage	15 V p-p Nominal	*
Fan-Out	32 max	*
POWER SUPPLY
REQUIREMENTS	+15 V ± 5%
Input Voltage		*
Supply Current
Unloaded	35 mA	*
Each AD204 Adds	2.2 mA	*
Each 1 mA Load on AD204
+VISO or –VISO Adds	0.7 mA	*

AD202/AD204 DIP Package

Pin Function

1+INPUT

2INPUT/VISO COMMON

3–INPUT

18OUTPUT LO

19OUTPUT HI

20+15 V POWER IN (AD202 ONLY)

21CLOCK INPUT (AD204 ONLY)

22CLOCK/POWER COMMON

36+VISO OUTPUT

37–VISO OUTPUT

38INPUT FEEDBACK

NOTES

*Specifications the same as the AD246JY.

1The high current drive output will not support a short to ground. Specifications subject to change without notice.

AD246 Pin Designations

Pin (Y)	Pin (N)	Function
1	12	+15 V POWER IN
2	1	CLOCK OUTPUT
12	14	COMMON
13	24	COMMON

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%

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.

WARNING!

ESD SENSITIVE DEVICE

REV. B

–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.

FB	4					AD202
IN–	3			SIGNAL		DEMOD		HI
			MOD
IN+							38
	1		±5V				±5V	VOUT
VSIG	2		FS				F.S.	LO
							37
IN COM
+VISO OUT	6	+7.5V	RECT &	POWER
		–7.5V				OSCILLATOR	31	+15V DC
–VISO OUT	5		FILTER
			25kHz		25kHz
							32	POWER
								RETURN

Figure 1a. AD202 Functional Block Diagram

FB	4					AD204
IN–	3		MOD	SIGNAL		DEMOD	38	HI
IN+	1					±5V
			±5V					VOUT
VSIG
			FS			F.S.		LO
	2						37
IN COM
+VISO OUT	6	+7.5V	RECT &	POWER				CLOCK
		–7.5V				POWER	33 (15V
–VISO OUT	5		FILTER			CONV.		p-p/25kHz)
			25kHz		25kHz
							32	POWER
								RETURN

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

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

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