Analog Devices AD625SD, AD625SCHIPS, AD625KN, AD625CD, AD625BD Datasheet

a		Programmable Gain
		Instrumentation Amplifier
		AD625

FEATURES

User Programmed Gains of 1 to 10,000 Low Gain Error: 0.02% Max

Low Gain TC: 5 ppm/ C Max

Low Nonlinearity: 0.001% Max Low Offset Voltage: 25 V

Low Noise 4 nV/√Hz (at 1 kHz) RTI Gain Bandwidth Product: 25 MHz 16-Lead Ceramic or Plastic DIP Package,

20-Terminal LCC Package Standard Military Drawing Available MlL-Standard Parts Available

Low Cost

PRODUCT DESCRIPTION

The AD625 is a precision instrumentation amplifier specifically designed to fulfill two major areas of application: 1) Circuits requiring nonstandard gains (i.e., gains not easily achievable with devices such as the AD524 and AD624). 2) Circuits requiring a low cost, precision software programmable gain amplifier.

For low noise, high CMRR, and low drift the AD625JN is the most cost effective instrumentation amplifier solution available. An additional three resistors allow the user to set any gain from 1 to 10,000. The error contribution of the AD625JN is less than 0.05% gain error and under 5 ppm/°C gain TC; performance limitations are primarily determined by the external resistors. Common-mode rejection is independent of the feedback resistor matching.

A software programmable gain amplifier (SPGA) can be configured with the addition of a CMOS multiplexer (or other switch network), and a suitable resistor network. Because the ON resistance of the switches is removed from the signal path, an AD625 based SPGA will deliver 12-bit precision, and can be programmed for any set of gains between 1 and 10,000, with completely user selected gain steps.

For the highest precision the AD625C offers an input offset voltage drift of less than 0.25 V/°C, output offset drift below 15 V/°C, and a maximum nonlinearity of 0.001% at G = 1. All grades exhibit excellent ac performance; a 25 MHz gain bandwidth product, 5 V/ s slew rate and 15 s settling time.

The AD625 is available in three accuracy grades (A, B, C) for industrial (–40°C to +85°C) temperature range, two grades (J, K) for commercial (0°C to +70°C) temperature range, and one

(S) grade rated over the extended (–55°C to +125°C) temperature range.

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 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

	50					AD625
–INPUT	–	+	–	+
–GAIN						10k
SENSE						SENSE
–GAIN					10k
DRIVE						–
				VB
					10k	OUTPUT
						+
+GAIN
DRIVE						10k
+GAIN						REFERENCE
SENSE
+INPUT	50	+		+
	–		–

PRODUCT HIGHLIGHTS

1.The AD625 affords up to 16-bit precision for user selected fixed gains from 1 to 10,000. Any gain in this range can be programmed by 3 external resistors.

2.A 12-bit software programmable gain amplifier can be configured using the AD625, a CMOS multiplexer and a resistor network. Unlike previous instrumentation amplifier designs, the ON resistance of a CMOS switch does not affect the gain accuracy.

3.The gain accuracy and gain temperature coefficient of the amplifier circuit are primarily dependent on the user selected external resistors.

4.The AD625 provides totally independent input and output offset nulling terminals for high precision applications. This minimizes the effects of offset voltage in gain-ranging applications.

5.The proprietary design of the AD625 provides input voltage noise of 4 nV/√Hz at 1 kHz.

6.External resistor matching is not required to maintain high common-mode rejection.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: [phone]	World Wide Web Site: http://www.analog.com
Fax: [phone]	© Analog Devices, Inc., 2000

AD625–SPECIFICATIONS (typical @ VS = 15 V, RL = 2 k and TA = + 25 C, unless otherwise noted)

	AD625A/J/S					AD625B/K						AD625C
Model	Min	Typ			Max	Min	Typ			Max	Min	Typ			Max	Unit
GAIN			2 RF	+ 1				2 RF		+ 1			2 RF	+ 1
Gain Equation
	1		RG		10,000	1		RG	10,000		1		RG		110,000
Gain Range		±.035					±0.02					±0.01
Gain Error1					0.05				0.03						0.02	%
Nonlinearity, Gain = 1-256					±0.005				±0.002						±0.001	%
Gain>256					±0.01				±0.008						±0.005	%
Gain vs. Temp. Gain<10001					5				5						5	ppm/°C
GAIN SENSE INPUT					500				250						100
Gain Sense Current		300					150					50				nA
vs. Temperature		5			20		2		15			2			10	nA/°C
Gain Sense Offset Current		150			500		75		250			50			100	nA
vs. Temperature		2			15		1		10			2			10	nA/°C
VOLTAGE OFFSET (May be Nulled)																µV
Input Offset Voltage		50			200		25		50			10			25
vs. Temperature		1			2/2		0.25		0.50/1			0.1			0.25	µV/°C
Output Offset Voltage		4			5		2		3			1			2	mV
vs. Temperature		20			50/50		10		25/40			10			15	µV/°C
Offset Referred to the
Input vs. Supply
G = 1	70	75				75	85				80	90				dB
G = 10	85	95				90	100				95	105				dB
G = 100	95	100				105	110				110	120				dB
G = 1000	100	110				110	120				115	140				dB
INPUT CURRENT		±30					±20					±10
Input Bias Current					50				25						15	nA
vs. Temperature		±50					±50					±50				pA/°C
Input Offset Current		± 2			35		± 1		15			± 1			5	nA
vs. Temperature		±20					±20					±20				pA/°C
INPUT
Input Impedance																GΩ
Differential Resistance		1					1					1
Differential Capacitance		4					4					4				pF
Common-Mode Resistance		1					1					1				GΩ
Common-Mode Capacitance		4					4					4				pF
Input Voltage Range					±10				±10						±10
Differ. Input Linear (VDL)2						12 V – (G										V
Common-Mode Linear (VCM)	12 V – (G ×VD)								×VD)		12 V – (G ×VD)
		2					2					2
Common-Mode Rejection Ratio dc to
60 Hz with 1 kΩ Source Imbalance	70					75					80
G = 1		75					85					90				dB
G = 10	90	95				90	105				100	115				dB
G = 100	100	105				105	115				110	125				dB
G = 1000	110	115				110	125				120	140				dB
OUTPUT RATING		±10 V					±10 V					±10 V
		@ 5 mA					@ 5 mA					@ 5 mA
DYNAMIC RESPONSE
Small Signal –3 dB
G = 1 (RF = 20 kΩ)		650					650					650				kHz
G = 10		400					400					400				kHz
G = 100		150					150					150				kHz
G = 1000		25					25					25				kHz
Slew Rate		5.0					5.0					5.0				V/µs
Settling Time to 0.01%, 20 V Step																µs
G = 1 to 200		15					15					15
G = 500		35					35					35				µs
G = 1000		75					75					75				µs

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									AD625
		AD625A/J/S		AD625B/K			AD625C
Model	Min	Typ	Max	Min Typ	Max	Min	Typ	Max		Unit
NOISE
Voltage Noise, 1 kHz										nV/√Hz
R.T.I.		4		4			4
R.T.O.		75		75			75			nV/√Hz
R.T.I., 0.1 Hz to 10 Hz										µV p-p
G = 1		10		10			10
G = 10		1.0		1.0			1.0			µV p-p
G = 100		0.3		0.3			0.3			µV p-p
G = 1000		0.2		0.2			0.2			µV p-p
Current Noise
0.1 Hz to 10 Hz		60		60			60			pA p-p
SENSE INPUT										kΩ
RIN		10		10			10
IIN	±10	30		30		±10	30			µA
Voltage Range				±10						V
Gain to Output		1 ± 0.01		1 ± 0.01			1 ± 0.01			%
REFERENCE INPUT										kΩ
RIN		20		20			20
IIN	±10	30		30		±10	30			µA
Voltage Range				±10						V
Gain to Output		1 ± 0.01		1 ± 0.01			1 ± 0.01			%
TEMPERATURE RANGE
Specified Performance										°C
J/K Grades	0		+70	0	+70
A/B/C Grades	–40		+85	–40	+85	–40		+85		°C
S Grade	–55		+125							°C
Storage	–65		+150	–65	+150	–65		+150		°C
POWER SUPPLY		±6 to ±18		±6 to ±18			±6 to ± 18
Power Supply Range										V
Quiescent Current		3.5	5	3.5	5		3.5	5		mA

NOTES

1Gain Error and Gain TC are for the AD625 only. Resistor Network errors will add to the specified errors.

2VDL is the maximum differential input voltage at G = 1 for specified nonlinearity. VDL at other gains = 10 V/G. VD = actual differential input voltage. Example: G = 10, VD = 0.50; VCM = 12 V – (10/2 × 0.50 V) = 9.5 V.

Specifications subject to change without notice.

All min and max specifications are guaranteed. Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels.

REV. D

–3–

AD625

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . . 450 mW

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± VS Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . ± VS Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite

Storage Temperature Range (D, E) . . . . . . . . –65°C to +150°C Storage Temperature Range (N) . . . . . . . . . . –65°C to +125°C

Operating Temperature Range

AD625J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C AD625A/B/C . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C AD625S . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C Lead Temperature Range (Soldering 10 sec) . . . . . . . . +300°C

*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

ORDERING GUIDE

Model	Temperature Range	Package Description	Package Option
AD625AD	–40°C to +85°C	16-Lead Ceramic DIP	D-16
AD625BD	–40°C to +85°C	16-Lead Ceramic DIP	D-16
AD625BD/+	–40°C to +85°C	16-Lead Ceramic DIP	D-16
AD625CD	–40°C to +85°C	16-Lead Ceramic DIP	D-16
AD625SD	–55°C to +125°C	16-Lead Ceramic DIP	D-16
AD625SD/883B	–55°C to +125°C	16-Lead Ceramic DIP	D-16
AD625SE/883B	–55°C to +125°C	20-Terminal Leadless Chip Carrier	E-20A
AD625JN	0°C to +70°C	16-Lead Plastic DIP	N-16
AD625KN	0°C to +70°C	16-Lead Plastic DIP	N-16
AD625ACHIPS	–40°C to +85°C	Die
AD625SCHIPS	–55°C to +125°C	Die
5962-87719012A*	–55°C to +125°C	20-Terminal Leadless Chip Carrier	E-20A
5962-8771901EA*	–55°C to +125°C	16-Lead Ceramic DIP	D-16

*Standard Military Drawing Available

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 AD625 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

PIN CONNECTIONS

Ceramic DIP (D) and Plastic DIP (N) Packages

Leadless Chip Carrier (E) Package

		+INPUT	1				16	–INPUT
	+GAIN SENSE		2				15	–GAIN SENSE
		RTI NULL						RTO NULL
			3				14		–VS
	+VS	10k		AD625				10k
			4				13
		RTI NULL						RTO NULL
				TOP VIEW
								–GAIN DRIVE
	+GAIN DRIVE		5	(Not to Scale)			12
		NC						SENSE
			6				11
	REFERENCE							VOUT
			7				10
		–VS						+VS
			8				9
			NC = NO CONNECT

	+GAIN SENSE	+INPUT	NC	–INPUT	–GAIN SENSE
	3	2	1	20 19
RTI NULL 4						18 RTO NULL
RTI NULL 5		AD625				17 RTO NULL
NC 6						16 NC
		TOP VIEW
+GAIN DRIVE 7	(Not to Scale)					15 –GAIN NULL
NC 8						14 SENSE
	9	10	11 12		13
	REFERENCE	S	NC	S	OUT
		–V		+V	V

NC = NO CONNECT

–4–

REV. D

V	20
	15
–
RANGE
VOLTAGE	10
INPUT						25 C
	5
	0
	0		5	10		15		20

SUPPLY VOLTAGE – V

Figure 1. Input Voltage Range vs.

	Supply Voltage, G = 1
	–160
	–140	G = 1000
	–120	G = 100
– dM	–100	G = 10
	–80	G = 1
CMRR
	–60
	–40
	–20
	0	10	100	1k	10k	100k	10M
	0
			FREQUENCY – Hz

Figure 4. CMRR vs. Frequency RTI, Zero to 1 kΩ Source Imbal-

ance
	–1
V	0
–	1
VALUE
	2
FINAL	3
FROM	4
	5
OS
V	6
	7	1.0	2.0	3.0	4.0	5.0	6.0	7.0	8.0
	0

WARM-UP TIME – Minutes

Figure 7. Offset Voltage, RTI, Turn

On Drift

Typical Performance Characteristics–AD625

20					30
15					VOLTAGEOUTPUTSWING – V p-p
VOLTAGEOUTPUTSWING –V
					20
10
					10
5
0					0	100	1k	10k
0	5	10	15	20	10
	SUPPLY VOLTAGE – V					LOAD RESISTANCE –

Figure 2. Output Voltage Swing	Figure 3. Output Voltage Swing
vs. Supply Voltage	vs. Load Resistance

	30
p-p
V			G = 1, 100
–
RESPONSE	20
			BANDWIDTH
		G = 500		LIMITED
POWER
	10
				G = 100
FULL
	0	G = 1000
		10k	100k	1M
	1k
		FREQUENCY – Hz

Figure 5. Large Signal Frequency

Response

	160
dB	140		–VS = –15V dc+
			1V p-p SINEWAVE
–	G = 500
REJECTION	120
	G = 100
	100
	G = 1
	80
SUPPLY
	60
POWER	40
	20
	0	100	1k	10k	100k
	10

FREQUENCY – Hz

Figure 8. Negative PSRR vs. Frequency

1000
100
GAIN
10
1
100	1k	10k	100k	1M	10M

FREQUENCY – Hz

Figure 6. Gain vs. Frequency

	160
dB	140		+VS = +15V dc+
			1V p-p SINEWAVE
–	G = 500
REJECTION	120
	G = 100
	100
	G = 1
	80
SUPPLY
	60
POWER	40
	20
	0	100	1k	10k	100k
	10

FREQUENCY – Hz

Figure 9. Positive PSRR vs. Frequency

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–5–