Datasheet

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Single and Dual-Supply, Rail-to-Rail,

Low Cost Instrumentation Amplifier

Data Sheet

AD623

Rev. G Document Feedback

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FEATURES

Easy to use

Rail-to-rail output swing

Input voltage range extends 150 mV below ground

(single supply)

Low power, 550 µA maximum quiescent current

Gain set with one external resistor

Gain range: 1 to 1000

High accuracy dc performance

0.10% gain error (G = 1)

0.35% gain error (G > 1)

Noise: 35 nV/√Hz RTI noise at 1 kHz

Optimal dynamic specifications

800 kHz bandwidth (G = 1)

20 µs settling time to 0.01% (G = 10)

APPLICATIONS

Low power medical instrumentation

Transducer interfaces

Thermocouple amplifiers

Industrial process controls

Difference amplifiers

Low power data acquisition

GENERAL DESCRIPTION

The AD623 is an integrated, single- or dual-supply instrumentation

amplifier that delivers rail-to-rail output swing using supply

voltages from 2.7 V to 12 V. T h e AD623 offers user flexibility by

allowing single gain set resistor programming and by conforming

to the 8-lead industry standard pinout configuration. With no

external resistor, the AD623 is configured for unity gain (G = 1),

and with an external resistor, the AD623 can be programmed for

gains of up to 1000.

The accuracy of the AD623 is the result of increasing ac

common-mode rejection ratio (CMRR) coincident with

increasing gain. Line noise harmonics are rejected due to

constant CMRR up to 200 Hz. The AD623 has a wide input

common-mode range and amplifies signals with common-

mode voltages as low as 150 mV below ground. The AD623

maintains optimal performance with dual and single polarity

power supplies.

Table 1. Low Power Upgrades for the AD623

Part No. Total Supply Voltage, V

(V dc)

Typical Quiescent

Current, I

(µA)

AD8235

5.5

AD8236 5.5 33

AD8237 5.5 33

AD8226

350

AD8227 36 325

AD8420 36 85

AD8422 36 300

AD8426 36 325 (per channel)

FUNCTIONAL BLOCK DIAGRAM

00778-054

50kΩ

50kΩ 50kΩ

OUTPUT

REF

–R

–V

DIFF

–

DIFF

–

–IN

+IN

Figure 1.

Summary of content (32 pages)

PAGE 1
Single and Dual-Supply, Rail-to-Rail, Low Cost Instrumentation Amplifier AD623 Data Sheet FEATURES GENERAL DESCRIPTION Easy to use Rail-to-rail output swing Input voltage range extends 150 mV below ground (single supply) Low power, 550 µA maximum quiescent current Gain set with one external resistor Gain range: 1 to 1000 High accuracy dc performance 0.10% gain error (G = 1) 0.
PAGE 2
AD623 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Basic Connection ....................................................................... 24 Applications ....................................................................................... 1 Gain Selection ............................................................................. 24 General Description ......................................................
PAGE 3
Data Sheet AD623 Added Additional Information Section .......................................23 Added Evaluation Board Section and Figure 56 .........................24 Updated Outline Dimensions ........................................................25 Changes to Ordering Guide ...........................................................26 7/2008—Rev. C to Rev. D Updated Format..................................................................
PAGE 4
AD623 Data Sheet SPECIFICATIONS SINGLE SUPPLY Typical at 25°C, single supply, +VS = 5 V, −VS = 0 V, and load resistance (RL) = 10 kΩ, unless otherwise noted. Table 2. Parameter GAIN Gain Range Gain Error 1 G=1 G = 10 G = 100 G = 1000 Nonlinearity G = 1 to 1000 Gain vs. Temperature G=1 G > 11 VOLTAGE OFFSET Input Offset, VOSI Over Temperature Average Temperature Coefficient (Tempco) Output Offset, VOSO Over Temperature Average Tempco Offset Referred to the Input vs.
PAGE 5
Data Sheet Parameter INPUT Input Impedance Differential Common-Mode Input Voltage Range 2 Common-Mode Rejection at 60 Hz with 1 kΩ Source Imbalance G=1 G = 10 G = 100 G = 1000 OUTPUT Output Swing DYNAMIC RESPONSE Small Signal −3 dB Bandwidth G=1 G = 10 G = 100 G = 1000 Slew Rate Settling Time to 0.
PAGE 6
AD623 Data Sheet DUAL SUPPLIES Typical at 25°C dual supply, VS = ±5 V, and RL = 10 kΩ, unless otherwise noted. Table 3. Parameter GAIN Gain Range Gain Error 1 G=1 G = 10 G = 100 G = 1000 Nonlinearity G = 1 to 1000 Gain vs. Temperature G=1 G > 11 VOLTAGE OFFSET Input Offset, VOSI Over Temperature Average Tempco Output Offset, VOSO Over Temperature Average Tempco Offset Referred to the Input vs.
PAGE 7
Data Sheet Parameter Common-Mode Rejection at 60 Hz with 1 kΩ Source Imbalance G=1 G = 10 G = 100 G = 1000 OUTPUT Output Swing DYNAMIC RESPONSE Small Signal −3 dB Bandwidth G=1 G = 10 G = 100 G = 1000 Slew Rate Settling Time to 0.01% G=1 G = 10 1 2 AD623 AD623ANZ, AD623ARZ Min Typ Max AD623ARM Min Typ Max AD623BNZ, AD623BRZ Min Typ Max Unit VCM = +3.5 V to −5.15 V VCM = +3.5 V to −5.15 V VCM = +3.5 V to −5.15 V VCM = +3.5 V to −5.
PAGE 8
AD623 Data Sheet SPECIFICATIONS COMMON TO DUAL AND SINGLE SUPPLIES Table 4. Parameter NOISE Voltage Noise, 1 kHz Input, Voltage Noise, eni Output, Voltage Noise, eno RTI, 0.1 Hz to 10 Hz G=1 G = 1000 Current Noise 0.
PAGE 9
Data Sheet AD623 ABSOLUTE MAXIMUM RATINGS Table 5. Parameter Supply Voltage Internal Power Dissipation1 Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) 1 Rating 12 V 650 mW ±6 V Indefinite −65°C to +125°C −40°C to +85°C 300°C Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product.
PAGE 10
AD623 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD623 8 +RG –IN 2 7 +VS +IN 3 6 OUTPUT –VS 4 5 REF TOP VIEW (Not to Scale) 00778-001 –RG 1 Figure 2. Pin Configuration Table 6. Pin Function Descriptions Pin No. 1 2 3 4 5 6 7 8 Mnemonic −RG −IN +IN −VS REF OUTPUT +VS +RG Description Inverting Terminal of External Gain Setting Resistor, RG. Inverting In-Amp Input. Noninverting In-Amp Input. Negative Supply Terminal. In-Amp Output Reference Input.
PAGE 11
Data Sheet AD623 TYPICAL PERFORMANCE CHARACTERISTICS At 25°C, VS = ±5 V, and RL = 10 kΩ, unless otherwise noted. 300 22 280 260 20 240 18 220 16 200 14 UNITS UNITS 180 160 140 12 10 120 100 8 80 6 60 4 40 2 20 20 40 60 80 100 120 140 0 –600 –500 –400 –300 –200 –100 0 00778-006 0 INPUT OFFSET VOLTAGE (µV) 00778-003 0 –100 –80 –60 –40 –20 100 200 300 400 500 OUTPUT OFFSET VOLTAGE (µV) Figure 3.
PAGE 12
Data Sheet 22 1400 21 1200 20 1000 19 800 600 17 400 16 200 15 0 75 80 85 90 95 100 105 110 115 120 125 130 CMRR (dB) 14 –4 0 2 4 Figure 12. Bias Current (IBIAS) vs. Common-Mode Voltage, N-8 Package Option 1k 16 IBIAS (nA) 15 G=1 100 14 13 G= 10 12 G= 100 100 1k 10k 100k FREQUENCY (Hz) 11 –6 –4 –2 0 2 4 COMMON-MODE VOLTAGE (V) Figure 10. Voltage Noise Spectral Density vs. Frequency, N-8 Package Option 00778-113 10 00778-010 G= 1000 10 1 Figure 13.
PAGE 13
Data Sheet AD623 16 20.0 19.5 15 19.0 14 IBIAS (nA) IBIAS (nA) 18.5 13 18.0 17.5 12 17.0 11 –40 –20 0 20 40 60 80 100 120 16.0 –4 00778-115 10 –60 140 TEMPERATURE (°C) Figure 15. IBIAS vs. Temperature, RM-8 and R-8 Package Options –1 0 1 2 Figure 18. IBIAS vs. Common-Mode Voltage, VS = ±2.
PAGE 14
Data Sheet 2.0 120 1.5 110 1.0 0.5 0 –0.5 –1.0 –1.5 100 G = ×1000 90 G = ×100 80 70 G = ×10 60 50 G = ×1 40 0 1 2 3 4 5 6 7 8 9 10 TIME (Seconds) Figure 21. 0.1 Hz to 10 Hz Current Noise vs. Time, RM-8 and R-8 Package Option 1µV/DIV 30 00778-121 –2.0 1 10 100 1k 10k 100k FREQUENCY (Hz) 00778-017 COMMON-MODE REJECTION (dB) CURRENT NOISE (pA p-p) AD623 Figure 24. Common-Mode Rejection vs. Frequency, +VS = 5 V, − VS = 0 V, VREF = 2.
PAGE 15
AD623 130 5 120 4 110 3 COMMON-MODE INPUT (V) 100 90 80 70 60 50 40 30 100 1k 10k 100k –2 –1 0 1 2 3 4 5 4 3 COMMON-MODE INPUT (V) G = 100 30 G = 10 10 G=1 2 1 VS = ±2.5 V 0 –1 –2 –3 –4 –20 –5 1k 10k 100k 1M FREQUENCY (Hz) –6 –5 00778-019 –30 100 –4 –3 –2 –1 0 1 2 3 4 5 MAXIMUM OUTPUT VOLTAGE (V) Figure 31. Common-Mode Input vs. Maximum Output Voltage, G = 1, RL = 100 kΩ for Two Supply Voltages, RM-8 and R-8 Package Options Figure 28. Gain vs.
PAGE 16
AD623 Data Sheet 5 5 4 4 2 COMMON-MODE INPUT (V) COMMON-MODE INPUT (V) 3 VS = ±2.5 V 1 0 –1 –2 –3 3 2 1 –4 0 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 MAXIMUM OUTPUT VOLTAGE (V) –1 00778-133 –6 –6 0 4 4 COMMON-MODE INPUT (V) 0 5 3 2 1 1 2 3 4 5 MAXIMUM OUTPUT VOLTAGE (V) –1 00778-022 0 0 1 2 3 4 5 MAXIMUM OUTPUT VOLTAGE (V) 00778-137 0 –1 Figure 37. Common-Mode Input vs.
PAGE 17
Data Sheet AD623 140 140 G G G G 120 = 1000 = 100 = 10 =1 G = 1000 120 NEGATIVE PSRR (dB) 80 60 40 100 80 G = 10 60 G=1 40 20 20 1 10 100 1k 10k 100k FREQUENCY (Hz) 0 00778-139 0 1 10 100 1k 10k 100k FREQUENCY (Hz) 00778-026 POSITIVE PSRR (dB) G = 100 100 Figure 42. Negative PSRR vs. Frequency for Various Gain Settings, N-8 Package Option Figure 39. Positive PSRR vs.
PAGE 18
AD623 Data Sheet 1k SETTLING TIME (µs) 500µV 1V 10µs 100 1 100 1k GAIN (V/V) Figure 48. Large Signal Pulse Response and Settling Time, G = −10 (0.250 mV = 0.01%), CL = 100 pF, N-8 Package Option Figure 45. Settling Time to 0.01% vs. Gain, for a 5 V Step at Output, CL = 100 pF 1V 3 300 2 200 1 100 0 0 20µs OUTPUT VOLTAGE (V) 500µV –100 –1 –200 00778-029 –2 VOUT DELTA_mV –3 –10 –300 0 10 20 30 40 50 60 70 80 TIME (µs) Figure 46.
PAGE 19
Data Sheet AD623 300 3 1 100 0 0 –1 –100 –2 –200 –3 –40 10 60 110 160 210 260 310 –300 360 TIME (µs) 00778-033 200 ERROR VOLTAGE (mV) 2 2µs 00778-151 OUTPUT VOLTAGE (V) 20mV Figure 51. Large Signal Pulse Response and Settling Time, G = 100, CL = 100 pF, RM-8 and R-8 Package Options Figure 54.
PAGE 20
AD623 Data Sheet 120 20mV 100 500µs OUTPUT VOLTAGE (mV) 80 60 40 20 0 –20 –40 –60 00778-036 –80 –120 0 5 10 15 20 25 30 35 40 TIME (µs) 00778-157 –100 Figure 57. Small Signal Pulse Response, G = 10, RL = 10 kΩ, CL = 100 pF, RM-8 and R-8 Package Options Figure 60. Small Signal Pulse Response, G = 1000, RL = 10 kΩ, CL = 100 pF, N-8 Package Option 120 20mV 50µs 100 OUTPUT VOLTAGE (mV) 80 60 40 20 0 –20 –40 –60 00778-035 –80 –120 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.
PAGE 21
Data Sheet AD623 5 6 4 GAIN NONLINEARITY (ppm) –5 –10 –15 –20 2 0 –2 –4 –25 –3.8 –2.8 –1.8 –0.8 0.2 1.2 2.2 3.2 OUTPUT VOLTAGE (V) –6 –4.8 00778-163 –30 –4.8 –3.8 –2.8 –1.8 –0.8 0.2 1.2 2.2 3.2 4.2 OUTPUT VOLTAGE (V) Figure 63. Gain Nonlinearity vs. Output Voltage, G = −1, RM-8 and R-8 Package Options Figure 65. Gain Nonlinearity vs.
PAGE 22
AD623 Data Sheet GAIN NONLINEARITY (ppm) 60 50 40 30 20 0 –10 –20 –3.8 –2.8 –1.8 –0.8 0.2 1.2 2.2 3.2 4.2 OUTPUT VOLTAGE (V) (V+) –2.5 (V–) +0.5 V– 1.5 2.0 00778-040 OUTPUT VOLTAGE SWING (V) (V+) –1.5 1.0 –3.5 2 –4.0 SWING FROM –VS 1 –4.5 –5.0 1 2 3 4 5 6 7 OUTPUT CURRENT (mA) (V+) –0.5 OUTPUT CURRENT (mA) 3 8 9 10 11 Figure 69. Positive and Negative Output Voltage Swing vs. Output Current, RM-8 and R-8 Package Options V+ 0.5 –3.0 0 Figure 67.
PAGE 23
Data Sheet AD623 THEORY OF OPERATION The AD623 is an instrumentation amplifier based on a modified classic 3-op-amp approach to ensure single- or dual-supply operation even at common-mode voltages at the negative supply rail. Low voltage offsets (input and output), absolute gain accuracy, and one external resistor to set the gain make the AD623 a versatile instrumentation amplifier. pin is 100 kΩ.
PAGE 24
AD623 Data Sheet APPLICATIONS INFORMATION BASIC CONNECTION Table 7. Required Values of Gain Resistors Figure 71 and Figure 72 show the basic connection circuits for the AD623. The +VS and −VS terminals are connected to the power supply. The supply can be either bipolar (VS = ±2.5 V to ±6 V) or single supply (−VS = 0 V, +VS = 2.7 V to 12 V). Capacitively decouple power supplies close to the power pins of the device. For optimal results, use surface-mount 0.
PAGE 25
Data Sheet AD623 INPUT PROTECTION Internal supply referenced clamping diodes allow the input, reference, output, and gain terminals of the AD623 to safely withstand overvoltages of 0.3 V above or below the supplies. This overvoltage protection is true at all gain settings and when cycling power on and off. Overvoltage protection is particularly important because the signal source and amplifier can be powered separately. enough to significantly increase the noise of the circuit.
PAGE 26
AD623 Data Sheet The circuit in Figure 74 must be built using a printed circuit board (PCB) with a ground plane on both sides. All component leads must be as short as possible. The R1 and R2 resistors can be common 1% metal film units. However, the C1 and C2 capacitors must be ±5% tolerance devices to avoid degrading the common-mode rejection of the circuit. Either the traditional 5% silver mica units or Panasonic ±2% polyphenylene sulfide (PPS) film capacitors are recommended.
PAGE 27
Data Sheet AD623 Ground Returns for Input Bias Currents Output Buffering Input bias currents are dc currents that must flow to bias the input transistors of an amplifier, which are usually transistor base currents. When amplifying floating input sources, such as transformers or ac-coupled sources, there must be a direct dc path into each input so that the bias current can flow.
PAGE 28
AD623 Data Sheet |VDIFFMAX| = 2 (+VS − 0.7 V − VCM)/Gain INPUT DIFFERENTIAL AND COMMON-MODE RANGE vs. SUPPLY AND GAIN |VDIFFMAX| = 2 (VCM − −VS + 0.590 V)/Gain Figure 83 shows a simplified block diagram of the AD623. The voltages at the outputs of Amplifier 1 (A1) and Amplifier 2 (A2) are given by VA2 = VCM + VDIFF/2 + 0.6 V + VDIFF × RF/RG = VCM + 0.
PAGE 29
Data Sheet AD623 Table 10. Maximum Attainable Gain and Resulting Output Swing for Different Input Conditions VCM (V) 0 0 0 0 0 2.5 2.5 2.5 1.5 1.5 0 0 Differential Voltage (VDIFF) ±10 mV ±100 mV ±10 mV ±100 mV ±1 V ±10 mV ±100 mV ±1 V ±10 mV ±100 mV ±10 mV ±100 mV REF Pin (V) 2.5 2.5 0 0 0 2.5 2.5 2.5 1.5 1.5 1.5 1.5 Supply Voltages (V) +5 +5 ±5 ±5 ±5 +5 +5 +5 +3 +3 +3 +3 ADDITIONAL INFORMATION For an updated design of the AD623, see the AD8223.
PAGE 30
AD623 Data Sheet EVALUATION BOARD The EVAL-INAMP-62RZ can be used to evaluate the AD620, AD621, AD622, AD623, AD627, AD8223, and AD8225 instrumentation amplifiers. In addition to the basic in-amp connection, circuit options enable the user to adjust the offset voltage, apply an output reference, or provide shield drivers with user supplied components.
PAGE 31
Data Sheet AD623 OUTLINE DIMENSIONS 0.400 (10.16) 0.365 (9.27) 0.355 (9.02) 8 5 1 4 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.100 (2.54) BSC 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.060 (1.52) MAX 0.210 (5.33) MAX 0.015 (0.38) MIN 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) SEATING PLANE 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) GAUGE PLANE 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) 0.430 (10.92) MAX 0.005 (0.13) MIN 0.070 (1.78) 0.060 (1.52) 0.045 (1.
PAGE 32
AD623 Data Sheet 3.20 3.00 2.80 8 3.20 3.00 2.80 1 5.15 4.90 4.65 5 4 PIN 1 IDENTIFIER 0.65 BSC 0.95 0.85 0.75 15° MAX 1.10 MAX 0.40 0.25 6° 0° 0.23 0.09 COMPLIANT TO JEDEC STANDARDS MO-187-AA 0.80 0.55 0.40 10-07-2009-B 0.15 0.05 COPLANARITY 0.10 Figure 87.