Datasheet

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Low Power, Rail-to-Rail Output, Precision

JFET Amplifiers

Data Sheet

AD8641/AD8642/AD8643

Rev. E

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FEATURES

Low supply current: 250 μA max

Very low input bias current: 1 pA max

Low offset voltage: 750 μV max

Single-supply operation: 5 V to 26 V

Dual-supply operation: ±2.5 V to ±13 V

Rail-to-rail output

Unity-gain stable

No phase reversal

SC70 package

APPLICATIONS

Line-/battery-powered instruments

Photodiode amplifiers

Precision current sensing

Medical instrumentation

Industrial controls

Precision filters

Portable audio

ATE

GENERAL DESCRIPTION

The AD8641/AD8642/AD8643 are low power, precision JFET

input amplifiers featuring extremely low input bias current and

rail-to-rail output. The ability to swing nearly rail-to-rail at the

input and rail-to-rail at the output enables designers to buffer

CMOS DACs, ASICs, and other wide output swing devices in

single-supply systems. The outputs remain stable with

capacitive loads of more than 500 pF.

The AD8641/AD8642/AD8643 are suitable for applications

utilizing multichannel boards that require low power to manage

heat. Other applications include photodiodes, ATE reference

level drivers, battery management, and industrial controls.

The AD8641/AD8642/AD8643 are fully specified over the

extended industrial temperature range of –40°C to +125°C. The

AD8641 is available in 5-lead SC70 and 8-lead SOIC lead-free

packages. The AD8642 is available in 8-lead MSOP and 8-lead

SOIC lead-free packages. The AD8643 is available in 14-lead

SOIC and 16-lead, 3 mm × 3 mm, LFCSP lead-free packages.

PIN CONFIGURATIONS

OUT

+IN

VEE

VCC

–IN

AD8641

TOP VIEW

(Not to Scale)

05072-101

Figure 1. 5-Lead SC70 (KS-5)

–IN

+IN

VEE

VCC

OUT

AD8641

TOP VIEW

(Not to Scale)

05072-102

NC = NO CONNECT

Figure 2. 8-Lead SOIC (R-8)

OUT

–IN A

+IN A

V–

V+

OUT B

–IN B

+IN B

AD8642

TOP VIEW

(Not to Scale)

05072-105

Figure 3. 8-Lead SOIC (R-8)

OUT A

–IN A

+IN A

V–

V+

OUT B

–IN B

+IN B

AD8642

TOP VIEW

(Not to Scale)

05072-064

Figure 4. 8-Lead MSOP (RM-8)

05072-103

OUT

OUT D

–IN A

–IN D

+IN A

+IN D

V+

V–

+IN B

+IN C

–IN B

–IN C

OUT B

OUT C

TOP VIEW

(Not to Scale)

AD8643

Figure 5. 14-Lead SOIC (R-14)

05072-104

+IN C

V–

+IN D

–IN D

–IN A

–IN B

OUT B

OUT C

–IN C

+IN B

V+

+IN A

AD8643

TOP VIEW

PIN 1

INDICATOR

OUT A

OUT D

NOTES

1. NC = NO CONNECT.

2. EXPOSED PAD SHOULD BE CONNECTED TO V+.

Figure 6. 16-Lead LFCSP (CP-16) (Not Drawn to Scale)

Summary of content (16 pages)

PAGE 1
PIN CONFIGURATIONS OUT 1 +IN 3 NC 7 VCC 6 OUT 5 NC NC = NO CONNECT OUT A 1 –IN A 2 +IN A 3 V– 4 AD8642 TOP VIEW (Not to Scale) 8 V+ 7 OUT B 6 –IN B 5 +IN B 05072-105 Figure 2. 8-Lead SOIC (R-8) OUT A 1 –IN A 2 AD8642 +IN A 3 TOP VIEW (Not to Scale) V– 4 8 V+ 7 OUT B 6 –IN B 5 +IN B 05072-064 Figure 3. 8-Lead SOIC (R-8) Figure 4.
PAGE 2
AD8641/AD8642/AD8643 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Absolute Maximum Ratings ............................................................5 Applications....................................................................................... 1 Thermal Resistance .......................................................................5 General Description .................................................
PAGE 3
Data Sheet AD8641/AD8642/AD8643 SPECIFICATIONS ELECTRICAL CHARACTERISTICS VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol Conditions Min VOS Typ Max Unit 50 750 1 1.5 1.6 1 180 0.5 60 3 93 140 2.5 μV mV mV mV pA pA pA pA V dB V/mV μV/°C 0.01 ±6 V V V V mA AD8643 LFCSP only –40°C < TA < +85°C +85°C < TA < +125°C, VCM = 1.5 V Input Bias Current IB 0.
PAGE 4
AD8641/AD8642/AD8643 Data Sheet VS= ±13 V, VCM = 0 V, TA =25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol Conditions Min VOS Typ Max Unit 70 750 1 1.5 1 260 0.5 65 +10 107 290 2.5 μV mV mV pA pA pA pA V dB V/mV μV/°C ±12 V V V V mA AD8643 LFCSP only –40° < TA < +125°C Input Bias Current IB 0.
PAGE 5
Data Sheet AD8641/AD8642/AD8643 ABSOLUTE MAXIMUM RATINGS Absolute maximum ratings apply at 25°C, unless otherwise noted. Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range KS-5, R-8, RM-8, R-14, CP-16 Packages Operating Temperature Range Junction Temperature Range KS-5, R-8, RM-8, R-14, CP-16 Packages Lead Temperature (Soldering, 60 sec) Rating 27.
PAGE 6
AD8641/AD8642/AD8643 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 20 80 VSY = ±13V VSY = 5V VCM = 1.5V 18 70 16 NUMBER OF AMPLIFIERS FREQUENCY 60 50 40 30 20 14 12 10 8 6 9.5 10.0 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 0 TCVOS (μV/°C) Figure 7. Input Offset Voltage 05072-005 VOS (mV) 1.0 0 05072-002 0 –0.60 –0.55 –0.50 –0.45 –0.40 –0.35 –0.30 –0.25 –0.20 –0.15 –0.10 –0.05 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 2 0.
PAGE 7
Data Sheet AD8641/AD8642/AD8643 1000 500 VSY = ±13V VSY = 5V 400 200 VOS (μV) INPUT BIAS CURRENT (pA) 300 100 10 100 0 –100 –200 1 –300 –400 25 50 75 100 125 150 TEMPERATURE (°C) –500 0 0.5 1.0 1.5 2.0 05072-011 0 05072-008 0.1 2.5 VCM (V) Figure 16. Input Offset Voltage vs. VCM Figure 13. Input Bias Current vs. Temperature 10M 1.0 VSY = +5V OR ±5V 0.8 OPEN-LOOP GAIN (V/V) 0.6 INPUT BIAS (pA) 0.4 0.2 0 –0.2 –0.4 1M VSY = ±13V VSY = ±2.5V 100k –0.
PAGE 8
AD8641/AD8642/AD8643 Data Sheet 10000 600 VSY = ±13V VSY = ±13V 500 SATURATION VOLTAGE (mV) OFFSET VOLTAGE (μV) 400 300 200 100 0 100kΩ –100 –200 –300 10kΩ 1kΩ VSY – VOH 1000 100 –VSY – VOL 10 –400 –10 –5 0 5 10 15 OUTPUT VOLTAGE (V) 1 0.001 05072-014 –600 –15 0.01 0.1 1 10 05072-017 –500 100 LOAD CURRENT (mA) Figure 22. Output Saturation Voltage vs. Load Current Figure 19. Input Error Voltage vs.
PAGE 9
Data Sheet AD8641/AD8642/AD8643 50 GAIN 30 270 120 225 100 180 80 135 20 90 PHASE 10 45 0 0 –10 –20 –90 –30 10k –135 100k 1M VSY = ±13V 60 40 20 0 –45 –20 05072-020 GAIN (dB) 40 140 –40 –60 1k 10M 10k 100k 1M FREQUENCY (Hz) FREQUENCY (Hz) Figure 25. Open-Loop Gain and Phase Margin vs. Frequency Figure 28. CMRR vs.
PAGE 10
AD8641/AD8642/AD8643 Data Sheet 140 1.0 VSY = 5V 100 1 VIN INPUT BIAS (pA) 0.4 60 40 –PSRR 20 0.2 0 –0.2 0 –0.4 –20 –0.6 –40 –0.8 2 100k 1M 10M FREQUENCY (Hz) VOUT –1.0 CH1 –4 10.0V –3CH2 –2 10.0V–1 –5 CH1 4 1.00V5 0M400μ1s 2 A 3 T 0.00000s VCM (V) 05072-009 10k 05072-026 –60 1k Figure 34. No Phase Reversal Figure 31. PSRR vs. Frequency 15 1000 VSY = ±13V VS = ±13V GAIN = +5 G = +100 10 100 TS + (1%) OUTPUT SWING (V) 10 G = +10 1 G = +1 0.1 5 TS + (0.
PAGE 11
Data Sheet AD8641/AD8642/AD8643 70 1k 40 OS– 30 OS+ 20 0 1 10 100 1000 CAPACITANCE (pF) 10 1 05072-032 10 100 10 100 Figure 37. Small Signal Overshoot vs. Load Capacitance 10k Figure 40. Voltage Noise Density 1k 1.0 VS = ±13V G = +1M CH1 p-p = 4.26V VSY = 5V VOLTAGE NOISE DENSITY (nV/ Hz) 0.8 0.6 0.4 INPUT BIAS (pA) 1k FREQUENCY (Hz) 0.2 10 –0.2 –0.4 10 05072-033 –0.6 100 –1.0 CH1 –4 1.00V –3 –5 –2 –1 0M1.00s1 2 A CH1 3 1 05072-009 –0.8 4–20.
PAGE 12
AD8641/AD8642/AD8643 Data Sheet –40 20kΩ –50 2kΩ – –60 + –70 VIN – 2kΩ 2kΩ + –80 VIN = 18V p-p –110 –120 VIN = 4.5V p-p –130 –140 –150 –160 20 VIN = 9V p-p 100 05072-041 (dB) –90 –100 1k 10k 100k FREQUENCY (Hz) Figure 43. Channel Separation Rev.
PAGE 13
Data Sheet AD8641/AD8642/AD8643 OUTLINE DIMENSIONS 2.20 2.00 1.80 1.35 1.25 1.15 5 2.40 2.10 1.80 4 1 2 3 0.65 BSC 1.10 0.80 0.10 MAX COPLANARITY 0.10 SEATING PLANE 0.30 0.15 0.40 0.10 0.46 0.36 0.26 0.22 0.08 072809-A 1.00 0.90 0.70 COMPLIANT TO JEDEC STANDARDS MO-203-AA Figure 44. 5-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-5) Dimensions shown in millimeters 5.00 (0.1968) 4.80 (0.1890) 1 5 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.
PAGE 14
AD8641/AD8642/AD8643 Data Sheet 3.20 3.00 2.80 8 3.20 3.00 2.80 5.15 4.90 4.65 5 1 4 PIN 1 IDENTIFIER 0.65 BSC 0.95 0.85 0.75 15° MAX 1.10 MAX 0.80 0.55 0.40 0.23 0.09 6° 0° 0.40 0.25 10-07-2009-B 0.15 0.05 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 46. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters 8.75 (0.3445) 8.55 (0.3366) 8 14 1 6.20 (0.2441) 5.80 (0.2283) 7 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 0.50 (0.
PAGE 15
Data Sheet AD8641/AD8642/AD8643 ORDERING GUIDE Model 1 AD8641AKSZ-R2 AD8641AKSZ-REEL7 AD8641AKSZ-REEL AD8641ARZ AD8641ARZ-REEL7 AD8641ARZ-REEL AD8642ARMZ AD8642ARMZ-REEL AD8642ARZ AD8642ARZ-REEL7 AD8642ARZ-REEL AD8643ARZ AD8643ARZ-REEL7 AD8643ARZ-REEL AD8643ACPZ-R2 AD8643ACPZ-REEL7 AD8643ACPZ-REEL 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°
PAGE 16
AD8641/AD8642/AD8643 Data Sheet NOTES ©2004–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05072-0-9/11(E) Rev.