Analog Devices AD8500 Service Manual

Micropower Precision CMOS

FEATURES

Supply current: 1 μA maximum
Offset voltage: 1 mV maximum
Single-supply or dual-supply operation
Rail-to-rail input and output
No phase reversal
Unity gain stable

APPLICATIONS

Portable equipment
Remote sensors
Low power filters
Threshold detectors
Current sensing

GENERAL DESCRIPTION

The AD8500 is a low power, precision CMOS op amp featuring
a maximum supply current of 1 μA. The AD8500 has a maximum
offset voltage of 1 mV and a typical input bias current of 1 pA; it
operates rail-to-rail on both the input and output. The AD8500
can operate from a single-supply voltage of +1.8 V to +5.5 V or
a dual-supply voltage of ±0.9 V to ±2.75 V.

With its low power consumption, low input bias current, and
rail-to-rail input and output, the AD8500 is ideally suited for
a variety of battery-powered portable applications. Potential
applications include ECGs, pulse monitors, glucose meters,
smoke and fire detectors, vibration monitors, and backup
battery sensors.

Operational Amplifier

AD8500

PIN CONFIGURATION

OUT A

1

AD8500

V–

2

TOP VIEW

(Not to Scale)

3

+IN

Figure 1. 5-Lead SC70

The ability to swing rail-to-rail at both the input and output helps
maximize dynamic range and signal-to-noise ratio in systems
that operate at very low voltages. The low offset voltage allows
the AD8500 to be used in systems with high gain without having
excessively large output offset errors, and it provides high accuracy
without the need for system calibration.

The AD8500 is fully specified over the industrial temperature
range (−40°C to +85°C) and is operational over the extended
industrial temperature range (−40°C to +125°C). It is available
in a 5-lead, SC70 surface-mount package.

V+

5

4

–IN

06005-001

Rev. A

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2006 Analog Devices, Inc. All rights reserved.

AD8500

TABLE OF CONTENTS

Features.............................................................................................. 1

Applications....................................................................................... 1

General Description ......................................................................... 1

Pin Configuration............................................................................. 1

Revision History ............................................................................... 2

Specifications..................................................................................... 3

Electrical Characteristics ............................................................. 3

REVISION HISTORY

8/06—Rev. 0 to Rev. A

Updated Format..................................................................Universal

Changes to Figure 17, Figure 18, and Figure 19 ........................... 8

4/06—Revision 0: Initial Version

Absolute Maximum Ratings ............................................................5

Thermal Resistance.......................................................................5

ESD Caution...................................................................................5

Typical Performance Characteristics..............................................6

Outline Dimensions....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. A | Page 2 of 12

AD8500

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

@ VS = 5 V, VCM = VS/2, TA = 25°C, unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS 0 V < VCM < 5 V 0.235 1 mV
Offset Voltage Drift ∆VOS/∆T −40°C < TA < +85°C 3 10 μV/°C
Input Voltage Range −0.3 +5.3 V
Input Bias Current IB 1 10 pA

−40°C < TA < +85°C 100 pA

−40°C < TA < +125°C 600 pA
Input Offset Current IOS 0.5 5 pA

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 100 pA
Common-Mode Rejection Ratio CMRR 0 V < VCM < 5 V 75 90 dB

−40°C < TA < +85°C 70 90 dB
Large Signal Voltage Gain AVO 0.1 V < V

0.1 V < V
Input Capacitance C

C

2 pF

DIFF

4.5 pF

CM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R
R
Output Voltage Low VOL R
R
Short-Circuit Current ISC V

LOAD

LOAD

LOAD

LOAD

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR 1.8 V < VS < 5 V 90 110 dB

−40°C < TA < +85°C 80 dB
Supply Current/Amplifier ISY V

= VS/2 0.75 1 μA

O

−40°C < TA < +85°C 1.5 μA

−40°C < TA < +125°C 2 μA

DYNAMIC PERFORMANCE

Slew Rate SR 0.004 V/μs
Gain Bandwidth Product GBP 7 kHz
Phase Margin ØO 60 Degrees

NOISE PERFORMANCE

Peak-to-Peak Noise 0.1 Hz to 10 Hz 6 μV p-p
Voltage Noise Density en f = 1 kHz 190 nV/√Hz
Current Noise Density in f = 1 kHz 0.1 pA/√Hz

< 4.9 V 98 120 dB

OUT

< 4.9 V; −40°C < TA < +85°C 80 dB

OUT

= 100 kΩ to GND 4.970 4.995 V
= 10 kΩ to GND 4.900 4.960 V
= 100 kΩ to VS 0.85 5 mV
= 10 kΩ to VS 6.5 15 mV

= GND ±5 mA

Rev. A | Page 3 of 12

AD8500

@ VS = 1.8 V, VCM = VS/2, TA = 25°C, unless otherwise noted.

Table 2.

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage VOS 0 V < VCM < 1.8 V 0.235 1 mV
Offset Voltage Drift ∆VOS/∆T −40°C < TA < +85°C 3.5 12 μV/°C
Input Voltage Range −0.3 +2.1 V
Input Bias Current IB 1 10 pA

−40°C < TA < +85°C 100 pA

−40°C < TA < +125°C 600 pA
Input Offset Current IOS 0.5 5 pA

−40°C < TA < +85°C 50 pA

−40°C < TA < +125°C 100 pA
Common-Mode Rejection Ratio CMRR 0 V < VCM < 1.8 V 65 85 dB

−40°C < TA < +85°C 60 83 dB
Large Signal Voltage Gain AVO 0.1 V < V

0.1 V < V
Input Capacitance C

C

2 pF

DIFF

4.5 pF

CM

OUTPUT CHARACTERISTICS

Output Voltage High VOH R
R

Output Voltage Low VOL R
R

LOAD

LOAD

LOAD

LOAD

Short-Circuit Current ISC ±2 mA

POWER SUPPLY

Power Supply Rejection Ratio PSRR 1.8 V < VS < 5 V 90 110 dB

−40°C < TA < +85°C 80 dB
Supply Current/Amplifier ISY V

= VS/2 0.65 1 μA

O

−40°C < TA < +85°C 1.5 μA

−40°C < TA < +125°C 2 μA

DYNAMIC PERFORMANCE

Slew Rate SR 0.004 V/μs
Gain Bandwidth Product GBP 7 kHz
Phase Margin ØO 60 Degrees

NOISE PERFORMANCE

Peak-to-Peak Noise 0.1 Hz to 10 Hz 6 μV p-p
Voltage Noise Density en f = 1 kHz 190 nV/√Hz
Current Noise Density in f = 1 kHz 0.1 pA/√Hz

< 1.7 V 88 115 dB

OUT

< 1.7 V; −40°C < TA < +85°C 70 dB

OUT

= 100 kΩ to GND 1.790 1.798 V
= 10 kΩ to GND 1.760 1.783 V

= 100 kΩ to VS 0.70 5 mV
= 10 kΩ to VS 5 15 mV

Rev. A | Page 4 of 12

AD8500

ABSOLUTE MAXIMUM RATINGS

TA = 25°C, unless otherwise noted.

Table 3.

Parameter Rating

Supply Voltage 6 V
Input Voltage VSS − 0.4 V to VDD + 0.4 V
Differential Input Voltage ±6 V
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +125°C
Junction Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 60 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.

Absolute maximum ratings apply at 25°C, unless other­wise noted.

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 4. Thermal Characteristics

Package Type θJA θ

5-Lead SC70 (KS-5) 376 126 °C/W

Unit

JC

ESD 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 this product 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. A | Page 5 of 12

AD8500

TYPICAL PERFORMANCE CHARACTERISTICS

1200

1000

1000

800

600

400

NUMBER OF AMPLIFIERS

200

0

–1000 –750 750–500 500–250 2500 1000

VOS (µV)

Figure 2. Input Offset Voltage Distribution

(0 V < V

12

10

8

6

4

NUMBER OF AMPLIFIERS

2

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4. 5 5.0 5.5 6.0

< 5.0 V)

CM

TCVOS (µV/°C)

Figure 3. Input Offset Voltage Drift Distribution

(−40°C < T

1000

800

600

400

200

(µV)

0

OS

V

–200

–400

–600

–800

–1000

012345

< +85°C)

A

VCM (V)

Figure 4. Input Offset Voltage vs. Common-Mode Voltage

100

10

1

0.1

INPUT BIAS CURRENT (pA)

0.01

0.001
–40 –20 0 20 40 6 0 80 100 12 0

06005-002

TEMPERATURE ( °C)

06005-005

Figure 5. Input Bias Current vs. Temperature

= 1.8 V and 5.0 V)

(V

S

1000

(+125°C)

I

B

100

IB (+85°C)

10

1

I

(+25°C)

B

0.1

INPUT BIAS CURRENT (pA)

0.01

0.001

06005-003

(–40°C)

I

B

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

VCM (V)

06005-006

Figure 6. Input Bias Current vs. Common-Mode Voltage

70

60

50

40

30

20

NUMBER OF AMPLIFIERS

10

0

0.5 0.6 0.7 0.8 0.9 1.0

06005-004

SUPPLY CURRENT (µA)

06005-007

Figure 7. Supply Current Distribution

Rev. A | Page 6 of 12

AD8500

1.0

0.9

0.8

0.7

0.6

0.5

(µA)

SY

I

0.4

0.3

0.2

0.1

0

0123456

VS (V)

Figure 8. Supply Current vs. Supply Voltage

1.2

1.0

0.8

0.6

(µA)

SY

I

0.4

ISY AT 5.0V

I

AT 1.8V

SY

06005-008

1000

100

SOURCE

10

1

0.1

OUTPUT SATURATIO N VOLTAGE (mV)

0.01

0.001 0.01 0.1 1

LOAD CURRENT (mA)

SINK

Figure 11. Output Saturation Voltage vs. Load Current

100

V

@ 10kΩ LOAD

OH

10

V

@ 10kΩ LOAD

OL

VOH @ 100kΩ LOAD

VOL @ 100kΩ LOAD

1

06005-011

0.2

0

–40 –25 –10 5 20 35 50 65 80 95 110 125

TEMPERATURE (° C)

Figure 9. Supply Current vs. Temperature

900

850

800

(µA)

750

SY

I

700

650

600

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

VCM (V)

Figure 10. Supply Current vs. Input Common-Mode Voltage

OUTPUT SAT URATION VOLTAGE (mV )

0.1
–40 10–15 35 60 85

06005-009

TEMPERATURE ( °C)

06005-012

Figure 12. Output Saturation Voltage vs. Temperature

80

60

40

20

0

–20

OPEN-LOOP GAIN (dB)

–40

–60

–80

10 100 1k 10k 100k

06005-010

FREQUENCY (Hz)

135

90

45

0

–45

–90

–135

–180

PHASE MARGIN (Degrees)

06005-013

Figure 13. Open-Loop Gain and Phase vs. Frequency

Rev. A | Page 7 of 12

AD8500

120

1

1

0

100

90

80

70

60

50

CMRR (dB)

40

30

0

2

10

0

0.01 0. 1 1 10 100

FREQUENCY (kHz)

Figure 14. CMRR vs. Frequency

100

90

80

70

60

50

PSRR (dB)

40

30

2

0

10

0

0.01 0. 1 1 10 100

FREQUENCY (kHz)

Figure 15. PSRR vs. Frequency

35

06005-014

6005-015

0.20

0.15

0.10

0.05

(V)

0

OUT

V

–0.05

–0.10

–0.15

–0.20

–0.0005 0 0. 0005 0.0010 0.0015

TIME (Second s)

Figure 17. Small Signal Transient Response

(No Load)

0.20

0.15

0.10

0.05

(V)

0

OUT

V

–0.05

–0.10

–0.15

–0.20

–0.0005 0 0. 0005 0.0010 0.0015

TIME (Second s)

Figure 18. Small Signal Transient Response

(100 pF Load Capacitance)

6

06005-017

06005-018

30

25

20

15

OVERSHOOT (%)

10

5

0

10 100 1000

LOAD CAPACITANCE (p F)

OS+

OS–

Figure 16. Small Signal Overshoot vs. Load Capacitance

06005-016

Rev. A | Page 8 of 12

5

4

(V)

3

OUT

V

2

1

0

–0.002 0.001 0.002 0.003 0.004 0.005 0.006 0.0070–0.001 0.008

TIME (Second s)

Figure 19. Large Signal Transient Response

(No Load)

6005-019

AD8500

1000

V

S

100

VOLTS (V)

V

OUT

TIME (µs)

Figure 20. Turn-On Transient Response

4

V

3

2

1

0

–1

OUTPUT VOLTAGE (V)

–2

–3

–4
–0.005 –0.003 –0.001 0.001 0.003 0.005 0.007 0.009

OUT

V

IN

TIME (µs)

Figure 21. No Phase Reversal

4

GAIN = +1
V

= V

IN

S/2

VOLTAG E NO ISE DENSITY (nV/ Hz)

10

06005-020

1 10 100 1k 10k

FREQUENCY (Hz)

06005-023

Figure 23. Voltage Noise Density

= 1.8 V and 5.0 V)

(V

S

500

400

300

200

NUMBER OF AMPLIFIERS

100

0

–1000 –750 –500 -250 0 250 500 750 1000

06005-021

VOS (µV)

06005-024

Figure 24. Input Offset Voltage Distribution

(0 V < V

12

< 1.8 V)

CM

3

2

1

0

–1

–2

PEAK-TO-PE AK VOLTAGE (µV)

–3

–4

–5 –4 –3 –2 –1 0 1 2 3 4 5

TIME (Seconds)

Figure 22. 0.1 Hz to 10 Hz Input Voltage Noise

= 5 V and 1.8 V)

(V

S

06005-022

Rev. A | Page 9 of 12

10

8

6

4

NUMBER OF AMPLIFIERS

2

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5

TCVOS (µV/°C)

Figure 25. Input Offset Voltage Drift Distribution

(−40°C < T

< +85°C)

A

06005-025

AD8500

1000

800

600

400

200

(µV)

0

OS

V

–200

–400

–600

–800

–1000

0 0.3 0.6 0.9 1.2 1.5 1.8

VCM (V)

Figure 26. Input Offset Voltage vs. Input Common-Mode Voltage

1000

IB (+125°C)

06005-026

700

650

600

(µA)

SY

I

550

500

0 0.30.60.91.21.51.8

VCM (V)

Figure 29. Supply Current vs. Input Common-Mode Voltage

1000

06005-029

100

(+85°C)

I

10

1

(pA)
I

(+25°C)

I

B

B

0.1

0.01

0.001
0 0.3 0.6 0.9 1.2 1.5 1.8

VCM (V)

B

(–40°C)

I

B

Figure 27. Input Bias Current vs. Input Common-Mode Voltage

70

60

50

40

30

20

NUMBER OF AMPLIFIERS

10

100

SOURCE

10

1

0.1

OUTPUT SATURATION VOLTAGE (mV)

0.01

0.001 0. 01 0.1 1

06005-027

LOAD CURRENT (mA)

SINK

06005-030

Figure 30. Output Saturation Voltage vs. Load Current

100

VOH @ 10kΩ LOAD

10

@ 10kΩ LOAD

V

OL

V

@ 100kΩ LOAD

OH

1

@ 100kΩ LOAD

V

OL

OUTPUT SATURATION VOLTAGE (mV)

0

0.50.4 0.6 0.7 0.8 0.9

SUPPLY CURRENT (µA)

Figure 28. Supply Current Distribution

6005-028

Rev. A | Page 10 of 12

0.1
–40 –15 10 35 8560

TEMPERATURE ( °C)

Figure 31. Output Saturation Voltage vs. Temperature

06005-031

AD8500

80

60

40

20

0

–20

OPEN-LOOP GAIN (dB)

–40

–60

–80

10 100 1k 10k 100k

FREQUENCY (Hz)

Figure 32. Open-Loop Gain and Phase vs. Frequency

100

90

80

70

60

50

CMRR (dB)

40

30

20

10

0

0.01 0. 1 1 10 100

FREQUE NCY (kHz)

Figure 33. CMRR vs. Frequency

35

30

25

20

15

OVERSHOOT (%)

10

5

0

10 100 1000

LOAD CAPACITANCE ( pF)

OS–

Figure 34. Small Signal Overshoot vs. Load Capacitance

OS+

135

90

45

0

–45

–90

–135

–180

0.20

0.15

0.10

0.05

(mV)

0

OUT

V

–0.05

PHASE MARGIN ( Degrees)

06005-032

–0.10

–0.15

–0.20

–0.0005 0 0.0005 0.0010 0.0015

TIME (Seconds)

06005-035

Figure 35. Small Signal Transient Response

(No Load)

0.20

0.15

0.10

0.05

(mV)

0

OUT

V

–0.05

–0.10

–0.15

–0.20

–0.0005

06005-033

0 0.0005 0.0010 0. 0015

TIME (S econds)

6005-036

Figure 36. Small Signal Transient Response

(100 pF Load Capacitance)

2.0

1.8

1.6

1.4

1.2

(mV)

1.0

OUT

V

0.8

0.6

0.4

0.2

0

–0.002 –0.001 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008

06005-034

TIME (Seconds)

06005-037

Figure 37. Large Signal Transient Response

(No Load)

Rev. A | Page 11 of 12

AD8500

OUTLINE DIMENSIONS

2.20

2.00

1.80

1.35

1.25

1.15

PIN 1

1.00

0.90

0.70

0

.

1

0

M

A

X

0.10 COPLANARITY

123

0.30

0.15

COMPLIANT TO JEDEC STANDARDS MO-203-AA

45

0.65 BSC

2.40

2.10

1.80

1.10

0.80

SEATING
PLANE

0.40

0.10

0.22

0.08

0.46

0.36

0.26

Figure 38. 5-Lead Thin Shrink Small Outline Transistor Package [SC70]

(KS-5)

Dimensions shown in millimeters

ORDERING GUIDE

Model Temperature Range Package Description Package Option Branding

AD8500AKSZ-R2
AD8500AKSZ-REEL
AD8500AKSZ-REEL7

1

Z = Pb-free part.

1

1

1

−40°C to +125°C 5-Lead SC70 KS-5 A0F

−40°C to +125°C 5-Lead SC70 KS-5 A0F

−40°C to +125°C 5-Lead SC70 KS-5 A0F

©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06005-0-8/06(A)

Rev. A | Page 12 of 12