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.

AD8500

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

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

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

Analog Devices AD8500 Service Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

PIN CONFIGURATION

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ELECTRICAL CHARACTERISTICS