Datasheet AD8544, AD8542, AD8541 Datasheet (Analog Devices)

General Purpose CMOS

a

FEATURES
Single Supply Operation: +2.7 V to +5.5 V
Low Supply Current: 45 ␮A/Amplifier
Wide Bandwidth: 1 MHz
No Phase Reversal
Low Input Currents: 4 pA
Unity Gain Stable
Rail-to-Rail Input and Output

APPLICATIONS
ASIC Input or Output Amplifier
Sensor Interface
Piezo Electric Transducer Amplifier
Medical Instrumentation
Mobile Communication
Audio Output
Portable Systems

GENERAL DESCRIPTION

The AD8541/AD8542/AD8544 are single, dual and quad rail­to-rail input and output single supply amplifiers featuring very
low supply current and 1 MHz bandwidth. All are guaranteed to
operate from a +2.7 V single supply as well as a +5 V supply.
These parts provide 1 MHz bandwidth at low current consump­tion of 45 µA per amplifier.

Very low input bias currents enable the AD8541/AD8542/AD8544
to be used for integrators, photodiode amplifiers, piezo electric
sensors and other applications with high source impedance. Supply
current is only 45 µA per amplifier, ideal for battery operation.

Rail-to-rail inputs and outputs are useful to designers buffering
ASICs in single supply systems. The AD8541/AD8542/AD8544
are optimized to maintain high gains at lower supply voltages,
making them useful for active filters and gain stages.

The AD8541/AD8542/AD8544 are specified over the extended
industrial (–40°C to +125°C) temperature range. The AD8541
is available in 8-lead SO and 5-lead SOT-23 packages. The
AD8542 is available in 8-lead SO, 8-lead MSOP, and 8-lead
TSSOP surface mount packages. The AD8544 is available in
14-lead narrow SO-14 and 14-lead TSSOP surface mount pack­ages. All TSSOP, MSOP, and SOT versions are available in tape
and reel only.

Rail-to-Rail Amplifiers

AD8541/AD8542/AD8544

PIN CONFIGURATIONS

SO-8 (R) SOT-23-5 (RT)

Vⴚ

V+

1

2

3

1

2

3

4

5

6

7

AD8541

AD8544

5

4

14

13

12

11

10

V+

ⴚIN A

9

8

OUT D

ⴚIN D

+IN D

Vⴚ

+IN C

ⴚIN C

OUT C

NC

1

ⴚIN A

2

+IN A

3

Vⴚ

4

NC = NO CONNECT

AD8541

8

7

6

5

NC

V+

OUT A

NC

OUT A

+IN A

SO-8 (R), RM-8, and RU-8 SO-14 (R) and RU-14

OUT A

ⴚIN A

+IN A

Vⴚ

1

2

3

4

AD8542

8

7

6

5

V+

OUT B

ⴚIN B

+IN B

OUT A

ⴚIN A

+IN A

+IN B

ⴚIN B

OUT B

REV. A

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.

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

AD8541/AD8542/AD8544–SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

(VS = +2.7 V, VCM = +1.35 V, TA = +25ⴗC unless otherwise noted)

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

Input Offset Current I

B

OS

OS

–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

≤ +125°C7mV

A

≤ +85°C 100 pA

A

≤ +125°C 1,000 pA

A

≤ +85°C50pA

A

≤ +125°C 500 pA

A

16 mV

460 pA

0.1 30 pA

Input Voltage Range 0 +2.7 V
Common-Mode Rejection Ratio CMRR V

Large Signal Voltage Gain A

Offset Voltage Drift ∆V
Bias Current Drift ∆I

VO

/∆T –40°C ≤ TA ≤ +125°C4µV/°C

OS

/∆T –40°C ≤ TA ≤ +85°C 100 fA/°C

B

= 0 V to +2.7 V 40 45 dB

CM

–40°C ≤ T

≤ +125°C38 dB

A

RL = 100 kΩ , VO = +0.5 V to +2.2 V 100 500 V/mV
–40°C ≤ T
–40°C ≤ T

–40°C ≤ T

≤ +85°C 50 V/mV

A

≤ +125°C 2 V/mV

A

≤ +125°C 2,000 fA/°C

A

Offset Current Drift ∆IOS/∆T –40°C ≤ TA ≤ +125°C 25 fA/°C

OUTPUT CHARACTERISTICS

Output Voltage High V

Output Voltage Low V

Output Current I

Closed Loop Output Impedance Z

OUT

±I

OH

OL

SC

OUT

IL = 1 mA +2.575 +2.65 V
–40°C ≤ T

≤ +125°C +2.550 V

A

IL = 1 mA 35 100 mV
–40°C ≤ T
V

OUT

≤ +125°C 125 mV

A

= VS – 1 V 15 mA

±20 mA

f = 200 kHz, AV = 1 50 Ω

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = +2.5 V to +6 V 65 76 dB

Supply Current/Amplifier I

SY

–40°C ≤ T
VO = 0 V 38 55 µA

≤ +125°C60 dB

A

–40°C ≤ TA ≤ +125°C75µA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 100 kΩ 0.4 0.75 V/µs
Settling Time t

S

To 0.1% (1 V Step) 5 µs

Gain Bandwidth Product GBP 980 kHz
Phase Margin Φo 63 Degrees

NOISE PERFORMANCE

Voltage Noise Density e

Current Noise Density i

Specifications subject to change without notice.

n

e

n

n

f = 1 kHz 40 nV/√Hz
f = 10 kHz 38 nV/√Hz

<0.1 pA/√Hz

–2–

REV. A

AD8541/AD8542/AD8544

ELECTRICAL CHARACTERISTICS

(VS = +3.0 V, VCM = +1.5 V, TA = +25ⴗC unless otherwise noted)

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

Input Offset Current I

B

OS

OS

–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

≤ +125°C7mV

A

≤ +85°C 100 pA

A

≤ +125°C 1,000 pA

A

≤ +85°C50pA

A

≤ +125°C 500 pA

A

16 mV

460 pA

0.1 30 pA

Input Voltage Range 0+3V
Common-Mode Rejection Ratio CMRR V

Large Signal Voltage Gain A

Offset Voltage Drift ∆V
Bias Current Drift ∆I

VO

/∆T –40°C ≤ TA ≤ +125°C4µV/°C

OS

/∆T –40°C ≤ TA ≤ +85°C 100 fA/°C

B

= 0 V to +3 V 40 45 dB

CM

–40°C ≤ T

≤ +125°C38 dB

A

RL = 100 kΩ , VO = +0.5 V to +2.2 V 100 500 V/mV
–40°C ≤ T
–40°C ≤ T

–40°C ≤ T

≤ +85°C 50 V/mV

A

≤ +125°C 2 V/mV

A

≤ +125°C 2,000 fA/°C

A

Offset Current Drift ∆IOS/∆T –40°C ≤ TA ≤ +125°C 25 fA/°C

OUTPUT CHARACTERISTICS

Output Voltage High V

Output Voltage Low V

Output Current I

Closed Loop Output Impedance Z

OUT

±I

OH

OL

SC

OUT

IL = 1 mA +2.875 +2.955 V
–40°C ≤ T

≤ +125°C +2.850 V

A

IL = 1 mA 32 100 mV
–40°C ≤ T
V

OUT

≤ +125°C 125 mV

A

= VS – 1 V 18 mA

±25 mA

f = 200 kHz, AV = 1 50 Ω

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = +2.5 V to +6 V 65 76 dB

≤ +125°C60 dB

A

Supply Current/Amplifier I

SY

–40°C ≤ T
VO = 0 V 40 60 µA
–40°C ≤ TA ≤ +125°C75µA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 100 kΩ 0.4 0.8 V/µs
Settling Time t

S

To 0.01% (1 V Step) 5 µs

Gain Bandwidth Product GBP 980 kHz
Phase Margin Φo 64 Degrees

NOISE PERFORMANCE

Voltage Noise Density e

Current Noise Density i

Specifications subject to change without notice.

n

e

n

n

f = 1 kHz 42 nV/√Hz
f = 10 kHz 38 nV/√Hz

<0.1 pA/√Hz

–3–REV. A

AD8541/AD8542/AD8544–SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

(VS = +5.0 V, VCM = +2.5 V, TA = +25ⴗC unless otherwise noted)

Parameter Symbol Conditions Min Typ Max Units

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

Input Offset Current I

B

OS

OS

–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

–40°C ≤ T
–40°C ≤ T

≤ +125°C7mV

A

≤ +85°C 100 pA

A

≤ +125°C 1,000 pA

A

≤ +85°C50pA

A

≤ +125°C 500 pA

A

16 mV

460 pA

0.1 30 pA

Input Voltage Range 0+5V
Common-Mode Rejection Ratio CMRR V

Large Signal Voltage Gain A

Offset Voltage Drift ∆V
Bias Current Drift ∆I

VO

/∆T –40°C ≤ TA ≤ +125°C4µV/°C

OS

/∆T –40°C ≤ TA ≤ +85°C 100 fA/°C

B

= 0 V to +5 V 40 48 dB

CM

–40°C ≤ T

≤ +125°C38 dB

A

RL = 100 kΩ , VO = +0.5 V to +2.2 V 20 40 V/mV
–40°C ≤ T
–40°C ≤ T

–40°C ≤ T

≤ +85°C 10 V/mV

A

≤ +125°C 2 V/mV

A

≤ +125°C 2,000 fA/°C

A

Offset Current Drift ∆IOS/∆T –40°C ≤ TA ≤ +125°C 25 fA/°C

OUTPUT CHARACTERISTICS

Output Voltage High V

Output Voltage Low V

Output Current I

Closed Loop Output Impedance Z

OUT

±I

OH

OL

SC

OUT

IL = 1 mA +4.9 +4.965 V
–40°C ≤ T

≤ +125°C +4.875 V

A

IL = 1 mA 25 100 mV
–40°C ≤ T
V

OUT

≤ +125°C 125 mV

A

= VS – 1 V 30 mA

±60 mA

f = 200 kHz, AV = 1 45 Ω

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = +2.5 V to +6 V 65 76 dB

Supply Current/Amplifier I

SY

–40°C ≤ T
VO = 0 V 45 65 µA

≤ +125°C60 dB

A

–40°C ≤ TA ≤ +125°C85µA

DYNAMIC PERFORMANCE

Slew Rate SR RL = 100 kΩ, CL = 200 pF 0.45 0.92 V/µs
Full-Power Bandwidth BW
Settling Time t

S

P

1% Distortion 70 kHz
To 0.1% (1 V Step) 6 µs

Gain Bandwidth Product GBP 1,000 kHz
Phase Margin Φo 67 Degrees

NOISE PERFORMANCE

Voltage Noise Density e

Current Noise Density i

Specifications subject to change without notice.

n

e

n

n

f = 1 kHz 42 nV/√Hz
f = 10 kHz 38 nV/√Hz

<0.1 pA/√Hz

–4–

REV. A

ABSOLUTE MAXIMUM RATINGS

WARNING!

ESD SENSITIVE DEVICE

1

Supply Voltage(VS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6 V

Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to V

S

Differential Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . . ± 6 V

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 Range (Soldering, 60 sec) . . . . . . .+300°C

NOTES

1

Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.

2

For supplies less than +6 V, the differential input voltage is equal to ± VS.

ORDERING GUIDE

Temperature Package Package Branding

Model Range Description Option Information

AD8541AR –40°C to +125°C 8-Lead SOIC SO-8
AD8541ART* –40°C to +125°C 5-Lead SOT-23 RT-5 A4A
AD8542AR –40°C to +125°C 8-Lead SOIC SO-8
AD8542ARM* –40°C to +125°C 8-Lead MSOP RM-8 AVA
AD8542ARU* –40°C to +125°C 8-Lead TSSOP RU-8
AD8544AR –40°C to +125°C 14-Lead SOIC SO-14
AD8544ARU* –40°C to +125°C 14-Lead TSSOP RU-14

*Available in reels only.

AD8541/AD8542/AD8544

PACKAGE INFORMATION

Package Type ␪

5-Lead SOT-23 (RT) 256 81 °C/W
8-Lead SOIC (R) 158 43 °C/W
8-Lead MSOP (RM) 210 45 °C/W
8-Lead TSSOP (RU) 240 43 °C/W
14-Lead SOIC (R) 120 36 °C/W
14-Lead TSSOP (RU) 240 43 °C/W

NOTE

1

θJA is specified for worst case conditions, i.e., θ

onto a circuit board for surface mount packages.

1

JA

␪

JC

is specified for device soldered

JA

Units

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 AD8541/AD8542/AD8544 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.

–5–REV. A

AD8541/AD8542/AD8544

–Typical Performance Characteristics

180

160

140

120

100

80

60

NUMBER OF AMPLIFIERS

40

20

0

ⴚ4.5 ⴚ3.5

ⴚ2.5ⴚ1.5 ⴚ0.5

INPUT OFFSET VOLTAGE – mV

VS = +5V
V
T

1.5 2.5 3.50.5

= +2.5V

CM

= +25ⴗC

A

Figure 1. Input Offset Voltage
Distribution

400

VS = +2.7V AND +5V

350

V

= VS/2

CM

300

250

200

150

100

INPUT BIAS CURRENT – pA

50

0
ⴚ40 ⴚ20

0 20 40 80 100 12060

TEMPERATURE – ⴗC

Figure 4. Input Bias Current vs.
Temperature

4.5

140

1.0

VS = +2.7V AND +5V

0.5
V

= VS/2

CM

0.0

ⴚ0.5

ⴚ1.0

ⴚ1.5

ⴚ2.0

ⴚ2.5

ⴚ3.0

INPUT OFFSET VOLTAGE – mV

ⴚ3.5

ⴚ4.0

ⴚ55 ⴚ35

ⴚ15

5 25 45 65 85 105 125

TEMPERATURE – ⴗC

Figure 2. Input Offset Voltage
vs. Temperature

7

VS = +2.7V AND +5V

6

V

= VS/2

CM

5

4

3

2

1

INPUT OFFSET CURRENT – pA

0

ⴚ1

ⴚ15

ⴚ55 ⴚ35

25 85 105 12565

545

TEMPERATURE – ⴗC

Figure 5. Input Offset Current vs.
Temperature

145

145

9

VS = +2.7V AND +5V

8

V

= VS/2

CM

7

6

5

4

3

2

INPUT BIAS CURRENT – pA

1

0

ⴚ0.5

0.5 5.5

1.5 2.5 3.5 4.5

COMMON-MODE VOLTAGE – V

Figure 3. Input Bias Current vs.
Common-Mode Voltage

160

VS = +2.7V

140

T

= +25ⴗC

A

120

100

POWER SUPPLY REJECTION – dB

ⴚ20

ⴚ40

80

60

40

20

ⴚPSRR

+PSRR

0

100 1k 10M10k 100k 1M

FREQUENCY – Hz

Figure 6. Power Supply Rejection
Ratio vs. Frequency

10k

VS = +2.7V
T

= +25ⴗC

A

1k

100

10

1

⌬ OUTPUT VOLTAGE – mV

0.1

0.01

0.001 0.01 100

SOURCE

SINK

0.1 1 10

LOAD CURRENT – mA

Figure 7. Output Voltage to Supply
Rail vs. Load Current

3.0

2.5

2.0

1.5

1.0

OUTPUT SWING – Vp-p

0.5

0

1k 10k 10M

FREQUENCY – Hz

VS = +2.7V
V

IN

R

= 2k⍀

L

T

= +25ⴗC

A

100k 1M

= 2.5Vp-p

Figure 8. Closed-Loop Output
Voltage Swing vs. Frequency

–6–

60

VS = +2.7V
R

=

50

L

T

= +25ⴗC

A

40

+OS

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

ⴚOS

1k

Figure 9. Small Signal Overshoot vs.
Load Capacitance

REV. A

AD8541/AD8542/AD8544

60

VS = +2.7V
R

= 10k⍀

50

L

T

= +25ⴗC

A

40

+OS

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

ⴚOS

1k

Figure 10. Small Signal Overshoot
vs. Load Capacitance

1.35V

VS = +2.7V
R

= 2k

⍀

L

AV = +1
T

= +25ⴗC

A

500mV

10␮s

Figure 13. Large Signal Transient
Response

60

VS = +2.7V
R

= 2k⍀

50

L

T

= +25ⴗC

A

40

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

+OS

ⴚOS

1k

Figure 11. Small Signal Overshoot
vs. Load Capacitance

VS = +2.7V
R

= NO LOAD

L

T

= +25ⴗC

A

80

60

40

20

GAIN – dB

0

1k 10k 10M100k 1M

FREQUENCY – Hz

Figure 14. Open-Loop Gain and
Phase vs. Frequency

45

90

135

180

VS = +2.7V
R

= 100k

⍀

L

CL = 300pF
A

= +1

V

T

= +25ⴗC

A

1.35V

50mV

10␮s

Figure 12. Small Signal Transient
Response

160

VS = +5V

140

T

= +25ⴗC

A

120

100

80

ⴚPSRR

60

+PSRR

40

20

PHASE SHIFT – Degrees

0

ⴚ20

POWER SUPPLY REJECTION RATIO – dB

ⴚ40

100 1k 10M10k 100k 1M

FREQUENCY – Hz

Figure 15. Power Supply Rejection
Ratio vs. Frequency

90

VS = +5V

80

T

= +25ⴗC

A

70

60

50

40

30

20

10

COMMON-MODE REJECTION – dB

0

ⴚ10

1k 10k 10M100k 1M

FREQUENCY – Hz

Figure 16. Common-Mode Rejection
Ratio vs. Frequency

10k

VS = +5V
T

= +25ⴗC

A

1k

100

10

1

⌬ OUTPUT VOLTAGE – mV

0.1

0.01

0.001 0.01 100

SOURCE

SINK

0.1 1 10

LOAD CURRENT – mA

Figure 17. Output Voltage to Supply
Rail vs. Frequency

–7–REV. A

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

OUTPUT SWING – Vp-p

1.0

0.5

0

1k 10k 10M

FREQUENCY – Hz

VS = +5V
V

= +4.9Vp-p

IN

R

= NO LOAD

L

T

= +25ⴗC

A

100k 1M

Figure 18. Closed Loop Output
Voltage Swing vs. Frequency

AD8541/AD8542/AD8544

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

OUTPUT SWING – Vp-p

1.0

0.5

0

1k 10k 10M

FREQUENCY – Hz

VS = +5V
V

= +4.9Vp-p

IN

R

= 2k⍀

L

T

= +25ⴗC

A

100k 1M

Figure 19. Closed-Loop Output
Voltage Swing vs. Frequency

60

VS = +5V
R

=

50

L

T

= +25ⴗC

A

40

+OS

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

ⴚOS

1k

Figure 22. Small Signal Overshoot
vs. Load Capacitance

60

VS = +5V
R

= 10k⍀

50

L

T

= +25ⴗC

A

40

+OS

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

ⴚOS

1k

Figure 20. Small Signal Overshoot
vs. Load Capacitance

VS = +5V
R

= 100k

⍀

L

CL = 300pF
A

= +1

V

T

= +25ⴗC

A

2.5V

50mV

10␮s

Figure 23. Small Signal Transient
Response

60

VS = +5V
R

= 2k⍀

50

L

T

= +25ⴗC

A

40

30

20

10

SMALL SIGNAL OVERSHOOT – %

0

10 100 10k

CAPACITANCE – pF

+OS

ⴚOS

1k

Figure 21. Small Signal Overshoot
vs. Load Capacitance

2.5V

VS = +5V
R

= 2k

⍀

L

AV = +1
T

= +25ⴗC

A

1V

10␮s

Figure 24. Large Signal Transient
Response

VS = +5V
R

= NO LOAD

L

T

= +25ⴗC

A

80

60

40

20

GAIN – dB

0

1k 10k 10M100k 1M

FREQUENCY – Hz

45

90

135

180

Figure 25. Open-Loop Gain & Phase
vs. Frequency

V

IN

V

OUT

2.5V

PHASE SHIFT – Degrees

1V

Figure 26. No Phase Reversal

–8–

VS = +5V
R

= 10k

L

AV = +1
T

= +25ⴗC

A

20␮s

60

⍀

TA = +25ⴗC

50

40

30

20

10

SUPPLY CURRENT/AMPLIFIER – ␮A

0

01 6

23 45

SUPPLY VOLTAGE – V

Figure 27. Supply Current per
Amplifier vs. Supply Voltage

REV. A

AD8541/AD8542/AD8544

C

2C

R/2

R R

7

3

2

V

OUT

4

6

AD8541

5.0V

2.5V

REF

C

V

IN

55

50

45

40

35

30

25

SUPPLY CURRENT/AMPLIFIER – ␮A

20

ⴚ55 ⴚ35

VS = +5V

VS = +2.7V

ⴚ15

5 25 45 65 85 105 125

TEMPERATURE – ⴗC

Figure 28. Supply Current per
Amplifier vs. Temperature

145

1,000

VS = +2.7V AND +5V

900

A

= +1

V

T

= +25ⴗC

800

A

700

600

500

400

300

IMPEDANCE – ⍀

200

100

0

1k 10k 100M100k 1M 10M

FREQUENCY – Hz

Figure 29. Closed-Loop Output
Impedance vs. Frequency

NOTES ON THE AD854x AMPLIFIERS

The AD8541/AD8542/AD8544 amplifiers are improved perfor­mance general purpose operational amplifiers. Performance has
been improved over previous amplifiers in several ways.

Lower Supply Current for 1 MHz Gain Bandwidth

The AD854x series typically uses 45 microamps of current per
amplifier. This is much less than the 200 µA to 700 µA used in
earlier generation parts with similar performance. This makes
the AD854x series a good choice for upgrading portable designs
for longer battery life. Alternatively, additional functions and
performance can be added at the same current drain.

Higher Output Current

At +5 V single supply, the short circuit current is typically 60 µA.
Even 1 V from the supply rail, the AD854x amplifiers can provide
30 mA, sourcing or sinking.

Sourcing and sinking is strong at lower voltages, with 15 mA
available at +2.7 V, and 18 mA at 3.0 V. For even higher output
currents, please see the Analog Devices AD8531/AD853/AD8534
parts, with output currents to 250 mA. Information on these
parts is available from your Analog Devices representative, and
datasheets are available at the Analog Devices website at
www.analog.com.

Better Performance at Lower Voltages

The AD854x family parts have been designed to provide better ac
performance, at 3.0 V and 2.7 V, than previously available parts.
Typical gain-bandwidth product is close to 1 MHz at 2.7 V. Volt­age gain at 2.7 V and 3.0 V is typically 500,000. Phase margin is
typically over +60°C, making the part easy to use.

VS = +5V
A

= +1

V

MARKER SET @ 10kHz
MARKER READING: 37.6␮V/ Hz
T

= +25ⴗC

A

200mV/DIVISION

05 2510 15 20

FREQUENCY – kHz

Figure 30. Voltage Noise

the circuit to no longer attenuate at the ideal notch frequency.
To achieve desired performance, 1% or better component
tolerances or special component screens are usually required.
One method to desensitize the circuit-to-component mis­match is to increase R2 with respect to R1, which lowers Q. A
lower Q increases attenuation over a wider frequency range,
but reduces attenuation at the peak notch frequency.

5.0V

8

3

U1

2

7

U2

1/2 AD8542

1

4

5

6

2.5V

R2

2.5k⍀

R1

97.5k⍀

REF

V

OUT

2.5V

REF

1

f0 =

2πRC

f0 =

1 ⴚ

4

[ ]

R

100k⍀R100k⍀

C2

53.6␮F

50k⍀

C

26.7nF

1

R1

R1+R2

R/2

C

26.7nF

1/2 AD8542

Figure 31. 60 Hz Twin-T Notch Filter, Q = 10

APPLICATIONS
Notch Filter

The AD8542 has very high open loop gain (especially with supply
voltage below 4 V), which makes it useful for active filters of all
types. For example, Figure 31 illustrates the AD8542 in the clas­sic Twin-T Notch Filter design. The Twin-T Notch is desired for
simplicity, low output impedance and minimal use of op amps. In
fact, this notch filter may be designed with only one op amp if Q
adjustment is not required. Simply remove U2 as illustrated in
Figure 32. However, a major drawback to this circuit topology is
ensuring that all the Rs and Cs closely match. The components
must closely match or notch frequency offset and drift will cause

Figure 32. 60 Hz Twin-T Notch Filter, Q = ∞ (Ideal)

Figure 33 diagrams another example of the AD8542 in a
notch filter circuit. The FNDR notch filter has several
unique features as compared to the Twin-T Notch including:
less critical matching requirements; Q is directly proportional
to a single resistor R1. While matching component values is
still important, it is also much easier and/or less expensive to

–9–REV. A

AD8541/AD8542/AD8544

accomplish in the FNDR circuit. For example, the Twin-T
Notch uses three capacitors with two unique values, whereas the
FNDR circuit uses only two capacitors, which may be of the
same value. U3 is simply a buffer that is added to lower the out­put impedance of the circuit.

2.5V

REF

1/4 AD8544

f =

2π

L =

R2C2

1

LC1

R1

Q ADJUST

200⍀

C1

1␮F

C2

1␮F

6

7

U2

5

2.5V

R

2.61k⍀

R

2.61k⍀

R

2.61k⍀

R

2.61k⍀

REF

1/4 AD8544

9

U3

10

3

2

13

12

2.5V

REF

8

1/4 AD8544

4

1

U1

11

1/4 AD8544

14

U4

SPARE

V

OUT

NC

Figure 33. FNDR 60 Hz Notch Filter with Output Buffer

Comparator Function

A comparator function is a common application for a spare op
amp in a quad package. Figure 34 illustrates 1/4 of the AD8544
as a comparator in a standard overload detection application.
Unlike so many op amps, the AD854x family can double as
comparator because this op amp family has rail-to-rail differen­tial input range, rail-to-rail output, and a great speed vs. power
ratio. R2 is used to introduce hysteresis. The AD854x when
used as comparators have 5 µs propagation delay @ 5 V and 5 µs
overload recovery time.

Photodiode Application

The AD854x family has very high impedance with input bias
current typically around 4 pA. This characteristic allows the
AD854x op amps to be used in photodiode applications and
other applications that require high input impedance. Note that
the AD854x has significant voltage offset, which can be removed
by capacitive coupling or software calibration.

Figure 35, illustrates a photodiode or current measurement
application. The feedback resistor is limited to 10 MΩ to avoid
excessive output offset. Also note that a resistor is not needed
on the noninverting input to cancel bias current offset, because
the bias current related output offset is not significant when
compared to the voltage offset contribution. For the best per­formance follow the standard high impedance layout techniques
including: shield circuit, clean circuit board, put a trace con­nected to the noninverting input around the inverting input,
and use separate analog and digital power supplies.

C

100pF

R

10M⍀

V+

7

2

6

3

4

AD8541

V

OUT

2.5V

OR

REF

D

2.5V

REF

Figure 35. High Input Impedance Application–Photodiode
Amplifier

R2

DC

1M⍀

1/4 AD8544

V

OUT

R1

1k⍀

V

IN

2.5V

REF

2.5V

Figure 34. The AD854x Comparator Application–Overload
Detector

–10–

REV. A

AD8541/AD8542/AD8544

* AD8542 SPICE Macro-model Typical Values
* 6/98, Ver. 1
* TAM / ADSC
*
* Copyright 1998 by Analog Devices
*
* Refer to “README.DOC” file for License State-

ment. Use of this

* model indicates your acceptance of the terms

and provisions in
* the License Statement.
*
* Node Assignments
* noninverting input
* | inverting input
* | | positive supply
* | | | negative supply
* | | | | output
* | | | | |
* | | | | |
.SUBCKT AD8542 1 2 99 50 45
*
* INPUT STAGE
*
M1 4 1 8 8 PIX L=0.6E-6 W=16E-6
M2 6 7 8 8 PIX L=0.6E-6 W=16E-6
M3 11 1 10 10 NIX L=0.6E-6 W=16E-6
M4 12 7 10 10 NIX L=0.6E-6 W=16E-6
RC1 4 50 20E3
RC2 6 50 20E3
RC3 99 11 20E3
RC4 99 12 20E3
C1 4 6 1.5E-12
C2 11 12 1.5E-12
I1 99 8 1E-5
I2 10 50 1E-5
V1 99 9 0.2
V2 13 50 0.2
D1 8 9 DX
D2 13 10 DX
EOS 7 2 POLY(3) (22,98) (73,98) (81,0) 1E-3 1 1

1
IOS 1 2 2.5E-12
*
* CMRR 64dB, ZERO AT 20kHz
*
ECM1 21 98 POLY(2) (1,98) (2,98) 0 .5 .5
RCM1 21 22 79.6E3
CCM1 21 22 100E-12
RCM2 22 98 50
*
* PSRR=90dB, ZERO AT 200Hz
*
RPS1 70 0 1E6
RPS2 71 0 1E6
CPS1 99 70 1E-5
CPS2 50 71 1E-5
EPSY 98 72 POLY(2) (70,0) (0,71) 0 1 1
RPS3 72 73 1.59E6
CPS3 72 73 500E-12
RPS4 73 98 25
*

* VOLTAGE NOISE REFERENCE OF 35nV/rt(Hz)
*
VN1 80 0 0
RN1 80 0 16.45E-3
HN 81 0 VN1 35
RN2 81 0 1
*
* INTERNAL VOLTAGE REFERENCE
*
VFIX 90 98 DC 1
S1 90 91 (50,99) VSY_SWITCH
VSN1 91 92 DC 0
RSY 92 98 1E3
EREF 98 0 POLY(2) (99,0) (50,0) 0 .5 .5
GSY 99 50 POLY(1) (99,50) 0 3.7E-6
*
* ADAPTIVE GAIN STAGE
* AT Vsy>+4.2, AVol=45 V/mv
* AT Vsy<+3.8, AVol=450 V/mv
*
G1 98 30 POLY(2) (4,6) (11,12) 0 2.5E-5 2.5E-5
VR1 30 31 DC 0
H1 31 98 POLY(2) VR1 VSN1 0 5.45E6 0 0 49.05E9
CF 45 30 10E-12
D3 30 99 DX
D4 50 30 DX
*
* OUTPUT STAGE
*
M5 45 46 99 99 POX L=0.6E-6 W=375E-6
M6 45 47 50 50 NOX L=0.6E-6 W=500E-6
EG1 99 46 POLY(1) (98,30) 1.05 1
EG2 47 50 POLY(1) (30,98) 1.04 1
*
* MODELS
*
.MODEL POX PMOS (LEVEL=2,KP=20E-6,VTO=-

+1,LAMBDA=0.067)

.MODEL NOX NMOS (LEVEL=2,KP=20E-

+6,VTO=1,LAMBDA=0.067)

.MODEL PIX PMOS (LEVEL=2,KP=20E-6,VTO=-

+0.7,LAMBDA=0.01,KF=1E-31)

.MODEL NIX NMOS (LEVEL=2,KP=20E-

+6,VTO=0.7,LAMBDA=0.01,KF=1E-31)
.MODEL DX D(IS=1E-14)
.MODEL VSY_SWITCH VSWITCH(ROFF=100E3,RON=1,VOFF=-

+4.2,VON=-3.5)
.ENDS AD8542

–11–REV. A

AD8541/AD8542/AD8544

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

0.177 (4.50)

PIN 1

0.006 (0.15)

0.002 (0.05)

SEATING

PLANE

0.1574 (4.00)

0.1497 (3.80)

0.122 (3.10)

0.114 (2.90)

8

0.169 (4.30)

1

0.0256 (0.65)
BSC

0.0118 (0.30)

0.0075 (0.19)

0.1968 (5.00)

0.1890 (4.80)

85

41

8-Lead TSSOP

(RU-08)

5

0.256 (6.50)

0.246 (6.25)

4

0.0433
(1.10)
MAX

0.0079 (0.20)

0.0035 (0.090)

8-Lead SOIC

(SO-8)

0.2440 (6.20)

0.2284 (5.80)

8ⴗ
0ⴗ

0.028 (0.70)

0.020 (0.50)

0.177 (4.50)

0.006 (0.15)

0.002 (0.05)

SEATING

PLANE

0.1574 (4.00)

0.1497 (3.80)

0.201 (5.10)

0.193 (4.90)

14

0.169 (4.30)

1

PIN 1

0.0256
(0.65)

BSC

0.3444 (8.75)

0.3367 (8.55)

14 8

14-Lead TSSOP

(RU-14)

8

0.256 (6.50)

0.246 (6.25)

7

0.0433
(1.10)

0.0118 (0.30)

0.0075 (0.19)

MAX

0.0079 (0.20)

0.0035 (0.090)

14-Lead SOIC

(SO-14)

0.2440 (6.20)

71

0.2284 (5.80)

8ⴗ
0ⴗ

C3414–0–3/00 (rev. A)

0.028 (0.70)

0.020 (0.50)

0.0098 (0.25)

0.0040 (0.10)

0.0669 (1.70)

0.0590 (1.50)

0.0512 (1.30)

0.0354 (0.90)

PIN 1

SEATING

PLANE

PIN 1

0.0059 (0.15)

0.0019 (0.05)

0.0688 (1.75)

0.0532 (1.35)

0.0500

0.0192 (0.49)

(1.27)

0.0138 (0.35)

BSC

5-Lead SOT-23

0.1181 (3.00)

0.1102 (2.80)

1 3

2

0.0748 (1.90)
BSC

0.0197 (0.50)

0.0138 (0.35)

0.0098 (0.25)

0.0075 (0.19)

(RT Suffix)

4 5

0.1181 (3.00)

0.1024 (2.60)

0.0374 (0.95) BSC

0.0571 (1.45)

0.0374 (0.95)

SEATING
PLANE

0.0196 (0.50)

0.0099 (0.25)

8ⴗ
0ⴗ

0.0500 (1.27)

0.0160 (0.41)

10ⴗ

0ⴗ

x 45ⴗ

0.0079 (0.20)

0.0031 (0.08)

0.0217 (0.55)

0.0138 (0.35)

0.0098 (0.25)

0.0040 (0.10)

SEATING

PLANE

0.122 (3.10)

0.114 (2.90)

0.006 (0.15)

0.002 (0.05)

PIN 1

0.0500
(1.27)

BSC

0.122 (3.10)

0.114 (2.90)

85

1

PIN 1

0.0256 (0.65) BSC

0.016 (0.40)

0.010 (0.25)

0.0688 (1.75)

0.0532 (1.35)

0.0192 (0.49)

0.0138 (0.35)

0.0099 (0.25)

0.0075 (0.19)

8-Lead MSOP

(RM-8)

0.193
(4.90)

BSC

4

0.043
(1.10)
MAX

SEATING
PLANE

0.009 (0.23)

0.005 (0.13)

0.0196 (0.50)

0.0099 (0.25)

8ⴗ
0ⴗ

0.0500 (1.27)

0.0160 (0.41)

6ⴗ
0ⴗ

x 45ⴗ

0.037 (0.95)

0.030 (0.75)

0.028 (0.70)

0.016 (0.40)

PRINTED IN U.S.A.

–12–

REV. A