General-Purpose CMOS
Rail-to-Rail Amplifiers
AD8541/AD8542/AD8544
Rev. E
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FEATURES
Single-supply operation: 2.7 V to 5.5 V
Low supply current: 45 μA/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 amplifiers
Sensor interfaces
Piezoelectric transducer amplifiers
Medical instrumentations
Mobile communications
Audio outputs
Portable systems
GENERAL DESCRIPTION
The AD8541/AD8542/AD8544 are single, dual, and quad rail-
to-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 a low current consumption
of 45 A per amplifier.
Very low input bias currents enable the AD8541/AD8542/AD8544
to be used for integrators, photodiode amplifiers, piezoelectric
sensors, and other applications with high source impedance.
The supply current is only 45 A 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 temperature range (–40°C to +125°C). The AD8541
is available in 8-lead SOIC, 5-lead SC70, and 5-lead SOT-23
packages. The AD8542 is available in 8-lead SOIC, 8-lead
MSOP, and 8-lead TSSOP surface-mount packages. The
AD8544 is available in 14-lead narrow SOIC and 14-lead
TSSOP surface-mount packages. All MSOP, SC70, and SOT
versions are available in tape and reel only.
PIN CONFIGURATIONS
1
2
3
5
4–IN A
+IN A
V+
OUT A
AD8541
V–
00935-001
Figure 1. 5-Lead SC70 and 5-Lead SOT-23
(KS and RJ Suffixes)
NC
–IN A
+IN A
V–
V+
OUT A
NC
NC
1
2
3
4
8
7
6
5
AD8541
NC = NO CONNECT
00935-002
Figure 2. 8-Lead SOIC
(R Suffix)
AD8542
1
2
3
4
8
7
6
5
OUT A
–IN A
+IN A
V– +IN B
–IN B
OUT B
V+
00935-003
Figure 3. 8-Lead SOIC, 8-Lead MSOP, and 8-Lead TSSOP
(R, RM, and RU Suffixes)
AD8544
1
2
3
4
14
13
12
11
OUT A
–IN A
+IN A
V+ V–
+IN D
–IN D
OUT D
5
6
7
10
9
8
+IN B
–IN B
OUT B
OUT C
–IN C
+IN C
00935-004
Figure 4. 14-Lead SOIC and 14-Lead TSSOP
(R and RU Suffixes)
AD8541/AD8542/AD8544
Rev. E | Page 2 of 20
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description......................................................................... 1
Pin Configurations ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Electrical Characteristics............................................................. 3
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution.................................................................................. 6
Typical Performance Characteristics ..............................................7
Theory of Operation ...................................................................... 12
Notes on the AD854x Amplifiers............................................. 12
Applications..................................................................................... 13
Notch Filter ................................................................................. 13
Comparator Function................................................................ 13
Photodiode Application ............................................................ 14
Outline Dimensions ....................................................................... 15
Ordering Guide .......................................................................... 17
REVISION HISTORY
1/07—Rev. D to Rev. E
Updated Format..................................................................Universal
Changes to Photodiode Application Section .............................. 14
Changes to Ordering Guide .......................................................... 17
8/04—Rev. C to Rev. D
Changes to Ordering Guide ............................................................ 5
Changes to Figure 3........................................................................ 10
Updated Outline Dimensions....................................................... 12
1/03—Rev. B to Rev. C
Updated Format..................................................................Universal
Changes to General Description .................................................... 1
Changes to Ordering Guide ............................................................ 5
Changes to Outline Dimensions................................................... 12
AD8541/AD8542/AD8544
Rev. E | Page 3 of 20
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
VS = 2.7 V, VCM = 1.35 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 1 6 mV
–40°C ≤ TA ≤ +125°C 7 mV
Input Bias Current IB 4 60 pA
–40°C ≤ TA ≤ +85°C 100 pA
–40°C ≤ TA ≤ +125°C 1000 pA
Input Offset Current IOS 0.1 30 pA
–40°C ≤ TA ≤ +85°C 50 pA
–40°C ≤ TA ≤ +125°C 500 pA
Input Voltage Range 0 2.7 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.7 V 40 45 dB
–40°C ≤ TA ≤ +125°C 38 dB
Large Signal Voltage Gain AVO RL = 100 kΩ , VO = 0.5 V to 2.2 V 100 500 V/mV
–40°C ≤ TA ≤ +85°C 50 V/mV
–40°C ≤ TA ≤ +125°C 2 V/mV
Offset Voltage Drift ΔVOS/ΔT –40°C ≤ TA ≤ +125°C 4 μV/°C
Bias Current Drift ΔIB/ΔT –40°C ≤ TA ≤ +85°C 100 fA/°C
–40°C ≤ TA ≤ +125°C 2000 fA/°C
Offset Current Drift ΔIOS/ΔT –40°C ≤ TA ≤ +125°C 25 fA/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH IL = 1 mA 2.575 2.65 V
–40°C ≤ TA ≤ +125°C 2.550 V
Output Voltage Low VOL IL = 1 mA 35 100 mV
–40°C ≤ TA ≤ +125°C 125 mV
Output Current IOUT VOUT = VS – 1 V 15 mA
±ISC ±20 mA
Closed-Loop Output Impedance ZOUT f = 200 kHz, AV = 1 50 Ω
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.5 V to 6 V 65 76 dB
–40°C ≤ TA ≤ +125°C 60 dB
Supply Current/Amplifier ISY VO = 0 V 38 55 μA
–40°C ≤ TA ≤ +125°C 75 μA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 100 kΩ 0.4 0.75 V/μs
Settling Time tS To 0.1% (1 V step) 5 μs
Gain Bandwidth Product GBP 980 kHz
Phase Margin Φo 63 Degrees
NOISE PERFORMANCE
Voltage Noise Density en f = 1 kHz 40 nV/√Hz
e
n f = 10 kHz 38 nV/√Hz
Current Noise Density in <0.1 pA/√Hz
AD8541/AD8542/AD8544
Rev. E | Page 4 of 20
VS = 3.0 V, VCM = 1.5 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 1 6 mV
–40°C ≤ TA ≤ +125°C 7 mV
Input Bias Current IB 4 60 pA
–40°C ≤ TA ≤ +85°C 100 pA
–40°C ≤ TA ≤ +125°C 1000 pA
Input Offset Current IOS 0.1 30 pA
–40°C ≤ TA ≤ +85°C 50 pA
–40°C ≤ TA ≤ +125°C 500 pA
Input Voltage Range 0 3 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 3 V 40 45 dB
–40°C ≤ TA ≤ +125°C 38 dB
Large Signal Voltage Gain AVO RL = 100 kΩ , VO = 0.5 V to 2.2 V 100 500 V/mV
–40°C ≤ TA ≤ +85°C 50 V/mV
–40°C ≤ TA ≤ +125°C 2 V/mV
Offset Voltage Drift ΔVOS/ΔT –40°C ≤ TA ≤ +125°C 4 μV/°C
Bias Current Drift ΔIB/ΔT –40°C ≤ TA ≤ +85°C 100 fA/°C
–40°C ≤ TA ≤ +125°C 2000 fA/°C
Offset Current Drift ΔIOS/ΔT –40°C ≤ TA ≤ +125°C 25 fA/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH IL = 1 mA 2.875 2.955 V
–40°C ≤ TA ≤ +125°C 2.850 V
Output Voltage Low VOL IL = 1 mA 32 100 mV
–40°C ≤ TA ≤ +125°C 125 mV
Output Current IOUT VOUT = VS – 1 V 18 mA
±ISC ±25 mA
Closed-Loop Output Impedance ZOUT f = 200 kHz, AV = 1 50 Ω
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.5 V to 6 V 65 76 dB
–40°C ≤ TA ≤ +125°C 60 dB
Supply Current/Amplifier ISY VO = 0 V 40 60 μA
–40°C ≤ TA ≤ +125°C 75 μA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 100 kΩ 0.4 0.8 V/μs
Settling Time tS To 0.01% (1 V step) 5 μs
Gain Bandwidth Product GBP 980 kHz
Phase Margin Φo 64 Degrees
NOISE PERFORMANCE
Voltage Noise Density en f = 1 kHz 42 nV/√Hz
e
n f = 10 kHz 38 nV/√Hz
Current Noise Density in <0.1 pA/√Hz
AD8541/AD8542/AD8544
Rev. E | Page 5 of 20
VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted.
Table 3.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 1 6 mV
–40°C ≤ TA ≤ +125°C 7 mV
Input Bias Current IB 4 60 pA
–40°C ≤ TA ≤ +85°C 100 pA
–40°C ≤ TA ≤ +125°C 1000 pA
Input Offset Current IOS 0.1 30 pA
–40°C ≤ TA ≤ +85°C 50 pA
–40°C ≤ TA ≤ +125°C 500 pA
Input Voltage Range 0 5 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 5 V 40 48 dB
–40°C ≤ TA ≤ +125°C 38 dB
Large Signal Voltage Gain AVO RL = 100 kΩ , VO = 0.5 V to 2.2 V 20 40 V/mV
–40°C ≤ TA ≤ +85°C 10 V/mV
–40°C ≤ TA ≤ +125°C 2 V/mV
Offset Voltage Drift ΔVOS/ΔT –40°C ≤ TA ≤ +125°C 4 μV/°C
Bias Current Drift ΔIB/ΔT –40°C ≤ TA ≤ +85°C 100 fA/°C
–40°C ≤ TA ≤ +125°C 2000 fA/°C
Offset Current Drift ΔIOS/ΔT –40°C ≤ TA ≤ +125°C 25 fA/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH IL = 1 mA 4.9 4.965 V
–40°C ≤ TA ≤ +125°C 4.875 V
Output Voltage Low VOL IL = 1 mA 25 100 mV
–40°C ≤ TA ≤ +125°C 125 mV
Output Current IOUT VOUT = VS – 1 V 30 mA
±ISC ±60 mA
Closed-Loop Output Impedance ZOUT f = 200 kHz, AV = 1 45 Ω
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.5 V to 6 V 65 76 dB
–40°C ≤ TA ≤ +125°C 60 dB
Supply Current/Amplifier ISY VO = 0 V 45 65 μA
–40°C ≤ TA ≤ +125°C 85 μA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 100 kΩ, CL = 200 pF 0.45 0.92 V/μs
Full-Power Bandwidth BWP 1% distortion 70 kHz
Settling Time tS To 0.1% (1 V step) 6 μs
Gain Bandwidth Product GBP 1000 kHz
Phase Margin Φo 67 Degrees
NOISE PERFORMANCE
Voltage Noise Density en f = 1 kHz 42 nV/√Hz
e
n f = 10 kHz 38 nV/√Hz
Current Noise Density in <0.1 pA/√Hz
AD8541/AD8542/AD8544
Rev. E | Page 6 of 20
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
Supply Voltage (VS) 6 V
Input Voltage GND to VS
Differential Input Voltage1 ±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 (Soldering, 60 sec) 300°C
1 For supplies less than 6 V, the differential input voltage is equal to ±VS.
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.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 5.
Package Type θJA θ
JC Unit
5-Lead SC70 (KS) 376 126 °C/W
5-Lead SOT-23 (RJ) 230 146 °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
ESD CAUTION
AD8541/AD8542/AD8544
Rev. E | Page 7 of 20
TYPICAL PERFORMANCE CHARACTERISTICS
INPUT OFFSET VOLTAGE (mV)
–4.5 –3.5 4.5–2.5 –1.5 –0.5 0.5
NUMBER OF AMPLIFIERS
180
160
0
80
60
40
20
140
100
120
1.5 2.5 3.5
V
S
=5V
V
CM
=2.5V
T
A
= 25°C
00935-005
Figure 5. Input Offset Voltage Distribution
INPUT OFFSET VOLTAGE (mV)
1.0
–2.5
–4.0
–55 –35 –15
0.5
–2.0
–3.0
–3.5
–1.0
–1.5
0
–0.5
145
5 25 45 65 85 105 125
TEMPERATURE (°C)
VS = 2.7V AND 5V
VCM = VS/2
00935-006
Figure 6. Input Offset Voltage vs. Temperature
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT (pA)
9
8
0
4
3
2
1
7
5
6
–0.5 0.5 1.5 2.5 3.5 4.5 5.5
V
S
= 2.7V AND 5V
V
CM
= V
S
/2
00935-007
Figure 7. Input Bias Current vs. Common-Mode Voltage
TEMPERATURE (°C)
INPUT BIAS CURRENT (pA)
400
0
350
200
150
100
50
300
250
–40 –20 0 20 40 60 80 100 120 140
VS = 2.7V AND 5V
VCM = VS/2
00935-008
Figure 8. Input Bias Current vs. Temperature
TEMPERATURE (°C)
INPUT OFFSET CURRENT (pA)
7
–1
6
3
2
1
0
5
4
V
S
= 2.7V AND 5V
V
CM
= V
S
/2
–55 –35 –15 5 25 45 65 85 105 125 145
00935-009
Figure 9. Input Offset Current vs. Temperature
FREQUENCY (Hz)
POWER SUPPLY REJECTION (dB)
160
140
–40
120
100
80
60
40
20
0
–20
100 1k 10k 100k 1M 10M
+PSRR
–PSRR
V
S
= 2.7V
T
A
= 25°C
00935-010
Figure 10. Power Supply Rejection Ratio vs. Frequency
AD8541/AD8542/AD8544
Rev. E | Page 8 of 20
LOAD CURRENT (mA)
Δ OUTPUT VOLTAGE (mV)
10k
100
0.01
1
0.1
10
1k
0.001 0.01 0.1 1 10 100
V
S
= 2.7V
T
A
= 25°C
SOURCE
SINK
00935-011
Figure 11. Output Voltage to Supply Rail vs. Load Current
OUTPUT SWING (V p-p)
3.0
2.5
0
2.0
1.5
0.5
1.0
FREQUENCY (Hz)
1k 10k 100k 1M 10M
V
S
= 2.7V
V
IN
= 2.5V p-p
R
L
= 2kΩ
T
A
= 25°C
00935-012
Figure 12. Closed-Loop Output Voltage Swing vs. Frequency
CAPACITANCE (pF)
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
10 100 1k 10k
+OS
–OS
VS = 2.7V
RL =
∞
TA = 25°C
00935-013
Figure 13. Small Signal Overshoot vs. Load Capacitance
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
CAPACITANCE (pF)
10 100 1k 10k
+OS
–OS
V
S
= 2.7V
R
L
= 10kΩ
T
A
= 25°C
00935-014
Figure 14. Small Signal Overshoot vs. Load Capacitance
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
CAPACITANCE (pF)
10 100 1k 10k
+OS
–OS
V
S
= 2.7V
R
L
= 2kΩ
T
A
= 25°C
00935-015
Figure 15. Small Signal Overshoot vs. Load Capacitance
1.35
V
50mV 10µs
VS = 2.7V
RL = 100kΩ
CL = 300pF
AV = 1
TA = 25°C
0
0935-016
Figure 16. Small Signal Transient Response
AD8541/AD8542/AD8544
Rev. E | Page 9 of 20
1.35V
V
S
= 2.7V
R
L
= 2kΩ
A
V
= 1
T
A
= 25°C
500mV 10µs
00935-017
Figure 17. Large Signal Transient Response
GAIN (dB)
80
60
40
20
0
45
90
135
180
PHASE SHIFT (Degrees)
FREQUENCY (Hz)
1k 10k 100k 1M 10M
V
S
= 2.7V
R
L
= NO LOAD
T
A
= 25°C
00935-018
Figure 18. Open-Loop Gain and Phase vs. Frequency
POWER SUPPLY REJECTION RATIO (dB)
160
140
–40
120
100
80
60
40
20
–20
0
FREQUENCY (Hz)
100 1k 10k 100k 1M 10M
+PSRR
–PSRR
V
S
= 5V
T
A
= 25°C
00935-019
Figure 19. Power Supply Rejection Ratio vs. Frequency
COMMON-MODE REJECTION (dB)
60
50
40
30
20
10
0
–10
70
80
90
FREQUENCY (Hz)
1k 10k 100k 1M 10M
V
S
= 5V
T
A
= 25°C
00935-020
Figure 20. Common-Mode Rejection Ratio vs. Frequency
LOAD CURRENT (mA)
Δ OUTPUT VOLTAGE (mV)
100
0.01
1
0.1
10
1k
0.001 0.01 0.1 1 10 100
V
S
= 5V
T
A
= 25°C
SOURCE
SINK
10k
00935-021
Figure 21. Output Voltage to Supply Rail vs. Frequency
OUTPUT SWING (V p-p)
3.0
2.5
0
2.0
1.5
0.5
1.0
4.0
3.5
5.0
4.5
FREQUENCY (Hz)
1k 10k 100k 1M 10M
V
S
= 5V
V
IN
= 4.9V p-p
R
L
= NO LOAD
T
A
= 25°C
00935-022
Figure 22. Closed-Loop Output Voltage Swing vs. Frequency
AD8541/AD8542/AD8544
Rev. E | Page 10 of 20
OUTPUT SWING (V p-p)
3.0
2.5
0
2.0
1.5
0.5
1.0
4.0
3.5
5.0
4.5
FREQUENCY (Hz)
1k 10k 100k 1M 10M
VS = 5V
VIN = 4.9V p-p
RL = 2kΩ
TA = 25°C
00935-023
Figure 23. Closed-Loop Output Voltage Swing vs. Frequency
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
CAPACITANCE (pF)
10 100 1k 10k
+OS
–OS
VS = 5V
RL = 10kΩ
TA = 25°C
00935-024
Figure 24. Small Signal Overshoot vs. Load Capacitance
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
CAPACITANCE (pF)
10 100 1k 10k
V
S
= 5V
R
L
= 2kΩ
T
A
= 25°C
+OS
–OS
00935-025
Figure 25. Small Signal Overshoot vs. Load Capacitance
SMALL SIGNAL OVERSHOOT (%)
60
0
30
20
10
40
50
CAPACITANCE (pF)
10 100 1k 10k
+OS
–OS
V
S
= 5V
R
L
=
∞
T
A
= 25°C
00935-026
Figure 26. Small Signal Overshoot vs. Load Capacitance
2.5V
V
S
= 5V
R
L
= 100kΩ
C
L
= 300pF
A
V
= 1
T
A
= 25°C
50mV 10µs
00935-027
Figure 27. Small Signal Transient Response
2.5V
VS = 5V
RL = 2kΩ
AV = 1
TA = 25°C
1V 10µs
00935-028
Figure 28. Large Signal Transient Response
AD8541/AD8542/AD8544
Rev. E | Page 11 of 20
GAIN (dB)
80
60
40
20
0
45
90
135
180
PHASE SHIFT (Degrees)
FREQUENCY (Hz)
1k 10k 100k 1M 10M
VS = 5V
RL = NO LOAD
TA = 25°C
00935-029
SUPPLY CURRENT/AMPLIFIER (µA)
55
20
50
45
40
35
30
25
TEMPERATURE (°C)
–55 –35 –15 5 25 45 65 85 105 125 145
V
S
= 5V
V
S
= 2.7V
00935-032
Figure 32. Supply Current per Amplifier vs. Temperature
Figure 29. Open-Loop Gain and Phase vs. Frequency
2.5V
VS = 5V
RL = 10kΩ
AV = 1
TA = 25°C
1V 20µs
VIN
VOUT
00935-030
IMPEDANCE (Ω)
1000
900
0
800
700
600
500
400
300
200
100
FREQUENCY (Hz)
1k 10k 100k 1M 10M 100M
V
S
= 2.7V AND 5V
A
V
=1
T
A
=25°C
00935-033
Figure 33. Closed-Loop Output Impedance vs. Frequency
Figure 30. No Phase Reversal
FREQUENCY (kHz)
15nV/DI
V
V
S
=5V
MARKER SET @ 10kHz
MARKER READING: 37.6nV/ Hz
T
A
=25°C
0 5 10 15 20 25
00935-034
SUPPLY VOLTAGE (V)
SUPPLY CURRENT/AMPLIFIER (µA)
60
0
50
40
30
20
10
T
A
= 25°C
0123456
00935-031
Figure 34. Voltage Noise
Figure 31. Supply Current per Amplifier vs. Supply Voltage
AD8541/AD8542/AD8544
Rev. E | Page 12 of 20
THEORY OF OPERATION
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 A of current per amplifier.
This is much less than the 200 A to 700 A 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 A.
Even 1 V from the supply rail, the AD854x amplifiers can
provide a 30 mA output current, sourcing or sinking.
Sourcing and sinking are strong at lower voltages, with 15 mA
available at 2.7 V and 18 mA at 3.0 V. For even higher output
currents, see the Analog Devices, Inc. AD8531/AD8532/AD8534
parts, with output currents to 250 mA. Information on these
parts is available from your Analog Devices representative, and
data sheets are available at www.analog.com.
Better Performance at Lower Voltages
The AD854x family of parts was 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.
AD8541/AD8542/AD8544
Rev. E | Page 13 of 20
APPLICATIONS
NOTCH FILTER
The AD854x have very high open-loop gain (especially with a
supply voltage below 4 V), which makes it useful for active
filters of all types. For example, Figure 35 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 can be designed with only
one op amp if Q adjustment is not required. Simply remove U2
as illustrated in Figure 36. 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 causes 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.
1/2 AD8542
5
6
7
8
3
2 4 1
1/2 AD8542
5.0
V
U1
V
OUT
U2
R2
2.5kΩ
R1
97.5kΩ
2.5V
REF
C
26.7nF
C
26.7nF
2
.5
V
REF
R/2
50kΩ
R
100kΩ
R
100kΩ
C2
53.6µF
f
0
=
f
0
= 1
2πRC
1
R1
R1 + R2
4 1 –
00935-035
Figure 35. 60 Hz Twin-T Notch Filter, Q = 10
C
2C
R/2
RR 7
3
2
4 6
AD8541
5.0
V
C
V
OUT
2.5V
REF
V
IN
00935-036
Figure 36. 60 Hz Twin-T Notch Filter, Q = ∞ (Ideal)
Figure 37 is an example of the AD8544 in a notch filter circuit.
The frequency dependent negative resistance (FNDR) notch
filter has fewer critical matching requirements than the twin-T
notch and for the FNDR 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
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.
4
1/4 AD8544
11
6
1/4 AD8544
1/4 AD8544
10
8
9
2
1
3
1/4 AD8544
12
14
13
5
7
U3
U1
U4
U2
C2
1µF
C1
1µF
R1
Q ADJUST
200Ω
R
2.61kΩ
R
2.61kΩ
R
2.61kΩ
R
2.61kΩ
V
OUT
2.5V
REF
2.5V
REF
2
.5
V
REF
NC
f = 1
2π LC1
L = R
2
C2
00935-037
Figure 37. 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 38 illustrates ¼ of the AD8544 as
a comparator in a standard overload detection application.
Unlike many op amps, the AD854x family can double as
comparators because this op amp family has a 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 at 5 V
and 5 µs overload recovery time.
1/4 AD8541
R1
1kΩ
VOUT
2.5V
REF
V
IN
R2
1MΩ
2.5V
DC
00935-038
Figure 38. AD854x Comparator Application—Overload Detector
AD8541/AD8542/AD8544
Rev. E | Page 14 of 20
PHOTODIODE APPLICATION
The AD854x family has very high impedance with an 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 that can be removed
by capacitive coupling or software calibration.
Figure 39 illustrates a photodiode or current measurement
application. The feedback resistor is limited to 10 M 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 best
performance, follow the standard high impedance layout
techniques, which include:
• Shielding the circuit.
• Cleaning the circuit board.
• Putting a trace connected to the noninverting input around
the inverting input.
• Using separate analog and digital power supplies.
AD8541
4
6
7
3
2
D
OR
V+
2.5VREF
C
100pF
R
10MΩ
2.5VREF
VOUT
00935-039
Figure 39. High Input Impedance Application—Photodiode Amplifier
AD8541/AD8542/AD8544
Rev. E | Page 15 of 20
OUTLINE DIMENSIONS
PIN 1
1.60 BSC 2.80 BSC
1.90
BSC
0.95 BSC
5
123
4
0.22
0.08
10°
5°
0°
0.50
0.30
0.15 MAX SEATING
PLANE
1.45 MAX
1.30
1.15
0.90
2.90 BSC
0.60
0.45
0.30
COMPLIANT TO JEDEC STANDARDS MO-178-AA
4.50
4.40
4.30
14 8
71
6.40
BSC
PIN 1
5.10
5.00
4.90
0.65
BSC
SEATING
PLANE
0.15
0.05 0.30
0.19
1.20
MAX
1.05
1.00
0.80 0.20
0.09
8°
0°
0.75
0.60
0.45
COPLANARITY
0.10
COMPLIANT TO JEDEC STANDARDS MO-153-AB-1
Figure 40. 5-Lead Small Outline Transistor Package [SOT-23]
(RJ-5)
Dimensions shown in millimeters
Figure 41. 14-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-14)
Dimensions shown in millimeters
COMPLIANT TO JEDEC STANDARDS MO-203-AA
0.30
0.15
0.10 MAX
1.00
0.90
0.70
0.46
0.36
0.26
SEATING
PLANE
0.22
0.08
1.10
0.80
45
123
PIN 1
0.65 BSC
2.20
2.00
1.80
2.40
2.10
1.80
1.35
1.25
1.15
0.10 COPLANARITY
0.40
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-012-AB
060606-A
14 8
7
1
6.20 (0.2441)
5.80 (0.2283)
4.00 (0.1575)
3.80 (0.1496)
8.75 (0.3445)
8.55 (0.3366)
1.27 (0.0500)
BSC
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0039)
0.51 (0.0201)
0.31 (0.0122)
1.75 (0.0689)
1.35 (0.0531)
0.50 (0.0197)
0.25 (0.0098)
1.27 (0.0500)
0.40 (0.0157)
0.25 (0.0098)
0.17 (0.0067)
COPLANARITY
0.10
8°
0°
45°
Figure 42. 5-Lead Thin Shrink Small Outline Transistor Package [SC70]
(KS-5)
Dimensions shown in millimeters
Figure 43. 14-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-14)
Dimensions shown in millimeters and (inches)
AD8541/AD8542/AD8544
Rev. E | Page 16 of 20
COMPLIANT TO JEDEC STANDARDS MO-187-AA
0.80
0.60
0.40
8°
0°
4
8
1
5
PIN 1
0.65 BSC
SEATING
PLANE
0.38
0.22
1.10 MAX
3.20
3.00
2.80
COPLANARITY
0.10
0.23
0.08
3.20
3.00
2.80
5.15
4.90
4.65
0.15
0.00
0.95
0.85
0.75
85
41
PIN 1
0.65 BSC
SEATING
PLANE
0.15
0.05
0.30
0.19
1.20
MAX
0.20
0.09
8°
0°
6.40 BSC
4.50
4.40
4.30
3.10
3.00
2.90
COPLANARIT
Y
0.10
0.75
0.60
0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AA
Figure 44. 8-Lead Mini Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters
Figure 45. 8-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-8)
Dimensions shown in millimeters
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-012-A A
060506-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
85
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2440)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
Figure 46. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
AD8541/AD8542/AD8544
Rev. E | Page 17 of 20
ORDERING GUIDE
Model Temperature Range Package Description
Package
Option Branding
AD8541AKS-R2 –40°C to +125°C 5-Lead SC70 KS-5 A4B
AD8541AKS-REEL7 –40°C to +125°C 5-Lead SC70 KS-5 A4B
AD8541AKSZ-R21 –40°C to +125°C 5-Lead SC70 KS-5 A12
AD8541AKSZ-REEL71 –40°C to +125°C 5-Lead SC70 KS-5 A12
AD8541AR –40°C to +125°C 8-Lead SOIC_N R-8
AD8541AR-REEL –40°C to +125°C 8-Lead SOIC_N R-8
AD8541AR-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8
AD8541ARZ1 –40°C to +125°C 8-Lead SOIC_N R-8
AD8541ARZ-REEL1 –40°C to +125°C 8-Lead SOIC_N R-8
AD8541ARZ-REEL71 –40°C to +125°C 8-Lead SOIC_N R-8
AD8541ART-R2 –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A
AD8541ART-REEL –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A
AD8541ART-REEL7 –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A
AD8541ARTZ-R21 –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A#
AD8541ARTZ-REEL1 –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A#
AD8541ARTZ-REEL71 –40°C to +125°C 5-Lead SOT-23 RJ-5 A4A#
AD8542AR –40°C to +125°C 8-Lead SOIC_N R-8
AD8542AR-REEL –40°C to +125°C 8-Lead SOIC_N R-8
AD8542AR-REEL7 –40°C to +125°C 8-Lead SOIC_N R-8
AD8542ARZ1 –40°C to +125°C 8-Lead SOIC_N R-8
AD8542ARZ-REEL1 –40°C to +125°C 8-Lead SOIC_N R-8
AD8542ARZ-REEL71 –40°C to +125°C 8-Lead SOIC_N R-8
AD8542ARM-R2 –40°C to +125°C 8-Lead MSOP RM-8 AVA
AD8542ARM-REEL –40°C to +125°C 8-Lead MSOP RM-8 AVA
AD8542ARMZ-R21 –40°C to +125°C 8-Lead MSOP RM-8 AVA#
AD8542ARMZ-REEL1 –40°C to +125°C 8-Lead MSOP RM-8 AVA#
AD8542ARU –40°C to +125°C 8-Lead TSSOP RU-8
AD8542ARU-REEL –40°C to +125°C 8-Lead TSSOP RU-8
AD8542ARUZ1 –40°C to +125°C 8-Lead TSSOP RU-8
AD8542ARUZ-REEL1 –40°C to +125°C 8-Lead TSSOP RU-8
AD8544AR –40°C to +125°C 14-Lead SOIC_N R-14
AD8544AR-REEL –40°C to +125°C 14-Lead SOIC_N R-14
AD8544AR-REEL7 –40°C to +125°C 14-Lead SOIC_N R-14
AD8544ARZ1 –40°C to +125°C 14-Lead SOIC_N R-14
AD8544ARZ-REEL1 –40°C to +125°C 14-Lead SOIC_N R-14
AD8544ARZ-REEL71 –40°C to +125°C 14-Lead SOIC_N R-14
AD8544ARU –40°C to +125°C 14-Lead TSSOP RU-14
AD8544ARU-REEL –40°C to +125°C 14-Lead TSSOP RU-14
AD8544ARUZ1 –40°C to +125°C 14-Lead TSSOP RU-14
AD8544ARUZ-REEL1 –40°C to +125°C 14-Lead TSSOP RU-14
1 Z = Pb-free part; # denotes lead-free product, may be top or bottom marked.
AD8541/AD8542/AD8544
Rev. E | Page 18 of 20
NOTES
AD8541/AD8542/AD8544
Rev. E | Page 19 of 20
NOTES
AD8541/AD8542/AD8544
Rev. E | Page 20 of 20
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
C00935-0-1/07(E)
