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24 MHz Rail-to-Rail Amplifiers with Shutdown Option AD8646/AD8647/AD8648
FEATURES
Offset voltage: 2.5 mV maximum Single-supply operation: 2.7 V to 5.5 V Low noise: 8 nV/Hz Wide bandwidth: 24 MHz Slew rate: 11 V/s Short-circuit output current: 120 mA No phase reversal Low input bias current: 1 pA Low supply current per amplifier: 2 mA maximum Unity gain stable
PIN CONFIGURATIONS
OUTA 1 -INA 2 +INA 3
8
V+ OUTB
06527-001 06527-003 06527-002
AD8646
7
TOP VIEW 6 -INB (Not to Scale) V- 4 5 +INB
Figure 1. 8-Lead SOIC and MSOP
OUTA 1 -INA 2 +INA 3 V- 4 SDA 5
10 V+
AD8647
TOP VIEW (Not to Scale)
9 8 7 6
OUTB -INB +INB SDB
APPLICATIONS
Battery-powered instruments Multipole filters ADC front ends Sensors Barcode scanners ASIC input or output amplifiers Audio amplifiers Photodiode amplifiers Datapath/mux/switch control
Figure 2. 10-Lead MSOP
OUTA 1 -INA 2 +INA 3 V+ 4 +INB 5 -INB 6 OUTB 7
14 13
OUTD -IND +IND V- +INC -INC OUTC
AD8648
TOP VIEW (Not to Scale)
12 11 10 9 8
Figure 3. 14-Lead SOIC and TSSOP
GENERAL DESCRIPTION
The AD8646 and the AD8647 are the dual, and the AD8648 is the quad, rail-to-rail, input and output, single-supply amplifiers featuring low offset voltage, wide signal bandwidth, low input voltage, and low current noise. The AD8647 also has a low power shutdown function. The combination of 24 MHz bandwidth, low offset, low noise, and very low input bias current makes these amplifiers useful in a wide variety of applications. Filters, integrators, photodiode amplifiers, and high impedance sensors all benefit from the combination of performance features. AC applications benefit from the wide bandwidth and low distortion. TheAD8646/ AD8647/AD8648 offer high output drive capability, which is excellent for audio line drivers and other low impedance applications. Applications include portable and low powered instrumentation, audio amplification for portable devices, portable phone headsets, barcode scanners, and multipole filters. The ability to swing rail to rail at both the input and output enables designers to buffer CMOS ADCs, DACs, ASICs, and other wide output swing devices in single-supply systems.
Rev. B
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 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: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2006-2007 Analog Devices, Inc. All rights reserved.
AD8646/AD8647/AD8648 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configurations ........................................................................... 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 ESD Caution...................................................................................6 Typical Performance Characteristics ..............................................7 Theory of Operation ...................................................................... 15 Power-Down Operation ............................................................ 15 Multiplexing Operation............................................................. 15 Outline Dimensions ....................................................................... 16 Ordering Guide .......................................................................... 18
REVISION HISTORY
Revision History: AD8646/AD8647/AD8648 10/07--Revision B: Initial Combined Version Revision History: AD8646 10/07--Rev. 0 to Rev. B
Combined with AD8648....................................................Universal Added AD8647 ...................................................................Universal Deleted Figure 4 and Figure 7......................................................... 7 Deleted Figure 33............................................................................ 11 Deleted Figure 7.................................................................................6 Deleted Figure 11...............................................................................7 Deleted Figure 16 and Figure 17 .....................................................8 Deleted Figure 24...............................................................................9 Deleted Figure 27, Figure 28, Figure 31, and Figure 32 ............ 10
6/07--Rev. 0 to Rev. A
Changes to General Description .....................................................1 Updated Outline Dimensions....................................................... 12 Changes to Ordering Guide .......................................................... 12
8/07--Revision 0: Initial Version Revision History: AD8648 10/07--Rev. A to Rev. B
Combined with AD8646....................................................Universal Added AD8647 ...................................................................Universal
1/06--Revision 0: Initial Version
Rev. B | Page 2 of 20
AD8646/AD8647/AD8648 SPECIFICATIONS
VSY = 5 V, VCM = VSY/2, TA = +25oC, unless otherwise noted. Table 1.
Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift Input Bias Current Symbol VOS VOS/T IB Conditions VCM = 0 V to 5V -40C < TA < +125C -40C < TA < +125C -40C < TA < +85C -40C < TA < +125C Input Offset Current IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance Differential Common Mode OUTPUT CHARACTERISTICS Output Voltage High VCM CMRR AVO CDIFF CCM VOH IOUT = 1 mA -40C < TA < +125C IOUT = 10 mA -40C < TA < +125C IOUT = 1 mA -40C < TA < +125C IOUT = 10 mA -40C < TA < +125C Short circuit At 1 MHz, AV = 1 VSY = 2.7 V to 5.5 V -40C < TA < +125C Shutdown of both amplifiers (AD8647 only) -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C (shutdown active) RL = 2 k +2.0 +0.8 1 1 11 24 74 0.5 1 1 4.98 4.90 4.85 4.70 VCM = 0 V to 5 V RL = 2 k, VO = 0.5 V to 4.5 V 0 67 104 84 116 2.5 6.7 4.99 4.92 8.4 78 120 5 63 80 1.5 10 1 20 40 145 200 0.1 Min Typ 0.6 1.8 0.3 Max 2.5 3.2 7.5 1 50 550 0.5 50 250 5 Unit mV mV V/C pA pA pA pA pA pA V dB dB pF pF V V V V mV mV mV mV mA dB mA mA nA A V V A nA V/s MHz Degrees s s s
Output Voltage Low
VOL
Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier Supply Current Shutdown Mode (AD8647) SHUTDOWN INPUTS (AD8647) Logic High Voltage (Enabled) Logic Low Voltage (Power-Down) Logic Input Current (Per Pin) Output Pin Leakage Current DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin Settling Time Amplifier Turn-On Time (AD8647) Amplifier Turn-Off Time (AD8647)
Isc ZOUT PSRR ISY ISD
2.0 2.5
VINH VINL IIN
SR GBP Om ts ton toff
To 0.1% 25C, AV = 1, RL = 1 k (see Figure 44) 25C, AV = 1, RL = 1 k (see Figure 45)
Rev. B | Page 3 of 20
AD8646/AD8647/AD8648
Parameter NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Channel Separation Total Harmonic Distortion Plus Noise Symbol en p-p en CS THD + N Conditions 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 10 kHz f = 100 kHz V p-p = 0.1 V, RL = 600 , f = 25 kHz, TA = 25C AV = +1 AV = -10 Min Typ 2.3 8 6 -115 -110 0.010 0.021 Max Unit V nV/Hz nV/Hz dB dB % %
Rev. B | Page 4 of 20
AD8646/AD8647/AD8648
VSY = 2.7 V, VCM = VSY/2, TA = +25oC, unless otherwise noted. Table 2.
Parameter INPUT CHARACTERISTICS Offset Voltage Offset Voltage Drift Input Bias Current Symbol VOS VOS/T IB Conditions VCM = 0 V to 2.7 V -40C < TA < +125C -40C < TA < +125C -40C < TA < +85C -40C < TA < +125C Input Offset Current IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance Differential Common Mode OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier Supply Current Shutdown Mode (AD8647) SHUTDOWN INPUTS (AD8647) Logic High Voltage (Enabled) Logic Low Voltage (Power-Down) Logic Input Current (Per Pin) Output Pin Leakage Current DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin Settling Time Amplifier Turn-On Time (AD8647) Amplifier Turn-Off Time (AD8647) NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Channel Separation VCM CMRR AVO CDIFF CCM VOH VOL IOUT ZOUT PSRR ISY ISD IOUT = 1 mA -40C < TA < +125C IOUT = 1 mA -40C < TA < +125C Short circuit At 1 MHz, AV = 1 VSY = 2.7 V to 5.5 V -40C < TA < +125C Shutdown of both amplifiers (AD8647 only) -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C -40C < TA < +125C (shutdown active) RL = 2 k +2.0 +0.8 1 1 11 24 53 0.3 1.2 1 2.3 8 6 -115 -110 2.65 2.60 VCM = 0 V to 2.7 V RL = 2 k, VO = 0.5 V to 2.2 V 0 62 95 79 102 2.5 7.8 2.68 11 63 5 63 80 1.6 10 1 25 30 0.1 Min Typ 0.6 1.8 0.2 Max 2.5 3.2 7.0 1 50 550 0.5 50 250 2.7 Unit mV mV V/C pA pA pA pA pA pA V dB dB pF pF V V mV mV mA dB mA mA nA A V V A nA V/s MHz Degrees s s s V nV/Hz nV/Hz dB dB
2.0 2.5
VINH VINL VIN
SR GBP Om ts ton toff en p-p en CS
To 0.1% 25C, AV = 1, RL = 1 k (see Figure 41) 25C, AV = 1, RL = 1 k (see Figure 42) 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 10 kHz f = 100 kHz
Rev. B | Page 5 of 20
AD8646/AD8647/AD8648 ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short Circuit to GND Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering 60 sec) Junction Temperature Rating 6V GND to VSY 3 V Indefinite -65C to +150C -40C to +125C 300C 150C
THERMAL RESISTANCE
JA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4. Thermal Resistance
Package Type 8-Lead SOIC_N 8-Lead MSOP 10-Lead MSOP 14-Lead SOIC_N 14-Lead TSSOP JA 125 210 200 120 180 JC 43 45 44 36 35 Unit C/W C/W C/W C/W C/W
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.
ESD CAUTION
Rev. B | Page 6 of 20
AD8646/AD8647/AD8648 TYPICAL PERFORMANCE CHARACTERISTICS
300 250
NUMBER OF AMPLIFIERS
VSY = 2.7V VCM = 1.35V TA = 25C 2244 AMPLIFIERS
NUMBER OF AMPLIFIERS
200 180 160 140 120 100 80 60 40 20
06527-004
VSY = 5V VCM = 2.5V TA = 25C 2244 AMPLIFIERS
200
150
100
50
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
VOS (mV)
VOS (mV)
Figure 4. Input Offset Voltage Distribution
Figure 7. Input Offset Voltage Distribution
35 30
NUMBER OF AMPLIFIERS
VSY = 2.7V -40C < TA < +125C
35 30
NUMBER OF AMPLIFIERS
VSY = 5V -40C < TA < +125C
25 20 15 10 5 0 0 1 2 3 4 5 6 7 TCVOS (V/C)
25 20 15 10 5 0 0 1 2 3 4 5 6 7 8 TCVOS (V/C)
06527-005
Figure 5. VOS Drift (TCVOS) Distribution
Figure 8. VOS Drift (TCVOS) Distribution
2500 2000
INPUT OFFSET VOLTAGE (V)
VSY = 2.7V TA = 25C
INPUT OFFSET VOLTAGE (V)
2500 2000 1500 1000 500 0 -500 -1000 -1500 -2000
VSY = 5V TA = 25C
1500 1000 500 0 -500 -1000 -1500 -2000 0 0.5 1.0 1.5 2.0 2.5 3.0
06527-006
-2500
0
INPUT COMMON-MODE VOLTAGE (V)
1 2 3 4 INPUT COMMON-MODE VOLTAGE (V)
5
Figure 6. Input Offset Voltage vs. Input Common-Mode Voltage
Figure 9. Input Offset Voltage vs. Input Common-Mode Voltage
Rev. B | Page 7 of 20
06527-009
-2500
06527-008
06527-007
0 -2.0
0 -2.0
AD8646/AD8647/AD8648
10000
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (mV)
VSY = 2.7V TA = 25C VSY - VOH
10000
VSY = 5V TA = 25C
1000
1000
100
100
10 VOL 1
10 VSY - VOH 1 VOL 0.01 0.1 1 10 100 1000
06527-013
0.01
0.1
1
10
100
LOAD CURRENT (mA)
06527-010
0.1 0.001
0.1 0.001
LOAD CURRENT (mA)
Figure 10. Output Saturation Voltage vs. Load Current
Figure 13. Output Saturation Voltage vs. Load Current
25
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (mV)
VSY = 2.7V IL = 1mA
120
VSY = 5V VSY - VOH = 10mA
20 VSY - VOH 15
100
80 VOL = 10mA 60
10
VOL
40
5
20
VSY - VOH = 1mA VOL = 1mA -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
06527-014
-25
-10
5
20
35
50
65
80
95
110
125
TEMPERATURE (C)
Figure 11. Output Saturation Voltage vs. Temperature
06527-011
0 -40
0 -40
Figure 14. Output Saturation Voltage vs. Temperature
300
VSY = 2.7V TA = 125C
INPUT BIAS CURRENT (pA)
300
VSY = 5V TA = 125C
250
INPUT BIAS CURRENT (pA)
250
200
200
150
150
100
100
50
50
06527-012
0.75
1.00
1.25
1.50
1.75
2.00
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
COMMON-MODE VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
Figure 12. Input Bias Current vs. Common-Mode Voltage
Figure 15. Input Bias Current vs. Common-Mode Voltage
Rev. B | Page 8 of 20
06527-015
0 0.50
0 0.5
AD8646/AD8647/AD8648
80 OPEN-LOOP PHASE SHIFT (Degrees)
06527-021 06527-020
06527-019
OPEN-LOOP PHASE SHIFT (Degrees)
60
VSY = 2.7V RL = 1k CL = 10pF
0
80
45
60 OPEN-LOOP GAIN (dB)
VSY = 5V RL = 1k CL = 10pF PHASE
0
45
OPEN-LOOP GAIN (dB)
40
90
40
90
20
M = 52
135
20
M = 74
135
GAIN
0 180
0
180
-20
225
-20
225
100k
1M FREQUENCY (Hz)
10M
06527-016
-40 10k
270 100M
-40 10k
100k
1M FREQUENCY (Hz)
10M
270 100M
Figure 16. Open-Loop Gain and Phase vs. Frequency
Figure 19. Open-Loop Gain and Phase vs. Frequency
60 AV = 100
VSY = 2.7V TA = 25C
60 AV = 100
VSY = 5V TA = 25C
40
40
CLOSED-LOOP GAIN (dB)
20
AV = 10
CLOSED-LOOP GAIN (dB)
20
AV = 10
0
AV = 1
0
AV = 1
-20
-20
-40
-40
10k
100k
1M
10M
100M
06527-017
-60 1k
-60 1k
10k
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 17. Closed-Loop Gain vs. Frequency
Figure 20. Closed-Loop Gain vs. Frequency
250
VSY = 2.7V TA = 25C
120
VSY = 5V TA = 25C
200 AV = 1
100 AV = 1 80
ZOUT ()
ZOUT ()
150
60 AV = 100 40
AV = 10
100 AV = 100 50
AV = 10
20
06527-018
0 1 10 100 1k 10k 100k 1M FREQUENCY (kHz)
0 1 10 100 1k 10k 100k 1M FREQUENCY (kHz)
Figure 18. ZOUT vs. Frequency
Figure 21. ZOUT vs. Frequency
Rev. B | Page 9 of 20
AD8646/AD8647/AD8648
100 VSY = 2.7V TA = 25C
100 VSY = 5V TA = 25C
80
80
CMRR (dB)
40
CMRR (dB)
60
60
40
20
20
06527-022
10k
100k
1M
10M
100M
10k
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 22. CMRR vs. Frequency
Figure 25. CMRR vs. Frequency
100 PSRR+ 80
VSY = 2.7V TA = 25C
100
PSRR+
VSY = 5V TA = 25C
80 PSRR-
PSRR (dB)
40
PSRR (dB)
60
PSRR-
60
40
20
20
10k
100k FREQUENCY (Hz)
1M
10M
06527-023
10k
100k FREQUENCY (Hz)
1M
10M
Figure 23. PSRR vs. Frequency
Figure 26. PSRR vs. Frequency
60
VSY = 1.35V TA = 25C -OS
70 60 50
OVERSHOOT (%)
50 +OS
VSY = 5V RL = 10k TA = 25C
OVERSHOOT (%)
40
40 OS+ 30 20 OS-
30
20
10
10 0 10
06527-024
0 1 10 CLOAD (pF) 100 1000
100 CLOAD (pF)
1000
Figure 24. Overshoot vs. Load Capacitance
Figure 27. Overshoot vs. Load Capacitance
Rev. B | Page 10 of 20
06527-027
06527-026
0 1k
0 1k
06527-025
0 1k
0 1k
AD8646/AD8647/AD8648
VSY = 2.7V, VCM = 1.35V, VIN = 100mV p-p, TA = 25C, RL = 10k, CL = 100pF VSY = 5V, VCM = 2.5V, VIN = 100mV p-p, TA = 25C, RL = 10k, CL = 100pF
(50mV/DIV)
06527-028
(50mV/DIV)
(200ns/DIV)
(200ns/DIV)
Figure 28. Small-Signal Transient Response
Figure 31. Small-Signal Transient Response
VSY = 2.7V, VIN = 2V p-p, TA = 25C, RL = 10k, CL = 100pF
VSY = 5V, VIN = 4V p-p, TA = 25C, RL = 10k, CL = 100pF
(2V/DIV)
06527-029
(2V/DIV)
(200ns/DIV)
(200ns/DIV)
Figure 29. Large-Signal Transient Response
Figure 32. Large-Signal Transient Response
0.08
VSY = 2.5V RL = 600 0.07 AV = 1 TA = 25C 0.06 0.05 0.04 0.03 0.02 0.01 0 10
0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01
VSY = 2.5V RL = 600 AV = -10 TA = 25C
THD + N (%)
THD + N (%)
06527-030
100
1k FREQUENCY (Hz)
10k
100k
100
1k FREQUENCY (Hz)
10k
100k
Figure 30. THD + Noise vs. Frequency
Figure 33. THD + Noise vs. Frequency
Rev. B | Page 11 of 20
06527-033
0 10
06527-032
06527-031
AD8646/AD8647/AD8648
VSY = 2.7V TO 5V TA = 25C
1
0.1
VOLTAGE (1V/DIV)
THD + N (%)
0.01
0.001
06527037
VSY = 5V AV = 1 BW = 30kHz RL = 100k f = 1kHz 0.01 0.1 1
06527-034
TIME (1s/DIV)
0.0001 0.001
OUTPUT AMPLITUDE (V rms)
Figure 34. 0.1 Hz to 10 Hz Voltage Noise
Figure 37. THD + Noise vs. Output Amplitude
1000
VSY = 2.7V TO 5V TA = 25C
1000
VSY = 5V
VOLTAGE NOISE DENSITY (nV/Hz)
100
INPUT BIAS CURRENT (pA)
100
10
10
1
100 FREQUENCY (Hz)
1k
10k
06527-035
45
65
80
105
125
TEMPERATURE (C)
Figure 35. Voltage Noise Density vs. Frequency
Figure 38. Input Bias Current vs. Temperature
2.5
TA = 25C
5.0 4.5
SUPPLY CURRENT PER AMPLIFIER (mA)
2.0
4.0
OUTPUT SWING (V p-p)
VSY = 5V VIN = 4.9V AV = 1 RL = 10k TA = 25C
3.5 3.0 2.5 2.0 1.5 1.0 0.5
1.5
1.0
0.5
06527-039
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
1k FREQUENCY (kHz)
10k
SUPPLY VOLTAGE (V)
Figure 36. Supply Current per Amplifier vs. Supply Voltage
Figure 39. Maximum Output Swing vs. Frequency
Rev. B | Page 12 of 20
06527-036
0
0 100
06527-038
1 10
0.1 25
AD8646/AD8647/AD8648
4.0
0
VOUT = VSY/2
SUPPLY CURRENT PER AMPLIFIER (mA)
3.5
-20
CHANNEL SEPARATION (dB)
VSY = 5V RL = 2k AV = -100 TA = 25C
CS (dB) = 20 log (VOUT/100 = VIN) V+ 3 VIN + - 0 2 V+ V- V- U1 R3 2k 0
R1 20 V- U2 5 V- V+ V+ R2 6 200 7 0 0
3.0 2.5 2.0 1.5 1.0 0.5 0 -40 VSY = 2.7V VSY = 5V
-40
-60
-80 VIN = 2V p-p VIN = 0.5V p-p 10k FREQUENCY (Hz) 100k
06527-042
-100
-20
0
20
40
60
80
100
120
TEMPERATURE (C)
Figure 40. Supply Current per Amplifier vs. Temperature
06527-040
-120 1k
Figure 43. Channel Separation
SHUTDOWN PIN VSY = 2.7V RL = 1k AV = 1 TA = 25C
VSY = 5V RL = 1k AV = 1 TA = 25C VOLTAGE (1V/DIV)
SHUTDOWN PIN
VOLTAGE (1V/DIV)
AMPLIFIER OUTPUT
AMPLIFIER OUTPUT
06527-043
06527-045
TIME (200ns/DIV)
TIME (200ns/DIV)
Figure 41. Turn-On Time
Figure 44. Turn-On Time
VSY = 2.7V RL = 1k AV = 1 TA = 25C
VSY = 5V RL = 1k AV = 1 TA = 25C
VOLTAGE (1V/DIV)
VOLTAGE (1V/DIV)
SHUTDOWN PIN
SHUTDOWN PIN
AMPLIFIER OUTPUT
06527-046
AMPLIFIER OUTPUT
TIME (200ns/DIV)
TIME (200ns/DIV)
Figure 42. Turn-Off Time
Figure 45. Turn-Off Time
Rev. B | Page 13 of 20
06527-044
AD8646/AD8647/AD8648
100 VSY = 2.7V
100 VSY = 5V
10
10
ISY (nA)
1
ISY (nA)
06527-048
1
0.1
0.1
-25
-10
5
20
35
50
65
80
95
110
125
-25
-10
5
20
35
50
65
80
95
110
125
TEMPERATURE (C)
TEMPERATURE (C)
Figure 46. Supply Current with Op-Amp Shutdown vs. Temperature
Figure 47. Supply Current with Op-Amp Shutdown vs. Temperature
Rev. B | Page 14 of 20
06527-047
0.01 -40
0.01 -40
AD8646/AD8647/AD8648 THEORY OF OPERATION
POWER-DOWN OPERATION
The shutdown function of the AD8647 is referenced to the negative supply voltage of the operational amplifier. A logic level high (> 2.0 V) enables the device, while a logic level low (< 0.8 V) disables the device and places the output in a high impedance condition. Several outputs can be wire-OR'ed, thus eliminating a multiplexer. The logic input is a high impedance CMOS input. If dual or split supplies are used, the logic signals must be properly referred to the negative supply voltage.
8 7 5kHz 5V
1/2 AD8647
9 6
1/2 AD8647
2 3 13kHz 4 10 1 5
MULTIPLEXING OPERATION
Because each op amp has a separate logic input enable pin, the outputs can be connected together if it can be guaranteed that only one op amp is active at any time. By connecting the op amps as shown in Figure 48, a multiplexer can be eliminated. With the reasonably short turn-on and turn-off times, low frequency signal paths can be smoothly selected. The turn-off time is slightly faster than the turn-on time so, even when using sections from two different packages, the overlap is less than 300 nanoseconds.
1 2kHz 2
06527-049
Figure 48. AD8647 Output Switching
2V 1V 0V
5V 0V
06527-050
TIME (200s/DIV)
Figure 49. Switching Waveforms
Rev. B | Page 15 of 20
AD8646/AD8647/AD8648 OUTLINE DIMENSIONS
5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497)
8 1 5 4
6.20 (0.2441) 5.80 (0.2284)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) COPLANARITY 0.10 SEATING PLANE
1.75 (0.0688) 1.35 (0.0532)
0.50 (0.0196) 0.25 (0.0099) 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157)
45
0.51 (0.0201) 0.31 (0.0122)
COMPLIANT TO JEDEC STANDARDS MS-012-A A 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.
Figure 50. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches)
3.20 3.00 2.80
3.20 3.00 2.80
8
5
1
5.15 4.90 4.65
4
PIN 1 0.65 BSC 0.95 0.85 0.75 0.15 0.00 0.38 0.22 SEATING PLANE 1.10 MAX 8 0 0.80 0.60 0.40
0.23 0.08
COPLANARITY 0.10
COMPLIANT TO JEDEC STANDARDS MO-187-AA
Figure 51. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters
Rev. B | Page 16 of 20
012407-A
AD8646/AD8647/AD8648
3.10 3.00 2.90 3.10 3.00 2.90 PIN 1 0.50 BSC 0.95 0.85 0.75 0.15 0.05 0.33 0.17 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-BA 1.10 MAX 8 0 0.80 0.60 0.40
10 6
1
5
5.15 4.90 4.65
SEATING PLANE
0.23 0.08
Figure 52. 10 Lead Mini Small Outline Package [MSOP] (RM-10) Dimensions shown in millimeters
5.10 5.00 4.90
14
8
4.50 4.40 4.30
1 7
6.40 BSC
PIN 1 1.05 1.00 0.80 0.65 BSC 1.20 MAX 0.15 0.05 0.30 0.19
0.20 0.09
SEATING COPLANARITY PLANE 0.10
8 0
0.75 0.60 0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AB-1
Figure 53. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters
Rev. B | Page 17 of 20
AD8646/AD8647/AD8648
8.75 (0.3445) 8.55 (0.3366)
14 1 8 7
4.00 (0.1575) 3.80 (0.1496)
6.20 (0.2441) 5.80 (0.2283)
1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 0.51 (0.0201) 0.31 (0.0122)
1.75 (0.0689) 1.35 (0.0531) SEATING PLANE
0.50 (0.0197) 0.25 (0.0098) 8 0 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157)
45
COMPLIANT TO JEDEC STANDARDS MS-012-AB 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.
Figure 54. 14-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model AD8646ARZ 1 AD8646ARZ-REEL1 AD8646ARZ-REEL71 AD8646ARMZ-R21 AD8646ARMZ-REEL1 AD8647ARMZ-R21 AD8647ARMZ-REEL1 AD8648ARZ1 AD8648ARZ-REEL1 AD8648ARZ-REEL71 AD8648ARUZ1 AD8648ARUZ-REEL1
1
Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C
Package Description 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead MSOP 8-Lead MSOP 10-Lead MSOP 10-Lead MSOP 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead TSSOP 14-Lead TSSOP
Package Option R-8 R-8 R-8 RM-8 RM-8 RM-10 RM-10 R-14 R-14 R-14 RU-14 RU-14
060606-A
Branding
A1V A1V A1W A1W
Z = RoHS Compliant Part.
Rev. B | Page 18 of 20
AD8646/AD8647/AD8648 NOTES
Rev. B | Page 19 of 20
AD8646/AD8647/AD8648 NOTES
(c)2006-2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06527-0-10/07(B)
Rev. B | Page 20 of 20

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