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Low Cost, High Speed Rail-to-Rail Output Op Amp ADA4851-1
FEATURES
High speed 130 MHz -3 dB bandwidth 800 V/s slew rate 85 ns settling time to 0.1% Fully specified at +3 V, +5 V, and 5 V supplies Single-supply operation Output swings to within 70 mV of either rail Rail-to-rail output 0.1 dB flatness: 14 MHz Differential gain: 0.04% Differential phase: 0.06 Low voltage offset: 0.6 mV Wide supply range: 3 V to 10 V Low power: 2.5 mA Power-down mode Available in space-saving package: SOT-23-6
PIN CONFIGURATION
VOUT 1 -VS 2 +IN 3
ADA4851-1
6 5 4
+VS POWER DOWN
05143-001
-IN
TOP VIEW (Not to Scale)
Figure 1. 6-Lead SOT-23 (RJ-6)
APPLICATIONS
Consumer video Professional video Video switchers Active filters
GENERAL DESCRIPTION
The ADA4851-1 is a low cost, high speed, voltage feedback rail-to-rail output op amp. Despite its low price, the ADA4851-1 provides excellent overall performance and versatility. The 130 MHz -3 dB bandwidth and 800 V/s slew rate make this amplifier well-suited for many general-purpose, high speed applications. The ADA4851-1 is designed to operate at supply voltages as low as 3 V and up to 5 V using only 2.5 mA of supply current. To further reduce power consumption, the amplifier is equipped with a power-down mode, which lowers the supply current to 0.2 mA. The ADA4851-1 provides users with a true single-supply capability, allowing input signals to extend 200 mV below the negative rail and to within 2 V of the positive rail. On the output, the amplifier can swing within 70 mV of either supply rail. With its combination of low price, excellent differential gain (0.04%), differential phase (0.06), and 0.1dB flatness out to 14 MHz, this amplifier is ideal for consumer video applications.
Rev. 0
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.
The ADA4851-1 is available in a SOT-23-6 package and is designed to work in the extended temperature range (-40C to +125C).
4 3 2 G = +1 VS = 2.5V RL = 1k CL = 5pF
CLOSED-LOOP GAIN (dB)
1 0 -1 -2 -3 -4 -5
05143-004
-6 1 10 100 1k FREQUENCY (MHz)
Figure 2. Small Signal Frequency Response
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2004 Analog Devices, Inc. All rights reserved.
ADA4851-1 TABLE OF CONTENTS
Specifications..................................................................................... 3 Specifications with +3 V Supply ................................................. 3 Specifications with +5 V Supply ................................................. 4 Specifications with 5 V Supply ................................................. 5 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 ESD Caution.................................................................................. 6 Typical Performance Characteristics ..............................................7 Circuit Description......................................................................... 13 Headroom Considerations........................................................ 13 Overload Behavior and Recovery ............................................ 14 Outline Dimensions ....................................................................... 15 Ordering Guide .......................................................................... 15
REVISION HISTORY
10/04--Revision 0: Initial Version
Rev. 0 | Page 2 of 16
ADA4851-1 SPECIFICATIONS
SPECIFICATIONS WITH +3 V SUPPLY
TA = 25C, RF = 0 for G = +1, RF = 1 k for G > +1, RL = 1 k, unless otherwise noted. Table 1.
Parameter DYNAMIC PERFORMANCE -3 dB Bandwidth Bandwidth for 0.1 dB Flatness Slew Rate NOISE/DISTORTION PERFORMANCE Harmonic Distortion (dBc) HD2/HD3 Input Voltage Noise Input Current Noise DC PERFORMANCE Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Bias Current Drift Input Bias Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Input Overdrive Recovery Time (Rise/Fall) Common-Mode Rejection Ratio POWER-DOWN Power-Down Input Voltage Turn-Off Time Turn-On Time Power-Down Bias Current Enabled Power-Down OUTPUT CHARACTERISTICS Output Overdrive Recovery Time (Rise/Fall) Output Voltage Swing Short-Circuit Current POWER SUPPLY Operating Range Quiescent Current Quiescent Current (Power-Down) Positive Power Supply Rejection Negative Power Supply Rejection Conditions G = +1, VO = 0.1 V p-p G = +1, VO = 1 V p-p G = +2, VO = 0.5 V p-p, RL = 150 G = +2, VO = 2 V Step fC = 1 MHz, VO = 0.2 V p-p, G = +2 f = 100 kHz f = 100 kHz Min 112 54 Typ 130 65 20 140 -85/-113 10 2.5 0.6 4 1.8 6 20 102 0.5/5.0 1.2 -0.2 to +0.8 60/60 -118 < 1.1 0.7 60 +4 -14 70/100 0.02 to 2.94 90/70 12 2.7 0.3 +6 -20 3.3 3.7 Max Unit MHz MHz MHz V/s dBc nV/Hz pA/Hz mV V/C A nA/C nA dB M pF V ns dB V s ns A A ns V mA V mA mA dB dB
VO = 2 V to 3 V Differential/common-mode
83
VIN = +3.5 V, -0.5 V, G = +1 VCM = 0.5 V Power-down
-81
Power-down = 3 V Power-down = 0 V VIN = +0.7 V, -0.1 V, G = +5 0.05 to 2.92 Sinking/sourcing 3 Power-down = Low +VS = +2.5 V to +3.5 V, -VS = -0.5 V +VS = +2.5 V,-VS = -0.5 V to -1.5 V
-84 -83
2.4 0.2 -102 -102
Rev. 0 | Page 3 of 16
ADA4851-1
SPECIFICATIONS WITH +5 V SUPPLY
TA = 25C, RF = 0 for G = +1, RF = 1 k for G > +1, RL = 1 k, unless otherwise noted. Table 2.
Parameter DYNAMIC PERFORMANCE -3 dB Bandwidth Bandwidth for 0.1 dB Flatness Slew Rate Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion (dBc) HD2/HD3 Input Voltage Noise Input Current Noise Differential Gain Differential Phase DC PERFORMANCE Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Bias Current Drift Input Bias Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Input Overdrive Recovery Time (Rise/Fall) Common-Mode Rejection Ratio POWER-DOWN Power-Down Input Voltage Turn-Off Time Turn-On Time Power-Down Bias Current Enabled Power-Down OUTPUT CHARACTERISTICS Output Overdrive Recovery Time (Rise/Fall) Output Voltage Swing Short-Circuit Current POWER SUPPLY Operating Range Quiescent Current Quiescent Current (Power-Down) Positive Power Supply Rejection Negative Power Supply Rejection Conditions G = +1, VO = 0.1 V p-p G = +1, VO = 1 V p-p G = +2, VO = 2 V p-p, RL = 150 G = +2, VO = 3 V Step G = +2, VO = 1 V Step, RL = 150 fC = 1 MHz, VO = 0.2 V p-p, G = +2 f = 100 kHz f = 100 kHz G = +2, NTSC, RL = 150 G = +2, NTSC, RL = 150 Min 107 54 Typ 125 65 15 410 85 -98/-113 10 2.5 0.05 0.09 0.6 4 1.7 6 20 111 0.5/5.0 1.2 -0.2 to +2.8 50/45 -130 < 1.1 0.7 50 33 -22 60/70 0.05 to 4.94 110/90 12 2.8 0.3 40 -30 3.4 3.6 Max Unit MHz MHz MHz V/s ns dBc nV/Hz pA/Hz % Degrees mV V/C A nA/C nA dB M pF V ns dB V s ns A A ns V mA V mA mA dB dB
VO = 1 V to 4 V Differential/common-mode
97
VIN = +5.5 V, -0.5 V, G = +1 VCM = 2 V Power-down
-88
Power-down = 5 V Power-down = 0 V VIN = +1.1 V, -0.1 V, G = +5 0.09 to 4.92 Sinking/sourcing 3 Power-down = Low +VS = +5 V to +6 V, -VS = 0 V +VS = +5 V,-VS = -0 V to -1 V
-85 -84
2.5 0.2 -101 -101
Rev. 0 | Page 4 of 16
ADA4851-1
SPECIFICATIONS WITH 5 V SUPPLY
TA = 25C, RF = 0 for G = +1, RF = 1 k for G > +1, RL = 1 k, unless otherwise noted. Table 3.
Parameter DYNAMIC PERFORMANCE -3 dB Bandwidth Bandwidth for 0.1 dB Flatness Slew Rate Settling Time to 0.1% NOISE/DISTORTION PERFORMANCE Harmonic Distortion (dBc) HD2/HD3 Input Voltage Noise Input Current Noise Differential Gain Differential Phase DC PERFORMANCE Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Bias Current Drift Input Bias Offset Current Open-Loop Gain INPUT CHARACTERISTICS Input Resistance Input Capacitance Input Common-Mode Voltage Range Input Overdrive Recovery Time (Rise/Fall) Common-Mode Rejection Ratio POWER-DOWN Power-Down Input Voltage Turn-Off Time Turn-On Time Power-Down Bias Current Enabled Power-Down OUTPUT CHARACTERISTICS Output Overdrive Recovery Time (Rise/Fall) Output Voltage Swing Short-Circuit Current POWER SUPPLY Operating Range Quiescent Current Quiescent Current (Power-Down) Positive Power Supply Rejection Negative Power Supply Rejection Conditions G = +1, VO = 0.1 V p-p G = +1, VO = 1 V p-p G = +2, VO = 2 V p-p, RL = 150 G = +2, VO = 8 V p-p Step G = +2, VO = 2 V p-p Step G = +2, VO = 2 V Step, RL = 150 fC = 1 MHz, VO = 1 V p-p, G = +1 f = 100 kHz f = 100 kHz G = +2, NTSC, RL = 150 G = +2, NTSC, RL = 150 Min 43 64 Typ 105 78 14 800 400 90 -90/-117 10 2.5 0.04 0.06 0.6 4 1.7 6 20 111 0.5/5.0 1.2 -5.2 to +2.8 50/25 -123 < -3.9 0.7 30 0.1 -0.05 80/50 -4.93 to +4.93 125/110 6 3.2 0.3 0.13 -0.06 3.5 3.7 Max Unit MHz MHz MHz V/s V/s ns dBc nV/Hz pA/Hz % Degrees mV V/C A nA/C nA dB M pF V ns dB V s ns mA mA ns V mA V mA mA dB dB
VO = 2.5 V Differential/common-mode
99
VIN = 6 V, G = +1 VCM = 4 V Power-down
-91
Power-down = +5 V Power-down = -5 V VIN = 1.2 V, G = +5 -4.9 to +4.91 Sinking/sourcing 1.5 Power-down = Low +VS = +5 V to +6 V, -VS = -5 V +VS = +5 V,-VS = -5 V to -6 V
-85 -84
2.9 0.2 -102 -102
Rev. 0 | Page 5 of 16
ADA4851-1 ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Supply Voltage Power Dissipation Common-Mode Input Voltage Differential Input Voltage Storage Temperature Operating Temperature Range Lead Temperature Range (Soldering 10 sec) Junction Temperature Rating 12.6 V See Figure 3 -VS - 0.5 V to +VS + 0.5 V +VS to -VS -65C to +125C -40C to +125C 300C 150C
The power dissipated in the package (PD) is the sum of the quiescent power dissipation and the power dissipated in the die due to the ADA4851-1 drive at the output. The quiescent power is the voltage between the supply pins (VS) times the quiescent current (IS). PD = Quiescent Power + (Total Drive Power - Load Power)
V V V 2 PD = (VS x I S ) + S x OUT - OUT RL RL 2 RMS output voltages should be considered. If RL is referenced to -VS, as in single-supply operation, the total drive power is VS x IOUT. If the rms signal levels are indeterminate, consider the worst case, when VOUT = VS/4 for RL to midsupply.
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.
PD = (VS x I S ) +
(VS /4 )2
RL
THERMAL RESISTANCE
JA is specified for the worst-case conditions, i.e., JA is specified for device soldered in circuit board for surface-mount packages. Table 5. Thermal Resistance
Package Type SOT-23-6 JA 170 Unit C/W
In single-supply operation with RL referenced to -VS, worst case is VOUT = VS/2. Airflow increases heat dissipation, effectively reducing JA. Also, more metal directly in contact with the package leads and exposed paddle from metal traces, through holes, ground, and power planes reduce JA. Figure 3 shows the maximum safe power dissipation in the package vs. the ambient temperature for the SOT-23-6 (170C/W) package on a JEDEC standard 4-layer board. JA values are approximations.
1.4
Maximum Power Dissipation
The maximum safe power dissipation for the ADA4851-1 is limited by the associated rise in junction temperature (TJ) on the die. At approximately 150C, which is the glass transition temperature, the plastic changes its properties. Even temporarily exceeding this temperature limit may change the stresses that the package exerts on the die, permanently shifting the parametric performance of the ADA4851-1. Exceeding a junction temperature of 150C for an extended period of time can result in changes in silicon devices, potentially causing degradation or loss of functionality.
MAXIMUM POWER DISSIPATION (W)
1.2 1.0
0.8 0.6
0.4
0.2 0 -40
-20
0
20
40
60
80
100
120
AMBIENT TEMPERATURE (C)
Figure 3. Maximum Power Dissipation vs. Temperature for a 4-Layer Board
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. 0 | Page 6 of 16
05143-048
ADA4851-1 TYPICAL PERFORMANCE CHARACTERISTICS
1 0 VS = 5V RL = 150 VOUT = 0.1V p-p
4 3 2 G = +1 VS = 2.5V RL = 1k VOUT = 0.1V p-p 10pF 10pF + 25 RSNUB
CLOSED-LOOP GAIN (dB)
CLOSED-LOOP GAIN (dB)
-1 -2 -3 G = +10 -4 -5 -6 -7 1 10 FREQUENCY (MHz) G = +2
G = -1
1 0 -1 -2 -3 -4 -5 RSNUB CL RL 5pF 0pF
05143-006
100
1
10 FREQUENCY (MHz)
100
300
Figure 4. Small Signal Frequency Response for Various Gains
1 RL = 150 0
Figure 7. Small Signal Frequency Response for Various Capacitor Loads
1
0
+85C VS = 5V G = +1 VOUT = 0.1V p-p -40C +25C +125C
CLOSED-LOOP GAIN (dB)
CLOSED-LOOP GAIN (dB)
-1 -2
VS = 5V G = +1 VOUT = 0.1V p-p
RL = 1k
-1 -2
-3
-3
-4 -5
-4 -5
05143-009
1
10 FREQUENCY (MHz)
100
300
1
10 FREQUENCY (MHz)
100
300
Figure 5. Small Signal Frequency Response for Various Loads
2 1 G = +1 RL = 150 VOUT = 0.1V p-p VS = 2.5V
Figure 8. Small Signal Frequency Response for Various Temperatures
1 0 VS = 5V RL = 150 VOUT = 1V p-p
CLOSED-LOOP GAIN (dB)
-1 -2 -3 -4 -5 -6 1 10
VS = 5V
CLOSED-LOOP GAIN (dB)
0
-1 -2 -3 -4 -5 G = -1 -6 G = +10 G = +2
1
10 FREQUENCY (MHz)
100
FREQUENCY (MHz)
Figure 6. Small Signal Frequency Response for Various Supplies
Figure 9. Large Signal Frequency Response for Various Gains
Rev. 0 | Page 7 of 16
05143-012
100
300
05143-007
-7
05143-008
-6
-6
05143-010
-6
ADA4851-1
6.2 6.1 VS = 5V G = +2 RL = 150
-50 G = +2 RL = 1k VOUT = 200mV p-p -60
CLOSED-LOOP GAIN (dB)
6.0 5.9 5.8 VOUT = 1V p-p 5.7 VOUT = 100mV p-p 5.6 VOUT = 2V p-p 5.5 5.4 0.1
HARMONIC DISTORTION (dBc)
VS = +3V HD2
-70 -80 VS = 5V HD2
-90
-100 -110
VS = +3V HD3 VS = 5V HD3
05143-021
1
10 FREQUENCY (MHz)
100
1
10 FREQUENCY (MHz)
100
Figure 10. 0.1 dB Flatness Response
1 VS = 5V G = +1 VOUT = 1V p-p
Figure 13. Harmonic Distortion vs. Frequency for Various Supplies
-50 G = +2 VS = 5V RL = 1k f = 2MHz
0
-60
HARMONIC DISTORTION (dBc)
CLOSED-LOOP GAIN (dB)
HD2
-1 RL = 1k -2 RL = 150 -3
-70
-80 HD3 -90
-4 -5
-100
-110
05143-015
1
10 FREQUENCY (MHz)
100
300
0
1
2
3
4
5
6
7
8
9
10
OUTPUT AMPLITUDE (V p-p)
Figure 11. Large Frequency Response for Various Loads
140 VS = 5V 120 100 80 60 40 GAIN 20 0 -20 10 -180 -210 -240 1G PHASE -30 -60 -90 -120 -150 0
-50
Figure 14. Harmonic Distortion vs. Output Voltage
-60
G = +1 VS = 5V VOUT = 1V p-p
HARMONIC DISTORTION (dBc)
OPEN-LOOP PHASE (Degrees)
OPEN-LOOP GAIN (dB)
-70 RL = 150 HD2 -80 RL = 1k HD2 -90
-100 -110
RL = 150 HD3
RL = 1k HD3
100
1k
10k
100k
1M
10M
100M
05143-029
1 FREQUENCY (MHz)
10
FREQUENCY (Hz)
Figure 12. Open-Loop Gain and Phase vs. Frequency
Figure 15. Harmonic Distortion vs. Frequency for Various Loads
Rev. 0 | Page 8 of 16
05143-016
-120 0.1
05143-017
-6
-120
05143-014
-120 0.1
ADA4851-1
-50 G = +1 VS = 5V RL = 1k VOUT = 2V p-p HD2
0.075 G = +1 OR +2 RL = 1k 0.050
-60
HARMONIC DISTORTION (dBc)
OUTPUT VOLTAGE (V)
-70 -80 VOUT = 2V p-p HD3
0.025
0
-90
-0.025 VS = 2.5V -0.050
-100 -110
VOUT = 200mV p-p HD2
VS = 5V
VOUT = 200mV p-p HD3
05143-013
1
10 FREQUENCY (MHz)
100
0
50
100 TIME (ns)
150
200
Figure 16. Harmonic Distortion vs. Frequency for Various VOUT
6 5 OUTPUT 5 x INPUT G = +5 VS = 5V RL = 150 f = 1MHz
Figure 19. Small Signal Transient Response for Various Supplies
0.075 G = +1 VS = 2.5V RL = 150
10pF 0pF
INPUT AND OUTPUT VOLTAGE (V)
4 3 2 1 0 -1 -2 -3 -4 -5
0.050
OUTPUT VOLTAGE (V)
0.025
0
-0.025
-0.050
05143-019
0
100
200
300
400
500
600
700
800
900
1k
0
20
40
60
80
100
120
140
160
180
200
TIME (ns)
TIME (ns)
Figure 17. Output Overdrive Recovery
6
Figure 20. Small Signal Transient Response for Capacitive Load
1.5 0.5
INPUT AND OUTPUT VOLTAGE (V)
4 3 2 1 0 -1 -2 -3 -4 -5 OUTPUT
1.0 VS = 5V 0.5 VS = 2.5V
0
-0.5
0
-1.0
-0.5
-1.5
-1.0
-2.0
05143-022
0
100
200
300
400
500
600
700
800
900
1k
0
50
100 TIME (ns)
150
TIME (ns)
Figure 18. Input Overdrive Recovery
Figure 21. Large Signal Transient Response for Various Supplies
Rev. 0 | Page 9 of 16
05143-028
-6
-1.5
-2.5 200
OUTPUT VOLTAGE FOR 2.5V SUPPLY (V)
OUTPUT VOLTAGE FOR 5V SUPPLY (V)
5
INPUT
G = +1 VS = 5V RL = 150 f = 1MHz
G = +2 RL = 150
05143-026
-6
-0.075
05143-024
-120 0.1
-0.075
ADA4851-1
1.5 0.5
6
OUTPUT VOLTAGE FOR 2.5V SUPPLY (V)
OUTPUT VOLTAGE FOR 5V SUPPLY (V)
G = +2 RL = 150 1.0 VS = 5V 0.5 VS = 2.5V -0.5 0
5 VDISABLE
G = +2 VS = 5V fIN = 400kHz
4
VOLTAGE (V)
3
0
-1.0
2
-0.5
-1.5
1 0 VOUT 0 15 TIME (s) 30 45
05143-033
-1.0
-2.0
0
50
100 TIME (ns)
150
05143-027
-1.5
-2.5 200
-1
Figure 22. Large Signal Transient Response for Various Supplies
0.5
Figure 25. Enable/Disable Time
3.5
VOLTAGE DIFFERENTIAL FROM VS (V)
+VS - VOUT 0.4
3.0 VS = 5V
SUPPLY CURRENT (mA)
VS = +3V 0.3
VS = 5V
2.5
VS = 2.5V VS = +3V
2.0
-VS - VOUT 0.2
1.5
1.0
0.1
0.5
0 0 5 10 15 20 25 30 35 LOAD CURRENT (mA)
05143-049
-4
-3
-2
-1
0
1
2
3
4
5
DISABLE VOLTAGE (V)
Figure 23. Output Saturation Voltage vs. Load Current
1.2k
300
Figure 26. Supply Current vs. POWER DOWN Pin Voltage
1.0k
INPUT OFFSET VOLTAGE (V)
G = +2 VS = 5V RL = 1k 25% TO 75% OF VO NEGATIVE SLEW RATE
200 VS = +3V VS = 5V 0 VS = 2.5V
SLEW RATE (V/s)
100
800
600 POSITIVE SLEW RATE 400
-100
-200 -300
200
05143-032
0 0 1 2 3 4 5 6 7 8 9 10 OUTPUT VOLTAGE STEP (V p-p)
-25
-10
5
20
35
50
65
80
95
110
125
TEMPERATURE (C)
Figure 24. Slew Rate vs. Output Voltage
Figure 27. Input Offset Voltage vs. Temperature for Various Supplies
Rev. 0 | Page 10 of 16
05143-035
-400 -40
05143-034
0 -5
ADA4851-1
2.2 1k G = +10 2.0
INPUT BIAS CURRENT (A)
VOLTAGE NOISE (nV/ Hz)
100
1.8 IB+, VS = 2.5V 1.6
IB+, VS = 5V IB-, VS = 5V
IB-, VS = 2.5V
10
1.4
05143-036
-25
-10
5
20
35
50
65
80
95
110
125
10
100
1k
10k
100k
1M
10M
TEMPERATURE (C)
FREQUENCY (Hz)
Figure 28. Input Bias Current vs. Temperature for Various Supplies
0.09
100
Figure 31. Voltage Noise vs. Frequency
VOLTAGE DIFFERENTIAL FROM VS (V)
VS = 5V 0.08 +VS - VOUT 0.07 +VS - VOUT 0.06 -VS - VOUT VS = 2.5V
G = +2
CURRENT NOISE (pA/ Hz)
10
0.05 -VS - VOUT 0.04 -40
1 10 100 1k 10k 100k 1M 10M 100M FREQUENCY (Hz)
05143-037
-25
-10
5
20
35
50
65
80
95
110
125
TEMPERATURE (C)
Figure 29. Output Saturation vs. Temperature for Various Supplies
3.2 VS = 5V 3.0
80 70 60
Figure 32. Current Noise vs. Frequency
VS = 5V N = 420 x = -260V = 780V
SUPPLY CURRENT (mA)
2.8
50
2.6
VS = 2.5V
COUNT
40 30
2.4 VS = +3V 2.2
10 20
05143-038
-25
-10
5
20
35
50
65
80
95
110
125
-3k
-2k
-1k
0
1k
2k
3k
4k
TEMPERATURE (C)
VOFFSET (V)
Figure 30. Supply Current vs. Temperature for Various Supplies
Figure 33. Input Offset Voltage Distribution
Rev. 0 | Page 11 of 16
05143-047
2.0 -40
0 -4k
05143-045
05143-044
1.2 -40
1
ADA4851-1
-30 -40 VS = 5V 0 -10 VS = 5V
POWER SUPPLY REJECTION (dB)
COMMON-MODE REJECTION (dB)
-20 -30 -40 -50 -60 -70 -80 -90 -100 +PSR -PSR
-50 -60 -70 -80 -90 -100 -110
05143-020
1k
10k
100k
1M
10M
100M
1G
1k
10k
100k
1M
10M
100M
1G
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 34. Common-Mode Rejection Ratio (CMRR) vs. Frequency
Figure 35. Power Supply Rejection (PSR) vs. Frequency
Rev. 0 | Page 12 of 16
05143-023
-120
-110 100
ADA4851-1 CIRCUIT DESCRIPTION
The ADA4851-1 features a high slew rate input stage that is a true single-supply topology, capable of sensing signals at or below the minus supply rail. The rail-to-rail output stage can pull within 70 mV of either supply rail when driving light loads and within 0.17 V when driving 150 . High speed performance is maintained at supply voltages as low as 2.7 V.
440 460 480 500
VOS (V)
520 540 560 580 600 -6 -5 -4 -3 -2 -1 VCM (V) 0 1 2 3 4
HEADROOM CONSIDERATIONS
This amplifier is designed for use in low voltage systems. To obtain optimum performance, it is useful to understand the behavior of the amplifier as input and output signals approach the amplifier's headroom limits. The ADA4851-1's input common-mode voltage range extends from the negative supply voltage (actually 200 mV below this), or ground for single-supply operation, to within 2 V of the positive supply voltage. Therefore, at a gain of 2, the ADA4851-1 can provide full rail-to-rail output swing for supply voltage as low as 3.6 V, assuming the input signal swing is from -VS (or ground) to +VS/2. At a gain of 4, the ADA4851-1 can provide a rail-to-rail output range down to 3 V total supply voltage. Exceeding the headroom limit is not a concern for any inverting gain on any supply voltage, as long as the reference voltage at the amplifier's positive input lies within the amplifier's input common-mode range. The input stage is the headroom limit for signals when the amplifier is used in a gain of 1 for signals approaching the positive rail. Figure 36 shows a typical offset voltage vs. the input common-mode voltage for the ADA4851-1 amplifier on a 5 V supply. Accurate dc performance is maintained from approximately 200 mV below the minus supply to within 2 V of the positive supply. For high speed signals, however, there are other considerations. Figure 37 shows -3 dB bandwidth vs. dc input voltage for a unity-gain follower. As the common-mode voltage approaches the positive supply, the amplifier responds well, but the bandwidth begins to drop at 2 V within +VS.
Figure 36. VOS vs. Common-Mode Voltage, VS = 5 V
2 1 0 VCM = 3.1V -1 G = +1 RL = 1k VS = 5V
VCM = 3.0V
GAIN (dB)
-2 -3 -4 -5 -6 0.1
VCM = 3.2V VCM = 3.3V
1
10 FREQUENCY (MHz)
100
1000
Figure 37. Unity-Gain Follower Bandwidth vs. Input Common-Mode
This can manifest itself in increased distortion or settling time. Higher frequency signals require more headroom than the lower frequencies to maintain distortion performance. Figure 38 illustrates how the rising edge settling time for the amplifier configured as a unity-gain follower stretches out as the top of a 1 V step input approaches and exceeds the specified input common-mode voltage limit. For signals approaching the minus supply and inverting gain and high positive gain configurations, the headroom limit is the output stage. The ADA4851-1 amplifiers use a common emitter output stage. This output stage maximizes the available output range, limited by the saturation voltage of the output transistors. The saturation voltage increases with the drive current the output transistor is required to supply, due to the output transistors' collector resistance.
Rev. 0 | Page 13 of 16
05143-050
05143-046
ADA4851-1
3.6 3.4 3.2 G = +1 RL = 1k VS = 5V
3.50 G = +1 RL = 1k VS = 5V VSTEP = 2.25V TO 3.25V VSTEP = 2.25V TO 3.5V, 4V, AND 5V
3.25
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
3.0 2.8 2.6 2.4 2.2 2.0 1.8 0 10 20 30 40 50 TIME (ns) 60 70 80 90 100 VSTEP = 2V TO 3V VSTEP = 2.1V TO 3.1V VSTEP = 2.2V TO 3.2V VSTEP = 2.3V TO 3.3V VSTEP = 2.4V TO 3.4V
3.00
2.75
2.50
2.25
05143-052
0
100
200
300
400
500
600
700
800
900
1k
TIME (ns)
Figure 38. Output Rising Edge for 1 V Step at Input Headroom Limits
Figure 39. Pulse Response of G = 1 Follower, Input Step Overloading the Input Stage
As the saturation point of the output stage is approached, the output signal shows increasing amounts of compression and clipping. As in the input headroom case, higher frequency signals require a bit more headroom than the lower frequency signals. Figure 14 illustrates this point by plotting the typical distortion vs. the output amplitude.
Output
Output overload recovery is typically within 35 ns after the amplifier's input is brought to a nonoverloading value. Figure 40 shows output recovery transients for the amplifier recovering from a saturated output from the top and bottom supplies to a point at midsupply.
7 6 VOUT = 5V TO 2.5V G = -1 RL = 1k VS = 5V
OVERLOAD BEHAVIOR AND RECOVERY
Input
The specified input common-mode voltage of the ADA4851-1 is 200 mV below the negative supply to within 2 V of the positive supply. Exceeding the top limit results in lower bandwidth and increased settling time, as seen in Figure 37 and Figure 38. Pushing the input voltage of a unity-gain follower less than 2 V from the positive supply leads to the behavior shown in Figure 39--an increasing amount of output error as well as much increased settling time. The recovery time from input voltages 2 V or closer to the positive supply is approximately 85 ns, which is limited by the settling artifacts caused by transistors in the input stage coming out of saturation. The ADA4851-1 does not exhibit phase reversal, even for input voltages beyond the voltage supply rails. Going more than 0.6 V beyond the power supplies turns on protection diodes at the input stage, which greatly increase the device's current draw.
INPUT AND OUTPUT VOLTAGE (V)
5 4 3 2 1 0 -1 -2 0 10 20 30 40 50 TIME (ns) 60 70 80 90 100 INPUT VOLTAGE EDGES VOUT = 0V TO 2.5V
Figure 40. Overload Recovery
Rev. 0 | Page 14 of 16
05143-053
05143-051
2.00
ADA4851-1 OUTLINE DIMENSIONS
2.90 BSC
6
5
4
1.60 BSC
1 2 3
2.80 BSC
PIN 1 INDICATOR 0.95 BSC 1.30 1.15 0.90 1.90 BSC
1.45 MAX
0.22 0.08 10 4 0 0.60 0.45 0.30
0.15 MAX
0.50 0.30
SEATING PLANE
COMPLIANT TO JEDEC STANDARDS MO-178AB
Figure 41. 6-Lead Small Outline Transistor Package [SOT-23] (RJ-6) Dimensions shown in millimeters
ORDERING GUIDE
Model ADA4851-1YRJZ-R21 ADA4851-1YRJZ-RL1 ADA4851-1YRJZ-RL71 Temperature Range -40C to +125C -40C to +125C -40C to +125C Package Description 6-Lead Small Outline Transistor Package (SOT-23) 6-Lead Small Outline Transistor Package (SOT-23) 6-Lead Small Outline Transistor Package (SOT-23) Package Outline RJ-6 RJ-6 RJ-6 Branding HHB HHB HHB
1
Z = Pb-free part.
Rev. 0 | Page 15 of 16
ADA4851-1 NOTES
(c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05143-0-10/04(0)
Rev. 0 | Page 16 of 16
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