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19-1525; Rev 0; 9/99
Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70 MAX4490/MAX4491/MAX4492
General Description
The MAX4490/MAX4491/MAX4492 single/dual/quad, low-cost CMOS op amps feature Rail-to-Rail(R) input and output capability from either a single +2.7V to +5.5V supply or dual 1.35V to 2.75V supplies. These amplifiers exhibit a high-performance slew rate of 10V/s and a gain-bandwidth product of 10MHz. They can drive 2k resistive loads to within 55mV of either supply rail and remain unity-gain stable with capacitive loads up to 200pF. The MAX4490 is offered in the ultra-small, 5-pin SC70 package, which is 50% smaller than the standard 5-pin SOT23 package. Specifications for all parts are guaranteed over the automotive (-40C to +125C) temperature range. o 10V/s Slew Rate o Rail-to-Rail Input Common-Mode Voltage Range o Rail-to-Rail Output Voltage Swing o 10MHz Gain-Bandwidth Product o Unity-Gain Stable with Capacitive Loads Up to 200pF o 50pA Input Bias Current o Ultra-Small, 5-Pin SC70 Package (MAX4490)
Features
o +2.7V to +5.5V Single-Supply Operation
Applications
Battery-Powered Instruments Portable Equipment Audio Signal Conditioning Low-Power/Low-Voltage Applications Sensor Amplifiers RF Power Amplifier Control High-Side/Low-Side Current Sensors
PART
Ordering Information
TEMP. RANGE PINPACKAGE 5 SC70-5 5 SOT23-5 8 SOT23-8 14 SO 14 TSSOP TOP MARK AAB ADKQ -- -- --
MAX4490AXK-T -40C to +125C MAX4490AUK-T MAX4491AKA* MAX4492ASD* MAX4492AUD* -40C to +125C -40C to +125C -40C to +125C -40C to +125C
*Future product--contact factory for availability.
Pin Configurations/Functional Diagrams
TOP VIEW
MAX4490
IN+ 1 5 VDD
OUTA 1 INA2 3 -+ +-
14 OUTD 13 IND12 IND+
MAX4491
OUTA INAINA+ VSS 1 2 3 4 8 +7 6 5 VDD OUTB INBINB+
INA+
VDD 4 +VSS 2 -+ INB+ 5
MAX4492
-+ +-
11 VSS 10 INC+ 9 8 INCOUTC
INB- 6 OUTB 7
IN- 3
4
OUT
SOT23/SC70
SOT23
SO/TSSOP
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ Maxim Integrated Products 1
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70 MAX4490/MAX4491/MAX4492
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VDD to VSS)..................................................+6V All Other Pins ...................................(VDD + 0.3V) to (VSS - 0.3V) Output Short-Circuit Duration .............................................10sec Continuous Power Dissipation (TA = +70C) 5-Pin SC70 (derate 2.5mW/C above +70C) ............ 200mW 5-Pin SOT23 (derate 7.1mW/C above +70C).......... 571mW 14-Pin TSSOP (derate 8.3mW/C above +70C) ........ 667mW 8-Pin MAX (derate 4.1mW/C above +70C) ............ 330mW 8-Pin SO (derate 5.9mW/C above +70C)................. 471mW 14-Pin SO (derate 8.3mW/C above +70C)............... 667mW Operating Temperature Range ........................ -40C to +125C Junction Temperature ..................................................... +150C Storage Temperature Range ............................ -65C to +150C Lead Temperature (soldering, 10sec) ............................ +300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL = 100k connected to VDD/2, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Supply Voltage Range Supply Current (per amplifier) Input Offset Voltage Input Bias Current Input Offset Current Input Resistance Input Common-Mode Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio Large-Signal Voltage Gain Output Voltage Swing High Output Voltage Swing Low Output Short-Circuit Current Gain-Bandwidth Product Input Capacitance Phase Margin Gain Margin Slew Rate Voltage Noise Density Current Noise Density Capacitive Load Drive SR en in SYMBOL VDD IS VOS IB IOS RIN VCM CMRR PSRR AV VOH VOL IOUT(SC) GBWP CIN CL = 10pF CL = 10pF Measured from 10% to 90% of 4Vp-p step = 10kHz = 10kHz AV(CL) = 1, no sustained oscillations Inferred from CMRR test VSS VCM VDD 2.7V VDD 5.5V (VSS + 0.25V) VOUT (VDD - 0.25V) Specified as VDD - VOH Specified as VOL - VSS Sourcing or sinking CL = 10pF RL = 100k RL = 2k RL = 100k RL = 2k RL = 100k RL = 2k 65 VSS 54 65 75 100 110 85 1.5 55 1.5 35 50 10 5 60 10 10 12 1 200 150 200 (Note 3) (Note 3) (Note 3) TA = +25C TA = TMIN to TMAX 0.05 0.05 1000 VDD (Note 2) CONDITIONS MIN 2.7 0.8 1.5 TYP MAX 5.5 2 10 16 2.5 2.5 UNITS V mA mV nA nA M V dB dB dB mV mV mA MHz pF deg dB V/s nV/Hz fAHz pF
Note 1: All units production tested at TA = +25C. Limits over temperature guaranteed by design. Note 2: Guaranteed by the Power-Supply Rejection Ratio (PSRR) test. Note 3: Input Offset Voltage, Input Bias Current, and Input Offset Current are all tested and guaranteed at both ends of the common-mode range.
2
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70
Typical Operating Characteristics
(VDD = +5V, VSS = 0V, VCM = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted.)
MAX4490/MAX4491/MAX4492
SUPPLY CURRENT PER AMPLIFIER vs. TEMPERATURE
MAX4490 toc 01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4490 toc02
INPUT OFFSET VOLTAGE vs. TEMPERATURE
-0.2 -0.4 OFFSET VOLTAGE (mV) -0.6 -0.8 -1.0 -1.2 -1.4 -1.6 -1.8 -2.0
MAX4490 toc03
850 800 SUPPLY CURRENT (A) 750 700 650 VDD = +2.7V 600 550 500 VDD = +5.0V
1000 900 800 SUPPLY CURRENT (A) 700 600 500 400 300 200 100 0
0
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
SUPPLY VOLTAGE (V)
OUTPUT SWING HIGH vs. TEMPERATURE
70 60 VDD - VOUT (mV) VOUT - VSS (mV) 50 40 30 20 10 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) VDD = +5.0V OR +2.7V RL = 100k VDD = +2.7V RL = 2k VDD = +5.0V RL = 2k
MAX4490 toc04
OUTPUT SWING LOW vs. TEMPERATURE
MAX4490 toc05
OP AMP GAIN AND PHASE vs. FREQUENCY
60 50 40 GAIN GAIN (dB) 30 20 PHASE 10 0 -10 -20 100 AV = +1000 CL = 10pF 1k 10k 100k 1M -45 -90 -135 -180 10M 45 0
MAX4490 toc06
80
80 70 60 50 40 30 20 10 0 VDD = +5.0V OR +2.7V RL = 100k VDD = +2.7V RL = 2k VDD = +5.0V RL = 2k
180 135 90 PHASE (DEGREES)
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
FREQUENCY (Hz)
GAIN AND PHASE vs. FREQUENCY (WITH CLOAD)
60 50 40 GAIN (dB) 30 20 10 0 -10 -20 100 1k 10k 100k 1M FREQUENCY (Hz) AV = +1000 CLOAD = 200pF PHASE GAIN
LARGE-SIGNAL GAIN vs. TEMPERATURE
MAX4490 toc08
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
-10 -20 -30 PSSR (dB) AV = +1
MAX4490 toc09
MAX4490 toc07
180 135 LARGE-SIGNAL GAIN (dB) 90 45 0 -45 -90 -135 PHASE (DEGREES)
130 VDD = 5.0V 120
0
110
-40 -50 -60 -70
100
90
-80 -90
-180 10M
80 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
-100 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70 MAX4490/MAX4491/MAX4492
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted.)
OUTPUT IMPEDANCE vs. FREQUENCY
MAX4490 toc10
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4490 toc11
LARGE-SIGNAL TRANSIENT RESPONSE (NONINVERTING)
MAX4490toc12
1k AV = +1 100 OUTPUT IMPEDANCE ()
0.040 0.035 0.030 THD + NOISE (%) AV = +1V/V 2Vp-p SIGNAL 500kHz LOWPASS FILTER RL = 2k 0.025 0.020 0.015 0.010 0.005 RL = 10k
IN 2V/div
10
1
0.1 0.01 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
OUT 2V/div
0 10 100 1k 10k 100k 40s/div AV = +1 FREQUENCY (Hz)
LARGE-SIGNAL TRANSIENT RESPONSE (INVERTING)
MAX4490toc13
SMALL-SIGNAL TRANSIENT RESPONSE (NONINVERTING)
MAX4490toc14
SMALL-SIGNAL TRANSIENT RESPONSE (INVERTING)
MAX4490toc15
IN 2V/div
IN 50mV/div
IN 50mV/div
OUT 2V/div 40s/div
OUT 50mV/div 40s/div AV = +1
OUT 50mV/div
AV = -1
40s/div AV = -1
POWER-UP TRANSIENT RESPONSE
MAX4490toc16
SLEW RATE vs. SUPPLY VOLTAGE
MAX4490 toc17
12 10 SLEW RATE (V/S) 8 6 4 2 0 AV = +1 4Vp-p STEP
VDD 2V/div
OUT 1V/div 4s/div VIN CONNECTED TO VDD/2
2.5 RL = 2k
3.0
3.5
4.0
4.5
5.0
5.5
AV = +1
SUPPLY VOLTAGE (V)
4
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70
Pin Description
PIN NAME MAX4490 1 2 3 4 5 - - - - - - - - - MAX4491 - 4 - - 8 3 2 1 5 6 7 - - - MAX4492 - 11 - - 4 3 2 1 5 6 7 10, 12 9, 13 8, 14 IN+ VSS INOUT VDD INA+ INAOUTA INB+ INBOUTB INC+, IND+ INC-, INDOUTC, OUTD Noninverting Input Negative Supply Input. Connect to ground for single-supply operation. Inverting Input Amplifier Output Positive Supply Input Noninverting Input to Amplifier A Inverting Input to Amplifier A Amplifier A Output Noninverting Input to Amplifier B Inverting Input to Amplifier B Amplifier B Output Noninverting Inputs to Amplifiers C and D Inverting Inputs to Amplifiers C and D Amplifiers C and D Outputs FUNCTION
MAX4490/MAX4491/MAX4492
Detailed Description
Rail-to-Rail Input Stage
The MAX4490/MAX4491/MAX4492 CMOS operational amplifiers have parallel-connected N- and P-channel differential input stages that combine to accept a common-mode range extending to both supply rails. The Nchannel stage is active for common-mode input voltages typically greater than (VSS + 1.2V), and the Pchannel stage is active for common-mode input voltages typically less than (VDD - 1.2V).
when the load is connected to VDD/2. Consistent resistive drive capability is (2.5 - 0.1) / 2.2 = 1.1k. For the same application, resistive drive capability is 2.2k when the load is connected to VDD or VSS.
Applications Information
Power-Supply Considerations
The MAX4490/MAX4491/MAX4492 operate from a single +2.7V to +5.5V supply or from dual 1.35V to 2.25V supplies with typically 800A supply current per amplifier. A high power-supply rejection ratio of 100dB allows for extended operation from a decaying battery voltage, thereby simplifying designs for portable applications. For single-supply operation, bypass the power supply with a 0.1F ceramic capacitor placed close to the VDD pin. For dual-supply operation, bypass each supply to ground.
Rail-to-Rail Output Stage
The MAX4490/MAX4491/MAX4492 CMOS operational amplifiers feature class-AB push/pull output stages that can drive a 100k load to within 1.5mV of either supply rail. Short-circuit output current is typically 50mA. Figures 1a and 1b show the typical temperature dependence of output source and sink currents, respectively, for three fixed values of (VDD - VOH) and (VOL - VSS). For example, at VDD = +5.0V, the load currents that maintain (VDD - VOH) = 100mV and (VOL - VSS) = 100mV at TA = +25C are 2.2mA and 3.3mA, respectively,
Input Capacitance
One consequence of the parallel-connected differential input stages for rail-to-rail operation is a relatively large input capacitance CIN (typically 5pF). This introduces a
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5
Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70 MAX4490/MAX4491/MAX4492
pole at frequency (2RCIN)-1, where R is the parallel combination of the gain-setting resistors for the inverting or noninverting amplifier configuration (Figure 2). If the pole frequency is less than or comparable to the unity-gain bandwidth (10MHz), the phase margin will be reduced, and the amplifier will exhibit degraded AC performance through either ringing in the step response or sustained oscillations. The pole frequency is 10MHz when R = 3.2k. To maximize stability, R <3k is recommended. Applications that require rail-to-rail operation with minimal loading (for small VDD - VOH and VOL - VSS) will typically require R values >3k. To improve step response under these conditions, connect a small capacitor Cf between the inverting input and output. Choose Cf as follows: Cf = 5(R / Rf) [pf] where Rf is the feedback resistor and R is the gain-setting resistor (Figure 2). Figure 3 shows the step response for a noninverting amplifier subject to R = 4k with and without the Cf feedback capacitor.
6 OUTPUT SOURCE CURRENT (mA) 5 4 3 VDD = +2.7V
INVERTING VDD - VOH = 200mV VDD - VOH = 100mV VDD - VOH = 50mV VDD = +5.0V VIN R VOUT Cf
Rf
2 1 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
MAX4490
R = R || Rf RfCf = RCIN
Figure 1a. Output Source Current vs. Temperature
NONINVERTING VIN
9 8 OUTPUT SINK CURRENT (mA) 7 6 5 4 3 2 1 0 VDD = +2.7V
VOUT VDD - VOH = 200mV VDD - VOH = 100mV VDD - VOH = 50mV VDD = +5.0V
MAX4490
Rf Cf
R
R = R || Rf RfCf = RCIN
-40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C)
Figure 2. Inverting and Noninverting Amplifier with Feedback Compensation
Figure 1b. Output Sink Current vs. Temperature
6
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70
Driving Capacitive Loads
In conjunction with op amp output resistance, capacitive loads introduce a pole frequency that can reduce phase margin and lead to unstable operation. The MAX4490/MAX4491/MAX4492 drive capacitive loads up to 200pF without significant degradation of step response and slew rate (Figure 4). Figure 5 shows regions of stable and marginally stable (step overshoot <10%) operation for different combinations of capacitive and resistive loads. Improve stability for large capacitive loads by adding an isolation resistor (typically 10) in series with the output (Figure 6). Note that the isolation resistor forms a voltage divider with potential for gain error.
MAX4490/MAX4491/MAX4492
Chip Information
TRANSISTOR COUNT: 60 SUBSTRATE CONNECTED TO VSS.
WITHOUT FEEDBACK COMPENSATION AV = -1 3a) RL = 4k Cf = 0 AV = +1 4a)
WITHOUT CAPACITIVE LOADING RL = 100k CL = 0
WITH FEEDBACK COMPENSATION AV = -1 3b) RL = 4k Cf = 5pF AV = +1 4b)
WITH CAPACITIVE LOADING RL = 100k CL =200pF
Figure 3. Step Response With and Without Feedback Compensation
Figure 4. Step Response With and Without Capacitive Loading
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Low-Cost, High-Slew-Rate, Rail-to-Rail I/O Op Amps in SC70 MAX4490/MAX4491/MAX4492
6000 5000 CAPACITIVE LOAD (pF) VIN 4000 3000 UNSTABLE 2000 1000 STABLE 0 100 1k 10k 100k RESISTIVE LOAD ()
MAX4490
RS
VOUT
CLOAD
Figure 5. Capacitive Load Stability
Figure 6. Isolation Resistor for Large Capacitive Loads
Package Information
SC70, 5L.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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