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19-2137; Rev 1; 10/02
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
General Description
The MAX4475-MAX4478/MAX4488/MAX4489 wideband, low-noise, low-distortion operational amplifiers offer Rail-to-Rail(R) outputs and single-supply operation down to 2.7V. They draw 2.2mA of quiescent supply current per amplifier while featuring ultra-low distortion (0.0002% THD + N), as well as low input voltage-noise density (4.5nV/Hz) and low input current-noise density (0.5fA/Hz). These features make the devices an ideal choice for applications that require low distortion and/or low noise. For power conservation, the MAX4475/MAX4488 offer a low-power shutdown mode that reduces supply current to 0.01A and places the amplifiers' outputs into a highimpedance state. These amplifiers have outputs which swing rail-to-rail and their input common-mode voltage range includes ground. The MAX4475-MAX4478 are unity-gain stable with a gain-bandwidth product of 10MHz. The MAX4488/MAX4489 are internally compensated for gains of +5V/V or greater with a gain-bandwidth product of 42MHz. The single MAX4475/ MAX4476/MAX4488 are available in space-saving, 6-pin SOT23 packages.
Features
o Low Input Voltage-Noise Density: 4.5nV/Hz o Low Input Current-Noise Density: 0.5fA/Hz o Low Distortion: 0.0002% THD + N (1k load) o Single-Supply Operation from +2.7V to +5.5V o Input Common-Mode Voltage Range Includes Ground o Rail-to-Rail Output Swings with a 1k Load o 10MHz GBW Product, Unity-Gain Stable (MAX4475-MAX4478) o 42MHz GBW Product, Stable with AV +5V/V (MAX4488/MAX4489) o Excellent DC Characteristics VOS = 70V IBIAS = 1pA Large-Signal Voltage Gain = 120dB o Low-Power Shutdown Mode: Reduces Supply Current to 0.01A Places Output in High-Impedance State o Available in Space-Saving SOT23, MAX, and TSSOP Packages
MAX4475-MAX4478/MAX4488/MAX4489
Applications
ADC Buffers DAC Output Amplifiers Low-Noise Microphone/Preamplifiers Digital Scales Strain Gauges/Sensor Amplifiers Medical Instrumentation
Ordering Information
PART MAX4475AUT-T MAX4475AUA MAX4475ASA MAX4476AUT-T MAX4477AUA TEMP RANGE -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C PINPACKAGE 6 SOT23-6 8 MAX 8 SO 6 SOT23-6 8 MAX TOP MARK AAZV -- -- AAZX --
Typical Operating Characteristic
INPUT VOLTAGE-NOISE DENSITY vs. FREQUENCY
VIN EQUIVALENT INPUT NOISE VOLTAGE (nV/Hz)
MAX4475 toc20
25
Ordering Information continued at end of data sheet. Pin Configurations and Typical Operating Circuit appear at end of data sheet.
20
Selector Guide
15 10
PART MAX4475 MAX4476 MAX4477 MAX4478 MAX4488 MAX4489
GAIN BW (MHz) 10 10 10 10 42 42
STABLE GAIN (V/V) 1 1 1 1 5 5
NO. OF AMPS 1 1 2 4 1 2
SHDN Yes -- -- -- Yes --
5
0 10 100 1k FREQUENCY (Hz) 10k 100k
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
________________________________________________________________ Maxim Integrated Products
1
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
ABSOLUTE MAXIMUM RATINGS
Power-Supply Voltage (VDD to VSS) ......................-0.3V to +6.0V Analog Input Voltage (IN_+, IN_-)....(VSS - 0.3V) to (VDD + 0.3V) SHDN Input Voltage....................................(VSS - 0.3V) to +6.0V Output Short-Circuit Duration to Either Supply ..........Continuous Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 9.1mW/C above +70C)...........727mW 8-Pin MAX (derate 4.5mW/C above +70C) ............362mW 8-Pin SO (derate 5.88mW/C above +70C)...............471mW 14-Pin SO (derate 8.33mW/C above +70C)..............667mW 14-Pin TSSOP (derate 9.1mW/C above +70C) .........727mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+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.
DC ELECTRICAL CHARACTERISTICS
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER Supply Voltage Range Quiescent Supply Current Per Amplifier Input Offset Voltage Input Offset Voltage Tempco Input Bias Current Input Offset Current Differential Input Resistance Input Common-Mode Voltage Range SYMBOL VDD ID (Note 3) Normal mode VDD = 3V VDD = 5V CONDITIONS MIN 2.7 2.2 2.5 0.01 70 0.3 (Note 4) (Note 4) Guaranteed by CMRR Test (VSS - 0.2V) VCM (VDD 1.6V) (VSS - 0.1V) VCM (VDD 1.7V) VDD = 2.7 to 5.5V RL = 10k to VDD/2; VOUT = 100mV to (VDD - 125mV) Large-Signal Voltage Gain AVOL RL = 1k to VDD/2; VOUT = 200mV to (VDD - 250mV) RL = 500 to VDD/2; VOUT = 350mV to (VDD - 500mV) TA = +25C TA = -40C to +125C TA = +25C -0.2 -0.1 90 115 dB TA = -40C to +125C 90 90 90 85 85 120 120 110 110 dB dB 1 1 1000 VDD - 1.6 VDD - 1.7 4.4 1.0 350 750 6 150 150 TYP MAX 5.5 UNITS V mA A V V/C pA pA G V
Shutdown mode (SHDN = VSS) (Note 2) VOS TCVOS IB IOS RIN VCM TA = +25C TA = -40C to +125C
Common-Mode Rejection Ratio
CMRR
Power-Supply Rejection Ratio
PSRR
2
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
DC ELECTRICAL CHARACTERISTICS (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = -40C to +125C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER SYMBOL CONDITIONS |VIN+ - VIN-| 10mV, RL = 10k to VDD/2 Output Voltage Swing VOUT |VIN+ - VIN-| 10mV, RL = 1k to VDD/2 |VIN+ - VIN-| 10mV, RL = 500 to VDD/2 Output Short-Circuit Current Output Leakage Current SHDN Logic Low SHDN Logic High SHDN Input Current Input Capacitance CIN ISC ILEAK VIL VIH SHDN = VSS to VDD 0.7 x VDD 0.01 10 1 Shutdown mode (SHDN = VSS), VOUT = VSS to VDD VDD - VOH VOL - VSS VDD - VOH VOL - VSS VDD - VOH VOL - VSS MIN TYP 10 10 80 50 100 80 48 0.001 1.0 0.3 x VDD MAX 45 40 200 150 300 250 mA A V V A pF mV UNITS
MAX4475-MAX4478/MAX4488/MAX4489
AC ELECTRICAL CHARACTERISTICS
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = +25C.)
PARAMETER Gain-Bandwidth Product Slew Rate Full-Power Bandwidth (Note 5) Peak-to-Peak Input Noise Voltage en(P-P) SYMBOL GBWP SR CONDITIONS MAX4475-MAX4478 MAX4488/MAX4489 MAX4475-MAX4478 MAX4488/MAX4489 MAX4475-MAX4478 MAX4488/MAX4489 f = 0.1Hz to 10Hz f = 10Hz Input Voltage-Noise Density Input Current-Noise Density en in f = 1kHz f = 30kHz f = 1kHz VOUT = 2VP-P, AV = +1V/V (MAX4475-MAX4478), RL = 10k to GND VOUT = 2VP-P, AV = +1V/V (MAX4475-MAX4478), RL = 1k to GND VOUT = 2VP-P, AV = +5V/V (MAX4488/MAX4489), RL = 10k to GND f = 1kHz f = 20kHz f = 1kHz f = 20kHz f = 1kHz f = 20kHz AV = +1V/V AV = +5V/V AV = +1V/V AV = +5V/V AV = +1V/V AV = +5V/V MIN TYP 10 42 3 10 0.4 1.25 260 21 4.5 3.5 0.5 0.0002 0.0007 0.0002 0.001 0.0004 0.0006 % fA/Hz nV/Hz MAX UNITS MHz V/s MHz nVP-P
Total Harmonic Distortion Plus Noise (Note 6)
THD + N
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3
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
AC ELECTRICAL CHARACTERISTICS (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = +25C.)
PARAMETER Total Harmonic Distortion Plus Noise (Note 6) Capacitive-Load Stability Gain Margin Phase Margin Settling Time Delay Time to Shutdown Enable Delay Time from Shutdown Power-Up Delay Time tSH tEN VOUT = 2.5V, VOUT settles to 0.1% VDD = 0 to 5V step, VOUT stable to 0.1% GM M MAX4475-MAX4478, AV = +1V/V MAX4488/MAX4489, AV = +5V/V To 0.01%, VOUT = 2V step SYMBOL CONDITIONS VOUT = 2VP-P, AV = +5V/V (MAX4488/MAX4489), RL = 1k to GND No sustained oscillations f = 1kHz f = 20kHz MIN TYP 0.0005 % 0.008 200 12 70 80 2 1.5 10 13 pF dB degrees s s s s MAX UNITS
THD + N
Note 1: Note 2: Note 3: Note 4: Note 5:
All devices are 100% tested at TA = +25C. Limits over temperature are guaranteed by design. SHDN is available on the MAX4475/MAX4488 only. Guaranteed by the PSRR test. Guaranteed by design. Full-power bandwidth for unity-gain stable devices (MAX4475-MAX4478) is measured in a closed-loop gain of +2V/V to accommodate the input voltage range, VOUT = 4VP-P. Note 6: Lowpass-filter bandwidth is 22kHz for f = 1kHz and 80kHz for f = 20kHz. Noise floor of test equipment = 10nV/Hz.
Typical Operating Characteristics
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
INPUT OFFSET VOLTAGE DISTRIBUTION
MAX4475-8 toc1
OFFSET VOLTAGE vs. TEMPERATURE
MAX4475 toc02
INPUT OFFSET VOLTAGE vs. INPUT COMMON-MODE VOLTAGE
MAX4475 toc03
18 16 PERCENTAGE OF UNITS (%) 14 12 10 8 6 4 2 0 -50 -40 -30 -20 -10 0 10 20 30 40 50 VOS (V)
250 200 INPUT OFFSET VOLTAGE (V) 150 100 50 0 -50 -100 -150 -200 -250 -50
VCOM = 0V
50
INPUT OFFSET VOLTAGE (V)
40
30
20 VDD = 3V 10 0 VDD = 5V
-25
0
25
50
75
100
125
-0.5
0.5
1.5
2.5
3.5
4.5
TEMPERATURE (C)
INPUT COMMON-MODE VOLTAGE (V)
4
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. OUTPUT LOAD CURRENT
MAX4475 toc04
MAX4475-MAX4478/MAX4488/MAX4489
OUTPUT VOLTAGE SWING (VOH) vs. TEMPERATURE
MAX4475 toc05
OUTPUT VOLTAGE SWING (VOL) vs. TEMPERATURE
MAX4475 toc06
0.25 VDD = 3V OR 5V VDIFF = 10mV 0.20 OUTPUT VOLTAGE (V)
70 60 50
70 60 50 VOL (mV) 40 30 20 RL = 1k 10 0 RL = 10k -50 -25 0 25 50 75 100
0.15 VDD - VOH 0.10 VOL 0.05
VDD - VOH (mV)
40 30 20 10 RL = 1k
RL = 10k -50 -25 0 25 50 75 100 125
0 0 1 2 3 4 5 6 7 8 9 10 OUTPUT LOAD CURRENT (mA)
0 TEMPERATURE (C)
125
TEMPERATURE (C)
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
MAX4475 toc07
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
MAX4475 toc08
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
120 110 RL = 2k RL = 200k RL = 20k
MAX4475 toc09
130 120 110 100 AV (dB) RL = 2k RL = 20k RL = 200k
130 120 110 RL = 20k RL = 200k 100 AV (dB) 90 80 70
130
100 AV (dB) RL = 2k 90 80 70 VDD = 3V RL REFERENCED TO VDD 0 50 100 150 200 250 60 50 0 50 100 150 200 250 VOUT SWING FROM EITHER SUPPLY (mV) VOUT SWING FROM EITHER SUPPLY (mV) VDD = 5V RL REFERENCED TO GND
90 80 70 60 50 0 50 100 150 200 250 VOUT SWING FROM EITHER SUPPLY (mV) VDD = 3V RL REFERENCED TO GND
60 50
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
MAX4475 toc10
LARGE-SIGNAL VOLTAGE GAIN vs. TEMPERATURE
MAX4475 toc11
SUPPLY CURRENT vs. TEMPERATURE
PER AMPLIFIER 2.5 SUPPLY CURRENT (mA) 2.0 1.5 1.0 0.5
MAX4475 toc12
130 120 110 RL = 20k 100 AV (dB) 90 80 70 60 50 0 50 100 150 200 VDD = 5V RL REFERENCED TO VDD RL = 2k RL = 200k
140 130 120 110 AVOL (dB) 100 90 80 70 60 50 VOUT = 150mV TO 4.75V RL = 10k RL = 100k
3.0
0 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (C) TEMPERATURE (C)
250
VOUT SWING FROM EITHER SUPPLY (mV)
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX4475 toc13
SUPPLY CURRENT vs. OUTPUT VOLTAGE
MAX4475 toc14
INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE
15 INPUT OFFSET VOLTAGE (V) 10 5 0 -5 -10 -15 -20
MAX4475 toc15
3.0 PER AMPLIFIER 2.5 SUPPLY CURRENT (mA) 2.0 1.5 1.0 0.5 0 2.5 3.0 3.5 4.0 4.5 5.0
3.0 2.5 SUPPLY CURRENT (mA) 2.0 1.5 1.0 0.5 0 VDD = 5V
20
VDD = 3V
5.5
0
1
2
3
4
5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE (V)
SUPPLY VOLTAGE (V)
MAX4475-MAX4478 GAIN AND PHASE vs. FREQUENCY
60 50 40 30 GAIN (dB) 20 10 0 -10 -20 -30 -40 100 1k 10k 100k 1M 10M INPUT FREQUENCY (Hz) PHASE GAIN
MAX4475 toc16
MAX4488/MAX4489 GAIN AND PHASE vs. FREQUENCY
180 144 108 72 PHASE (degrees) GAIN (dB) 36 0 -36 -72 -108 -144 -180 100M 60 50 40 30 20 10 0 -10 -20 -30 -40 100 1k 10k 100k 1M 10M INPUT FREQUENCY (Hz) VDD = 3V OR 5V RL = 50k CL = 20pF AV = +1000V/V GAIN
MAX4475 toc17
VDD = 3V OR 5V RL = 50k CL = 20pF AV = +1000V/V
180 144 108 72 36 0 -36 -72 PHASE (degrees)
PHASE
-108 -144 -180 100M
MAX4475-MAX4478 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
0 VDD = 3V OR 5V -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 0.001 0.1
MAX4475 toc18
OUTPUT IMPEDANCE vs. FREQUENCY
MAX4475 toc19
1000
OUTPUT IMPEDANCE ()
100
PSRR (dB)
10 AV = +5 1 AV = +1 0.1 0.01
10
1000
100,000
1
10
100 FREQUENCY (Hz)
1k
10k
FREQUENCY (kHz)
6
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
INPUT VOLTAGE-NOISE DENSITY vs. FREQUENCY
VIN EQUIVALENT INPUT NOISE VOLTAGE (nV/Hz)
MAX4475 toc20
MAX4475-MAX4478/MAX4488/MAX4489
0.1Hz TO 10HzP-P NOISE
VDD = 3V OR 5V VP-P NOISE = 260nVP-P
AV = +1
20
1 THD + N (%)
15 200nV/div 10
0.1
0.01 fO = 20kHz, FILTER BW = 80kHz
5
0.001 fO = 3kHz, FILTER BW = 30kHz 0.0001 10 100 1k FREQUENCY (Hz) 10k 100k 1s/div 0 1 2 3 4 OUTPUT VOLTAGE (VP-P)
0
MAX4475 toc23
MAX4475 toc24
AV = +5
1 0.1 THD + N (%) 0.01 0.001 0.0001 0.00001 0 1 2 3 OUTPUT VOLTAGE (VP-P) VDD = 3V, fO = 3kHz FILTER BW = 30kHz VDD = +3V, fO = 20kHz FILTER BW = 80kHz
FILTER BW = 80kHz VOUT = 2VP-P AV = +1 RL = 1k
THD + N (%)
0.001
AV = +10, VDD = 3V AV = +10, VDD = 5V FILTER BW = 22kHz RL = 10k TO GND R1 = 5.6k, R2 = 53k VOUT = 2VP-P
THD + N (%)
RL TO VDD/2
RL TO GND RL TO VDD
0.0001 0 5k 10k FREQUENCY (Hz) 15k 20k
0.001 0 5k 10k
15k
20k
FREQUENCY (Hz)
0.1 THD + N (%)
FILTER BW = 80kHz RL = 10k TO GND R1 = 5.6k, R2 = 53k VOUT = 2.75VP-P
MAX4475 toc26
1
MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4475-MAX4478 LARGE-SIGNAL PULSE RESPONSE
MAX4475 toc27
MAX4475-MAX4478 SMALL-SIGNAL PULSE RESPONSE
MAX4475 toc28
MAX4475 toc25
10
MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE SWING
0.01
MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
0.01
MAX4475-MAX4478 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4475 toc22
25
MAX4475 toc21
10
MAX4475 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE SWING
0.6V 2.5V
0.01
20mV/div
0.001
AV = +5, VDD = 3V
0.5V
0.5V
AV = +5, VDD = 5V 0.0001 0 5k 10k FREQUENCY (Hz) 15k 20k 1s/div VDD = 3V, RL = 10k, CL = 100pF VIN = 2V 4s/div VDD = 3V, RL = 10k, CL = 100pF VIN = 100mV PULSE
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
MAX4488/MAX4489 LARGE-SIGNAL PULSE RESPONSE
MAX4475 toc29
MAX4488/MAX4489 SMALL-SIGNAL PULSE RESPONSE
MAX4475 toc30
MAX4477/MAX4478/MAX4489 CROSSTALK vs. FREQUENCY
MAX4475 toc31
-20 -30 CROSSTALK (dB) 1.6V VOUT 50mV/div VOUT 200mV/div 1.5V -40 -50 -60 -70 -80 -90
1s/div VDD = 3V, RL = 10k, CL = 50pF VIN = 20mV PULSE, AV = +5V/V
1s/div VDD = 3V, RL = 10k, CL = 50pF VIN = 20mV PULSE, AV = +5V/V
10
100
1000
10k 100k
1M
10M 100M
FREQUENCY (Hz)
Pin Description
PIN MAX4475/ MAX4488 SOT23 1 MAX4475/ MAX4488 SO/MAX 6 MAX4476 SOT23 1 MAX4477/ MAX4489 SO/MAX 1, 7 MAX4478 SO/TSSOP 1, 7, 8, 14 OUT, OUTA, OUTB, OUTC, OUTD VSS IN+, INA+, INB+, INC+, IND+ IN-, INA-, INB-, INC-, INDVDD Amplifier Output Negative Supply. Connect to ground for singlesupply operation Noninverting Amplifier Input Inverting Amplifier Input Positive Supply Shutdown Input. Connect to VDD for normal operation (amplifier(s) enabled). No Connection. Not internally connected. NAME FUNCTION
2
4
2
4
11
3
3
3
3, 5
3, 5, 10, 12
4 6
2 7
4 6
2, 6 8
2, 6, 9, 13 4
5
8
--
--
--
SHDN
--
1, 5
5
--
--
N.C.
8
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Detailed Description
The MAX4475-MAX4478/MAX4488/MAX4489 singlesupply operational amplifiers feature ultra-low noise and distortion. Their low distortion and low noise make them ideal for use as preamplifiers in wide dynamicrange applications, such as 16-bit analog-to-digital converters (see Typical Operating Circuit). Their highinput impedance and low noise are also useful for signal conditioning of high-impedance sources, such as piezoelectric transducers. These devices have true rail-to-rail ouput operation, drive loads as low as 1k while maintining DC accuracy, and can drive capactive loads up to 200pF without oscillation. The input common-mode voltage range extends from (VDD - 1.6V) to 200mV below the negative rail. The push-pull output stage maintains excellent DC characteristics, while delivering up to 5mA of current. The MAX4475-MAX4478 are unity-gain stable, while the MAX4488/MAX4489 have a higher slew rate and are stable for gains 5V/V. The MAX4475/MAX4488 feature a low-power shutdown mode, which reduces the supply current to 0.01A and disables the outputs.
CZ RF RG VOUT
MAX4475-MAX4478/MAX4488/MAX4489
VIN
Figure 1. Adding Feed-Forward Compensation
AV = +2 RF = RG = 100k 100mV 0V VIN 100mV/div
Low Distortion
Many factors can affect the noise and distortion that the device contributes to the input signal. The following guidelines offer valuable information on the impact of design choices on Total Harmonic Distortion (THD). Choosing proper feedback and gain resistor values for a particular application can be a very important factor in reducing THD. In general, the smaller the closedloop gain, the smaller the THD generated, especially when driving heavy resistive loads. The THD of the part normally increases at approximately 20dB per decade, as a function of frequency. Operating the device near or above the full-power bandwidth significantly degrades distortion. Referencing the load to either supply also improves the part's distortion performance, because only one of the MOSFETs of the push-pull output stage drives the output. Referencing the load to midsupply increases the part's distortion for a given load and feedback setting. (See the Total Harmonic Distortion vs. Frequency graph in the Typical Operating Characteristics.) For gains 5V/V, the decompensated devices MAX4488/MAX4489 deliver the best distortion performance, since they have a higher slew rate and provide a higher amount of loop gain for a given closed-loop gain setting. Capacitive loads below 100pF do not significantly affect distortion results. Distortion performance is relatively constant over supply voltages.
VOUT 100mV/div
2s/div
Figure 2a. Pulse Response with No Feed-Forward Compensation
AV = +2 RF = RG = 100k VIN 100mV/div
VOUT 100mV/div
2s/div
Figure 2b. Pulse Response with 10pF Feed-Forward Compensation
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
Low Noise
The amplifier's input-referred noise-voltage density is dominated by flicker noise at lower frequencies, and by thermal noise at higher frequencies. Because the thermal noise contribution is affected by the parallel combination of the feedback resistive network (R F || R G , Figure 1), these resistors should be reduced in cases where the system bandwidth is large and thermal noise is dominant. This noise contribution factor decreases, however, with increasing gain settings. For example, the input noise-voltage density of the circuit with R F = 100k, R G = 11k (A V = +5V/V) is e n = 14nV/Hz, e n can be reduced to 6nV/Hz by choosing RF = 10k, RG = 1.1k (AV = +5V/V), at the expense of greater current consumption and potentially higher distortion. For a gain of 100V/V with RF = 100k, RG = 1.1k, the en is still a low 6nV/Hz.
AV = +1 VDD = +5V RL = 10k
VIN 2V/div
0V
VOUT 2V/div
40s/div
Figure 3. Overdriven Input Showing No Phase Reversal
Using a Feed-Forward Compensation Capacitor, CZ
The amplifier's input capacitance is 10pF. If the resistance seen by the inverting input is large (feedback network), this can introduce a pole within the amplifier's bandwidth resulting in reduced phase margin. Compensate the reduced phase margin by introducing a feed-forward capacitor (CZ) between the inverting input and the output (Figure 1). This effectively cancels the pole from the inverting input of the amplifier. Choose the value of CZ as follows: CZ = 10 x (RF / RG) [pF] In the unity-gain stable MAX4475-MAX4478, the use of a proper CZ is most important for AV = +2V/V, and A V = -1V/V. In the decompensated MAX4488/ MAX4489, C Z is most important for A V = +10V/V. Figures 2a and 2b show transient response both with and without CZ. Using a slightly smaller CZ than suggested by the formula above achieves a higher bandwidth at the expense of reduced phase and gain margin. As a general guideline, consider using CZ for cases where RG || R F is greater than 20k (MAX4475-MAX4478) or greater than 5k (MAX4488/MAX4489).
20s/div 5V
VOUT 1V/div
0V
Figure 4. Rail-to-Rail Output Operation
Ground-Sensing and Rail-to-Rail Outputs
The common-mode input range of these devices extends below ground, and offers excellent commonmode rejection. These devices are guaranteed not to undergo phase reversal when the input is overdriven (Figure 3). Figure 4 showcases the true rail-to-rail output operation of the amplifier, configured with AV = 5V/V. The output swings to within 8mV of the supplies with a 10k load, making the devices ideal in low-supply voltage applications.
Applications Information
The MAX4475-MAX4478/MAX4488/MAX4489 combine good driving capability with ground-sensing input and rail-to-rail output operation. With their low distortion and low noise, they are ideal for use in ADC buffers, medical instrumentation systems and other noise-sensitive applications.
Power Supplies and Layout
The MAX4475-MAX4478/MAX4488/MAX4489 operate from a single +2.7V to +5.5V power supply or from dual supplies of 1.35V to 2.75V. For single-supply operation, bypass the power supply with a 0.1F ceramic
10
______________________________________________________________________________________
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Typical Application Circuit
+5V +2.5V +5V
MAX4475-MAX4478/MAX4488/MAX4489
CS SERIAL INTERFACE SCLK
VDD
7 REF OUT 3
U2 MAX4475AUA
6 0 to +2.5V OUTPUT
U1 MAX5541ESA
DIN DGND
AGND 2 4 8
SHDN
Typical Operating Circuit
5V 470pF 0.1F 3.09k 1% 7.87k 1% 220pF
1/2 MAX4477
220pF 3 8 1 3.83k 1% 13.7k 1% 220pF 2 4 6
1/2 MAX4477
5 7
7.15k 1% 220pF
10.0k 1%
10.0k 1% 10.0k 1% 15.0k 1%
capacitor placed close to the VDD pin. If operating from dual supplies, bypass each supply to ground. Good layout improves performance by decreasing the amount of stray capacitance and noise at the op amp's inputs and output. To decrease stray capacitance, minimize PC board trace lengths and resistor leads, and place external components close to the op amp's pins.
of error. In addition, the MAX4475 has excellent openloop gain and common-mode rejection, making this an excellent ouput buffer amplifier.
DC-Accurate Lowpass Filter
The MAX4475-MAX4478/MAX4488/MAX4489 offer a unique combination of low noise, wide bandwidth, and high gain, making them an excellent choice for active filters up to 1MHz. The Typical Operating Circuit shows the dual MAX4477 configured as a 5th order Chebyschev filter with a cutoff frequency of 100kHz. The circuit is implemented in the Sallen-Key topology, making this a DC-accurate filter.
Typical Application Circuit
The Typical Application Circuit shows the single MAX4475 configured as an output buffer for the MAX5541 16-bit DAC. Because the MAX5541 has an unbuffered voltage output, the input bias current of the op amp used must be less than 6nA to maintain 16-bit accuracy. The MAX4475 has an input bias current of only 150pA (max), virtually eliminating this as a source
______________________________________________________________________________________
11
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
Pin Configurations
TOP VIEW
N.C. 1 INA- 2 INA+ 3 8 7 SHDN VDD OUT N.C.
TOP VIEW
OUTA 1 INA- 2 INA+ 3 8 7 VDD OUTB INBINB+
MAX4475 MAX4488
6 5
MAX4477 MAX4489
6 5
VSS 4
VSS 4
SO/MAX TOP VIEW
14 OUTD 13 IND12 IND+ VSS 2 OUT 1 6 VDD
SO/MAX TOP VIEW
OUT 1 6 VDD
TOP VIEW
OUTA 1 INAINA+ 2 3
MAX4475 MAX4488
5
SHDN
VSS 2
MAX4476
5
N.C.
VDD 4 INB+ 5 INB- 6 OUTB 7
MAX4478
11 VSS 10 INC+ 9 8 INCOUTC IN+ 3 4 ININ+ 3 4 IN-
SOT23-6
SOT23-6
SO/TSSOP
Ordering Information (continued)
PART MAX4477AUA MAX4477ASA MAX4478AUD MAX4478ASD MAX4488AUT-T MAX4488AUA MAX4488ASA MAX4489AUA MAX4489ASA TEMP 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 PINPACKAGE 8 MAX 8 SO 14 TSSOP 14 SO 6 SOT23-6 8 MAX 8 SO 8 MAX 8 SO TOP MARK -- -- -- -- AAZW -- -- -- --
Chip Information
MAX4475/MAX4476 TRANSISTOR COUNT: 1095 MAX4477 TRANSISTOR COUNT: 2132 MAX4478 TRANSISTOR COUNT: 4244 MAX4488 TRANSISTOR COUNT: 1095 MAX4489 TRANSISTOR COUNT: 2132 PROCESS: BiCMOS
12
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SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX4475-MAX4478/MAX4488/MAX4489
8
4X S
8
INCHES DIM A A1 A2 b c D e E H MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1 0.60.1
E
H
1
0.60.1
1
D
L
S
BOTTOM VIEW
0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
e
c b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
J
1 1
______________________________________________________________________________________
8LUMAXD.EPS
13
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475-MAX4478/MAX4488/MAX4489
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
TSSOP4.40mm.EPS
e
10
4X S
10
INCHES MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 0.120 D1 0.116 0.118 0.114 D2 0.116 0.120 E1 E2 0.114 0.118 H 0.187 0.199 L 0.0157 0.0275 L1 0.037 REF b 0.007 0.0106 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S 0 6
MILLIMETERS MAX MIN 1.10 0.15 0.05 0.75 0.95 3.05 2.95 3.00 2.89 3.05 2.95 2.89 3.00 4.75 5.05 0.40 0.70 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0 6
H y 0.500.1 0.60.1
1
1
0.60.1
TOP VIEW
BOTTOM VIEW
D2 GAGE PLANE A2 A b D1 A1
E2 c E1 L1
L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0061
I
1 1
14
_______________________________________________________________________________________
10LUMAX.EPS
SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
SOICN .EPS
MAX4475-MAX4478/MAX4488/MAX4489
INCHES DIM A A1 B C e E H L MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050
MILLIMETERS MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D A e B A1 L C
0-8
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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