19-2137; Rev 0; 8/01 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps The MAX4475–MAX4478/MAX4488/MAX4489 wideband, low-noise, low-distortion operational amplifiers offer Rail-to-Rail® 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 0.01µA 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. Applications ADC Buffers DAC Output Amplifiers Low-Noise Microphone/Preamplifiers Digital Scales Strain Gauges/Sensor Amplifiers Medical Instrumentation Typical Operating Characteristic 25 MAX4475 toc20 VIN EQUIVALENT INPUT NOISE VOLTAGE (nV/√Hz) INPUT VOLTAGE NOISE DENSITY vs. FREQUENCY 20 Features ♦ Low Input Voltage Noise Density: 4.5nV/√Hz ♦ Low Input Current Noise Density: 0.5fA/√Hz ♦ Low Distortion: 0.0002% THD + N (1kΩ load) ♦ Single-Supply Operation from +2.7V to +5.5V ♦ Input Common-Mode Voltage Range Includes Ground ♦ Rail-to-Rail Output Swings with a 1kΩ Load ♦ 10MHz GBW Product, Unity-Gain Stable (MAX4475–MAX4478) ♦ 42MHz GBW Product, Stable with AV ≥ +5V/V (MAX4488/MAX4489) ♦ Excellent DC Characteristics VOS = 70µV IBIAS = 1pA Large-Signal Voltage Gain = 120dB ♦ Low-Power Shutdown Mode: Reduces Supply Current to 0.01µA Places Output in High-Impedance State ♦ Available in Space-Saving SOT23, µMAX, and TSSOP Packages Ordering Information TEMP. RANGE PINPACKAGE TOP MARK MAX4475AUT-T -40°C to +125°C 6 SOT23-6 AAZV MAX4475AUA -40°C to +125°C 8 µMAX — MAX4475ASA -40°C to +125°C 8 SO — MAX4476AUT-T -40°C to +125°C 6 SOT23-6 PART AAZX Ordering Information continued at end of data sheet. Pin Configurations and Typical Operating Circuit appear at end of data sheet. Selector Guide 15 10 PART GAIN BW (MHz) STABLE GAIN (V/V) NO. OF AMPS SHDN 5 MAX4475 10 1 1 Yes MAX4476 10 1 1 — MAX4477 10 1 2 — MAX4478 10 1 4 — 0 10 100 1k 10k 100k FREQUENCY (Hz) Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. MAX4488 42 5 1 Yes MAX4489 42 5 2 — ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX4475–MAX4478/MAX4488/MAX4489 General Description MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps 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 = +70°C) 6-Pin SOT23 (derate 9.1mW/°C above +70°C)...........727mW 8-Pin µMAX (derate 4.5mW/°C above +70°C) ............362mW 8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW 14-Pin SO (derate 8.33mW/°C above +70°C)..............667mW 14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C) (Notes 1, 2) PARAMETER Supply Voltage Range Quiescent Supply Current Per Amplifier Input Offset Voltage Input Offset Voltage Tempco Input Bias Current SYMBOL VDD ID VOS CONDITIONS (Note 3) 2.5 4.4 1.0 ±350 TA = -40°C to +125°C IOS (Note 4) Input Common-Mode Voltage Range VCM AVOL V ±70 RIN PSRR 5.5 0.01 Differential Input Resistance 2 VDD = 5V UNITS TA = +25°C Input Offset Current Large-Signal Voltage Gain 2.2 MAX Shutdown mode (SHDN = VSS) (Note 2) (Note 4) Power-Supply Rejection Ratio VDD = 3V ±750 TCVOS CMRR TYP 2.7 Normal mode IB Common-Mode Rejection Ratio MIN (VSS - 0.2V) ≤ VCM ≤ (VDD 1.6V) (VSS - 0.1V) ≤ VCM ≤ (VDD 1.7V) ±6 µV/°C ±150 pA ±1 ±150 pA GΩ -0.2 VDD - 1.6 TA = -40°C to +125°C -0.1 VDD - 1.7 90 µV ±1 TA = +25°C TA = +25°C µA ±0.3 1000 Guaranteed by CMRR Test mA V 115 dB TA = -40°C to +125°C 90 VDD = 2.7 to 5.5V 90 120 RL = 10kΩ to VDD/2; VOUT = 100mV to (VDD - 125mV) 90 120 RL = 1kΩ to VDD/2; VOUT = 200mV to (VDD - 250mV) 85 110 RL = 500Ω to VDD/2; VOUT = 350mV to (VDD - 500mV) 85 110 _______________________________________________________________________________________ dB dB SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS |VIN+ - VIN-| ≥ 10mV RL = 10kΩ to VDD/2 Output Voltage Swing Output Short-Circuit Current Output Leakage Current VOUT ILEAK VIL SHDN Logic High VIH SHDN Input Current TYP MAX VDD - VOH 10 45 VOL - VSS 10 40 |VIN+ - VIN-| ≥ 10mV, RL = 1kΩ to VDD/2 VDD - VOH 80 200 VOL - VSS 50 150 |VIN+ - VIN-| ≥ 10mV, RL = 500Ω to VDD/2 VDD - VOH 100 300 VOL - VSS 80 250 ISC SHDN Logic Low Input Capacitance MIN 48 Shutdown mode (SHDN = VSS), VOUT = VSS to VDD ±0.001 SHDN = VSS to VDD mV mA ±1.0 µA 0.3 x VDD V 0.7 x VDD V 0.01 CIN UNITS 1 10 µA pF AC ELECTRICAL CHARACTERISTICS (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = +25°C.) PARAMETER Gain-Bandwidth Product Slew Rate SYMBOL GBWP SR Full-Power Bandwidth (Note 5) Peak-to-Peak Input Noise Voltage Input Voltage Noise Density Input Current Noise Density Total Harmonic Distortion Plus Noise (Note 6) en(p-p) en in THD+N CONDITIONS MIN TYP MAX4475–MAX4478 AV = +1V/V 10 MAX4488/MAX4489 AV = +5V/V 42 MAX4475–MAX4478 AV = +1V/V 3 MAX4488/MAX4489 AV = +5V/V 10 MAX4475–MAX4478 AV = +1V/V 0.4 MAX4488/MAX4489 AV = +5V/V 1.25 f = 0.1Hz to 10Hz 260 f = 10Hz 21 f = 1kHz 4.5 f = 30kHz 3.5 f = 1kHz 0.5 VOUT = 2Vp-p, AV = +1V/V, (MAX4475–MAX4478) RL = 10kΩ to GND VOUT = 2Vp-p, AV = +1V/V, (MAX4475–MAX4478) RL = 1kΩ to GND VOUT = 2Vp-p, AV = +5V/V, MAX4488/MAX4489 RL = 10kΩ to GND f = 1kHz 0.0002 f = 20kHz 0.0007 f = 1kHz 0.0002 f = 20kHz 0.001 f = 1kHz 0.0004 f = 20kHz 0.0006 MAX UNITS MHz V/µs MHz nVp-p nV/√Hz fA/√Hz % _______________________________________________________________________________________ 3 MAX4475–MAX4478/MAX4488/MAX4489 DC ELECTRICAL CHARACTERISTICS (continued) AC ELECTRICAL CHARACTERISTICS (continued) (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD, TA = +25°C.) PARAMETER Total Harmonic Distortion Plus Noise (Note 6) SYMBOL THD+N Capacitive Load Stability CONDITIONS VOUT = 2Vp-p, AV = +5V/V, MAX4488/MAX4489 RL = 1kΩ to GND MIN GM Phase Margin ΦM Settling Time Delay Time to Shutdown tSH Enable Delay Time from Shutdown tEN Power-Up Delay Time TYP MAX f = 1kHz 0.0005 f = 20kHz 0.008 UNITS % No sustained oscillations Gain Margin 200 pF 12 dB MAX4475–MAX4478, AV = +1V/V 70 MAX4488/MAX4489, AV = +5V/V 80 To 0.01%, VOUT = 2V step 2 µs 1.5 µs VOUT = 2.5V, VOUT settles to 0.1% 10 µs VDD = 0 to 5V step, VOUT stable to 0.1% 13 µs degrees All devices are 100% tested at TA = +25°C. 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. Note 1: Note 2: Note 3: Note 4: Note 5: Typical Operating Characteristics (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/√Hz for all distortion measurements, TA = +25°C, unless otherwise noted.) 12 10 8 6 4 2 150 100 50 0 -50 -100 -150 50 40 30 20 VDD = 3V 10 VDD = 5V -200 0 0 -250 -50 -40 -30 -20 -10 0 10 20 30 40 50 VOS (µV) 4 VCOM = 0 200 INPUT OFFSET VOLTAGE (µV) 14 250 MAX4475 toc02 16 INPUT OFFSET VOLTAGE (µV) MAX4475-8 toc1 18 INPUT OFFSET VOLTAGE vs. INPUT COMMON-MODE VOLTAGE OFFSET VOLTAGE vs. TEMPERATURE MAX4475 toc03 INPUT OFFSET VOLTAGE DISTRIBUTION PERCENTAGE OF UNITS (%) MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 -0.5 0.5 1.5 2.5 3.5 INPUT COMMON-MODE VOLTAGE (V) _______________________________________________________________________________________ 4.5 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps OUTPUT VOLTAGE vs. OUTPUT LOAD CURRENT 0.20 70 60 60 50 VDD - VOH 0.10 VOL VOL (mV) VDD - VOH (mV) 50 0.15 40 30 RL = 1kΩ 20 30 RL = 1kΩ 0 10 RL = 10kΩ 2 3 4 5 6 7 8 9 10 -50 0 25 50 75 100 -50 125 50 75 100 LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING MAX4475 toc07 130 120 120 80 90 RL = 2kΩ 80 70 70 VDD = 3V RL REFERENCED TO VDD 60 50 50 100 150 200 250 50 0 50 100 150 200 VOUT SWING FROM EITHER SUPPLY (mV) VOUT SWING FROM EITHER SUPPLY (mV) LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING LARGE-SIGNAL VOLTAGE GAIN vs. TEMPERATURE 140 MAX4475 toc10 RL = 200kΩ 130 120 110 RL = 20kΩ RL = 2kΩ 90 80 RL = 10kΩ 100 90 70 VDD = 5V RL REFERENCED TO VDD 60 50 60 100 150 200 VOUT SWING FROM EITHER SUPPLY (mV) 250 100 150 200 250 3.0 PER AMPLIFIER 2.5 2.0 1.5 1.0 0.5 VOUT = 150mV TO 4.75V 0 50 50 50 SUPPLY CURRENT vs. TEMPERATURE 80 70 0 VOUT SWING FROM EITHER SUPPLY (mV) 110 AVOL (dB) 100 RL = 100kΩ 250 SUPPLY CURRENT (mA) 130 VDD = 5V RL REFERENCED TO GND 60 MAX4475 toc11 50 90 80 70 VDD = 3V RL REFERENCED TO GND RL = 200kΩ RL = 20kΩ 100 AV (dB) AV (dB) 100 60 RL = 2kΩ 110 RL = 20kΩ RL = 200kΩ 90 125 130 110 RL = 20kΩ RL = 200kΩ 100 0 25 TEMPERATURE (°C) RL = 2kΩ 120 0 TEMPERATURE (°C) 120 0 -25 OUTPUT LOAD CURRENT (mA) 130 110 -25 MAX4475 toc12 1 MAX4475 toc08 0 RL = 10kΩ 0 0 MAX4475 toc09 10 AV (dB) 40 20 0.05 AV (dB) MAX4475 toc06 VDD = 3V OR 5V VDIFF = ±10mV MAX4475 toc05 70 MAX4475 toc04 0.25 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE SWING (VOL) vs. TEMPERATURE OUTPUT VOLTAGE SWING (VOH) vs. TEMPERATURE -50 -25 0 25 50 75 TEMPERATURE (°C) 100 125 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX4475–MAX4478/MAX4488/MAX4489 Typical Operating Characteristics (continued) (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/√Hz for all distortion measurements, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/√Hz for all distortion measurements, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.5 1.0 0.5 2.0 VDD = 3V 1.5 1.0 0.5 0 3.0 3.5 4.0 4.5 5.0 5.5 1 2 3 4 GAIN 40 GAIN (dB) 30 3.0 50 108 40 108 72 30 72 20 36 10 0 0 -36 144 0 -36 -72 -108 -20 -30 -144 -30 -40 -180 100M -40 -10 -72 VDD = 3V OR 5V RL = 50kΩ CL = 20pF AV = +1000V/V 100 1k 10k -108 PHASE -144 100k 1M 10M -180 100M INPUT FREQUENCY (Hz) MAX4475–MAX4478 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY OUTPUT IMPEDANCE vs. FREQUENCY OUTPUT IMPEDANCE (Ω) MAX4475 toc19 MAX4475 toc18 1000 100 10 AV = +5 1 AV = +1 0.1 0.01 10 FREQUENCY (kHz) 1000 4.5 100,000 180 0 -20 10M GAIN 10 -10 PHASE MAX4475 toc17 144 36 1M 4.0 60 20 100k 3.5 SUPPLY VOLTAGE (V) INPUT FREQUENCY (Hz) PSRR (dB) 2.5 180 GAIN (dB) VDD = 3V OR 5V RL = 50kΩ CL = 20pF AV = +1000V/V 0 VDD = 3V OR 5V -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 0.001 0.1 -10 MAX4488/MAX4489 GAIN AND PHASE vs. FREQUENCY PHASE (degrees) 60 10k -5 OUTPUT VOLTAGE (V) MAX4475 toc16 1k 0 5 MAX4475–MAX4478 GAIN AND PHASE vs. FREQUENCY 100 5 -20 0 SUPPLY VOLTAGE (V) 50 10 -15 0 2.5 6 15 1 10 100 1k 10k FREQUENCY (Hz) _______________________________________________________________________________________ PHASE (degrees) 2.0 20 INPUT OFFSET VOLTAGE (µV) 2.5 SUPPLY CURRENT (mA) 2.5 VDD = 5V MAX4475 toc15 3.0 MAX4475 toc14 PER AMPLIFIER INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. OUTPUT VOLTAGE MAX4475 toc13 3.0 SUPPLY CURRENT (mA) MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps 5.0 5.5 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps MAX4475 toc21 10 AV = +1 1 THD + N (%) 20 VDD = 3V OR 5V Vp-p NOISE = 260nVp-p 15 200nV/div 10 0.1 0.01 fO = 20kHz, FILTER BW = 80kHz 5 0.001 0 0.0001 fO = 3kHz, FILTER BW = 30kHz 100 1k 10k 1s/div 100k 0 FREQUENCY (Hz) 0.01 MAX4475 toc24 1 MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 0.01 MAX4475 toc23 AV = +5 VDD = +3V, fO = 20kHz FILTER BW = 80kHz 0.001 0.001 AV = +10, VDD = 3V AV = +10, VDD = 5V FILTER BW = 22kHz RL = 10kΩ TO GND R1 = 5.6kΩ, R2 = 53kΩ VOUT = 2Vp-p VDD = 3V, fO = 3kHz FILTER BW = 30kHz 0.0001 1 2 0 3 5k 10k 15k MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX4475–MAX4478 LARGE-SIGNAL PULSE RESPONSE RL TO VDD 0 5k 10k 15k 20k MAX4475–MAX4478 SMALL-SIGNAL PULSE RESPONSE MAX4475 toc27 MAX4475 toc26 FILTER BW = 80kHz RL = 10kΩ TO GND R1 = 5.6kΩ, R2 = 53kΩ VOUT = 2.75Vp-p RL TO GND FREQUENCY (Hz) FREQUENCY (Hz) 1 FILTER BW = 80kHz VOUT = 2Vp-p AV = +1 RL = 1kΩ 0.001 20k OUTPUT VOLTAGE (Vp-p) 0.1 4 MAX4475–MAX4478 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY RL TO VDD/2 0.0001 0.00001 0 3 THD + N (%) THD + N (%) THD + N (%) 0.1 0.01 2 OUTPUT VOLTAGE (Vp-p) MAX4488/MAX4489 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE SWING 10 1 MAX4475 toc25 10 THD + N (%) MAX4475 toc22 MAX4475 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE SWING 0.1Hz TO 10Hzp-p NOISE 25 MAX4475 toc20 VIN EQUIVALENT INPUT NOISE VOLTAGE (nV/√Hz) INPUT VOLTAGE NOISE DENSITY vs. FREQUENCY MAX4475–MAX4478/MAX4488/MAX4489 Typical Operating Characteristics (continued) (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/√Hz for all distortion measurements, TA = +25°C, unless otherwise noted.) MAX4475 toc28 0.6V 2.5V 20mV/div 0.01 AV = +5, VDD = 3V 0.001 0.5V 0.5V AV = +5, VDD = 5V 0.0001 0 5k 10k FREQUENCY (Hz) 15k 20k 1µs/div VDD = 3V, RL = 10kΩ, CL = 100pF VIN = 2V 4µs/div VDD = 3V, RL = 10kΩ, CL = 100pF VIN = 100mV PULSE _______________________________________________________________________________________ 7 Typical Operating Characteristics (continued) (VDD = +5V, VSS = 0, VCM = 0, VOUT = VDD/2, RL tied to VDD/2, input noise floor of test equipment =10nV/√Hz for all distortion measurements, TA = +25°C, unless otherwise noted.) MAX4488/MAX4489 SMALL-SIGNAL PULSE RESPONSE MAX4488/MAX4489 LARGE-SIGNAL PULSE RESPONSE MAX4477/MAX4478/MAX4489 CROSSTALK vs. FREQUENCY MAX4475 toc30 MAX4475 toc29 MAX4475 toc31 -20 -30 1.6V VOUT 50mV/div VOUT 200mV/div 1.5V -40 CROSSTALK (dB) MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps -50 -60 -70 -80 -90 1µs/div 1µs/div 10 100 VDD = 3V, RL = 10kΩ, CL = 50pF VIN = 20mV PULSE, AV = +5V/V VDD = 3V, RL = 10kΩ, CL = 50pF VIN = 20mV PULSE, AV = +5V/V 1000 10k 100k 1M 10M 100M FREQUENCY (Hz) Pin Description PIN MAX4475/ MAX4488 MAX4475/ MAX4488 MAX4476 MAX4477/ MAX4489 MAX4478 SOT23 8 SO/µMAX SOT23 8 SO/µMAX SO/TSSOP 1 6 1 1, 7 1, 7, 8, 14 OUT, OUTA, OUTB, OUTC, OUTD 2 4 2 4 11 VSS 3 3 3 3, 5 3, 5, 10, 12 IN+, INA+, INB+, INC+, IND+ 4 2 4 2, 6 2, 6, 9, 13 IN-, INA-, INB-, INC-, IND- 6 7 5 8 4 VDD 5 8 — — — SHDN — 1, 5 — — — N.C. 8 NAME FUNCTION 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. _______________________________________________________________________________________ SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps 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 1kΩ 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 0.01µA and disables the outputs. MAX4475–MAX4478/MAX4488/MAX4489 Detailed Description CZ RF RG VOUT VIN Figure 1. Adding Feed-Forward Compensation AV = +2 RF = RG = 100kΩ VIN 100mV/div 100mV 0 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 mid-supply 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 2µs/div Figure 2a. Pulse Response with No Feed-Forward Compensation AV = +2 RF = RG = 100kΩ VIN 100mV/div VOUT 100mV/div 2µs/div Figure 2b. Pulse Response with 10pF Feed-Forward Compensation _______________________________________________________________________________________ 9 MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps 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 = 100kΩ, R G = 11kΩ (A V = +5V/V) is e n = 14nV/√Hz, e n can be reduced to 6nV/√Hz by choosing RF = 10kΩ, RG = 1.1kΩ (AV = +5V/V), at the expense of greater current consumption and potentially higher distortion. For a gain of 100V/V with R F = 100kΩ, RG = 1.1kΩ, the en is still a low 6nV/√Hz. 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 AV = -1V/V. In the decompensated MAX4488/MAX4489, CZ is most important for AV = +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 20kΩ (MAX4475–MAX4478) or greater than 5kΩ (MAX4488/MAX4489). 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. 10 AV = +1 VDD = +5V RL = 10kΩ VIN 2V/div 0 VOUT 2V/div 40µs/div Figure 3. Overdriven Input Showing No Phase Reversal 5V VOUT 1V/div 0 20µs/div 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 10kΩ load, making the devices ideal in low-supply-voltage 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 0.1µF ceramic ______________________________________________________________________________________ SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps +5V +5V 7 VDD CS SERIAL INTERFACE +2.5V U1 3 OUT SCLK MAX5541ESA DIN U2 REF MAX4475AUA 0 to +2.5V OUTPUT 6 AGND DGND 2 4 8 SHDN Typical Operating Circuit 5V 470pF 0.1µF 3.09kΩ 1% 7.87kΩ 1% 220pF 3 8 220pF 1 3.83kΩ 1% 13.7kΩ 1% 5 1/2 MAX4477 7 220pF 2 4 7.15kΩ 1% 1/2 MAX4477 220pF 6 10.0kΩ 1% 10.0kΩ 1% 10.0kΩ 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. 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 15.0kΩ 1% of error. In addition, the MAX4475 has excellent openloop gain and common-mode rejection, making this an excellent ouput buffer amplifier. DC-Accurate Low-Pass 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. ______________________________________________________________________________________ 11 MAX4475–MAX4478/MAX4488/MAX4489 Typical Application Circuit MAX4475–MAX4478/MAX4488/MAX4489 SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps Pin Configurations TOP VIEW TOP VIEW N.C. 1 INA- 2 INA+ MAX4475 MAX4488 3 VSS 4 8 SHDN 7 VDD OUTA 1 INA- 2 6 OUT 5 N.C. INA+ 3 MAX4477 MAX4489 VSS 4 14 OUTD INA- 2 13 IND- INA+ 3 12 IND+ VDD 4 MAX4478 7 OUTB 6 INB- 5 INB+ TOP VIEW TOP VIEW OUTA 1 VDD SO/µMAX SO/µMAX TOP VIEW 8 OUT 1 VSS 2 MAX4475 MAX4488 OUT 1 6 VDD 5 SHDN VSS 2 4 IN- IN+ 3 MAX4476 6 VDD 5 N.C. 4 IN- 11 VSS INB+ 5 10 INC+ INB- 6 9 INC- OUTB 7 8 OUTC IN+ 3 SOT23-6 SOT23-6 SO/TSSOP Ordering Information (continued) PART TEMP. RANGE PINPACKAGE MAX4477AUA -40°C to +125°C 8 µMAX — MAX4477ASA -40°C to +125°C 8 SO — MAX4478AUD -40°C to +125°C 14 TSSOP — MAX4478ASD -40°C to +125°C 14 SO — MAX4488AUT-T -40°C to +125°C 6 SOT23-6 MAX4488AUA -40°C to +125°C 8 µMAX — MAX4488ASA -40°C to +125°C 8 SO — MAX4489AUA -40°C to +125°C 8 µMAX — MAX4489ASA -40°C to +125°C 8 SO — 12 TOP MARK 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 AAZW ______________________________________________________________________________________ SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps 8LUMAXD.EPS ______________________________________________________________________________________ 13 MAX4475–MAX4478/MAX4488/MAX4489 Package Information SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps TSSOP,NO PADS.EPS MAX4475–MAX4478/MAX4488/MAX4489 Package Information (continued) 14 _______________________________________________________________________________________ SOT23, Low-Noise, Low-Distortion, Wide-Band, Rail-to-Rail Op Amps SOICN.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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX4475–MAX4478/MAX4488/MAX4489 Package Information (continued)