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19-1295; Rev 2; 4/98
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
General Description
The MAX4249-MAX4257 low-noise, low-distortion operational amplifiers offer Rail-to-Rail(R) outputs and singlesupply operation down to 2.4V. They draw only 400A of quiescent supply current per amplifier while featuring ultra-low distortion (0.0002% THD), as well as low input voltage noise density (7.9nV/Hz) and low input current noise density (0.5fA/Hz). These features make the devices an ideal choice for portable/battery-powered applications that require low distortion and/or low noise. For additional power conservation, the MAX4249/ MAX4251/MAX4253/MAX4256 offer a low-power shutdown mode that reduces supply current to 0.5A and puts the amplifiers' outputs into a high-impedance state. The MAX4249-MAX4257's outputs swing rail-to-rail and their input common-mode voltage range includes ground. The MAX4250-MAX4254 are unity-gain stable; the MAX4249/MAX4255/MAX4256/MAX4257 are internally compensated for gains of 10V/V or greater. The single MAX4250/MAX4255 are available in a space-saving, 5-pin SOT23 package.
____________________________Features
o o o o o o o o Low Input Voltage Noise Density: 7.9nV/Hz Low Input Current Noise Density: 0.5fA/Hz Low Distortion: 0.0002% THD (1k load) 400A Quiescent Supply Current per Amplifier Single-Supply Operation from +2.4V to +5.5V Input Common-Mode Voltage Range Includes Ground Outputs Swing within 8mV of Rails with a 10k Load 3MHz GBW Product, Unity-Gain Stable (MAX4250-MAX4254) 22MHz GBW Product, Stable with AV 10V/V (MAX4249/MAX4255/MAX4256/MAX4257) Excellent DC Characteristics: VOS = 70V IBIAS = 1pA Large-Signal Voltage Gain = 116dB Low-Power Shutdown Mode: Reduces Supply Current to 0.5A Places Outputs in a High-Impedance State 400pF Capacitive-Load Handling Capability Available in Space-Saving SOT23 and MAX Packages
MAX4249-MAX4257
o
o
Applications
Portable/Battery-Powered Equipment Medical Instrumentation ADC Buffers Digital Scales Strain Gauges Sensor Amplifiers Portable Communications Devices
Pin Configurations and Typical Operating Circuit appear at end of data sheet.
o o
Ordering Information
PART MAX4249ESD MAX4249EUB TEMP. RANGE -40C to +85C -40C to +85C PINPACKAGE 14 SO 10 MAX 5 SOT23-5 SOT TOP MARK -- -- ACCI
MAX4250EUK-T -40C to +85C
Ordering Information continued at end of data sheet.
Selector Guide
PART MAX4249 MAX4250 MAX4251 MAX4252 MAX4253 MAX4254 MAX4255 MAX4256 MAX4257 GAIN BANDWIDTH (MHz) 22 3 3 3 3 3 22 22 22 MINIMUM STABLE GAIN (V/V) 10 1 1 1 1 1 10 10 10 NO. OF AMPLIFIERS PER PACKAGE 2 1 1 2 2 4 1 1 2 SHUTDOWN MODE Yes -- Yes -- Yes -- -- Yes -- PACKAGES 10-pin MAX, 14-pin SO 5-pin SOT23 8-pin MAX/SO 8-pin MAX/SO 10-pin MAX, 14-pin SO 14-pin SO 5-pin SOT23 8-pin MAX/SO 8-pin MAX/SO
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468.
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
ABSOLUTE MAXIMUM RATINGS
Power-Supply Voltage (VDD to VSS) ......................+6.0V to -0.3V Analog Input Voltage (IN_+, IN_-)....(VDD + 0.3V) to (VSS - 0.3V) SHDN Input Voltage....................................+6.0V to (VSS - 0.3V) Output Short-Circuit Duration to Either Supply ..........Continuous Continuous Power Dissipation (TA = +70C) 5-Pin SOT23 (derate 7.1mW/C above +70C)............571mW 8-Pin MAX (derate 4.10mW/C above +70C) ...........330mW 8-Pin SO (derate 5.88mW/C above +70C)................471mW 10-Pin MAX (derate 5.6mW/C above +70C) ...........444mW 14-Pin SO (derate 8.33mW/C above +70C)..............667mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +160C 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 tied to VDD/2, SHDN = VDD or open, TA = -40C to +85C, 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 Common-Mode Rejection Ratio Power-Supply Rejection Ratio Large-Signal Voltage Gain IB IOS RIN VCM CMRR PSRR AV Guaranteed by CMRR test VSS - 0.2V VCM VDD - 1.1V VDD = 2.4V to 5.5V RL = 10k to VDD/2, VOUT = 25mV to 4.97V RL = 1k to VDD/2, VOUT = 150mV to 4.75V -0.2 70 75 80 80 115 100 116 112 8 7 77 47 68 Shutdown mode (SHDN = VSS), VOUT = VSS to VDD 0.8 x VDD SHDN = VSS to VDD 0.5 11 1.5 0.001 1.0 0.2 x VDD 25 20 200 100 mA A V V A pF mV (Note 4) (Note 4) SYMBOL VDD IQ VOS (Note 3) Normal mode VDD = 3V VDD = 5V CONDITIONS MIN 2.4 400 420 0.5 0.07 0.3 1 1 1000 VDD 1.1 100 100 575 1.5 0.75 mV V/C pA pA G V dB dB dB A TYP MAX 5.5 UNITS V
Shutdown mode (SHDN = VSS) (Note 1)
Output Voltage Swing
VOUT
VIN+ - VIN- 10mV, RL = 10k to VDD/2 VIN+ - VIN- 10mV,
RL = 1k to VDD/2
VDD - VOH VOL - VSS VDD - VOH VOL - VSS
Output Short-Circuit Current Output Leakage Current SHDN Logic Low SHDN Logic High SHDN Input Current Input Capacitance
ISC ILEAK VIL VIH IIL/IIH
2
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SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
ELECTRICAL CHARACTERISTICS (continued)
(VDD = +5V, VSS = 0V, VCM = 0V, VOUT = VDD/2, RL tied to VDD/2, SHDN = VDD or open, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2) PARAMETER Gain-Bandwidth Product Slew Rate Peak-to-Peak Input Noise Voltage Input Voltage Noise Density Input Current Noise Density SYMBOL GBW SR en(p-p) CONDITIONS MAX4250-MAX4254 MAX4249/MAX4255/MAX4256/MAX4257 MAX4250-MAX4254 MAX4249/MAX4255/MAX4256/MAX4257 f = 0.1Hz to 10Hz f = 10Hz en in f = 1kHz f = 30kHz f = 1kHz MAX4250-MAX4254, AV = +1V/V, VOUT = 2Vp-p, RL = 1k to GND (Note 5) Total Harmonic Distortion plus Noise THD+N MAX4249/MAX4255/MAX4256/ MAX4257, AV = +10V/V, RF = 100k, RG = 11k, VOUT = 4Vp-p, RL = 10k to GND (Note 5) No sustained oscillations MAX4250-MAX4254, AV = +1V/V Gain Margin GM MAX4249/MAX4255/MAX4256/MAX4257, AV = +10V/V MAX4250-MAX4254, AV = +1V/V Phase Margin M MAX4249/MAX4255/MAX4256/MAX4257, AV = +10V/V To 0.01%, VOUT = 2V step tSH MAX4250-MAX4254 MAX4249/MAX4255/MAX4256/ MAX4257 f = 1kHz f = 20kHz f = 1kHz f = 20kHz MIN TYP 3 22 0.3 2.1 760 27 8.9 7.9 0.5 0.0004 0.006 0.0012 0.007 400 10 12.5 74 68 6.7 1.6 0.8 1.2 8 s MAX4249/MAX4256 3.5 6 s s degrees dB pF % fA/Hz nV/Hz MAX UNITS MHz V/s nVp-p
MAX4249-MAX4257
Capacitive-Load Stability
Settling Time
Shutdown Delay Time
MAX4251/MAX4253 IVDD = 5% of normal operation MAX4249/MAX4256 VOUT = 2.5V, VOUT settles to 0.1% MAX4251/MAX4253
s
Enable Delay Time Power-Up Delay Time
tEN tPU
VDD = 0V to 5V step, VOUT stable to 0.1%
Note 1: SHDN is available on the MAX4249/MAX4251/MAX4253/MAX4256 only. Note 2: The MAX4249EUB, MAX425_EU_ specifications are 100% tested at TA = +25C. Limits over the extended temperature range are guaranteed by design, not production tested. Note 3: Guaranteed by the Power-Supply Rejection Ratio (PSRR) test. Note 4: Guaranteed by design. Note 5: Lowpass filter bandwidth is 22kHz for f = 1kHz, and 80kHz for f = 20kHz. Noise floor of test equipment = 10nV/Hz.
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3
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Typical Operating Characteristics
(VDD = +5V, VSS = 0V, VCM = VOUT = VDD/2, input noise floor of test equipment = 10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
MAX4251/MAX4256 INPUT OFFSET VOLTAGE DISTRIBUTION
MAX4249 TOC01
OFFSET VOLTAGE vs. TEMPERATURE
MAX4249 TOC02
INPUT OFFSET VOLTAGE vs. COMMON-MODE INPUT VOLTAGE
MAX4249 TOC03
40 35 30 NUMBER OF UNITS 25 20 15 10 5 -95 -75 -55 -35 -13 7 28 49 69 90 110 131 152 172 192 0 400 UNITS VCM = 0V TA = +25C
250 200 150 100 VOS (V) 50 0 -50 -100 -150 -200 -250 -40 -20 0 20 40 60 VCM = 0V
200
INPUT OFFSET VOLTAGE (V)
150
100 VDD = 3V VDD = 5V
50
0
80
-50 -0.5
0.5
1.5
2.5
3.5
4.5
VOS (V)
TEMPERATURE (C)
INPUT COMMON-MODE VOLTAGE (V)
OUTPUT VOLTAGE vs. OUTPUT LOAD CURRENT
VDD = 3V OR 5V VDIFF = 10mV VDD - VOH VDD - VOH (V) 0.4 0.3 0.2 0.1 0 0 1 2 3 4 5 6 7 8 9 10 OUTPUT LOAD CURRENT (mA)
MAX4249 TOC04
OUTPUT VOLTAGE SWING (VOH) vs. TEMPERATURE
MAX4249 TOC05
OUTPUT VOLTAGE SWING (VOL) vs. TEMPERATURE
MAX4249 TOC06
0.6 0.5 OUTPUT VOLTAGE (V)
0.10 0.09 0.08 0.07 RL = 1k
0.06 0.05 0.04 VOL (V) 0.03 0.02
RL = 1k
0.06 0.05 0.04 0.03 0.02 0.01 0 -40 -20 0 20 40 60 80 TEMPERATURE (C) RL = 10k RL = 100k
VOL
0.01 0 -40 -20 0 20
RL = 10k RL = 100k 40 60 80
TEMPERATURE (C)
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
MAX4249TOC07
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
MAX4249 TOC08
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
RL = 200k 130 120 110 AV (dB) 100 90 80 70 RL = 20k RL = 2k
MAX4249TOC09
140 130 120 110 AV (dB) 100 90 80 70 60 50 0 50 100 150 200 VDD = 3V RL REFERENCED TO GND RL = 200k RL = 20k RL = 2k
140 130 120 110 AV (dB) 100 90 80 70 60 0 50 100 VDD = 3V RL REFERENCED TO VDD 150 200 RL = 2k RL = 20k RL = 200k
140
60 50 250 0 50 100
VDD = 5V RL REFERENCED TO GND 150 200 250
250
VOUT SWING FROM EITHER SUPPLY (mV)
VOUT SWING FROM EITHER SUPPLY (mV)
VOUT SWING FROM EITHER SUPPLY (mV)
4
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SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = VOUT = VDD/2, input noise floor of test equipment = 10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
LARGE-SIGNAL VOLTAGE GAIN vs. OUTPUT VOLTAGE SWING
140 130 120 AV (dB) AV (dB) 110 100 90 80 70 60 50 0 50 100 150 200 250 VOUT SWING FROM EITHER SUPPLY (mV) VDD = 5V RL REFERENCED TO VDD 105 RL = 2k 115 RL = 100k VOUT = 10mV to 4.99V RL = 1k VOUT = 150mV to 4.75V -40 -20 0 20 RL = 10k VOUT = 20mV to 4.975V 40 60 80 RL = 200k RL = 20k
MAX4249 TOC10
MAX4249-MAX4257
LARGE-SIGNAL VOLTAGE GAIN vs. TEMPERATURE
MAX4249 TOC11
SUPPLY CURRENT AND SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
460 PER AMPLIFIER SHUTDOWN SUPPLY CURRENT (A) 440 SUPPLY CURRENT (A) 420 400 SHDN = VDD 380 SHDN = VSS 360 340 -40 -20 0 20 40 60 80 0.373 TEMPERATURE (C) 0.374 0.375
MAX4249 TOC12
150
125
0.376
120
RL REFERENCED T0 VDD/2 VDD = 5V
110
100 TEMPERATURE (C)
SUPPLY CURRENT AND SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
440 420 SUPPLY CURRENT (A) 400 380 360 340 320 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 5.5 SUPPLY VOLTAGE (V) SHDN = VDD SHDN = VSS
MAX4249 TOC 13A
SUPPLY CURRENT vs. OUTPUT VOLTAGE
MAX4249 TOC13B
INPUT OFFSET VOLTAGE vs. SUPPLY VOLTAGE
160 140 VOS (V) VCM = 0V VOUT = VDD/2 RL REFERENCED TO GND
MAX4249 TOC14
PER AMPLIFIER
0.6 SHUTDOWN SUPPLY CURRENT (A) 0.5 0.4 0.3 0.2 0.1 0
2000
180
SUPPLY CURRENT (A)
1000 VDD = 5V
120 100 80 60
RL = 10k RL = 1k
400 VDD = 3V
RL = 100k 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3
100 0.001
40 0.01 0.1 1 5 OUTPUT VOLTAGE (V) SUPPLY VOLTAGE (V)
MAX4250-MAX4254 GAIN AND PHASE vs. FREQUENCY
60 50 40 30 GAIN (dB) 20 10 0 -10 -20 -30 -40 100 1k 10k 100k 1M FREQUENCY (Hz) PHASE GAIN
MAX4249 TOC15
MAX4249, MAX4255/MAX4256/MAX4257 GAIN AND PHASE vs. FREQUENCY
180 144 108 72 36 0 -36 -72 -108 -144 -180 10M PHASE (DEGREES) 60 50 40 30 GAIN (dB) 20 10 0 -10 -20 -30 -40 100 1k 10k 100k 1M FREQUENCY (Hz) PHASE VDD = 3V, 5V RL = 50k CL = 20pF AV = 1000
MAX4249 TOC16
MAX4250-MAX4254 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100 -110 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) PSRRPSRR+ PHASE (DEGREES)
MAX4249 TOC17
VDD = 3V, 5V RL = 50k CL = 20pF AV = 1000
180 144
VDD = 3V, 5V
GAIN
108 72 36 0 -36 -72 -108 -144 -180 10M
_______________________________________________________________________________________
5
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = VOUT = VDD/2, input noise floor of test equipment = 10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
OUTPUT IMPEDANCE vs. FREQUENCY
Vn-EQUIVALENT INPUT NOISE VOLTAGE (nV/Hz) AV = +10 (MAX4249/MAX4255/ MAX4256/MAX4257) OUTPUT IMPEDANCE () 100
MAX4249 TOC18
INPUT VOLTAGE N0ISE DENSITY vs. FREQUENCY
MAX4249 TOC19
0.1Hz TO 10Hz p-p NOISE
MAX4249 TOC20
1000
30 25 20 15 10 5
VDD = 3V OR 5V
10
200nV/ div
1 AV = +1 (MAX4250-MAX4254) 0.1 1k 10k 100k FREQUENCY (Hz) 1M 10M
Vp-p NOISE = 760nVp-p 0 10 100 1k FREQUENCY (Hz) 10k 100k 1sec/div
MAX4250-MAX4254 FFT OF DISTORTION AND NOISE
MAX4249 TOC21
MAX4249/MAX4255/MAX4256/MAX4257 FFT OF DISTORTION AND NOISE
MAX4249 TOC22
MAX4250-MAX4254 THD PLUS NOISE vs. OUTPUT VOLTAGE (VDD = 5V)
AV = +10 VIN fO = 3kHz FILTER BW = 30kHz 11k 0.1 RL = 1k 100k VO RL
MAX4249 TOC23
0 -20 -40 AMPLITUDE (dBc) -60 -80 -100 -120 -140 -160 10 5k 10k 15k 20k FREQUENCY (Hz)
HD2 HD4 HD3 HD5
20 0 -20 AMPLITUDE (dBc) -40 -60 -80 -100 -120 -140 10 5k 10k 15k 20k FREQUENCY (Hz)
HD2 HD3
10
VOUT = 2Vp-p
RLOAD = 1k fO = 1kHz AV = +1
VOUT = 4Vp-p fO = 1kHz VIN fO 11k 100k VO 10k
1 THD+N (%)
fO
0.01 RL = 10k 0.001 0 1 2 RL = 100k 3 4 5 OUTPUT VOLTAGE (Vp-p)
MAX4250-MAX4254 THD PLUS NOISE vs. OUTPUT VOLTAGE SWING (VDD = 3V)
MAX4249 TOC24
MAX4249/MAX4255/MAX4256/MAX4257 THD PLUS NOISE vs. OUTPUT VOLTAGE SWING
MAX4249 TOC25
MAX4250-MAX4254 THD PLUS NOISE vs. FREQUENCY
VIN VOUT RL 0.1 THD+N (%) R1 R1 = 560, R2 = 53k 0.01 R1 = 5.6k, R2 = 53k 0.001 AV = 1 AV = 10 R2 AV = 100
MAX4249 TOC26
10 VIN VOUT 1 11k THD+N (%) 0.1 RL = 1k 100k RL
1
AV = +10
VIN VOUT RL 11k 100k
1
0.1 THD+N (%)
fO = 20kHz, FILTER BW = 80kHz 0.01
0.01
0.001 0
AV = +10 VDD = 3V fO = 3kHz FILTER BW = 30kHz 1
RL = 10k RL = 100k fO = 3kHz, FILTER BW = 30kHz 0.001 2 3 0 1 2 3 4 5 OUTPUT VOLTAGE (Vp-p)
0.0001 10 100
FILTER BW= 22kHz RL = 10k TO GND VO = 2Vp-p 1k 10k FREQUENCY (Hz)
OUTPUT VOLTAGE (Vp-p)
6
_______________________________________________________________________________________
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
Typical Operating Characteristics (continued)
(VDD = +5V, VSS = 0V, VCM = VOUT = VDD/2, input noise floor of test equipment = 10nV/Hz for all distortion measurements, TA = +25C, unless otherwise noted.)
MAX4249/MAX4255-MAX4257 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX4249 TOC27
MAX4249-MAX4257
MAX4250-MAX4254 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
FILTER BW = 80kHz AV = +1 RL = 1k VOUT = 2Vp-p 0.01 RL TO VDD/2 RL TO GND 0.001 RL TO VDD 0.5V VOUT 200mV/ div
MAX4249 TOC28
MAX4250-MAX4254 LARGE-SIGNAL PULSE RESPONSE
MAX4249 TOC29
0.1
VOUT = 2.75Vp-p FILTER BW = 80kHz AV = +100, R1 = 1k
VDD = 3V
0.1
1.5V
VDD = 5V 0.01 AV = +10, R1 = 11k VOUT R1 0.001 10 100 1k 10k FREQUENCY (Hz) 100k RL = 10k
VDD = 3V VDD = 5V
THD PLUSE NOISE (%)
THD PLUS NOISE (%)
VDD = 3V RL = 10k CL = 100pF VIN = 1V PULSE 2s/div
0.0001 10 100 1k 10k FREQUENCY (Hz)
MAX4250-MAX4254 SMALL-SIGNAL PULSE RESPONSE
MAX4249 TOC30
MAX4249/MAX4255/MAX4256/MAX4257 LARGE-SIGNAL PULSE RESPONSE
MAX4249 TOC31
0.6V
2V
VOUT 20mV/ div
VOUT 200mV/ div VDD = 3V RL = 10k CL = 100pF VIN = 100mV PULSE 2s/div VDD = 3V RL = 10k CL = 100pF VIN = 100mV PULSE AV = +10 2s/div
0.5V
1V
MAX4249/MAX4255/MAX4256/MAX4257 SMALL-SIGNAL PULSE RESPONSE
MAX4249 TOC32
MAX4252/MAX4253/MAX4254 CHANNEL SEPARATION vs. FREQUENCY
130 CHANNEL SEPARATION (dB) 120 110 100 90 80 70 0 1k 10k 100k FREQUENCY (Hz) 1M 10M
MAX4249 TOC33
140
1.6V VOUT 50mV/div 1.5V
VDD = 3V RL = 10k CL = 100pF VIN = 10mV PULSE AV = +10 2s/div
_______________________________________________________________________________________
7
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Pin Description
PIN MAX4250 MAX4255 5 SOT23 1 MAX4251 MAX4256 MAX4252 MAX4257 MAX4249/MAX4253 10 MAX 1, 9 14 SO 1, 13 MAX4254 14 SO 1, 7, 8, 14 OUT, OUTA, OUTB, OUTC, OUTD VSS IN+, INA+, INB+, INC+, IND+ IN-, INA-, INB-, INC-, INDVDD SHDN, SHDNA, SHDNB N.C. Amplifier Output Negative Supply. Connect to ground for single-supply operation. Noninverting Amplifier Input Inverting Amplifier Input Positive Supply Shutdown Input. Connect to VDD or leave unconnected for normal operation (amplifier(s) enabled). No Connection. Not internally connected. NAME FUNCTION
8 MAX/SO 6 1, 7
2
4
4
4
4
11
3 4 5
3 2 7
3, 5 2, 6 8
3, 7 2, 8 10
3, 11 2, 12 14
3, 5, 10, 12 2, 6, 9, 13 4
--
8
--
5, 6
6, 9
--
--
1, 5
--
--
5, 7, 8, 10
--
_______________Detailed Description
The MAX4249-MAX4257 single-supply operational amplifiers feature ultra-low noise and distortion while consuming very little power. Their low distortion and low noise make them ideal for use as preamplifiers in wide dynamic-range applications, such as 16-bit analog-to-digital converters (see Typical Operating Circuit). Their high input 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 output operation, drive loads as low as 1k while maintaining DC accuracy, and can drive capacitive loads up to 400pF without oscillation. The input common-mode voltage range extends from VDD - 1.1V to 200mV beyond the negative rail. The push/pull output stage maintains excellent DC characteristics, while delivering up to 5mA of current. The MAX4250-MAX4254 are unity-gain stable, whereas the MAX4249/MAX4255/MAX4256/MAX4257 have a higher slew rate and are stable for gains 10V/V. The MAX4249/ MAX4251/MAX4253/MAX4256 feature a lowpower shutdown mode, which reduces the supply current to 0.5A and disables the outputs.
8
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. Large-value feedback resistors can significantly improve distortion. 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.)
_______________________________________________________________________________________
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
For gains 10V/V, the decompensated devices (MAX4249/MAX4255/MAX4256/MAX4257) 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 400pF do not significantly affect distortion results. Distortion performance remains relatively constant over supply voltages.
MAX4249-MAX4257
CZ RF RG VOUT
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 = 10V/V) is e n = 15nV/Hz. e n can be reduced to 9nV/Hz by choosing RF = 10k, RG = 1.1k (AV = 10V/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 low (9nV/Hz).
VIN
Figure 1. Adding Feed-Forward Compensation
AV = +2 RF = RG = 100k 100mV VIN (50mV/ div)
0mV VOUT (100mV/ div)
Using a Feed-Forward Compensation Capacitor, CZ
The amplifier's input capacitance is 11pF. 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 (C Z) 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 11 x (RF / RG) [pF] In the unity-gain-stable MAX4250-MAX4254, the use of a proper CZ is most important for AV = +2V/V, and A V = -1V/V. In the decompensated MAX4249/ MAX4255/MAX4256/MAX4257, CZ 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 RGRF is greater than 20k (MAX4250-MAX4254) or greater than 5k (MAX4249/MAX4255/MAX4256/ MAX4257).
2s/div
Figure 2a. Pulse Response with No Feed-Forward Compensation
100mV VIN 0mV
AV = +2 RF = RG = 100k CZ = 11pF 50mV/ div
VOUT
100mV/ div
2s/div
Figure 2b. Pulse Response with 10pF Feed-Forward Compensation
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9
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Applications Information
The MAX4249-MAX4257 combine good driving capability with ground-sensing input and rail-to-rail output operation. With their low distortion, low noise and low power consumption, they are ideal for use in portable instrumentation systems and other low-power, noisesensitive applications.
VIN
RISO
VOUT CL
MAX4250 MAX4251 MAX4252 MAX4253 MAX4254
4.25V VOUT 0 OV
Figure 5. Capacitive-Load Driving Circuit
4.45V
Ground-Sensing and Rail-to-Rail Outputs
The common-mode input range of the MAX4249- MAX4257 extends down to ground, and offers excellent common-mode 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 = 10V/V. The output swings to within 8mV of the supplies with a 10k load, making the devices ideal in low-supply-voltage applications.
VIN 0 AV = +1 VDD = +5V RL = 10k -200mV
20s/div
Figure 3. Overdriven Input Showing No Phase Reversal
Output Loading and Stability
5V
VOUT
1V/ div
0V
VDD = +5V RL = 10k AV = +10 f = 1kHz 200s/div
Even with their low quiescent current of 400A, these amplifiers can drive 1k loads while maintaining excellent DC accuracy. Stability while driving heavy capacitive loads is another key feature. These devices maintain stability while driving loads up to 400pF. To drive higher capacitive loads, place a small isolation resistor in series between the output of the amplifier and the capacitive load (Figure 5). This resistor improves the amplifier's phase margin by isolating the capacitor from the op amp's output. Reference Figure 6 to select a resistance value that will ensure a load capacitance that limits peaking to <2dB (25%). For example, if the capacitive load is 1000pF, the corresponding isolation resistor is 150. Figure 7 shows that peaking occurs without the isolation resistor. Figure 8 shows the unity-gain bandwidth vs. capacitive load for the MAX4250-MAX4254.
Figure 4. Rail-to-Rail Output Operation
Power Supplies and Layout
The MAX4249-MAX4257 operate from a single +2.4V to +5.5V power supply or from dual supplies of 1.20V to 2.75V. For single-supply operation, bypass the
10
______________________________________________________________________________________
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
160 140 UNITY-GAIN BANDWIDTH (MHz) 120 RISO () 100 80 60 40 20 0 10 100 1000 10,000 CAPACITIVE LOADING (pF) NOTE: USING AN ISOLATION RESISTOR REDUCES PEAKING. SHADED AREA INDICATES STABLE OPERATION WITH NO NEED FOR ISOLATION RESISTOR. 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 10 100 1000 10,000 CAPACITIVE LOAD (pF) NOTE: RISO CHOSEN FOR PEAKING <2dB. SHADED AREA INDICATES STABLE OPERATION WITH NO NEED FOR ISOLATION RESISTOR. VDD = 3V
Figure 6. Isolation Resistance vs. Capacitive Loading to Minimize Peaking (<2dB)
Figure 8. MAX4250-MAX4254 Unity-Gain Bandwidth vs. Capacitive Load
___________________Chip Information
25 MAX4250-MAX4254 (AV = +1) MAX4249/MAX4255-MAX4257 (AV = +10) RISO = 0 SHADED AREA INDICATES STABLE OPERATION WITH NO NEED FOR ISOLATION RESISTOR. 20 PEAKING (dB)
TRANSISTOR COUNTS: MAX4250/MAX4251/MAX4255/MAX4256: 170 MAX4249/MAX4252/MAX4253/MAX4257: 340 MAX4254: 680
15
10
Ordering Information (continued)
5
PART
0 10 100 1000 10,000
TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
PINPACKAGE 8 SO 8 MAX 8 SO 8 MAX 10 MAX 14 SO 14 SO 5 SOT23-5 8 SO 8 MAX 8 SO 8 MAX
SOT TOP MARK -- -- -- -- -- -- -- ACCJ -- -- -- --
MAX4251ESA MAX4251EUA MAX4252ESA MAX4252EUA MAX4253EUB MAX4253ESD MAX4254ESD MAX4256ESA MAX4256EUA MAX4257ESA MAX4257EUA
CAPACITIVE LOAD (pF)
Figure 7. Peaking vs. Capacitive Load
power supply with a 0.1F ceramic 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.
MAX4255EUK-T -40C to +85C
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11
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Pin Configurations
TOP VIEW
OUT 1 5 VDD N.C. 1 IN- 2 IN+ 4 IN3 8 7 SHDN VDD OUT N.C.
VSS 2
MAX4250 MAX4255
MAX4251 MAX4256
6 5
IN+ 3
VSS 4
SOT23
MAX/SO
OUTA 1 INA- 2 INA+ 3
8 7
VDD OUTB INBINB+
OUTA 1 INAINA+ VSS 2 3 4 5
10 VDD 9 OUTB INBINB+ SHDNB
MAX4252 MAX4257
6 5
MAX4249 MAX4253
8 7 6
VSS 4
SHDNA
MAX/SO
MAX
OUTA 1 INAINA+ 2 3
14 VDD 13 OUTB 12 INB-
OUTA 1 INAINA+ 2 3
14 OUTD 13 IND12 IND+
VSS 4 N.C. 5 SHDNA 6 N.C. 7
MAX4249 MAX4253
11 INB+ 10 N.C. 9 8 SHDNB N.C.
VDD 4 INB+ 5 INB- 6 OUTB 7
MAX4254
11 VSS 10 INC+ 9 8 INCOUTC
SO
SO
12
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SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
Typical Operating Circuit
+5V
MAX4249-MAX4257
50k 2 7 6 VIN 3 AIN SHDN
VDD
MAX195
(16-BIT ADC) DOUT SCLK CS REF VSS -5V SHDN 4.096V SERIAL INTERFACE
MAX4256
4 8
5k
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13
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
Package Information
SOT5L.EPS
14
______________________________________________________________________________________
8LUMAXD.EPS
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps
___________________________________________Package Information (continued)
10LUMAXB.EPS
MAX4249-MAX4257
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15
SOT23, Single-Supply, Low-Noise, Low-Distortion, Rail-to-Rail Op Amps MAX4249-MAX4257
___________________________________________Package Information (continued)
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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