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19-2279; Rev 2; 11/02
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
General Description
The MAX4460/MAX4461/MAX4462 are instrumentation amplifiers with precision specifications, low-power consumption, and excellent gain-bandwidth product. Proprietary design techniques allow ground-sensing capability combined with ultra-low input current and increased common-mode rejection performance. These Rail-to-Rail(R) output instrumentation amplifiers are offered in fixed or adjustable gains and the option for either a shutdown mode or a pin to set the output voltage relative to an external reference (see Ordering Information and Selector Guide). The MAX4460 has an adjustable gain and uses ground as its reference voltage. The MAX4461 is offered in fixed gains of 1, 10, and 100, uses ground as its reference voltage, and has a logic-controlled shutdown input. The MAX4462 is offered in fixed gains of 1, 10, and 100 and has a reference input pin (REF). REF sets the output voltage for zero differential input to allow bipolar signals in single-supply applications. The MAX4460/MAX4461/MAX4462 have high-impedance inputs optimized for small-signal differential voltages. The MAX4461/MAX4462 are factory trimmed to gains of 1, 10, or 100 (suffixed U, T, and H) with 0.1% accuracy. The typical offset of the MAX4460/MAX4461/MAX4462 is 100V. All devices have a gain-bandwidth product of 2.5MHz. These amplifiers operate with a single-supply voltage from 2.85V to 5.25V and with a quiescent current of only 700A (less than 1A in shutdown for the MAX4461). The MAX4462 can also be operated with dual supplies. Smaller than most competitors, the MAX4460/ MAX4461/MAX4462 are available in space-saving 6-pin SOT23 packages. o Tiny 6-Pin SOT23 Package o Input Negative Rail Sensing o 1pA (typ) Input Bias Current o 100V Input Offset Voltage o Rail-to-Rail Output o 2.85V to 5.25V Single Supply o 700A Supply Current o 0.1% Gain Error o 2.5MHz Gain-Bandwidth Product o 18nV/Hz Input-Referred Noise
Features
MAX4460/MAX4461/MAX4462
Ordering Information
PART MAX4460EUT-T MAX4460ESA MAX4461UEUT-T MAX4461UESA MAX4461TEUT-T MAX4461TESA MAX4461HEUT-T MAX4461HESA MAX4462UEUT-T MAX4462UESA MAX4462TEUT-T MAX4462TESA MAX4462HEUT-T MAX4462HESA 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 -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 6 SOT23-6 8 SO 6 SOT23-6 8 SO 6 SOT23-6 8 SO 6 SOT23-6 8 SO 6 SOT23-6 8 SO 6 SOT23-6 8 SO 6 SOT23-6 8 SO TOP MARK AASS -- AAST -- AASU -- AASV -- AASW -- AASX -- AASY --
________________________Applications
Industrial Process Control Strain-Gauge Amplifiers Transducer Interface Precision Low-Side Current Sense Low-Noise Microphone Preamplifier Differential Voltage Amplification Battery-Powered Medical Equipment
Selector Guide appears at end of data sheet. Pin Configurations appear at end of data sheet. Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
Typical Application Circuits
VCC
VCM + V
3
5
MAX4462 1
VCM - V 4 2 6
OUT
REF
Typical Application Circuits continued at end of data sheet. 1
________________________________________________________________ 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.
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VDD to VSS) ...................................-0.3V to +6V All Other Pins ...................................(VSS - 0.3V) to (VDD + 0.3V) Output Short-Circuit Duration to Either Supply.........................1s Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C)............695mW 8-Pin SO (derate 5.9mW/C above +70C)..................470mW Operating Temperature Range ...........................-40C to +85C 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.
ELECTRICAL CHARACTERISTICS--MAX4460/MAX4461
(VDD = 5V, VCM = 0V, VDIFF = VIN+ - VIN- = 50mV to 100mV for G = 1, 20mV to 100mV for G = 10, 2mV to 48mV for G =100, MAX4460 is configured for G = 10, RL = 200k to GND, TA = +25C, unless otherwise noted.)
PARAMETER Supply Voltage Supply Current Shutdown Supply Current Input Offset Voltage (Note 1) VOS SYMBOL VDD CONDITIONS Guaranteed by PSRR test VDD = 5V, VDIFF = 0V VDD = 3V, VDIFF = 0V MAX4461, SHDN = GND MAX4460ESA MAX4461ESA MAX446_EUT Input Resistance Input Common-Mode Range Input Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Bias Current FB Input Current VIH SHDN Logic Levels VIL SHDN Input Current Input Voltage Noise en VOH Output Voltage Swing VOL Short-Circuit Current ISC MAX4461 MAX4461, V SHDN = 0V or VDD (Note 2) f = 10kHz f = 1kHz VDD - VOH (Note 3) RL = 200k RL = 20k (Note 4) RL = 200k RL = 20k 1 18 38 1 3 0 0 150 2.5 5 0.2 0.2 mA mV RIN VCM CMRR PSRR IB VCM = VDD/2 Guaranteed by CMRR test VCM = -0.1V to (VDD - 1.7V) VDD = 2.85V to 5.25V (Note 2) MAX4460 (Note 2) MAX4461 0.7 X VDD 0.3 X VDD 100 pA nV/Hz Differential mode Common mode -0.1 90 80 120 100 1 1 100 100 VDD = 5V MIN 2.85 0.80 0.68 0.1 50 50 100 2 2 VDD 1.7 TYP MAX 5.25 1.1 0.9 1 425 300 600 G V dB dB pA pA V UNITS V mA A
V
2
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
ELECTRICAL CHARACTERISTICS--MAX4460/MAX4461 (continued)
(VDD = 5V, VCM = 0V, VDIFF = VIN+ - VIN- = 50mV to 100mV for G = 1, 20mV to 100mV for G = 10, 2mV to 48mV for G =100, MAX4460 is configured for G = 10, RL = 200k to GND, TA = +25C, unless otherwise noted.)
PARAMETER SYMBOL CONDITIONS G = 1V/V, MAX4461UESA G = 10V/V, MAX4461TESA Gain Error RL = 20k G = 100V/V, MAX4461HESA G = 10V/V, MAX4460ESA MAX446_EUT Nonlinearity (Note 1) Maximum Capacitive Load -3dB Bandwidth Gain-Bandwidth Product Slew Rate CL BW-3dB GBWP SR RL = 20k No sustained oscillations G = 1V/V, MAX4461U CL = 100pF CL = 100pF G = 1V/V CL = 100pF G = 10V/V G = 100V/V Settling Time tS CL = 100pF, within 0.1% of G = 10V/V final value G = 100V/V G = 1V/V G = 10V/V, MAX4461T G = 100V/V, MAX4461H MIN TYP 0.1 0.12 0.15 0.15 0.15 0.05 100 2500 250 25 2.5 0.5 0.5 0.25 15 75 250 s V/s MHz kHz MAX 0.3 0.35 0.6 0.35 0.6 0.15 % pF % UNITS
MAX4460/MAX4461/MAX4462
ELECTRICAL CHARACTERISTICS--MAX4460/MAX4461
(VDD = 5V, VCM = 0V, VDIFF = VIN+ - VIN- = 50mV to 100mV for G = 1, 20mV to 100mV for G = 10, 2mV to 48mV for G = 100, MAX4460 is configured for G = 10, RL = 200k to GND, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER Supply Voltage Supply Current Shutdown Supply Current SYMBOL VDD CONDITIONS Guaranteed by PSRR test VDD = 5V, VDIFF = 0V VDD = 3V, VDIFF = 0V MAX4461, SHDN = GND MAX4460ESA VDD = 5V TA = 0C to +85C TA = -40C to +85C G=1 TA = 0C to +85C Input Offset Voltage (Note 1) VOS MAX4461ESA TA = -40C to +85C MAX446_EUT Input Offset-Voltage Drift TCVOS (Note 1) G = 10 G = 100 G=1 G = 10 G = 100 TA = 0C to +85C TA = -40C to +85C 1.5 MIN 2.85 TYP MAX 5.25 1.4 1.15 1 750 950 750 500 500 950 750 750 1400 1900 V/C V UNITS V mA A
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3
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
ELECTRICAL CHARACTERISTICS--MAX4460/MAX4461 (continued)
(VDD = 5V, VCM = 0V, VDIFF = VIN+ - VIN- = 50mV to 100mV for G = 1, 20mV to 100mV for G = 10, 2mV to 48mV for G = 100, MAX4460 is configured for G = 10, RL = 200k to GND, TA = TMIN to TMAX, unless otherwise noted.)
PARAMETER Input Common-Mode Range Input Common-Mode Rejection Ratio Power-Supply Rejection Ratio Input Bias Current FB Input Current VIH SHDN Logic Levels VIL SHDN Input Current VOH Output Voltage Swing VOL MAX4461 MAX4461, V SHDN = 0V or VDD (Note 2) VDD - VOH (Note 3) RL = 200k RL = 20k MAX4461UESA, RL = 20k MAX4461TESA, RL = 20k Gain Error MAX4461HESA, RL = 20k MAX4460ESA, RL = 20k MAX446_EUT, RL = 20k Nonlinearity RL = 20k (Note 1) TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C RL = 200k RL = 20k SYMBOL VCM CMRR PSRR IB CONDITIONS Guaranteed by CMRR test VCM = -0.1V to (VDD - 1.85V) VDD = 2.85V to 5.25V (Note 2) MAX4460 (Note 2) MAX4461 0.7 X VDD 0.3 X VDD 100 4 8 0.25 0.25 0.8 1.6 0.8 1.7 1.0 2.0 0.8 2.0 1.8 3.0 0.20 0.25 % % mV pA MIN -0.1 80 75 100 100 TYP MAX VDD 1.85 UNITS V dB dB pA pA
V
4
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
ELECTRICAL CHARACTERISTICS--MAX4462
(VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted. VDIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.)
PARAMETER Supply Voltage Supply Current Input Offset Voltage (Note 1) Input Resistance Input Common-Mode Range REF Input Range Input Common-Mode Rejection Ratio REF Input Rejection Ratio Power-Supply Rejection Ratio Input Bias Current Input Voltage Noise PSRR IB eN VOH Output Voltage Swing VOL Short-Circuit Current ISC VOL - VSS (Note 3) (Note 4) G = 1V/V, MAX4462UESA Gain Error RL = 10k G = 10V/V, MAX4462TESA G = 100V/V, MAX4462HESA MAX4462_EUT Nonlinearity RL = 10k CMRR VOS RIN VCM SYMBOL VDD CONDITIONS Guaranteed by PSRR test VDD = 5V, VDIFF = 0V VDD = 3V, VDIFF = 0V MAX4462_ESA MAX4462_EUT VCM = VDD/2 Differential mode Common mode VSS 0.1 VSS + 0.1 90 85 80 120 100 100 1 18 38 RL = 100k RL = 10k RL = 100k RL = 10k 1 3 2 6 150 0.1 0.12 0.15 0.15 0.05 0.30 0.35 0.5 0.5 0.15 % % 2.5 5 4 12 mA mV 100 MIN 2.85 0.8 0.68 50 100 2 2 VDD 1.7 VDD 1.7 TYP MAX 5.25 1.1 0.9 250 500 UNITS V mA V G V V dB dB dB pA nV/Hz
MAX4460/MAX4461/MAX4462
Guaranteed by Input CMRR test Guaranteed by REF rejection test VCM = (VSS - 0.1V) to (VDD - 1.7V) VCM = (VSS + 0.1V) to (VDD - 1.7V) VDD = 2.85V to 5.25V (Note 2) f = 10kHz f = 1kHz VDD - VOH (Note 3)
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5
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
ELECTRICAL CHARACTERISTICS--MAX4462 (continued)
(VDD = 5V, VSS = 0V, VCM = VREF = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted. VDIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.)
PARAMETER Maximum Capacitive Load -3dB Bandwidth Gain-Bandwidth Product Slew Rate SYMBOL CL BW-3dB GBWP SR CONDITIONS No sustained oscillations G = 1V/V, MAX4462U CL = 100pF CL = 100pF G = 1V/V, MAX4462U CL = 100pF CL = 100pF, within 0.1% of final value G = 10V/V, MAX4462T G = 100V/V, MAX4462H G = 1V/V, MAX4462U G = 10V/V, MAX4462T G = 100V/V, MAX4462H Settling Time tS G = 10V/V, MAX4462T G = 100V/V, MAX4462H MIN TYP 100 2500 250 25 2.5 0.5 0.5 0.25 15 75 250 s V/s MHz kHz MAX UNITS pF
ELECTRICAL CHARACTERISTICS--MAX4462
(V DD = 5V, V SS = 0V, V CM = V REF = V DD /2, R L = 100k to V DD /2, T A = T MIN to T MAX , unless otherwise noted. V DIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.) (Note 5)
PARAMETER Supply Voltage Supply Current SYMBOL VDD CONDITIONS Guaranteed by PSRR test VDD = 5V, VDIFF = 0V VDD = 3V, VDIFF = 0V MAX4462_ESA Input Offset Voltage (Note 1) VOS MAX4462_EUT Input Offset Voltage Drift Input Common-Mode Range REF Input Range Input Common-Mode Rejection Ratio REF Input Rejection Ratio Power-Supply Rejection Ratio Input Bias Current PSRR IB CMRR TCVOS VCM (Note 1) Guaranteed by input CMRR test Guaranteed by REF rejection test VCM = (VSS - 0.1V) to (VDD - 1.85V) VCM = (VSS + 0.1V) to (VDD - 1.85V) VDD = 2.85V to 5.25V (Note 2) VSS 0.1 VSS + 0.1 80 75 75 100 TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C 1.5 VDD 1.85 VDD 1.85 MIN 2.85 TYP MAX 5.25 1.4 1.15 500 750 1100 1300 V/C V V dB dB dB pA V UNITS V mA
6
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
ELECTRICAL CHARACTERISTICS--MAX4462 (continued)
(V DD = 5V, V SS = 0V, V CM = V REF = V DD /2, R L = 100k to V DD /2, T A = T MIN to T MAX , unless otherwise noted. V DIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.) (Note 5)
PARAMETER SYMBOL VOH Output Voltage Swing VOL VOL - VSS (Note 3) RL = 10k, MAX4462UESA RL = 10k, MAX4462TESA Gain Error GE RL = 10k, MAX4462HESA RL = 10k, MAX4462_EUT Nonlinearity NL RL = 10k VDD - VOH (Note 3) CONDITIONS RL = 100k RL = 10k RL = 100k RL = 10k TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C MIN TYP MAX 4 8 8 16 0.8 1.6 0.8 1.7 0.8 1.7 1.8 3.0 0.2 0.25 % % mV UNITS
MAX4460/MAX4461/MAX4462
Note 1: Offset Voltage is measured with a best straight-line (BSL) method (see A User Guide to Instrumentation Amplifier Accuracy Specifications section). Note 2: Guaranteed by design, not production tested. Note 3: Output swing high is measured only on G = 100 devices. Devices with G = 1 and G = 10 have output swing high limited by the range of VREF, VCM, and VDIFF (see Output Swing section). Note 4: Short-circuit duration limited to 1s (see Absolute Maximum Ratings). Note 5: SOT23 units are 100% production tested at +25C. Limits over temperature are guaranteed by design.
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7
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Typical Operating Characteristics
(VDD = 5V, VSS = 0V, VIN+ = VIN- = VREF = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted. VDIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.)
VOLTAGE OFFSET HISTOGRAM
MAX4460 toc01
VOLTAGE OFFSET DRIFT HISTOGRAM
MAX4460 toc02
GAIN ERROR HISTOGRAM
AV = 100
MAX4460 toc03 MAX4460 toc09
MAX4460 toc06
18 16 PERCENTAGE OF UNITS 14 12 10 8 6 4 2 0
-200 200 -150 100 300 50 150 250 -300 -100 -250 -50 0
16 14 PERCENTAGE OF UNITS 12 10 8 6 4 2 0 -5 -4 -3 -2 -1 0 1 2 3 4 5 VOLTAGE OFFSET DRIFT (V/C)
12 10 PERCENTAGE OF UNITS 8 6 4 2 0
-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2
0.3 0.4 0.5
VOLTAGE OFFSET (V)
GAIN ERROR (%)
GAIN-LINEARITY HISTOGRAM
MAX4460 toc04
COMMON-MODE REJECTION RATIO vs. FREQUENCY
-30 -40 -50 CMRR (dB) -60 -70 -80 -90 -100 -110 -120 -130 -120 0.1 1 10 100 1k 10k 0.01 -100 PSRR (dB) -40 -60 -80 AV = 1V/V
MAX4460 toc05
POWER-SUPPLY REJECTION RATIO VS. FREQUENCY
0 AV = 1V/V -20
16 14 PERCENTAGE OF UNITS 12 10 8 6 4 2 0
0
-20
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10
0.1
1
10
100
1k
10k
LINEARITY (%)
FREQUENCY (Hz)
FREQUENCY (Hz)
INPUT VOLTAGE NOISE vs. FREQUENCY
MAX4460 toc07
PEAK-TO-PEAK NOISE (0.1Hz TO 10Hz)
INPUT REFERRED G = 1, 10, OR 100
MAX4460 toc08
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
0.045 0.040 0.035 THD + N (%) 0.030 0.025 0.020 0.015
10,000 INPUT VOLTAGE NOISE (nV/Hz)
1000
100
2V/div
10
0.010 0.005
VOUT = 100mVP-P G=1 RL = 100k 10 100 1k FREQUENCY (Hz) 10k 100k
1 0.1 1 10 100 1k 10k 100k 1s/div FREQUENCY (Hz)
0
8
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Typical Operating Characteristics (continued)
(VDD = 5V, VSS = 0V, VIN+ = VIN- = VREF = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted. VDIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.)
SUPPLY CURRENT VS. SUPPLY VOLTAGE
1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300
MAX4460 toc10
SHUTDOWN CURRENT VS. SUPPLY VOLTAGE
MAX4460 toc11
MAX4462H NORMALIZED OUTPUT ERROR vs. COMMON-MODE VOLTAGE
0.18 NORMALIZED OUTPUT ERROR (%) 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 VCM (V) VDD = +2.5V, VEE = -2.5V VDIFF = 20mV VOUT = 2V G = 100V/V VREF = 0V
MAX4460 toc12
14 12 SUPPLY CURRENT (nA) 10 8 6 4 2 0 TA = -40C TA = +25C TA = +85C
0.20
TA = +85C
SUPPLY CURRENT (A)
TA = +25C
TA = -40C
2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 SUPPLY VOLTAGE (V)
2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 SUPPLY VOLTAGE (V)
0 -0.02 -0.04 -0.06 -0.08 -0.10 -0.12 -0.14 -0.16 -0.18 -0.20 -0.22 -0.24 -0.26 -0.28 -0.30
MAX4462H NORMALIZED OUTPUT ERROR vs. COMMON-MODE VOLTAGE
MAX4460 toc13
OUTPUT SWING HIGH
VS. OUTPUT CURRENT
MAX4460 toc14
OUTPUT SWING LOW vs. OUTPUT CURRENT
450 400 VOUT - VSS (mV) 350 300 250 200 150 VDD = 5.0V VDD = 3.3V VDD = 2.85V
MAX4460 toc15
200 180 160 VDD - VOUT (mV) 140 120 100 80 60 40 20 0 VDD = 5.0V VDD = 2.85V VDD = 3.3V
NORMALIZED OUTPUT ERROR (%)
VDD = +2.5V, VEE = -2.5V VDIFF = 20mV VOUT = 2V G = 100V/V VREF = 0V
500
100 50 0
-2.7 -2.4 -2.1 -1.8 -1.5 -1.2 -0.9 -0.6 -0.3 0 VCM (V)
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
GAIN vs. FREQUENCY
MAX4460 toc16
GAIN BANDWIDTH vs. TEMPERATURE
MAX4460 toc17
SETTLING TIME (GAIN = 100)
MAX4460 toc18
50 40 30 GAIN (dB) 20 AV = 10V/V 10 0 AV = 1V/V -10 0.01 0.1 1 10 100 1k AV = 100V/V
27
26 -3dB BANDWIDTH (kHz)
INPUT 10mV/div
25
OUTPUT 500mV/div
24 OUTPUT 10mV/div AV = 100V/V 22
23
10k
-40
-15
10
35
60
85
40s/div
FREQUENCY (Hz)
TEMPERATURE (C)
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9
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Typical Operating Characteristics (continued)
(VDD = 5V, VSS = 0V, VIN+ = VIN- = VREF = VDD/2, RL = 100k to VDD/2, TA = +25C, unless otherwise noted. VDIFF = VIN+ - VIN- = -100mV to +100mV for G = 1 and G = 10, -20mV to +20mV for G = 100.)
LARGE-SIGNAL PULSE RESPONSE (GAIN = 1V/V)
MAX4460 toc19
LARGE-SIGNAL PULSE RESPONSE (GAIN = 100V/V)
MAX4460 toc20
SMALL-SIGNAL PULSE RESPONSE (GAIN = 1V/V)
MAX4460 toc21
INPUT
INPUT 10mV/div
INPUT
50mV/div OUTPUT 1V/div OUTPUT
10mV/div
OUTPUT
1s/div
20s/div
1s/div
SMALL-SIGNAL PULSE RESPONSE (GAIN = 1V/V)
MAX4460 toc22
SMALL-SIGNAL PULSE RESPONSE (GAIN = 100V/V)
MAX4460 toc23
SMALL-SIGNAL PULSE RESPONSE (GAIN = 100V/V)
CL = +100V/V GAIN = 100pF CL = 100pF
MAX4460 toc24
CL = 100pF
INPUT 1mV/div
INPUT 1mV/div
INPUT 10mV/div
OUTPUT
OUTPUT 100mV/div
OUTPUT 100mV/div
1s/div
20s/div
20s/div
10
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
Pin Descriptions
PIN MAX4460 SOT23 1 2 3 -- 4 5 6 SO 1 2 3 4, 5 6 7 8 OUT GND IN+ N.C. INVDD FB Output Negative Supply Voltage Positive Differential Input No Connection. Not internally connected. Negative Differential Input Positive Supply Voltage Feedback Input. Connect FB to the center tap of a resistive divider from OUT to GND to set the gain. NAME FUNCTION
MAX4460/MAX4461/MAX4462
PIN MAX4461 SOT23 1 2 3 -- 4 5 6 SO 1 2 3 4, 5 6 7 8 OUT GND IN+ N.C. INVDD SHDN Output Negative Supply Voltage Positive Differential Input No Connection. Not internally connected. Negative Differential Input Positive Supply Voltage Shutdown Control. Drive SHDN high for normal operation. NAME FUNCTION
PIN MAX4462 SOT23 1 2 3 -- 4 5 6 SO 1 2 3 4, 5 6 7 8 OUT VSS IN+ N.C. INVDD REF Output Negative Supply Voltage Positive Differential Input No Connection. Not internally connected. Negative Differential Input Positive Supply Voltage Output Reference Level. Connect REF to an external, lowimpedance reference voltage. REF sets the OUT voltage for zero differential inputs. NAME FUNCTION
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11
SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Functional Diagrams
VDD VDD VDD
MAX4460 OUT
MAX4461 OUT
MAX4462 OUT
SHDN FB gM gM gM gM gM gM REF
VSS
Figure 1. Functional Diagrams
Detailed Description
The MAX4460/MAX4461/MAX4462 family of instrumentation amplifiers implements Maxim's proprietary indirect current-feedback design to achieve a precision specification and excellent gain-bandwidth product. These new techniques allow ground-sensing capability combined with an ultra-low input current and an increased common-mode rejection. The differential input signal is converted to a current by an input transconductance stage. An output transconductance stage converts a portion of the output voltage (equal to the output voltage divided by the gain) into another precision current. These two currents are subtracted and the result is fed to a loop amplifier with a class AB output stage with sufficient gain to minimize errors (Figure 1). The MAX4461U/T/H and MAX4462U/T/H have factorytrimmed gains of 1, 10, and 100, respectively. The MAX4460 has an adjustable gain, set with an external pair of resistors between pins OUT, FB, and GND (Figure 2). The MAX4462U/T/H has a reference input (REF) which is connected to an external reference for bipolar operation of the device. The range for VREF is 0.1V to (VDD 1.7V). For full output-swing capability, optimal performance is usually obtained with VREF = VDD/2. The MAX4460/MAX4461/MAX4462 operate with singlesupply voltages of 2.85V to 5.25V. It is possible to use the MAX4462U/T/H in a dual-supply configuration with up to 2.6V at VDD and VSS, with REF connected to ground.
VDD
MAX4460 OUT
R2 FB gM gM
R1
Figure 2. MAX4460 External Resistor Configuration
The MAX4461U/T/H has a shutdown feature to reduce the supply current to less than 1A. The MAX4461U/ T/H output is internally referenced to ground, making the part suitable for unipolar operations. The MAX4460 has an FB pin that can be used to externally set the gain through a pair of resistors (see Setting the Gain (MAX4460) section). The MAX4460 output is internally referenced to ground, making the part suitable for unipolar operations.
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
Input Common-Mode and Output Reference Ranges
MAX4460/MAX4461/MAX4462 have an input commonmode range of 100mV below the negative supply to 1.7V below the positive supply. The output reference voltage of MAX4462U/T/H is set by REF and ranges from 100mV above the negative supply to 1.7V below the positive supply. For maximum voltage swing in a bipolar operation, connect REF to VDD/2. The output voltages of the MAX4460 and MAX4461U/ T/H are referenced to ground. Unlike the traditional three-op-amp configuration of common instrumentation amplifiers, the MAX4460/MAX4461/MAX4462 have ground-sensing capability (or to V SS in dual-supply configuration) in addition to the extremely high input impedances of MOS input differential pairs. levels. In these cases, as the output approaches either supply, accuracy may degrade, especially under heavy output loading.
MAX4460/MAX4461/MAX4462
Shutdown Mode
The MAX4461U/T/H features a low-power shutdown mode. When the SHDN pin is pulled low, the internal transconductance and amplifier blocks are switched off and supply current drops to typically less than 0.1A (Figure 1). In shutdown, the amplifier output is high impedance. The output transistors are turned off, but the feedback resistor network remains connected. If the external load is referenced to GND, the output drops to approximately GND in shutdown. The output impedance in shutdown is typically greater than 100k. Drive SHDN high or connect to VCC for normal operation.
Input Differential Signal Range
The MAX4460/MAX4461/MAX4462 feature a proprietary input structure optimized for small differential signals. The unipolar output of the MAX4460/MAX4461 is nominally zero-for-zero differential input. However, these devices are specified for inputs of 50mV to 100mV for the unity-gain devices, 20mV to 100mV for gain of 10 devices, and 2mV to 48mV for gain of 100 devices. The MAX4460/MAX4461 can be used with differential inputs approaching zero, albeit with reduced accuracy. The bipolar output of the MAX4462 allows bipolar input ranges. The output voltage is equal to the reference voltage for zero differential input. The MAX4462 is specified for inputs of 100mV for the unity gain and gain of 10 devices, and 20mV for gain of 100 devices. The gain of 100 devices (MAX4462H) can be operated beyond 20mV signal provided the reference is chosen for unsymmetrical swing.
A User Guide to Instrumentation Amplifier Accuracy Specifications
As with any other electronic component, a complete understanding of instrumentation amplifier specifications is essential to successfully employ these devices in their application circuits. Most of the specifications for these differential closed-loop gain blocks are similar to the well-known specifications of operational amplifiers. However, there are a few accuracy specifications that could be confusing to first-time users. Therefore, some explanations and examples may be helpful. Accuracy specifications are measurements of closeness of an actual output response to its ideal expected value. There are three main specifications in this category:
G G
Gain error Gain nonlinearity error
Output Swing
The MAX4460/MAX4461/MAX4462 are designed to have rail-to-rail output voltage swings. However, depending on the selected gain and supply voltage (and output reference level of the MAX4462), the rail-torail output swing is not required. For example, consider the MAX4461U, a unity-gain device with its ground pin as the output reference level. The input voltage range is 0 to 100mV (50mV minimum to meet accuracy specifications). Because the device is unity gain and the output reference level is ground, the output only sees excursions from ground to 100mV. Devices with higher gain and with bipolar output such as the MAX4462, can be configured to swing to higher
G Offset error In order to understand these terms, we must look at the transfer function of an ideal instrumentation amplifier. As expected, this must be a straight line passing through origin with a slope equal to the ideal gain (Figure 3). If the ideal gain is equal to 10 and the extreme applied input voltages are -100mV and +100mV, then the value of the output voltages are -1V and +1V, respectively. Note that the line passes through the origin and therefore a zero input voltage gives a zero output response.
The transfer function of a real instrumentation amplifier is quite different from the ideal line pictured in Figure 3. Rather, it is a curve such as the one indicated as the typical curve in Figure 4, connecting end points A and B.
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
VOUT END-POINT LINE IDEAL TRANSFER FUNCTION (LINE) VOUT B
VOUT2 Z IDEAL LINE VIN1 0 VIN2 ACTUAL CURVE VIN 0 E VIN
VOUT1 A
Figure 3. Transfer Function of an Ideal Instrumentation Amplifier (Straight Line Passing Through the Origin)
Figure 4. Typical Transfer Function for a Real Instrumentation Amplifier
Looking at this curve, one can immediately identify three types of errors. First, there is an obvious nonlinearity (curvature) when this transfer function is compared to a straight line. More deviation is measured as greater nonlinearity error. This is explained in more detail below. Second, even if there was no nonlinearity error, i.e., the actual curve in Figure 4 was a straight line connecting end points A and B, there exists an obvious slope deviation from that of an ideal gain slope (drawn as the "ideal" line in Figure 4). This rotational error (delta slope) is a measure of how different the actual gain (GA) is from the expected ideal gain (GI) and is called gain error (GE) (see the equation below). Third, even if the actual curve between points A and B was a straight line (no nonlinearity error) and had the same slope as the ideal gain line (no gain error), there is still another error called the end-point offset error (OE on vertical axis), since the line is not passing through the origin. Figure 5 is the same as Figure 4, but the ideal line (CD) is shifted up to pass through point E (the Y intercept of end-points line AB). This is done to better visualize the rotational error (GE), which is the difference between the slopes of end points line AB and the shifted ideal line CD. Mathematically: GE (%) = 100 x (GA - GI) / GI
ACTUAL CURVE VOUT B END-POINT LINE D
Z NL+
IDEAL LINE SHIFT
E VIN
0
C
NL-
A
SLOPE(CD) = IDEAL GAIN = GI SLOPE(AB) = ACTUAL GAIN = GA GAIN ERROR (%) = GE (%) = 100 X (GA - GI) / GI OFFSET(END POINT) = OE NL- = NL+
Figure 5. Typical Transfer Function for a Real Instrumentation Amplifier (Ideal Line (CD) Is Shifted by the End-Points Offset (OE) to Visualize Gain Error)
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers
The rotational nature of gain error, and the fact that it is pivoted around point E in Figure 5, shows that gainerror contribution to the total output voltage error is directly proportional to the input voltage. At zero input voltage, the error contribution of gain error is zero, i.e., the total deviation from the origin (the expected zero output value) is only due to end-points OE and nonlinearity error at zero value of input (segment EZ on the vertical axis). The nonlinearity is the maximum deviation from a straight line, and the end-point nonlinearity is the deviation from the end-point line. As shown in Figure 5, it is likely that two nonlinearities are encountered, one positive and the other a negative nonlinearity error, shown as NL+ and NL- in Figure 5. Generally, NL+ and NL- have different values and this remains the case if the device is calibrated (trimmed) for end-points errors (which means changing the gain of the instrumentation amplifier in such a way that the slope of line AB becomes equal to that of CD, and the offset becomes trimmed such that OE vanishes to zero). This is an undesirable situation when nonlinearity is of prime interest. The straight line shown in Figure 6 is in parallel to endpoints line AB and has a Y intercept of OS on the vertical axis. This line is a shifted end-points line such that the positive and negative nonlinearity errors with respect to this line are equal. For this reason, the line is called the best straight line (BSL). Maxim internally trims the MAX4460/MAX4461/MAX4462 with respect to this line (changing the gain slope to be as close as possible to the slope of the ideal line and trimming the offset such that OS gets as close to the origin as possible) to minimize all the errors. The total accuracy error is still the summation of the gain error, nonlinearity, and offset errors. As an example, assume the following specification for an instrumentation amplifier: Gain = 10 GE = 0.15% Offset (BSL) = 250V NL = 0.05% VDIF (input) = -100mV to +100mV What is the maximum total error associated with the GE, offset (BSL), and NL? With a differential input range of -0.1V to +0.1V and a gain of 10, the output voltage assumes a range of -1V to +1V, i.e., a total full-scale range of 2V.
MAX4460/MAX4461/MAX4462
ACTUAL CURVE VOUT B END-POINT LINE
Z NL+
BSL LINE
S E 0 VIN
NL-
A NL+ = NL- = NL NLBSL (%) = (NL / FULL-SCALE OUTPUT RANGE) X 100 OFFSET (BSL) = OSL GAIN AND OFFSET WILL BE FACTORY-TRIMMED FOR BEST STRAIGHT LINE
Figure 6. To Minimize Nonlinearity Error, the MAX4460/MAX4461/ MAX4462 are Internally Trimmed to Adjust Gain and Offset for the Best Straight Line so NL- = NL+
The individual errors are as follows: GE = (0.15%) (10) (100mV) = 1.5mV Offset (BSL) = (250V) (10) = 2.5mV NL = (0.05%) (2V) = 1mV Maximum Total Error = 1.5mV + 2.5mV + 1mV = 5mV So, the absolute value of the output voltage, considering the above errors, would be at worst case between 0.995V to 1.005V. Note that other important parameters such as PSRR, CMRR, and noise also contribute to the total error in instrumentation applications. They are not considered here.
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Applications Information
Setting the Gain (MAX4460)
The MAX4460 gain is set by connecting a resistivedivider from OUT to GND, with the center tap connected to FB (Figure 2). The gain is calculated by: Gain = 1 + R2 / R1 Because FB has less than 100pA IB, high-valued resistors can be used without significantly affecting the gain accuracy. The sum of resistors (R1 + R2) near 100k is a good compromise. Resistor accuracy directly affects gain accuracy. Resistor sum less than 20k should not be used because their loading can slightly affect output accuracy.
Power-Supply Bypass and Layout
Good layout technique optimizes performance by decreasing the amount of stray capacitance at the instrumentation amplifier's gain-setting pins. Excess capacitance produces peaking in the amplifier's frequency response. To decrease stray capacitance, minimize trace lengths by placing external components as close to the instrumentation amplifier as possible. For best performance, bypass each power supply to ground with a separate 0.1F capacitor.
Microphone Amplifier
The MAX4462's bipolar output, along with its excellent common-mode rejection ratio, makes it suitable for precision microphone amplifier applications. Figure 7 illustrates one such circuit. In this case, the electret microphone is resistively biased to the supply voltage through a 2.2k pullup resistor. The MAX4462 directly senses the output voltage at its noninverting input, and indirectly senses the microphone's ground through an AC-coupling capacitor. This technique provides excellent rejection of common-mode noise picked up by the microphone lead wires. Furthermore, ground noise from distantly located microphones is reduced. The single-ended output of the MAX4462 is converted to differential through a single op amp, the MAX4335. The op amp forces the midpoint between OUT+ and OUT- to be equal to the reference voltage. The configuration does not change the MAX4662T's fixed gain of 10.
Capacitive-Load Stability
The MAX4460/MAX4461/MAX4462 are capable of driving capacitive loads up to 100pF. Applications needing higher capacitive drive capability may use an isolation resistor between OUT and the load to reduce ringing on the output signal. However this reduces the gain accuracy due to the voltage drop across the isolation resistor.
Output Loading
For best performance, the output loading should be to the potential seen at REF for the MAX4462 or to ground for the MAX4460/MAX4461.
REF Input (MAX4462)
The REF input of the MAX4462 can be connected to any voltage from (VSS + 0.1V) to (VDD - 1.7V). A buffered voltage-divider with sink and source capability works well to center the output swing at VDD/2. Unbuffered resistive dividers should be avoided because the 100k (typ) input impedance of REF causes amplitude-dependent variations in the divider's output. Bandgap references, either series or shunt, can be used to drive REF. This provides a voltage and temperature invariant reference. This same reference voltage can be used to bias bridge sensors to eliminate supply voltage ratiometricity. For proper operation, the reference must be able to sink and source at least 25A. In many applications, the MAX4462 is connected to a CODEC or other device with a reference voltage output. In this case, the receiving device's reference output makes an ideal reference voltage. Verify the reference output of the device is capable of driving the MAX4462's REF input.
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
3.3k VDD
4.7F
2.2k
MAX4462TEUT
3
5 1 OUT+
100k 4 2 6 20k 6 MIC 4
MAX4335
20k
3
1 2 0.1F
VREF
OUT-
Figure 7. Differential I/O Microphone Amplifier
Typical Application Circuits (continued)
VCC
Selector Guide
PART MAX4460 MAX4461U MAX4461T GAIN Adjustable 1 10 100 1 10 100 REF GND GND GND GND EXT EXT EXT SHUTDOWN NO YES YES YES NO NO NO
V
VCM + V V > 0 VCM
3
5
MAX4461
1 OUT SHDN
MAX4461H MAX4462U MAX4462T MAX4462H
4 2
6
Chip Information
TRANSISTOR COUNT: 421 PROCESS: BiCMOS
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
Pin Configurations
TOP VIEW
OUT 1 6 FB OUT 1 GND 2 5 VDD 8 7 FB VDD INN.C.
GND 2
MAX4460
MAX4460
IN+ 3 6 5 N.C. 4
IN+ 3
4
IN-
SOT23
SO
OUT 1
6
SHDN
OUT 1 GND 2
8 SHDN 7
GND 2
MAX4461
5
VDD
MAX4461
IN+ 3 6 5 N.C. 4
VDD INN.C.
IN+ 3
4
IN-
SOT23
SO
OUT 1
6
REF
OUT 1 VSS 2
8 7
REF VDD INN.C.
VSS 2
MAX4462
5
VDD
MAX4462
6 5
IN+
3
IN+ 3
4
IN-
N.C. 4
SOT23
SO
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
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
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SOT23, 3V/5V, Single-Supply, Rail-to-Rail Instrumentation Amplifiers MAX4460/MAX4461/MAX4462
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
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 C
A e B A1
0 -8 L
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.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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