LT1997-1 Precision, High Voltage, Gain Selectable Difference/Current Sense Amplifier FEATURES DESCRIPTION Precision Gain: Up to 80V/V nn Input Common Mode Voltage Range: V- to V- + 76V nn 109dB Minimum CMRR (Gain = 10) nn 0.012% (120ppm) Maximum Gain Error (Gain = 10) nn 1ppm/C Maximum Gain Error Drift nn 2ppm Maximum Gain Nonlinearity nn Wide Supply Voltage Range: 3.3V to 50V nn Rail-to-Rail Output nn 350A Supply Current nn 65V Maximum Op Amp Offset Voltage nn 650kHz -3dB Bandwidth (Gain = 10) nn Low Power Shutdown: 20A nn Space-Saving MSOP and DFN Packages The LT(R)1997-1 is a difference amplifier that can be used to amplify small differential signals while rejecting large common mode signals making it an ideal choice for current sense applications. It combines a precision operational amplifier with highly-matched resistors to form a one-chip solution to amplify and level shift voltages accurately using no external components. It comes with three standard pin-selectable gain options (10, 20 and 50), which can be further combined to form gains from 0.141 to 80 with accuracy of 0.012% (120ppm). The LT1997-1 also operates with input voltages between V- and V- + 76V (independent of V+), enabling robust operation in demanding industrial environments. Its excellent resistor matching results in a common mode rejection ratio of greater than 109dB (Gain = 10). APPLICATIONS The resistors maintain their excellent matching over temperature; the matching temperature coefficient is guaranteed less than 1ppm/C. The resistors are extremely linear with voltage, resulting in a gain nonlinearity of less than 2ppm. nn High Side or Low Side Current Sensing Bidirectional Wide Common Mode Range Current Sensing nn High Voltage to Low Voltage Level Translation nn Industrial Data-Acquisition Front-Ends nn Replacement for Isolation Circuits nn Differential to Single-Ended Conversion nn nn The LT1997-1 is fully specified at 5V and 15V supplies and from -40C to 125C. The device is available in space saving 16-lead MSOP and 4mm x 4mm DFN14 packages. All registered trademarks and trademarks are the property of their respective owners. TYPICAL APPLICATION Precision Wide Voltage Range, Bidirectional Current Monitor Typical Distribution of CMRR (G = 10) 15V VSOURCE = -15V TO 61V 250 V+ LT1997-1 -INA -INB -INC 3k RSENSE 1 RC 1 150k 15k - 15k + OUT 7.5k VOUT = 10mV/mA 300k REF2 300k REF1 3k LOAD +INA +INB +INC 19971 TA01a VS = 15V VCM = -15V TO +14.575V 150 100 50 0 SHDN V- -15V NUMBER OF UNITS 200 7.5k 661 UNITS FROM 2 RUNS MS16(12) -5 -4 -3 -2 -1 0 1 2 CMRR (V/V = ppm) 3 4 5 19971 TA01b Rev 0 Document Feedback For more information www.analog.com 1 LT1997-1 TABLE OF CONTENTS Features............................................................................................................................. 1 Applications........................................................................................................................ 1 Typical Application ................................................................................................................ 1 Description......................................................................................................................... 1 Absolute Maximum Ratings...................................................................................................... 3 Pin Configuration.................................................................................................................. 3 Order Information.................................................................................................................. 3 Electrical Characteristics......................................................................................................... 4 Typical Performance Characteristics........................................................................................... 9 Pin Functions......................................................................................................................14 Block Diagram.....................................................................................................................15 Applications Information........................................................................................................16 Package Description.............................................................................................................28 Typical Application...............................................................................................................30 Related Parts......................................................................................................................30 Rev 0 2 For more information www.analog.com LT1997-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Supply Voltages (V+ to V-).........................................60V +INA, -INA, +INB, -INB, +INC, -INC (Note 2)...................(V- + 80V) to (V- -0.3V) REF, REF1, REF2..................... (V- + 60V) to (V- - 0.3V) SHDN...................................... (V+ + 0.3V) to (V- - 0.3V) Output Current (Continuous) (Note 6).....................50mA Output Short-Circuit Duration (Note 3)...........................................Thermally Limited Temperature Range (Notes 4, 5) LT1997I-1..................................................-40 to 85C LT1997H-1.............................................. -40 to 125C Maximum Junction Temperature........................... 150C Storage Temperature Range.......................-65 to 150C MSOP Lead Temperature (Soldering, 10 sec)......... 300C PIN CONFIGURATION TOP VIEW +INA 14 -INA 1 16 -INA 12 -INB +INB 3 14 -INB 11 NC +INC REF1 REF2 V- +INB 3 NC 4 +INC 5 SHDN 6 10 -INC 9 V+ REF 7 8 15 V- TOP VIEW +INA 1 5 6 7 8 -INC V+ SHDN OUT 12 11 10 9 MS PACKAGE VARIATION: MS16 (12) 16-LEAD PLASTIC MSOP OUT DF PACKAGE 14(12)-LEAD (4mm x 4mm) PLASTIC DFN TJMAX = 150C, JA = 130C/W TJMAX = 150C, JA = 45C/W , JC = 3C/W EXPOSED PAD (PIN 15) IS V-, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT1997IDF-1#PBF LT1997IDF-1#TRPBF 19971 14-Lead (4mm x 4mm) Plastic DFN -40C to 85C LT1997HDF-1#PBF LT1997HDF-1#TRPBF 19971 14-Lead (4mm x 4mm) Plastic DFN -40C to 125C LT1997IMS-1#PBF LT1997IMS-1#TRPBF 19971 16-Lead Plastic MSOP -40C to 85C LT1997HMS-1#PBF LT1997HMS-1#TRPBF 19971 16-Lead Plastic MSOP -40C to 125C *The temperature grade is identified by a label on the shipping container. Consult ADI Marketing for parts specified with wider operating temperature ranges. Parts ending with PBF are RoHS and WEEE compliant. Tape and reel specifications. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. Rev 0 For more information www.analog.com 3 LT1997-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, -40C < TA < 85C for I-grade parts, -40C < TA < 125C for H-grade parts, otherwise specifications are at TA = 25C. Difference Amplifier Configuration, V+ = 15V, V- = -15V, VCM = VOUT = VREF = VREF1 = VREF2 = 0V. VCMOP is the common mode voltage of the internal op amp. SYMBOL PARAMETER CONDITIONS G VOUT = 10V G = 10 Gain Error MS16 Package MIN TYP MAX 0.005 0.012 0.014 0.022 0.028 0.038 0.04 % % % % % % 0.017 0.019 0.025 0.03 0.051 0.053 1 2 3 65 200 1.5 5 15 3 10 % % % % % % ppm/C ppm ppm V V V/C nA nA nA nA l 0.01 G = 20 l 0.015 G = 50 l G Gain Error DF14 Package VOUT = 10V G = 10 0.005 l 0.01 G = 20 l 0.015 G = 50 l G/T GNL Gain Drift vs Temperature (Note 6) Gain Nonlinearity VOUT = 10V VOUT = 10V VOS Op Amp Offset Voltage (Note 9) V- < VCMOP < V+ - 1.75V 0.2 1 l l 20 l VOS/T IB Op Amp Offset Voltage Drift (Note 6) Op Amp Input Bias Current V- < VCMOP < V+ - 1.75V V- + 0.25V < VCMOP < V+ - 1.75V l l -5 -15 -3 -10 l l l 69.3 66.1 64.2 82.5 78.75 76.5 95.7 91.4 88.8 k k k l l l 25.2 12.6 5 109 107 84 82 109 107 116 114 107 100 81 78 107 102 111 107 30 15 6 126 34.8 17.4 7 k k k dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB dB l IOS RIN CMRR Op Amp Input Offset Current Input Impedance (Note 8) Common Mode Rejection Ratio MS16 Package V- + 0.25V < VCMOP < V+ - 1.75V Common Mode G = 10 G = 20 G = 50 Differential G = 10 G = 20 G = 50 G = 10, VCM = -15V to +14.575V l G = 10, VCM = -15V to +61V, +INC = -INC = 0V l G = 20, VCM = -15V to +13.9125V l G = 50, VCM = -15V to +13.515V l CMRR Common Mode Rejection Ratio DF14 Package 0.5 2 UNITS G = 10, VCM = -15V to +14.575V l G = 10, VCM = -15V to +61V, +INC = -INC = 0V l G = 20, VCM = -15V to +13.9125V l G = 50, VCM = -15V to +13.515V l 0.5 98 128 130 123 96 124 125 Rev 0 4 For more information www.analog.com LT1997-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, -40C < TA < 85C for I-grade parts, -40C < TA < 125C for H-grade parts, otherwise specifications are at TA = 25C. Difference Amplifier Configuration, V+ = 15V, V- = -15V, VCM = VOUT = VREF = VREF1 = VREF2 = 0V. VCMOP is the common mode voltage of the internal op amp. SYMBOL PARAMETER CONDITIONS VCM Input Voltage Range (Note 7) R/R Reference Divider Matching Error R R -R = REF1 REF2 R RREF1 + RREF2 2 +INA/-INA +INA/-INA (+INC/-INC Connected to Ground) +INB/-INB +INC/-INC Available in MS16 Package Only Power Supply Rejection Ratio (Note 9) VS = 1.65V to 25V, VCM = VOUT = Mid-Supply eni Input Referred Noise Voltage Density f = 1kHz G = 10 G = 20 G = 50 f = 0.1Hz to 10Hz G = 10 G = 20 G = 50 No Load ISINK = 5mA No Load ISOURCE = 5mA 50 to V+ 50 to V- VOUT = 5V VOL ISC Output Voltage Swing Low (Referred to V-) Output Voltage Swing High (Referred to V+) Short-Circuit Output Current SR Slew Rate BW Small Signal -3dB Bandwidth tS Settling Time VOH VS TYP -15 -15 -15 -15 0.002 l PSRR Input Referred Noise Voltage MIN l l l l l 114 l l l l l l l 10 10 1.7 G = 10 G = 20 G = 50 G = 10 0.1%, VOUT = 10V 0.01%, VOUT = 10V G = 20 0.1%, VOUT = 10V 0.01%, VOUT = 10V G = 50 0.1%, VOUT = 10V 0.01%, VOUT = 10V Supply Voltage l tON Turn-On Time VIL SHDN Input Logic Low (Referred to V+) l VIH SHDN Input Logic High (Referred to V+) l ISHDN SHDN Pin Current l IS Supply Current MAX 14.575 61 13.9125 13.515 0.006 0.008 dB 31 26 22 nV/Hz nV/Hz nV/Hz 0.9 0.8 0.7 30 280 30 400 32 34 4 VP-P VP-P VP-P mV mV mV mV mA mA V/s 150 500 150 900 650 500 300 kHz kHz kHz 6.3 21.3 s s 7.5 15.4 s s 8.6 23 s s V V s 3 3.3 50 50 -2.5 V -10 -15 A 350 400 600 25 70 A A A A -1.2 V l 20 l V V V V % % 124 16 Active, VSHDN V+ - 1.2V Active, VSHDN V+ - 1.2V Shutdown, VSHDN V+ - 2.5V Shutdown, VSHDN V+ - 2.5V UNITS Rev 0 For more information www.analog.com 5 LT1997-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, -40C < TA < 85C for I-grade parts, -40C < TA < 125C for H-grade parts, otherwise specifications are at TA = 25C. Difference Amplifier Configuration, V+ = 5V, V- = 0V, VCM = VOUT = VREF = VREF1 = VREF2 = Mid-Supply. VCMOP is the common mode voltage of the internal op amp. SYMBOL PARAMETER CONDITIONS G VOUT = 1V to 4V G = 10 Gain Error MS16 Package MIN TYP MAX 0.005 0.012 0.014 0.022 0.028 0.035 0.037 % % % % % % 0.017 0.019 0.024 0.028 0.048 0.05 1 % % % % % % ppm/C l 0.01 G = 20 l 0.015 G = 50 l G Gain Error DF14 Package VOUT = 1V to 4V G = 10 0.005 l 0.01 G = 20 l 0.015 G = 50 l G/T Gain Drift vs Temperature (Note 6) VOUT = 1V to 4V GNL Gain Nonlinearity VOUT = 1V to 4V Op Amp Offset Voltage (Note 9) V- < V VOS CMOP 0.2 l 1 < V+ - 1.75V 20 l VOS/T IB Op Amp Offset Voltage Drift (Note 6) V- < VCMOP < V+ - 1.75V Op Amp Input Bias Current V- + 0.25V < VCMOP < V+ - 1.75V RIN CMRR Op Amp Input Offset Current Input Impedance (Note 8) Common Mode Rejection Ratio MS16 Package Common Mode G = 10 G = 20 G = 50 Differential G = 10 G = 20 G = 50 G = 10, VCM = 0V to +3.325V 69.3 66.1 64.2 82.5 78.75 76.5 95.7 91.4 88.8 k k k l l l 25.2 12.6 5 106 104 109 106 112 109 104 100 105 102 107 105 30 15 6 124 34.8 17.4 7 k k k dB dB dB dB dB dB dB dB dB dB dB dB % % l l G = 50, VCM = 0V to +3.265V l Common Mode Rejection Ratio DF14 Package G = 10, VCM = 0V to +3.325V l G = 20, VCM = 0V to +3.2875V l G = 50, VCM = 0V to 3.265V l R/R Reference Divider Matching Error Available in MS16 Package Only R - R REF2 R = REF1 R REF1 + R REF2 R 2 V V V/C l l l G = 20, VCM = 0V to +3.2875V CMRR 65 240 1.5 l V- + 0.25V < VCMOP < V+ - 1.75V 2 ppm -5 -15 -3 -10 l IOS 0.5 l UNITS 0.5 nA nA nA nA 125 126 119 120 121 0.002 l 5 15 3 10 0.006 0.008 Rev 0 6 For more information www.analog.com LT1997-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, -40C < TA < 85C for I-grade parts, -40C < TA < 125C for H-grade parts, otherwise specifications are at TA = 25C. Difference Amplifier Configuration, V+ = 5V, V- = 0V, VCM = VOUT = VREF = VREF1 = VREF2 = Mid-Supply. VCMOP is the common mode voltage of the internal op amp. SYMBOL PARAMETER CONDITIONS PSRR Power Supply Rejection Ratio (Note 9) VS = 1.65V to 25V, VCM = VOUT = Mid-Supply eni Input Referred Noise Voltage Density VOL VOH ISC SR BW tS VS f = 1kHz G = 10 G = 20 G = 50 Input Referred Noise Voltage f = 0.1Hz to 10Hz G = 10 G = 20 G = 50 - Output Voltage Swing Low (Referred to V ) No Load ISINK = 5mA + Output Voltage Swing High (Referred to V ) No Load ISOURCE = 5mA Short-Circuit Output Current 50 to V+ 50 to V- Slew Rate VOUT = 3V Small signal -3dB Bandwidth G = 10 G = 20 G = 50 Settling Time G = 10 0.1%, VOUT = 2V 0.01%, VOUT = 2V G = 20 0.1%, VOUT = 2V 0.01%, VOUT = 2V G = 50 0.1%, VOUT = 2V 0.01%, VOUT = 2V Supply Voltage l Turn-On Time SHDN Input Logic Low (Referred to V+) SHDN Input Logic High (Referred to V+) SHDN Pin Current Supply Current TYP 114 124 dB 31 26 22 nV/Hz nV/Hz nV/Hz 0.9 0.8 0.7 10 280 10 400 30 28 2.5 650 500 300 VP-P VP-P VP-P mV mV mV mV mA mA V/s kHz kHz kHz l l l l l l l l tON VIL VIH ISHDN IS MIN 10 10 1.5 MAX 50 500 50 800 9 20.4 s s 9.7 18.5 s s 10.9 31.2 s s V V s V V A A A A A 3 3.3 50 50 22 -2.5 l l l Active, VSHDN V+ - 1.2V Active, VSHDN V+ -1.2V Shutdown, VSHDN V+ - 2.5V Shutdown, VSHDN V+ - 2.5V -1.2 -10 330 l 15 l UNITS -15 370 525 20 40 Rev 0 For more information www.analog.com 7 LT1997-1 ELECTRICAL CHARACTERISTICS Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: See Common Mode Voltage Range in the Applications Information section of this data sheet for other considerations when taking +INA/ -INA/+INB/-INB/+INC/-INC pins to V- + 80V. Note 3: A heat sink may be required to keep the junction temperature below absolute maximum. This depends on the power supply, input voltages and the output current. Note 4: The LT1997I-1 is guaranteed functional over the operating temperature range of -40C to 85C. The LT1997H-1 is guaranteed functional over the operating temperature range of -40C to 125C. Note 5: The LT1997I-1 is guaranteed to meet specified performance from -40C to 85C. The LT1997H-1 is guaranteed to meet specified performance from -40C to 125C. Note 6: This parameter is not 100% tested. Note 7: The input voltage range is guaranteed by the 15V CMRR tests. The Input Voltage Range numbers specified in the table guarantee that the internal op amp operates in its normal operating region. The Input voltage range can be higher if the internal op amp operates in its Over-The-Top(R) operating region. See Common Mode Voltage Range in the Applications Information section to determine the valid input voltage range under various operating conditions. Note 8: Input impedance is tested by a combination of direct measurements and correlation to the CMRR and gain error tests. Note 9: Offset voltage, offset voltage drift and PSRR are defined as referred to the internal op amp. The following shows the calculation of output offset: In the case of balanced source resistance, VOS,OUT = (VOS * NOISEGAIN) + (IOS * 150k) + (IB * 150k * (1- RP/RN)) where RP and RN are the total resistance at the op amp positive and negative terminal, respectively. Rev 0 8 For more information www.analog.com LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VS = 15V, Difference Amplifier configuration, unless otherwise noted. Typical Distribution of CMRR (G = 10) 661 UNITS FROM 2 RUNS MS16(12) 150 100 50 0 693 UNITS FROM 2 RUNS DF14(12) 200 NUMBER OF UNITS NUMBER OF UNITS 200 250 VS = 15V VCM = -15V TO +14.575V 200 150 100 50 -5 -4 -3 -2 -1 0 1 2 CMRR (V/V = ppm) 3 4 0 5 684 UNITS FROM 2 RUNS DF14(12) -5 -4 -3 -2 -1 0 1 2 CMRR (V/V = ppm) 250 VS = 15V VCM = -15V TO +61V +INC = -INC = 0V 661 UNITS FROM 2 RUNS MS16(12) 200 150 100 50 3 4 0 -100 -80 -60 -40 -20 0 20 40 60 80 100 CMRR (V/V = ppm) 19971 G03 Typical Distribution of CMRR (G = 20) 250 VS = 15V VCM = -15V TO +13.9125V 200 150 100 0 100 -5 -4 -3 -2 -1 0 1 2 CMRR (V/V = ppm) 3 4 0 5 250 684 UNITS FROM 2 RUNS DF14(12) 100 50 3 4 5 Typical Distribution of Gain Error (G = 10) 400 VS = 15V VCM = -15V TO +13.515V 1357 UNITS 350 FROM 4 RUNS BOTH PACKAGES VS = 15V VOUT = 10V 300 NUMBER OF UNITS NUMBER OF UNITS 200 150 -5 -4 -3 -2 -1 0 1 2 CMRR (V/V = ppm) 19971 G06 Typical Distribution of CMRR (G = 50) VS = 15V VCM = -15V TO +13.515V VS = 15V VCM = -15V TO +13.9125V 150 19971 G05 Typical Distribution of CMRR (G = 50) 200 693 UNITS FROM 2 RUNS DF14(12) 50 19971 G04 652 UNITS FROM 2 RUNS MS16(12) 100 0 -100 -80 -60 -40 -20 0 20 40 60 80 100 CMRR (V/V = ppm) 5 50 250 150 Typical Distribution of CMRR (G = 20) NUMBER OF UNITS 200 VS = 15V VCM = -15V TO +61V +INC = -INC = 0V 50 NUMBER OF UNITS 250 652 UNITS FROM 2 RUNS MS16(12) 19971 G02 Typical Distribution of CMRR (G = 10) NUMBER OF UNITS 250 VS = 15V VCM = -15V TO +14.575V 19971 G01 NUMBER OF UNITS Typical Distribution of CMRR (G = 10) NUMBER OF UNITS 250 Typical Distribution of CMRR (G = 10) 150 100 250 200 150 100 50 50 0 -3 -2 -1 0 1 CMRR (V/V = ppm) 2 3 19971 G07 0 -3 -2 -1 0 1 CMRR (V/V = ppm) 2 3 19971 G08 0 -200-160-120 -80 -40 0 40 80 120 160 200 GAIN ERROR (ppm) 19971 G09 Rev 0 For more information www.analog.com 9 LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VS = 15V, Difference Amplifier configuration, unless otherwise noted. Typical Distribution of Gain Error (G = 20) 350 VS = 15V VOUT = 10V 1357 UNITS FROM 4 RUNS 300 BOTH PACKAGES 250 NUMBER OF UNITS 200 150 100 200 150 100 -200 -150 -100 -50 GAIN ERROR (ppm) 0 -400 -300 -200 -100 GAIN ERROR (ppm) 0 19971 G10 350 250 300 1365 UNITS FROM 4 RUNS 250 BOTH PACKAGES -20 0 20 OFFSET VOLTAGE (V) 40 VS = 1.65V to 25V 150 100 0 -1.5 60 -1 -0.5 0 0.5 PSRR (V/V) 1 19971 G13 VS = 12V 120 100 80 60 40 0 1.5 VS = 18V VS = 15V VS = 12V G = 10 G = 20 G = 50 20 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 19971 G15 Typical Gain Error for RL = 2k (G = 10) (Curves Offset for Clarity) Typical Gain Error for RL = 5k (G = 10) (Curves Offset for Clarity) OUTPUT ERROR (2mV/DIV) OUTPUT ERROR (2mV/DIV) VS = 15V 19971 G12 19971 G14 Typical Gain Error for RL = 10k (G = 10) (Curves Offset for Clarity) VS = 18V 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 GAIN NONLINEARITY (ppm) CMRR vs Frequency 50 -40 0 140 200 50 0 -60 0 100 COMMON MODE REJECTION RATIO (dB) NUMBER OF UNITS NUMBER OF UNITS 1388 UNITS FROM 4 RUNS 300 BOTH PACKAGES 100 150 Typical Distribution of Op Amp PSRR 350 150 200 19971 G11 Typical Distribution of Op Amp Offset Voltage 200 250 50 0 -500 50 1357 UNITS FROM 4 RUNS BOTH PACKAGES 300 100 50 0 -250 VS = 15V VOUT = 10V G = 10 400 350 250 50 450 VS = 15V VOUT = 10V OUTPUT ERROR (2mV/DIV) NUMBER OF UNITS 1357 UNITS FROM 4 RUNS 300 BOTH PACKAGES NUMBER OF UNITS 350 Typical Distribution of Gain Nonlinearity Typical Distribution of Gain Error (G = 50) VS = 18V VS = 15V VS = 12V VS = 10V VS = 10V VS = 10V -20 -16 -12 -8 -4 0 4 8 12 16 20 OUTPUT VOLTAGE (V) -20 -16 -12 -8 -4 0 4 8 12 16 20 OUTPUT VOLTAGE (V) -20 -16 -12 -8 -4 0 4 8 12 16 20 OUTPUT VOLTAGE (V) 19971 G16 19971 G17 19971 G18 Rev 0 10 For more information www.analog.com LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS configuration, unless otherwise noted. Output Voltage vs Load Current CMRR vs Temperature 10 20 160 16 8 15 120 12 6 80 8 4 40 4 0 0 -40 -4 -80 -8 0 -2 -4 -12 -6 -16 -8 -20 -200 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C) VS = 15V 10 UNITS G=10 -20 1 20 25 G = 20 20 G = 10 15 10 0 -10 5 MS16(12) JA = 130C/W 0 -60 -40 -20 0 20 40 60 80 100 120 140 160 AMBIENT TEMPERATURE (C) 0 0.001 0.01 0.1 FREQUENCY (MHz) 19971 G22 30 30 20 20 GAIN (dB) 40 -10 -20 0.001 0pF 270pF 560pF 1000pF 1800pF 2200pF 0.01 0.1 1 FREQUENCY (MHz) 2 -20 0.001 10 Input Referred Noise Density vs Frequency (G = 10) 60 10 0 -10 10 0.01 0.1 1 FREQUENCY (MHz) 19971 G24 Frequency Response vs Capacitive Load (G = 50) 40 0 1 0pF 270pF 560pF 1000pF 1800pF 19971 G23 Frequency Response vs Capacitive Load (G = 20) 30 30 G = 50 10 10 10 15 20 25 OUTPUT CURRENT (mA) 40 30 2 5 Frequency Response vs Capacitive Load (G = 10) 35 DF14(12) JA = 45C/W 3 0 19971 G21 40 GAIN (dB) MAXIMUM POWER DISSIPATION (W) -10 Gain vs Frequency 5 GAIN (dB) -5 19971 G20 Maximum Power Dissipation vs Temperature 4 130C 85C 25C -45C 0 -15 -10 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C) 19971 G19 5 GAIN (dB) -160 2 10 VOLTAGE NOISE DENSITY (nV/Hz) -120 VS = 15V VOUT = 10V RL = 10k 10 UNITS G=10 OUTPUT VOLTAGE (V) 20 CMRR (V/V = ppm) 200 GAIN ERROR (m%) GAIN ERROR (ppm) Gain Error vs Temperature TA = 25C, VS = 15V, Difference Amplifier -20 0.001 0pF 270pF 560pF 1000pF 1800pF 2200pF 3300pF 0.01 0.1 1 FREQUENCY (MHz) 19971 G25 10 19971 G26 50 40 30 20 10 0 1 10 100 1k FREQUENCY (Hz) 10k 100k 19971 G27 Rev 0 For more information www.analog.com 11 LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VS = 15V, Difference Amplifier configuration, unless otherwise noted. Input Referred 0.1Hz to 10Hz Noise (G = 10) Input Referred Noise Density vs Frequency (G = 20) Input Referred 0.1Hz to 10Hz Noise (G = 20) 50 NOISE VOLTAGE (200nV/DIV) NOISE VOLTAGE (200nV/DIV) VOLTAGE NOISE DENSITY (nV/Hz) 60 40 30 20 10 0 TIME (10s/DIV) 1 10 100 1k FREQUENCY (Hz) 10k 19971 G28 100k TIME (10s/DIV) 19971 G29 19971 G30 Input Referred 0.1Hz to 10Hz Noise (G = 50) Input Referred Noise Density vs Frequency (G = 50) Positive PSRR vs Frequency 50 40 30 20 10 0 POWER SUPPLY REJECTION RATIO (dB) 160 NOISE VOLTAGE (200nV/DIV) VOLTAGE NOISE DENSITY (nV/Hz) 60 1 10 100 1k FREQUENCY (Hz) 10k 7 6 20 10 100 60 40 100k 19971 G34 100k 19971 G33 Large-Signal Step Response G = 10 RL = 10k CL = 1000pF Rising Falling 5 4 3 2 1 20 1k 10k FREQUENCY (Hz) VOLTAGE (5V/DIV) SLEW RATE (V/s) POWER SUPPLY REJECTION RATIO (dB) 80 1k 10k FREQUENCY (Hz) 40 Slew Rate vs Temperature 100 100 60 19971 G32 G = 10 G = 20 G = 50 10 80 TIME (10s/DIV) 120 0 100 0 Negative PSRR vs Frequency 140 120 100k 19971 G31 160 G = 10 G = 20 G = 50 140 RL = 10k VOUT = 5V 0 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C) 19971 G35 TIME (4s/DIV) 19971 G36 Rev 0 12 For more information www.analog.com LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VS = 15V, Difference Amplifier configuration, unless otherwise noted. Small-Signal Step Response Small-Signal Step Response 120 G = 10 RL=10k 100 140 120 G = 20 RL=10k 100 CL = 1000pF 80 60 60 40 20 CL = 470pF -20 CL = 330pF -60 0 5 10 20 0 CL = 470pF -20 CL = 330pF -40 -60 CL = 20pF -80 -100 40 -80 15 20 25 TIME (s) 30 35 -100 40 0 5 10 30 35 G = 10 5 OUTPUT VOLTAGE 6 6 5 5 40 3 2 2 2 2 1 1 0 0 -1 -1 ERROR VOLTAGE (mV) 4 3 ERROR VOLTAGE 1 1 0 0 -1 -1 -2 -2 -3 -3 -4 -4 -4 -5 -5 -5 -5 -6 -6 -6 -6 -3 -3 -4 OUTPUT VOLTAGE TIME (10s/DIV) 19971 G43 40 50 0 -50 -100 19971 G42 Quiescent Current vs Supply Voltage 600 600 500 500 400 300 200 100 200 -75 -50 -25 0 25 50 75 100 125 150 175 TEMPERATURE (C) 35 -200 -60 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) QUIESCENT CURRENT (A) SUPPLY CURRENT (A) 500 250 30 100 Thermal Shutdown Hysteresis 10 UNITS 300 15 20 25 TIME (s) 19971 G41 Quiescent Current vs Temperature 350 10 -150 TIME (10s/DIV) 19971 G40 400 5 40 UNITS 150 OUTPUT VOLTAGE (V) 4 450 0 200 5 3 -2 CL = 330pF CL = 20pF 19971 G39 6 G = 10 4 ERROR VOLTAGE CL = 470pF Op Amp Offset Voltage vs Temperature 3 OUTPUT VOLTAGE (V) ERROR VOLTAGE (mV) -100 Settling Time 6 550 0 -20 19971 G38 Settling Time -2 20 -80 19971 G37 4 40 -60 15 20 25 TIME (s) CL = 1000pF -40 CL = 20pF OP AMP OFFSET VOLTAGE (V) 0 VOLTAGE (mV) 80 60 -40 QUIESCENT CURRENT (A) 120 G = 50 RL=10k 100 CL = 1000pF 80 VOLTAGE (mV) VOLTAGE (mV) Small-Signal Step Response 140 140 PARAMETRIC SWEEP IN ~25C TA = 150C INCREMENTS 400 300 TA = -55C 200 100 0 145 150 155 160 165 TEMPERATURE (C) 170 19971 G44 0 0 10 20 30 40 SUPPLY VOLTAGE (V) 50 19971 G45 Rev 0 For more information www.analog.com 13 LT1997-1 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VS = 15V, Difference Amplifier configuration, unless otherwise noted. Shutdown Quiescent Current vs Supply Voltage 40 25C -40C -55C VS = 15V 500 VSHDN = 0V 30 20 10 Minimum Supply Voltage 20 CHANGE IN OPAMP OFFSET VOLTAGE (V) 150C 125C 85C 550 QUIESCENT CURRENT (A) QUIESCENT CURRENT (A) 50 Quiescent Current vs SHDN Voltage 150C 125C 85C 25C -40C -55C 450 400 350 300 250 200 150 100 50 0 0 10 20 30 40 SUPPLY VOLTAGE (V) 50 0 0 5 10 SHDN VOLTAGE (V) 19971 G46 PIN FUNCTIONS 15 19971 G47 15 10 5 0 TA = 125C -5 TA = 25C -10 -15 -20 TA = -45C 0 1 2 3 4 TOTAL SUPPLY VOLTAGE (V) 5 19971 G48 (DFN/MSOP) V+ (Pin 9/Pin 11): Positive Supply Pin. V- (EXPOSED PAD Pin 15/Pin 8): Negative Supply Pin. OUT (Pin 8/Pin 9): Output Pin. +INA (Pin 1/Pin 1): Noninverting Gain-of-10 Input Pin. Connects a 15k internal resistor to the internal op amp's noninverting input. +INB (Pin 3/Pin 3): Noninverting Gain-of-20 Input Pin. Connects a 7.5k internal resistor to the internal op amp's noninverting input. +INC (Pin 5/Pin 5): Noninverting Gain-of-50 Input Pin. Connects a 3k internal resistor to the internal op amp's noninverting input. -INA (Pin 14/Pin 16): Inverting Gain-of-10 input Pin. Connects a 15k internal resistor to the internal op amp's inverting input. -INC (Pin 10/Pin 12): Inverting Gain-of-50 input Pin. Connects a 3k internal resistor to the internal op amp's inverting input. REF (Pin 7/NA): Reference Input Pin. Sets the output level when the difference between the inputs is zero. REF1 (NA/Pin 6): Reference 1 Input Pin. With REF2, sets the output level when the difference between the inputs is zero. REF2 (NA/Pin 7): Reference 2 Input Pin. With REF1, sets the output level when the difference between the inputs is zero. SHDN (Pin 6/Pin 10): Shutdown Pin. Amplifier is active when this pin is tied to V+ or left floating. Pulling the pin more than 2.5V below V+ causes the amplifier to enter a low power state. -INB (Pin 12/Pin 14): Inverting Gain-of-20 input Pin. Connects a 7.5k internal resistor to the internal op amp's inverting input. Rev 0 14 For more information www.analog.com LT1997-1 BLOCK DIAGRAM DFN -INA -INB V+ -INC 3k 150k 7.5k 15k OUT 15k 150k 7.5k 3k REF V+ 10A +INA +INB +INC SHDN V- 19971 BD02 MSOP -INA -INB V+ -INC 3k 150k 7.5k 15k OUT 15k 7.5k 3k V+ 300k REF1 300k REF2 10A +INA +INB +INC SHDN V- 19971 BD01 Rev 0 For more information www.analog.com 15 LT1997-1 APPLICATIONS INFORMATION V-IN is below V-, but the part will not be damaged as long as VCMOP is greater than V- - 25V and the junction temperature of the LT1997-1 does not exceed 150C. VS+ V+ -INA -INB -INC LT1997-1 3k 7.5k The voltage on LT1997-1's input pins should never be higher than V- + 80V or lower than V- - 0.3V under any circumstances. 150k - 15k OUT + 15k 7.5k 150k REF 3k +INA +INB +INC SHDN VOUT VREF V- 19971 F01 V+IN VS- Figure 1. Difference Amplifier with Dual-Supply Operation (Gain = 10) Introduction The LT1997-1 is a precision, high voltage, high gain amplifier combined with a highly-matched resistor network. It can easily be configured into many different gain circuits without adding external components, as it will be shown in this data sheet. The LT1997-1 provides the resistors and op amp together in a small package in order to save board space and reduce complexity. Highly accurate measurement circuits can be easily constructed with the LT1997-1. The circuits can be tailored to specific measurement applications. Common Mode Voltage Range The common mode voltage at the inputs of the internal op amp (VCMOP) is determined by the voltages on pins +INA, +INB, +INC and REF (see the Calculating Input Voltage Range section). This condition is true provided that the internal op amp's output is not clipped and feedback maintains the internal op amp's inputs at the same voltage. In addition to the limits mentioned above, the common mode input voltage of the amplifier should be chosen so that the input resistors do not dissipate too much power. The power dissipated in a 15k resistor must be less than 230mW. It must be less than 115mW for the 7.5k resistor and less than 46mW for the 3k resistor. For most applications, the pin voltage limitations will be reached before the resistor power limitation is reached. Calculating Input Voltage Range Figure 2 shows the LT1997-1 in the generalized case of a difference amplifier, with the inputs shorted for the common mode calculation. The values of RF and RG are dictated by how the positive inputs (+INA, +INB, +INC) and REF pin are connected. By superposition we can write: The common mode voltage range of the LT1997-1 is set by the voltage range allowed on the LT1997-1's input pins and by the input voltage range of the internal op amp. The internal op amp of LT1997-1 has 2 operating regions: a) if the common mode voltage at the inputs of the internal op amp (VCMOP) is between V- and V+ - 1.75V, the op amp operates in its normal region; b) If VCMOP is between V+ - 1.75V and V- + 76V, the op amp continues to operate, but in its Over-The-Top (OTT) region with degraded performance (see Over-The-Top Operation section of this data sheet for more detail). The LT1997-1 will not operate correctly if the commonmode voltage at the inputs of the internal op amp (VCMOP) VCMOP = VEXT * RF RF + R G + VREF * RG RF + R G Or, solving for VEXT: R R VEXT = VCMOP * 1+ G - VREF * G RF RF But valid VCMOP voltages are limited to VS+ - 1.75V (or VS- + 76V for OTT) on the high side and VS- on the low side, so: R R MAX VEXT = ( VS+ -1.75 ) * 1+ G - VREF * G RF RF Rev 0 16 For more information www.analog.com LT1997-1 APPLICATIONS INFORMATION and: 3.7k in Over-The-Top operation. This resistance appears across the summing nodes of the internal op amp and boosts noise and offset while decreasing speed. Noise and offset will increase by 33% to 76% depending on the gain setting. The bandwidth will be reduced by 25% to 43%. For more detail on Over-The-Top operation, consult the LT6015 data sheet. R R MIN VEXT = ( VS - ) * 1+ G - VREF * G RF RF RF RG VEXT RG - VCMOP VS+ VOUT + V S- 19971 F02 RF VREF Figure 2. Calculating the Common Mode Input Voltage Range Exceeding the MAX VEXT limit will cause the amplifier to transition into the Over-The-Top region. The maximum input voltage for the Over-The-Top region is: R R MAX VEXTOTT = ( VS - +76 ) * 1+ G - VREF * G RF RF Keep in mind that the above MAX and MIN values for input voltage range should not exceed (V- + 80V) to (V- - 0.3V), the absolute maximum voltage range specified earlier for LT1997-1's input pins. The negative inputs (-INA, -INB, -INC) are not limited by the internal op amp common mode range (VCMOP) because they do not affect it. They are limited by the output swing of the amplifier (and obviously by the allowed voltage range for the input pins). Difference Amplifiers The LT1997-1 is ideally suited to be used as a difference amplifier. Figure 3 shows the basic 4-resistor difference amplifier and the LT1997-1. A difference gain of 20 is shown, but can be altered by additional dashed connections. By connecting the 3k resistors in parallel with the 150k feedback resistors, the gain is reduced to 0.392. Of course there are many possible gains and Figure 4 shows circuit schematics of some of those difference amplifier gains. Note that the common mode voltage at the inputs of the internal op amp (VCMOP) is set by the voltages at pins +INA, +INB, +INC and REF. RF V-IN V+IN - + RG RG VOUT VOUT = GAIN * (V+IN - V-IN) GAIN = RF/RG RF DIFFERENCE AMPLIFIER CONFIGURATION VS+ V-IN -INA -INB -INC V+ 3k 150k 7.5k Over-The-Top Operation 15k When the input common mode voltage of the internal op amp (VCMOP) in the LT1997-1 is biased near or above the V+ supply, the op amp is operating in the Over-The-Top (OTT) region. The op amp continues to operate with an input common mode voltage of up to 76V above V- (regardless of the positive power supply voltage V+), but its performance is degraded. The op amp's input bias currents change from under 2nA to 14A. The op amp's input offset current rises to 50nA, which adds 7.5mV to the output offset voltage. In addition, when operating in the Over-The-Top region, the differential input impedance of the internal op amp decreases from 1M in normal operation to approximately LT1997-1 - + 15k 7.5k OUT 150k VOUT REF 3k +INA +INB +INC V+IN SHDN V- V S- 19971 F03 DIFFERENCE AMPLIFIER CONFIGURATION IMPLEMENTED WITH THE LT1997-1, RF = 150k, RG = 7.5k, GAIN = 20 ADDING THE DASHED CONNECTIONS CONNECT THE 3k RESISTOR IN PARALLEL WITH RF, SO RF IS REDUCED TO 2.94k. THE GAIN BECOMES 2.94k/7.5k = 0.392 Figure 3. The LT1997-1 Configured as a Difference Amplifier. Gain Is Set by Connecting the Correct Resistors or Combinations of Resistors. Gain of 20 Is Shown, with Dashed Lines Modifying It to a Gain of 0.392 Rev 0 For more information www.analog.com 17 LT1997-1 APPLICATIONS INFORMATION VS+ V-IN -INA -INB -INC V+ -INA -INB -INC 3k 150k 15k 7.5k OUT VOUT 150k 15k - + 7.5k 3k OUT VOUT - + 15k 7.5k 150k REF V- +INA +INB +INC SHDN VS- GAIN = 4.545 GAIN = 0.476 VS+ V+ -INA -INB -INC 3k V+ VS+ V-IN VS+ V-IN LT1997-1 -INA -INB -INC LT1997-1 150k 15k 7.5k 7.5k OUT VOUT 7.5k 3k OUT VOUT V- 7.5k 150k REF V+ VS- V+IN GAIN = 20 VS+ V-IN LT1997-1 -INA -INB -INC 3k V+ VS+ V-IN LT1997-1 -INA -INB -INC 150k 15k 7.5k 7.5k OUT VOUT 7.5k 3k OUT VOUT +INA +INB +INC SHDN V- 7.5k 150k REF V- +INA +INB +INC SHDN VS+ -INA -INB -INC V+ V-IN LT1997-1 VS+ -INA -INB -INC 3k 150k 7.5k OUT VOUT 150k REF - + 7.5k OUT VOUT 150k REF 3k V- VS- V+IN 150k 15k 3k +INA +INB +INC SHDN LT1997-1 7.5k 15k - + 15k V+ 3k 7.5k 15k V- GAIN = 60 GAIN = 50 V-IN VOUT 150k REF VS- V+IN VS- V+IN GAIN = 30 OUT 3k +INA +INB +INC SHDN VS- - + 15k 3k V+IN 150k 15k - + 15k 150k REF LT1997-1 7.5k 150k 15k - + 15k V+ 3k 3k 7.5k VOUT 150k REF V- +INA +INB +INC SHDN GAIN = 10 VS+ V-IN V- VS- V+IN GAIN = 6.364 OUT 3k +INA +INB +INC SHDN VS- V+IN - + 15k 3k +INA +INB +INC SHDN 150k 15k - + 15k 150k REF LT1997-1 7.5k 150k 15k - + 15k V+ 3k 3k 7.5k VOUT 150k REF V- +INA +INB +INC SHDN V+IN VS- V+IN GAIN = 0.141 V-IN V- +INA +INB +INC SHDN VS- OUT 3k 3k V+IN LT1997-1 7.5k 150k 15k 150k REF V+ 3k 7.5k 15k - + 15k -INA -INB -INC -INA -INB -INC LT1997-1 3k 7.5k -INA -INB -INC V+ VS+ V-IN VS+ V-IN LT1997-1 +INA +INB +INC SHDN VS- V+IN GAIN = 70 V- GAIN = 80 19971 F04 Figure 4. Many Difference Amplifier Gains Can Be Achieved by Strapping Pins Rev 0 18 For more information www.analog.com LT1997-1 APPLICATIONS INFORMATION Difference Amplifier: Additional Gains Using CrossCoupling Table 1. Difference Amplifier Gains GAIN V+IN V-IN GND (REF) OUT Figure 5 shows the basic difference amplifier as well as the LT1997-1 with cross-coupled inputs. The additional dashed connections reduce the differential gain from 50 to 40. Using this method, additional gains are achievable and a few example schematics of the difference amplifiers using cross-coupling are shown in Figure 6. To summarize, Table 1 shows a complete list of all difference amplifier gains and how they are constructed using (both conventional or cross-coupling) pin strapping. Note that there are 24 unique gains ranging from 0.141 to 80 which can be achieved with the LT1997-1 using no external components. 0.141 +INA -INA +INB, +INC -INB, -INC 0.196 +INA -INA +INC -INC 0.323 +INA -INA -INB, +INC +INB, -INC 0.328 +INB -INB +INA, +INC -INA, -INC 0.392 +INB -INB +INC -INC 0.476 +INA -INA +INB -INB RF V-IN V+IN - + RG RG VOUT VOUT = GAIN * (V+IN - V-IN) GAIN = RF/RG RF DIFFERENCE AMPLIFIER CONFIGURATION V-IN VS+ -INA -INB -INC V+ LT1997-1 3k 7.5k 150k 15k - + 15k 7.5k +INB -INB -INA, +INC +INA, -INC 0.588 +INA, +INB -INA, -INB +INC -INC 1.613 +INC -INC +INA, +INB -INA, -INB 1.818 +INB -INB +INA -INA 1.905 -INA, +INC +INA, -INC +INB -INB 2.381 +INC -INC +INB -INB 2.727 -INB, +INC +INB, -INC +INA -INA 2.857 +INA, +INC -INA, -INC +INB -INB 4.545 +INC -INC +INA -INA 6.364 +INB, +INC -INB, -INC +INA -INA 10 +INA -INA 20 +INB -INB 30 +INA, +INB -INA, -INB 40 -INA, +INC +INA, -INC 50 +INC -INC 60 +INA, +INC -INA, -INC 70 +INB, +INC -INB, -INC 80 OUT 150k 0.488 +INA, +INB, +INC -INA, -INB, -INC VOUT REF 3k +INA +INB +INC V+IN SHDN V- 19971 F05 VS- DIFFERENCE AMPLIFIER CONFIGURATION IMPLEMENTED WITH THE LT1997-1, RF = 150k, RG = 3k, GAIN = 50 GAIN CAN BE ADJUSTED BY CROSS-COUPLING THE INPUTS. MAKING THE DASHED CONNECTIONS REDUCES THE GAIN FROM 50 TO 40 Figure 5. Cross-Coupling of the LT1997-1 Allows Additional Gains to Be Constructed Rev 0 For more information www.analog.com 19 LT1997-1 APPLICATIONS INFORMATION V-IN V-IN VS+ V+ -INA -INB -INC LT1997-1 -INA -INB -INC 3k V+ VS+ LT1997-1 150k 15k 7.5k OUT VOUT 150k 150k REF 7.5k 7.5k OUT VOUT V- 150k REF 7.5k VS- V- +INA +INB +INC SHDN VS- V+IN OUT VOUT 150k REF 3k +INA +INB +INC SHDN GAIN = 1.905 - + 15k 3k +INA +INB +INC SHDN 150k 15k - + 15k 3k LT1997-1 3k 7.5k 15k - + 15k V+ -INA -INB -INC 3k 7.5k V+IN V-IN VS+ VS- V+IN GAIN = 2.727 V- GAIN = 40 19971 F06 Figure 6. Examples of More Difference Amplifier Gains That Can Be Achieved VS+ V-IN -INA -INB -INC V+ VS+ V-IN -INA -INB -INC LT1997-1 7.5k 7.5k 150k - + 15k 7.5k 3k +INA +INB +INC LT1997-1 3k 3k 15k V+ 150k 15k OUT 300k REF1 300k REF2 VOUT 7.5k VREF1 +INA +INB +INC 150k REF VOUT VREF SHDN V- V+IN VS- V+IN OUT 3k VREF2 SHDN V- - + 15k VS- LT1997-1 DFN 19971 F07 LT1997-1 MSOP Figure 7. The LT1997-1 Reference Resistors: Split Resistors in the MSOP Package, Single Resistor in the DFN Package Amplifiers for a Single-Ended Input Reference Resistors All of the difference amplifier configurations discussed in the preceding section can be used as noninverting or inverting amplifiers if the input is single-ended. For example, to achieve a positive attenuation for a single-ended input using the LT1997-1, simply ground V-IN and connect the input signal to V+IN. Similarly, to achieve a negative attenuation for a single-ended input using the LT1997-1 , simply ground V+IN and connect the input signal to V-IN. In the preceding discussions, the Reference resistor is shown as a single 150k resistor. This is true in the DFN package. In the MSOP package the reference resistor is split into two 300k resistors (Figure 7). Tying the REF1 and REF2 pins to the same voltage produces the same reference voltage as tying the VREF pin in the DFN package to that voltage. Connecting REF1 and REF2 to different voltages produces an effective reference voltage that is the average of VREF1 and VREF2. This feature is especially useful when the desired reference voltage is half way between the supRev 0 20 For more information www.analog.com LT1997-1 APPLICATIONS INFORMATION plies. Tying REF1 to VS+ and REF2 to VS- produces the desired mid-supply voltage without the help of another external reference voltage (Figure 7). The ratio of RREF1 to RREF2 is very precise: R R -R = REF1 REF2 < 60ppm RREF1 +RREF2 R 2 LT1997-1 with input common mode voltages that go from the normal to Over-The-Top operation will significantly degrade the LT1997-1's linearity as the op amp must transition between two different input stages. Driving resistive loads significantly smaller than the 150k internal feedback resistor will also degrade the amplifier's linearity performance. High Voltage Pin Spacing Shutdown The LT1997-1 has a shutdown pin (SHDN). Under normal operation this pin should be tied to V+ or allowed to float. Tying this pin 2.5V or more below V+ will cause the part to enter a low power state. The supply current is reduced to less than 25A and the op amp output becomes high impedance. The voltages at the input pins can still be present even in shutdown mode. Supply Voltage The positive supply pin of the LT1997-1 should be bypassed with a small capacitor (typically 0.1F) as close to the supply pins as possible. When driving heavy loads, an additional 4.7F electrolytic capacitor should be added. When using split supplies, the same is true for the V- supply pin. Output The output of the LT1997-1 can typically swing to within 30mV of either rail with no load and is capable of sourcing and sinking approximately 30mA at 25C. The LT1997-1 is internally compensated to drive at least 2nF of capacitance under any output loading conditions. For larger capacitive loads, a 0.22F capacitor in series with a 150 resistor between the output and ground will compensate the amplifier to drive capacitive loads greater than 2nF. Distortion The LT1997-1 features excellent distortion performance when the internal op amp is operating in the normal operating region. Operating the LT1997-1 with the internal op amp in the over the top region will increase distortion due to the lower loop gain of the op amp. Operating the For applications with high input voltages, the LT1997-1 pinout eases the printed circuit board (PCB) layout burden. Voltages at +INA, -INA, +INB, and -INB input pins are separated from other pins by virtue of unpopulated pin locations, as illustrated in the Pin Configuration section of this data sheet. Power Dissipation Considerations Because of the ability of the LT1997-1 to operate on power supplies up to 25V, to withstand very high input voltages and to drive heavy loads, there is a need to ensure the die junction temperature does not exceed 150C. The LT1997-1 is housed in DF14 (JA = 45C/W, JC = 3C/W) and MS16 (JA = 130C/W) packages. In general, the die junction temperature (TJ) can be estimated from the ambient temperature (TA), the device's power dissipation (PD) and the thermal resistance of the device and board (JA). TJ = TA + PD * JA The thermal resistance from the junction to the ambient environment (JA) is the sum of the thermal resistance from the junction to the exposed pad (JC) and the thermal resistance from the exposed pad to the ambient environment (CA). The CA value depends on how much PCB metal is connected to the exposed pad in the board. The more PCB metal that is used, the lower CA and JA will be. Power is dissipated by the amplifier's quiescent current, by the output current driving a resistive load, and by the input current driving the LT1997-1's internal resistor network. PD = ( ( VS+ - VS - ) * IS ) + POD + PRESD Rev 0 For more information www.analog.com 21 LT1997-1 APPLICATIONS INFORMATION For a given supply voltage, the worst-case output power dissipation POD(MAX) occurs with the output voltage at half of either supply voltage. POD(MAX) is given by: POD(MAX) = ( VS 2 ) PD = (50 * 0.6mA ) + 2 RLOAD The power dissipated in the internal resistors (PRESD) depends on the manner the input resistors have been configured as well as the input voltage, the output voltage and the voltage on the REF pin. The following equations and Figure 8 show the different components of PRESD corresponding to the different groups of the LT1997-1's internal resistors, assuming that the LT1997-1 is used with a dual supply configuration with REF pin at ground (refer to Figure 3 for resistor terminologies used in equations below). PRESDA 12.52 512 + 2.5k 165k 2 2 51* 10 51* 10 - 12.5 49.75 - 11 11 + + 15k 150k = 0.12W Assuming a thermal resistance of 45C/W, the die temperature will experience an 5.4C rise above ambient. This implies that the maximum ambient temperature the LT1997-1 should operate under the above conditions is: TA = 150C - 5.4C = 144.6C It is recommended that the exposed pad of the DFN package have as much PCB metal connected to it as reasonably available. The more PCB metal connected to the exposed 2 V+IN ) ( = RG + RF RF V - V * -IN +IN RG + RF PRESDB = RG V+IN = 51V and REF = 0V, the total power dissipation is given by: 2 RF V+IN * R + R - VOUT F G PRESDC = RF VS+ = 25V V-IN = 51V - VOUT/10 = 49.75V V+ -INA -INB -INC LT1997-1 PRESDC 150k 3k 7.5k 15k 2 PRESDB - PRESDA OUT + 15k VOUT = 12.5V 2.5k 7.5k 3k 150k PRESD = PRESDA + PRESDB + PRESDC In general, PRESD increases with higher input voltage and lower output and REF pin voltages. V+IN = 51V Example: For an LT1997-1 in a DFN package mounted on a PC board with a thermal resistance of 45C/W, operating on 25V supplies and driving a 2.5k load to 12.5V with +INA +INB +INC SHDN REF V- VS- = -25V 19971 F08 Figure 8. Power Dissipation Example Rev 0 22 For more information www.analog.com LT1997-1 APPLICATIONS INFORMATION pad, the lower the thermal resistance. Connecting a large amount of PCB metal to the exposed pad can reduce the JA to even less than 45C/W. Use multiple vias from the exposed pad to the V- plane. The exposed pad is electrically connected to the V- pin. In addition, a heat sink may be necessary if operating near maximum junction temperature. The MSOP package has no exposed pad and a higher thermal resistance (JA = 130C/W). It should not be used in applications which have a high ambient temperature, require driving a heavy load, or require an extreme input voltage. The ESD structures serve to protect the internal circuitry but also limit signal swing on certain nodes. The structures on the +INA, -INA, +INB, -INB, +INC, -INC pins and on the internal op amp inputs limit the voltage on these nodes to 0.3V below V- and 80V above V-. The voltage on the REF (DFN), REF1 (MSOP) and REF2 (MSOP) pins are limited to 0.3V below V- and 60V above V-. The voltage on the SHDN pin is limited to 0.3V below V- and 0.3V above V+. -INA -INB V- Thermal Shutdown For safety, the LT1997-1 will enter shutdown mode when the die temperature rises to approximately 163C. This thermal shutdown has approximately 9C of hysteresis requiring the die temperature to cool 9C before enabling the amplifier again. V- V+ -INC V- 7.5k V- 3k 150k - 15k OUT V- 15k 7.5k ESD Protection V- V- + V- V+ 3k The LT1997-1 is protected by a number of ESD structures. The structures are shown in Figure 9. LT1997-1 300k V- REF1 300k REF2 10A V- 19973 TA03 +INA +INB +INC V- SHDN V- 19971 F09 Figure 9. ESD Protection Rev 0 For more information www.analog.com 23 LT1997-1 TYPICAL APPLICATIONS LT1997-1 Configured for Differential Output with Gain = 20 VS+ V-IN V+ -INA -INB -INC LT1997-1 3k 7.5k 150k - 15k OUT 10k + 15k - + V+OUT VOCM LT6015 7.5k 150k 3k 10k REF V-OUT +INA +INB +INC SHDN V+IN V- 19971 TA02 VS- USE VOCM TO SET THE DESIRED OUTPUT COMMON MODE LEVEL Precision RRIO Single-Supply Difference Amplifier VBATTERY = 3.3V TO 50V VBATTERY V+ -INA -INB -INC LT1997-1 3k 7.5k V-IN VCM V+IN VCM = -0.3V TO VBATTERY 150k - 15k OUT + 15k 7.5k 3k +INA +INB +INC SHDN 300k REF2 300k REF1 V VOUT = BATTERY + 50 * (V+IN - V-IN) 2 V- 19971 TA03 Rev 0 24 For more information www.analog.com LT1997-1 TYPICAL APPLICATIONS Floating Input Difference Amplifier VS V+ -INA -INB -INC LT1997-1 3k 7.5k 150k - 15k VDIFF OUT + 15k VS 7.5k 3k 300k REF2 300k REF1 V- SHDN +INA +INB +INC VOUT = VS /2 + 50 * VDIFF 19971 TA04 VS THE INPUT SIGNAL FLOATS. THE VOLTAGE AT THE REF INPUTS AND THE OUTPUT VOLTAGE DETERMINE THE COMMON MODE VOLTAGE AT THE INPUT Create a Supply Using Control Signal V+ V+ -INA -INB -INC LT1997-1 3k 7.5k 150k - 15k OUT + 15k 7.5k 3k SHDN +INA +INB +INC 300k REF2 300k REF1 VOUT = VBATT + 10 * VCTRL VOUT CONNECTS TO LOAD VBATT V- 19971 TA05 + - VCTRL V+ V- THIS CIRCUIT USES A GROUND-REFERENCED CONTROL SIGNAL TO CREATE A SUPPLY ON TOP OF AN EXISTING SUPPLY (VBATT) Rev 0 For more information www.analog.com 25 LT1997-1 TYPICAL APPLICATIONS Fault Detection V+ V+ -INA -INB -INC LT1997-1 3k 7.5k + - 150k 15k - 15k + OUT VSENSE 7.5k 3k REF2 300k REF1 V- SHDN +INA +INB +INC 300k VOUT = 80 * VSENSE (e.g. 2.4V OUTPUT AT 30mV OF FAULT SIGNAL) 19971 TA06 + - V+ VCM FAULT DETECTION AT HIGH COMMON MODE VOLTAGE: LOOK FOR AN INCREASING VOLTAGE THAT MIGHT INDICATE BREAKAGE. Scale and Shift V+ TO LOAD V+ -INA -INB -INC LT1997-1 3k 7.5k 150k - 15k ILOAD RSENSE OUT + 15k 7.5k 3k +INA +INB +INC SHDN 300k REF2 300k REF1 VOUT = VSEC -10 * ILOAD * RSENSE + - V- VSEC 19971 TA07 + - VPRI V+ THIS CONFIGURATION SHOWS SCALING AND GROUND DOMAIN SHIFTING FROM VPRI TO VSEC. VSEC CAN, OF COURSE, BE GROUND. Rev 0 26 For more information www.analog.com LT1997-1 TYPICAL APPLICATIONS Scale and Not Shift V+ TO LOAD V+ -INA -INB -INC LT1997-1 3k 7.5k 150k - 15k ILOAD RSENSE OUT VOUT = VPRI -10 * ILOAD * RSENSE + 15k 7.5k 3k REF2 300k REF1 V- SHDN +INA +INB +INC 300k 19971 TA08 V- V+ + - VPRI THIS CONFIGURATION SCALES THE INPUT. THE OUTPUT SIGNAL IS REFERENCED TO THE SAME GROUND DOMAIN AS THE INPUT. THUS THE CIRCUIT CAN OPERATE AS A LOW SIDE CURRENT SENSE IN THE PRIMARY DOMAIN. RELATIVE TO THE INPUT GROUND DOMAIN, THE OUTPUT CAN BE TRULY DRIVEN TO "ZERO". Bidirectional High Side Current Sense VS VCM = -0.3V TO 76V V+ -INA -INB -INC VS = 3.3V TO 50V LT1997-1 3k 7.5k ILOAD 150k 15k - 15k + RSENSE OUT VOUT =VS/2 -80 * ILOAD * RSENSE VS 7.5k 3k 300k REF2 300k REF1 LOAD +INA +INB +INC SHDN V- 19971 TA09 VS OUTPUT OFFSET INCREASES WHEN VCM > VS Rev 0 For more information www.analog.com 27 LT1997-1 PACKAGE DESCRIPTION DF Package 14(12)-Lead Plastic DFN (4mm x 4mm) (Reference LTC DWG # 05-08-1963 Rev O) 1.00 BSC 3.00 REF 0.70 0.05 4.50 0.05 3.10 0.05 1.70 0.05 3.38 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 3.00 REF 4.00 0.10 (4 SIDES) 8 1.00 BSC 14 0.40 0.10 3.38 0.10 1.70 0.10 PIN 1 NOTCH 0.35 x 45 CHAMFER PIN 1 TOP MARK (NOTE 6) (DF14)(12) DFN 1113 REV 0 0.200 REF 7 R = 0.115 TYP 0.75 0.05 1 0.25 0.05 0.50 BSC BOTTOM VIEW--EXPOSED PAD 0.00 - 0.05 NOTE: 1. PACKAGE OUTLINE DOES NOT CONFORM TO JEDEC MO-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE Rev 0 28 For more information www.analog.com LT1997-1 PACKAGE DESCRIPTION MS Package 16 (12)-Lead Plastic MSOP with 4 Pins Removed (Reference LTC DWG # 05-08-1847 Rev B) 1.0 (.0394) BSC 5.10 (.201) MIN 0.889 0.127 (.035 .005) 3.20 - 3.45 (.126 - .136) 4.039 0.102 (.159 .004) (NOTE 3) 16 14 121110 9 0.50 (.0197) BSC 0.305 0.038 (.0120 .0015) TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.280 0.076 (.011 .003) REF 3.00 0.102 (.118 .004) (NOTE 4) 4.90 0.152 (.193 .006) DETAIL "A" 0 - 6 TYP 1 GAUGE PLANE 0.53 0.152 (.021 .006) DETAIL "A" 0.18 (.007) SEATING PLANE 1.10 (.043) MAX 0.17 - 0.27 (.007 - .011) TYP 0.50 (.0197) BSC 3 567 8 1.0 (.0394) BSC 0.86 (.034) REF 0.1016 0.0508 (.004 .002) MSOP (MS12) 0213 REV B NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX Rev 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license For is granted implication or otherwise under any patent or patent rights of Analog Devices. more by information www.analog.com 29 LT1997-1 TYPICAL APPLICATION Bidirectional Low Side Current Sense VS V+ -INA -INB -INC LOAD 7.5k ILOAD LT1997-1 3k 150k 15k - 15k + RSENSE OUT 7.5k 3k SHDN +INA +INB +INC VOUT =VS/2 -80 * ILOAD * RSENSE VS 300k REF2 300k REF1 V- 19971 TA10 VS THIS CIRCUIT PROVIDES BIDIRECTIONAL LOW SIDE CURRENT SENSE BECAUSE IT CAN WORK AT SLIGHTLY NEGATIVE VOLTGES ON THE -INA/-INB/-INC INPUT PINS, AS DRAWN RELATED PARTS PART NUMBER DESCRIPTION COMMENTS Difference Amplifiers LT1997-3 Precision, Wide Voltage Range Gain Selectable Amplifier 3.3V to 50V Operation, CMRR > 91dB, Input Voltage = 160V, Gain = 1, 3, 9 LT1997-2 Precision, Wide Voltage Range, Gain Selectable Funnel Amplifier 3.3V to 50V Operation, CMRR > 105dB, Input Voltage = 255V, Gain = 0.1, 0.2, 0.25 LT6375 270V Common Mode Voltage Difference Amplifier 3.3V to 50V Operation, CMRR > 97dB, Input Voltage = 270V, Gain = 1 LT6376 230V Common Mode Voltage G = 10 Difference Amplifier 3.3V to 50V Operation, CMRR > 90dB, Input Voltage = 230V, Gain = 10 LT1990 250V Input Range Difference Amplifier 2.7V to 36V Operation, CMRR > 70dB, Input Voltage = 250V, Gain = 1, 10 LT1991 Precision, 100A Gain Selectable Amplifier 2.7V to 36V Operation, 50V Offset, CMRR > 75dB, Input Voltage = 60V LT1996 Precision, 100A Gain Selectable Amplifier Micropower, Pin Selectable Up to Gain = 118 AD8275 G = 0.2, Level Translation, 16-Bit ADC Driver 3.3V to 15V Operation, CMRR > 86dB, Input Voltage = -35V to 40V, Gain = 0.2 AD8475 Precision, Selectable Gain, Fully Differential Funnel Amplifier 3.3V to 10V Operation, CMRR > 86dB, Input Voltage = 15V, Gain = 0.4, 0.8 Operational Amplifiers LT6015/LT6016/ LT6017 Single, Dual, and Quad Over-The-Top Precision Op Amp 3.2MHz, 0.8V/s, 50V VOS, 3V to 50V VS, 0.335mA IS, RRIO LT6018 33V, Ultralow Noise, Precision Op Amp VOS: 50V, GBW: 15MHz, SR: 30V/s, en: 1.2nV/Hz, IS: 7.2mA LTC6090/LTC6091 Single and Dual 140V Operational Amplifier 50pA IB, 1.6mV VOS, 9.5V to 140V VS, 4.5mA IS, RR Output Current Sense Amplifiers LT1999 High Voltage, Bidirectional Current Sense Amplifier -5V to 80V, 750V, CMRR 80dB at 100kHz, Gain = 10, 20, 50 LT6108 High Side Current Sense Amplifier with Reference and Comparator with Shutdown 2.7V to 60V, 125V, Resistor Set Gain, 1.25% Threshold Error LT1787/LT1787HV Precision, Bidirectional High Side Current Sense Amplifier 2.7V to 60V Operation, 75V Offset, 60A Current Draw LT6100 Gain-Selectable High Side Current Sense Amplifier 4.1V to 48V Operation, Pin-Selectable Gain: 10V/V, 12.5V/V, 20V/V, 25V/V, 40V/V, 50V/V LTC6101/ LTC6101HV High Voltage High Side Current Sense Amplifier 4V to 60V/5V to 100V Operation, External Resistor Set Gain, SOT23 LTC6102/ LTC6102HV Zero Drift High Side Current Sense Amplifier 4V to 60V/5V to 100V Operation, 10V Offset, 1s Step Response, MSOP8/DFN Packages LTC6104 Bidirectional, High Side Current Sense 4V to 60V, Gain Configurable, 8-Pin MSOP Package Rev 0 30 10/18 For more information www.analog.com www.analog.com ANALOG DEVICES, INC. 2018