LT1991 Precision, 100µA Gain Selectable Amplifier FEATURES DESCRIPTION n Pin Configurable as a Difference Amplifier, The LT®1991 combines a precision operational amplifier Inverting and Noninverting Amplifier with eight precision resistors to form a one-chip solution n Difference Amplifier for accurately amplifying voltages. Gains from –13 to 14 Gain Range 1 to 13 with a gain accuracy of 0.04% can be achieved using no CMRR >75dB external components. The device is particularly well suited n Noninverting Amplifier for use as a difference amplifier, where the excellent resis- Gain Range 0.07 to 14 tor matching results in a common mode rejection ratio of n Inverting Amplifier greater than 75dB. Gain Range –0.08 to –13 The amplifier features a 50µV maximum input offset volt- n Gain Error <0.04% age and a gain bandwidth product of 560kHz. The device n Gain Drift < 3ppm/°C operates from any supply voltage from 2.7V to 36V and n Wide Supply Range: Single 2.7V to Split ±18V draws only 100µA supply current on a 5V supply. The n Micropower: 100µA Supply Current output swings to within 40mV of either supply rail. n Precision: 50µV Maximum Input Offset Voltage The resistors have excellent matching, 0.04% over tem- n 560kHz Gain Bandwidth Product perature for the 450k resistors. The matching temperature n Rail-to-Rail Output coefficient is guaranteed less than 3ppm/°C. The resis- n Space Saving 10-Lead MSOP and DFN Packages tors are extremely linear with voltage, resulting in a gain nonlinearity of less than 10ppm. APPLICATIONS The LT1991 is fully specified at 5V and ±15V supplies n Handheld Instrumentation and from –40°C to 125°C. The device is available in space n Medical Instrumentation saving 10-lead MSOP and low profile (0.8mm) 3mm × n Strain Gauge Amplifiers 3mm DFN packages. n Differential to Single-Ended Conversion L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION Rail-to-Rail Gain = 1 Difference Amplifier Distribution of Resistor Matching VOUT = VREF + ∆VIN 5V SWING 40mV TO 40 EITHER RAIL 450k RESISTORS 50k 450k ROUT <0.1Ω 35 LT1991A %) 150k S ( 30 T NI 25 VM(IN) – 450k – 4pF E OF U 20 G ∆VIN + 450k NTA 15 VP(IN) + LT1991 CE R 150k 450k E 10 INPUT RANGE P –0.5V TO 5.1V RIN = 900kΩ 50k 5 4pF 0 –0.04 –0.02 0 0.02 0.04 VREF = 2.5V RESISTOR MATCHING (%) 1991 TA01 1991 TA01b 1991fh 1

LT1991 ABSOLUTE MAXIMUM RATINGS (Note 1) Specified Temperature Range (Note 5) Total Supply Voltage (V+ to V–) ................................40V LT1991C ...............................................–40°C to 85°C Input Voltage (Pins P1/M1, Note 2) ........................±60V LT1991I ................................................–40°C to 85°C Input Voltage LT1991H .............................................–40°C to 125°C (Other Inputs Note 2) ..................V+ + 0.2V to V– – 0.2V Maximum Junction Temperature Output Short-Circuit Duration (Note 3) ...........Indefinite DD Package .........................................................125°C Operating Temperature Range (Note 4) MS Package .........................................................150°C LT1991C ...............................................–40°C to 85°C Storage Temperature Range LT1991I ................................................–40°C to 85°C DD Package ...........................................–65°C to 125°C LT1991H .............................................–40°C to 125°C MS Package ...........................................–65°C to 150°C Lead Temperature (Soldering, 10 sec) ..................300°C PIN CONFIGURATION TOP VIEW P1 1 10 M1 TOP VIEW P3 2 9 M3 P1 1 10 M1 P3 2 9 M3 P9 3 8 M9 P9 3 8 M9 VEE 4 7 VCC VEE 4 7 VCC REF 5 6 OUT REF 5 6 OUT MS PACKAGE DD PACKAGE 10-LEAD PLASTIC MSOP 10-LEAD (3mm × 3mm) PLASTIC DFN EXPOSED PAD CONNECTED TO VEE PCB TJMAX = 150°C, qJA = 230°C/W CONNECTION OPTIONAL TJMAX = 125°C, qJA = 43°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE LT1991CDD#PBF LTCT1991CDD#TRPBF LBMM 10-Lead (3mm × 3mm) Plastic DFN 0°C to 70°C LT1991ACDD#PBF LT1991ACDD#TRPBF LBMM 10-Lead (3mm × 3mm) Plastic DFN 0°C to 70°C LT1991IDD#PBF LT1991IDD#TRPBF LBMM 10-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C LT1991AIDD#PBF LT1991AIDD#TRPBF LBMM 10-Lead (3mm × 3mm) Plastic DFN –40°C to 85°C LT1991HDD#PBF LT1991HDD#TRPBF LBMM 10-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C LT1991CMS#PBF LT1991CMS#TRPBF LTQD 10-Lead Plastic MSOP 0°C to 70°C LT1991ACMS#PBF LT1991ACMS#TRPBF LTQD 10-Lead Plastic MSOP 0°C to 70°C LT1991IMS#PBF LT1991IMS#TRPBF LTQD 10-Lead Plastic MSOP –40°C to 85°C LT1991AIMS#PBF LT1991AIMS#TRPBF LTQD 10-Lead Plastic MSOP –40°C to 85°C LT1991HMS#PBF LT1991HMS#TRPBF LTQD 10-Lead Plastic MSOP –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 1991fh 2

LT1991 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the operating temperature range of 0°C to 70°C for C-grade parts and –40°C to 85°C for I-grade parts, otherwise specifications are at T = 25°C. A Difference amplifier configuration, V = 5V, 0V or ±15V; V = V = half supply, unless otherwise noted. S CM REF SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS ∆G Gain Error V = ±15V, V = ±10V; R = 10k S OUT L G = 1; LT1991A l ±0.04 % G = 1; LT1991 l ±0.08 % G = 3 or 9; LT1991A l ±0.06 % G = 3 or 9; LT1991 l ±0.12 % GNL Gain Nonlinearity V = ±15V; V = ±10V; R = 10k l 1 10 ppm S OUT L ∆G/∆T Gain Drift vs Temperature (Note 6) V = ±15V; V = ±10V; R = 10k l 0.3 3 ppm/°C S OUT L CMRR Common Mode Rejection Ratio, V = ±15V; V = ±15.2V S CM Referred to Inputs (RTI) G = 9; LT1991A l 80 100 dB G = 3; LT1991A l 75 93 dB G = 1; LT1991A l 75 90 dB Any Gain; LT1991 l 60 70 dB V Input Voltage Range (Note 7) P1/M1 Inputs CM V = ±15V; V = 0V l –28 27.6 V S REF V = 5V, 0V; V = 2.5V l –0.5 5.1 V S REF V = 3V, 0V; V = 1.25V l 0.75 2.35 V S REF P1/M1 Inputs, P9/M9 Connected to REF V = ±15V; V = 0V l –60 60 V S REF V = 5V, 0V; V = 2.5V l –14 16.8 V S REF V = 3V, 0V; V = 1.25V l –1.5 7.3 V S REF P3/M3 Inputs V = ±15V; V = 0V l –15.2 15.2 V S REF V = 5V, 0V; V = 2.5V l 0.5 4.2 V S REF V = 3V, 0V; V = 1.25V l 0.95 1.95 V S REF P9/M9 Inputs V = ±15V; V = 0V l –15.2 15.2 V S REF V = 5V, 0V; V = 2.5V l 0.85 3.9 V S REF V = 3V, 0V; V = 1.25V l 1.0 1.9 V S REF V Op Amp Offset Voltage (Note 8) LT1991AMS, V = 5V, 0V 15 50 µV OS S l 135 µV LT1991AMS, V = ±15V 15 80 µV S l 160 µV LT1991MS 25 100 µV l 200 µV LT1991DD 25 150 µV l 250 µV ∆V /∆T Op Amp Offset Voltage Drift (Note 6) l 0.3 1 µV/°C OS IB Op Amp Input Bias Current (Note 11) 2.5 5 nA l 7.5 nA I Op Amp Input Offset Current (Note 11) LT1991A 50 500 pA OS l 750 pA LT1991 50 1000 pA l 1500 pA Op Amp Input Noise Voltage 0.01Hz to 1Hz 0.35 µV P-P 0.01Hz to 1Hz 0.07 µV RMS 0.1Hz to 10Hz 0.25 µV P-P 0.1Hz to 10Hz 0.05 µV RMS e Input Noise Voltage Density G = 1; f = 1kHz 180 nV/√Hz n G = 9; f = 1kHz 46 nV/√Hz 1991fh 3

LT1991 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the operating temperature range of 0°C to 70°C for C-grade parts and –40°C to 85°C for I-grade parts, otherwise specifications are at T = 25°C. A Difference amplifier configuration, V = 5V, 0V or ±15V; V = V = half supply, unless otherwise noted. S CM REF SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS RIN Input Impedance (Note 10) P1 (M1 = Ground) l 630 900 1170 kΩ P3 (M3 = Ground) l 420 600 780 kΩ P9 (M9 = Ground) l 350 500 650 kΩ M1 (P1 = Ground) l 315 450 585 kΩ M3 (P3 = Ground) l 105 150 195 kΩ M9 (P9 = Ground) l 35 50 65 kΩ ∆R Resistor Matching (Note 9) 450k Resistors, LT1991A l 0.01 0.04 % Other Resistors, LT1991A l 0.02 0.06 % 450k Resistors, LT1991 l 0.02 0.08 % Other Resistors, LT1991 l 0.04 0.12 % ∆R/∆T Resistor Temperature Coefficient (Note 6) Resistor Matching l 0.3 3 ppm/°C Absolute Value l –30 ppm/°C PSRR Power Supply Rejection Ratio V = ±1.35V to ±18V (Note 8) l 105 135 dB S Minimum Supply Voltage l 2.4 2.7 V V Output Voltage Swing (to Either Rail) No Load OUT V = 5V, 0V 40 55 mV S V = 5V, 0V l 65 mV S V = ±15V l 110 mV S 1mA Load V = 5V, 0V 150 225 mV S V = 5V, 0V l 275 mV S V = ±15V l 300 mV S I Output Short-Circuit Current (Sourcing) Drive Output Positive; 8 12 mA SC Short Output to Ground l 4 mA Output Short-Circuit Current (Sinking) Drive Output Negative; 8 21 mA Short Output to V or Midsupply l 4 mA S BW –3dB Bandwidth G = 1 110 kHz G = 3 78 kHz G = 9 40 kHz GBWP Op Amp Gain Bandwidth Product f = 10kHz 560 kHz t, t Rise Time, Fall Time G = 1; 0.1V Step; 10% to 90% 3 µs r f G = 9; 0.1V Step; 10% to 90% 8 µs t Settling Time to 0.01% G = 1; V = 5V, 0V; 2V Step 42 µs s S G = 1; V = 5V, 0V; –2V Step 48 µs S G = 1; V = ±15V, 10V Step 114 µs S G = 1; V = ±15V, –10V Step 74 µs S SR Slew Rate V = 5V, 0V; V = 1V to 4V l 0.06 0.12 V/µs S OUT V = ±15V; V = ±10V; V = ±5V l 0.08 0.12 V/µs S OUT MEAS I Supply Current V = 5V, 0V 100 110 µA s S l 150 µA V = ±15V 130 160 µA S l 210 µA 1991fh 4

LT1991 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the operating temperature range of –40°C to 125°C for H-grade parts, otherwise specifications are at T = 25°C. Difference amplifier configuration, A V = 5V, 0V or ±15V; V = V = half supply, unless otherwise noted. S CM REF SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS ∆G Gain Error V = ±15V, V = ±10V; R = 10k S OUT L G = 1 l ±0.08 % G = 3 or 9 l ±0.12 % GNL Gain Nonlinearity V = ±15V; V = ±10V; R = 10k l 1 10 ppm S OUT L ∆G/∆T Gain Drift vs Temperature (Note 6) V = ±15V; V = ±10V; R = 10k l 0.3 3 ppm/°C S OUT L CMRR Common Mode Rejection Ratio, V = ±15V; V = ±15.2V S CM Referred to Inputs (RTI) G = 9 l 77 100 dB G = 3 l 70 93 dB G = 1 l 70 90 dB V Input Voltage Range (Note 7) P1/M1 Inputs CM V = ±15V; V = 0V l –28 27.6 V S REF V = 5V, 0V; V = 2.5V l –0.5 5.1 V S REF V = 3V, 0V; V = 1.25V l 0.75 2.35 V S REF P1/M1 Inputs, P9/M9 Connected to REF V = ±15V; V = 0V l –60 60 V S REF V = 5V, 0V; V = 2.5V l –14 16.8 V S REF V = 3V, 0V; V = 1.25V l –1.5 7.3 V S REF P3/M3 Inputs V = ±15V; V = 0V l –15.2 15.2 V S REF V = 5V, 0V; V = 2.5V l 0.5 4.2 V S REF V = 3V, 0V; V = 1.25V l 0.95 1.95 V S REF P9/M9 Inputs V = ±15V; V = 0V l –15.2 15.2 V S REF V = 5V, 0V; V = 2.5V l 0.85 3.9 V S REF V = 3V, 0V; V = 1.25V l 1.0 1.9 V S REF V Op Amp Offset Voltage (Note 8) LT1991MS 25 100 µV OS l 285 µV LT1991DD 25 150 µV l 295 µV ∆V /∆T Op Amp Offset Voltage Drift (Note 6) l 0.3 1 µV/°C OS IB Op Amp Input Bias Current (Note 11) 2.5 5 nA l 25 nA I Op Amp Input Offset Current (Note 11) 50 1000 pA OS l 4500 pA Op Amp Input Noise Voltage 0.01Hz to 1Hz 0.35 µV P-P 0.01Hz to 1Hz 0.07 µV RMS 0.1Hz to 10Hz 0.25 µV P-P 0.1Hz to 10Hz 0.05 µV RMS e Input Noise Voltage Density G = 1; f = 1kHz 180 nV/√Hz n G = 9; f = 1kHz 46 nV/√Hz RIN Input Impedance (Note 10) P1 (M1 = Ground) l 630 900 1170 kΩ P3 (M3 = Ground) l 420 600 780 kΩ P9 (M9 = Ground) l 350 500 650 kΩ M1 (P1 = Ground) l 315 450 585 kΩ M3 (P3 = Ground) l 105 150 195 kΩ M9 (P9 = Ground) l 35 50 65 kΩ ∆R Resistor Matching (Note 9) 450k Resistors l 0.02 0.08 % Other Resistors l 0.04 0.12 % ∆R/∆T Resistor Temperature Coefficient (Note 6) Resistor Matching l 0.3 3 ppm/°C Absolute Value l –30 ppm/°C 1991fh 5

LT1991 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the operating temperature range of –40°C to 125°C for H-grade parts, otherwise specifications are at T = 25°C. Difference amplifier configuration, A V = 5V, 0V or ±15V; V = V = half supply, unless otherwise noted. S CM REF SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS PSRR Power Supply Rejection Ratio V = ±1.35V to ±18V (Note 8) l 105 135 dB S Minimum Supply Voltage l 2.4 2.7 V V Output Voltage Swing (to Either Rail) No Load OUT V = 5V, 0V 40 55 mV S V = 5V, 0V l 75 mV S V = ±15V l 120 mV S 1mA Load V = 5V, 0V 150 225 mV S V = 5V, 0V l 300 mV S V = ±15V l 340 mV S I Output Short-Circuit Current (Sourcing) Drive Output Positive; 8 12 mA SC Short Output to Ground l 4 mA Output Short-Circuit Current (Sinking) Drive Output Negative; 8 21 mA Short Output to V or Midsupply l 4 mA S BW –3dB Bandwidth G = 1 110 kHz G = 3 78 kHz G = 9 40 kHz GBWP Op Amp Gain Bandwidth Product f = 10kHz 560 kHz t, t Rise Time, Fall Time G = 1; 0.1V Step; 10% to 90% 3 µs r f G = 9; 0.1V Step; 10% to 90% 8 µs t Settling Time to 0.01% G = 1; V = 5V, 0V; 2V Step 42 µs s S G = 1; V = 5V, 0V; –2V Step 48 µs S G = 1; V = ±15V, 10V Step 114 µs S G = 1; V = ±15V, –10V Step 74 µs S SR Slew Rate V = 5V, 0V; V = 1V to 4V l 0.06 0.12 V/µs S OUT V = ±15V; V = ±10V; V = ±5V l 0.08 0.12 V/µs S OUT MEAS I Supply Current V = 5V, 0V 100 110 µA s S l 180 µA V = ±15V 130 160 µA S l 250 µA Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 6: This parameter is not 100% tested. may cause permanent damage to the device. Exposure to any Absolute Note 7: Input voltage range is guaranteed by the CMRR test at V = ±15V. S Maximum Rating condition for extended periods may affect device For the other voltages, this parameter is guaranteed by design and through reliability and lifetime. correlation with the ±15V test. See the Applications Information section to Note 2: The P3/M3 and P9/M9 inputs should not be taken more than 0.2V determine the valid input voltage range under various operating conditions. beyond the supply rails. The P1/M1 inputs can withstand ±60V if P9/M9 Note 8: Offset voltage, offset voltage drift and PSRR are defined as are grounded and V = ±15V (see Applications Information section about S referred to the internal op amp. You can calculate output offset as follows. “High Voltage CM Difference Amplifiers”). In the case of balanced source resistance, V = V • NOISEGAIN OS,OUT OS Note 3: A heat sink may be required to keep the junction temperature + I • 450k + I • 450k • (1– R /R ) where R and R are the total OS B P N P N below absolute maximum ratings. resistance at the op amp positive and negative terminal respectively. Note 4: Both the LT1991C and LT1991I are guaranteed functional over the Note 9: Applies to resistors that are connected to the inverting inputs. –40°C to 85°C temperature range. The LTC1991H is guaranteed functional Resistor matching is not tested directly, but is guaranteed by the gain over the –40°C to 125°C temperature range. error test. Note 5: The LT1991C is guaranteed to meet the specified performance Note 10: Input impedance is tested by a combination of direct from 0°C to 70°C and is designed, characterized and expected to meet measurements and correlation to the CMRR and gain error tests. specified performance from –40°C to 85°C but is not tested or QA sampled Note 11: I and I are tested at V = 5V, 0V only. B OS S at these temperatures. The LT1991I is guaranteed to meet specified performance from –40°C to 85°C. The LT1991H is guaranteed to meet specified performance from –40°C to 125°C. 1991fh 6

LT1991 TYPICAL PERFORMANCE CHARACTERISTICS (Difference Amplifier Configuration) Output Voltage Swing Output Voltage Swing Supply Current vs Supply Voltage vs Temperature vs Load Current (Output Low) 200 VCC 1400 VS = 5V, 0V VS = 5V, 0V 175 NO LOAD –20 1200 URRENT (µA) 111520050 TA = 25°C TA = 85°CTA = –40°C AGE SWING (mV) O(RUITGPHUTT A HXIIGSH) ––4600 OLTAGE (mV)1080000 TA = 25°C TA = 85°C SUPPLY C 7550 UTPUT VOLT 6400 OUTPUT LOW OUTPUT V 640000 TA = –40°C O 25 20 (LEFT AXIS) 200 0 VEE VEE 0 2 4 6 8 10 12 14 16 18 20 –50 –25 0 25 50 75 100 125 0 1 2 3 4 5 6 7 8 9 10 SUPPLY VOLTAGE (±V) TEMPERATURE (°C) LOAD CURRENT (mA) 1991 G01 1991 G02 1991 G03 Output Voltage Swing Output Short-Circuit Current Input Offset Voltage vs Load Current (Output High) vs Temperature vs Difference Gain –V10C0C VS = 5V, 0V mA) 25 VS = 5V, 0V SINKING 150 RVSE P=R 5EVS,E 0NVTATIVE PARTS OUTPUT VOLTAGE SWING (mV) –––––––234567800000000000000 TA = 85°CTA = 25°C TA = –40°C PUT SHORT-CIRCUIT CURRENT ( 2110505 SOURCING INPUT OFFSET VOLTAGE (µV)–1–1055000000 –900 UT O –1000 0 –150 0 1 2 3 4 5 6 7 8 9 10 –50 –25 0 25 50 75 100 125 1 2 3 4 5 6 7 8 9 10 11 12 13 LOAD CURRENT (mA) 1991 G04 TEMPERATURE (°C) 1991 G05 GAIN (V/V) 1991 G06 Output Offset Voltage vs Difference Gain Gain Error vs Load Current Slew Rate vs Temperature 1000 0.04 0.30 VS = 5V, 0V GAIN = 1 GAIN = 1 750 REPRESENTATIVE PARTS 0.03 VS = ±15V VS = ±15V V) VOUT = ±10V 0.25 VOUT = ±10V E (µ 500 0.02 TA = 25°C FFSET VOLTAG 2500 N ERROR (%) 0.010 W RATE (V/µs)00..2105 SR– (FALLINGS RE+D G(REI)SING EDGE) UT O–250 GAI–0.01 SLE0.10 TP–500 –0.02 U O 0.05 –750 –0.03 REPRESENTATIVE UNITS –1000 –0.04 0 1 2 3 4 5 6 7 8 9 10 11 12 13 0 1 2 3 4 5 –50 –25 0 25 50 75 100 125 GAIN (V/V) LOAD CURRENT (mA) TEMPERATURE (°C) 1991 G07 1991 G08 1991 G09 1991fh 7

LT1991 TYPICAL PERFORMANCE CHARACTERISTICS (Difference Amplifier Configuration) Bandwidth vs Gain CMRR vs Frequency PSRR vs Frequency 120 120 120 TVAS == 255V°, C0V 110 GAIN = 9 TVAS == 255V°, C0V 110 TVAS == 255V°, C0V 100 100 100 Hz) 90 GAIN = 1 GAIN = 3 90 GAIN = 9 TH (k 80 B) 8700 B) 8700 GAIN = 1 GAIN = 3 WID 60 R (d 60 R (d 60 D R R BAN CM 50 PS 50 B 40 40 40 d –3 30 30 20 20 20 10 10 0 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 10 100 1k 10k 100k 1M 10 100 1k 10k 100k GAIN SETTING (V/V) FREQUENCY (Hz) FREQUENCY (Hz) 1991 G10 1991 G11 1991 G12 Output Impedance vs Frequency CMRR vs Temperature Gain Error vs Temperature 1000 120 0.030 VS = 5V, 0V GAIN = 1 GAIN = 1 TA = 25°C VS = ±15V VS = ±15V 100 0.025 100 Ω) E ( 80 %)0.020 PUT IMPEDANC 101 GAIN = 3 GAIN = 9GAIN = 1 CMRR (dB) 6400 GAIN ERROR (00..001150 T U O 0.1 20 0.005 REPRESENTATIVE UNITS REPRESENTATIVE UNITS 0.01 0 0 1 10 100 1k 10k 100k –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 FREQUENCY (Hz) TEMPERATURE (°C) TEMPERATURE (°C) 1991 G13 1991 G14 1991 G15 Gain vs Frequency Gain and Phase vs Frequency 0.01Hz to 1Hz Voltage Noise 30 2 20 GAIN = 9 TVAS == 52V5,° 0CV 10 PHASE TGVASA I==N 52 =V5 ,°1 0CV 0 DIV) TMVASE =A= S2±U51°R5CVED IN G =13 GAIN V/ REFERRED TO OP AMP INPUTS n –1 –45 0 0 GAIN (dB) 100 GGAAIINN == 31 GAIN (dB) –––234 –90PHASE (deg AGE NOISE (1 ) LT –5 –135 VO P –10 –6 M A –7 –180 OP –20 –8 1 10 100 600 0.5 1 10 100 400 0 10 20 30 40 50 60 70 80 90 100 FREQUENCY (kHz) FREQUENCY (kHz) TIME (s) 1991 G16 1991 G17 1991 G21 1991fh 8

LT1991 TYPICAL PERFORMANCE CHARACTERISTICS Small Signal Transient Response Small Signal Transient Response Small Signal Transient Response GAIN = 1 GAIN = 3 GAIN = 9 50mV/DIV 50mV/DIV 50mV/DIV 5µs/DIV 1991 G18 5µs/DIV 1991 G19 5µs/DIV 1991 G20 PIN FUNCTIONS (Difference Amplifier Configuration) P1 (Pin 1): Noninverting Gain-of-1 input. Connects a 450k OUT (Pin 6): Output. V = V + 1 • (V – V ) + 3 • OUT REF P1 M1 internal resistor to the op amp’s noninverting input. (V – V ) + 9 • (V – V ). P3 M3 P9 M9 P3 (Pin 2): Noninverting Gain-of-3 input. Connects a 150k V (Pin 7): Positive Power Supply. Can be anything from CC internal resistor to the op amp’s noninverting input. 2.7V to 36V above the V voltage. EE P9 (Pin 3): Noninverting Gain-of-9 input. Connects a 50k M9 (Pin 8): Inverting Gain-of-9 input. Connects a 50k internal resistor to the op amp’s noninverting input. internal resistor to the op amp’s inverting input. V (Pin 4): Negative Power Supply. Can be either ground M3 (Pin 9): Inverting Gain-of-3 input. Connects a 150k EE (in single supply applications), or a negative voltage (in internal resistor to the op amp’s inverting input. split supply applications). M1 (Pin 10): Inverting Gain-of-1 input. Connects a 450k REF (Pin 5): Reference Input. Sets the output level when internal resistor to the op amp’s inverting input. difference between inputs is zero. Connects a 450k internal Exposed Pad: Must be soldered to PCB. resistor to the op amp’s noninverting input. BLOCK DIAGRAM M1 M3 M9 VCC OUT 10 9 8 7 6 50k 450k 150k 4pF 450k INM OUT 450k INP LT1991 150k 50k 450k 4pF 1 2 3 4 5 1991 BD P1 P3 P9 VEE REF 1991fh 9

LT1991 APPLICATIONS INFORMATION Introduction admittances. Because it has 9 times the admittance, the voltage applied to the P9 input has 9 times the effect of The LT1991 may be the last op amp you ever have to stock. the voltage applied to the P1 input. Because it provides you with several precision matched resistors, you can easily configure it into several different Bandwidth classical gain circuits without adding external components. The several pages of simple circuits in this data sheet The bandwidth of the LT1991 will depend on the gain you demonstrate just how easy the LT1991 is to use. It can select (or more accurately the noise gain resulting from be configured into difference amplifiers, as well as into the gain you select). In the lowest configurable gain of 1, inverting and noninverting single ended amplifiers. The the –3dB bandwidth is limited to 450kHz, with peaking of fact that the resistors and op amp are provided together about 2dB at 280kHz. In the highest configurable gains, in such a small package will often save you board space bandwidth is limited to 32kHz. and reduce complexity for easy probing. Input Noise The Op Amp The LT1991 input noise is dominated by the Johnson The op amp internal to the LT1991 is a precision device noise of the internal resistors (√4kTR). Paralleling all with 15µV typical offset voltage and 3nA input bias current. four resistors to the +input gives a 32.1kΩ resistance, The input offset current is extremely low, so matching the for 23nV/√Hz of voltage noise. The equivalent network source resistance seen by the op amp inputs will provide on the –input gives another 23nV/√Hz , and taking their for the best output accuracy. The op amp inputs are not RMS sum gives a total 33nV/√Hz input referred noise floor. rail-to-rail, but extend to within 1.2V of V and 1V of Output noise depends on configuration and noise gain. CC V . For many configurations though, the chip inputs will EE function rail-to-rail because of effective attenuation to the Input Resistance +input. The output is truly rail-to-rail, getting to within The LT1991 input resistances vary with configuration, 40mV of the supply rails. The gain bandwidth product of but once configured are apparent on inspection. Note that the op amp is about 560kHz. In noise gains of 2 or more, resistors connected to the op amp’s –input are looking it is stable into capacitive loads up to 500pF. In noise gains into a virtual ground, so they simply parallel. Any feedback below 2, it is stable into capacitive loads up to 100pF. resistance around the op amp does not contribute to input resistance. Resistors connected to the op amp’s +input The Resistors are looking into a high impedance, so they add as paral- The resistors internal to the LT1991 are very well matched lel or series depending on how they are connected, and SiChrome based elements protected with barrier metal. whether or not some of them are grounded. The op amp Although their absolute tolerance is fairly poor (±30%), +input itself presents a very high GΩ impedance. In the their matching is to within 0.04%. This allows the chip to classical noninverting op amp configuration, the LT1991 achieve a CMRR of 75dB, and gain errors within 0.04%. presents the high input impedance of the op amp, as is The resistor values are 50k, 150k, and 2 of 450k, con- usual for the noninverting case. nected to each of the inputs. The resistors have power limitations of 1watt for the 450k resistors, 0.3watt for the Common Mode Input Voltage Range 150k resistors and 0.5watt for the 50k resistors; however, The LT1991 valid common mode input range is limited in practice, power dissipation will be limited well below by three factors: these values by the maximum voltage allowed on the 1. Maximum allowed voltage on the pins input and REF pins. The 450k resistors connected to the M1 and P1 inputs are isolated from the substrate, and can 2. The input voltage range of the internal op amp therefore be taken beyond the supply voltages. The naming 3. Valid output voltage of the pins “P1,” “P3,” “P9,” etc., is based on their relative 1991fh 10

LT1991 APPLICATIONS INFORMATION The maximum voltage allowed on the P3, M3, P9, and as a gain of 13 difference amplifier on a single supply M9 inputs includes the positive and negative supply plus with the output REF connected to ground. This is a great a diode drop. These pins should not be driven more than circuit, but it does not support V = 0V at any common DM 0.2V outside of the supply rails. This is because they are mode because the output clips into ground while trying connected through diodes to internal manufacturing post- to produce 0V . It can be fixed simply by declaring the OUT package trim circuitry, and through a substrate diode to valid input differential range not to extend below +4mV, V . If more than 10mA is allowed to flow through these or by elevating the REF pin above 40mV, or by providing EE pins, there is a risk that the LT1991 will be detrimmed or a negative supply. damaged. The P1 and M1 inputs do not have clamp diodes or substrate diodes or trim circuitry and can be taken well Calculating Input Voltage Range outside the supply rails. The maximum allowed voltage on Figure 2 shows the LT1991 in the generalized case of the P1 and M1 pins is ±60V. a difference amplifier, with the inputs shorted for the The input voltage range of the internal op amp extends common mode calculation. The values of RF and RG are to within 1.2V of V and 1V of V . The voltage at which dictated by how the P inputs and REF pin are connected. CC EE the op amp inputs common mode is determined by the By superposition we can write: voltage at the op amp’s +input, and this is determined by V = V • (R /(R + R )) + V • (R /(R + R )) INT EXT F F G REF G F G the voltages on pins P1, P3, P9 and REF (see “Calculating Or, solving for V : Input Voltage Range” section). This is true provided that EXT the op amp is functioning and feedback is maintaining the V = V • (1 + R /R ) – V • R /R EXT INT G F REF G F inputs at the same voltage, which brings us to the third But valid V voltages are limited to V – 1.2V and V requirement. INT CC EE + 1V, so: For valid circuit function, the op amp output must not be MAX V = (V – 1.2) • (1 + R /R ) – V • R /R clipped. The output will clip if the input signals are attempt- EXT CC G F REF G F ing to force it to within 40mV of its supply voltages. This and: usually happens due to too large a signal level, but it can MIN V = (V + 1) • (1 + R /R ) – V • R /R EXT EE G F REF G F also occur with zero input differential and must therefore be included as an example of a common mode problem. Consider Figure 1. This shows the LT1991 configured RF 5V VCC 7 RG – 8 50k 450k 4pF VEXT VINT + 9 150k RG VEE –10 450k – RF VREF 1991 F02 0VVD+M1 450k 6 VOUT = 13 • VDM Figure 2. Calculating CM Input Voltage Range + VCM 4pF 2.5V 2 150k These two voltages represent the high and low extremes of the common mode input range, if the other limits have 3 50k 450k REF 5 not already been exceeded (1 and 3, above). In most LT1991 4 1991 F01 cases, the inverting inputs M1 through M9 can be taken further than these two extremes because doing this does Figure 1. Difference Amplifier Cannot Produce not move the op amp input common mode. To calculate 0V on a Single Supply. Provide a Negative Supply, or Raise Pin 5, or Provide 4mV of V the limit on this additional range, see Figure 3. Note that, DM 1991fh 11

LT1991 APPLICATIONS INFORMATION with V = 0, the op amp output is at V . From the representation of the circuit on the top. The LT1991 is MORE REF max V (the high cm limit), as V goes positive, the shown on the bottom configured in a precision gain EXT MORE op amp output will go more negative from V by the of 5.5. One of the benefits of the noninverting op amp REF amount V • R /R , so: configuration is that the input impedance is extremely MORE F G high. The LT1991 maintains this benefit. Given the finite V = V – V • R /R OUT REF MORE F G number of available feedback resistors in the LT1991, the Or: number of gain configurations is also finite. The complete list of such Hi-Z input noninverting gain configurations is V = (V – V ) • R /R MORE REF OUT G F shown in Table 1. Many of these are also represented in The most negative that V can go is V + 0.04V, so: OUT EE Figure 5 in schematic form. Note that the P-side resistor Max V = (V – V – 0.04V) • R /R inputs have been connected so as to match the source MORE REF EE G F (should be positive) impedance seen by the internal op amp inputs. Note also that gain and noise gain are identical, for optimal precision. The situation where this function is negative, and there- fore problematic, when V = 0 and V = 0, has already REF EE RF been dealt with in Figure 1. The strength of the equation is demonstrated in that it provides the three solutions suggested in Figure 1: raise V , lower V , or provide RG REF EE – some negative V . MORE VOUT Likewise, from the lower common mode extreme, mak- VIN + VOUT = GAIN • VIN ing the negative input more negative will raise the output GAIN = 1 + RF/RG voltage, limited by V – 0.04V. CLASSICAL NONINVERTING OP AMP CONFIGURATION. CC YOU PROVIDE THE RESISTORS. MIN V = (V – V + 0.04V) • R /R MORE REF CC G F (should be negative) RF 8 50k 450k 4pF VCC 9 150k RG VMORE – 10 450k – VEXT VINT + 6 MAX OR MIN VOUT RG VEE 1 450k + VREF RF 1991 F03 2 150k 4pF Figure 3. Calculating Additional Voltage Range of Inverting Inputs 3 50k 450k LT1991 5 Again, the additional input range calculated here is only VIN available provided the other remaining constraint is not CLASSICAL NONINVERTING OP AMP CONFIGURATION IMPLEMENTED WITH LT1991. RF = 225k, RG = 50k, GAIN = 5.5. violated, the maximum voltage allowed on the pin. GAIN IS ACHIEVED BY GROUNDING, FLOATING OR FEEDING BACK THE AVAILABLE RESISTORS TO ARRIVE AT DESIRED RF AND RG. The Classical Noninverting Amplifier: High Input Z WE PROVIDE YOU WITH <0.1% RESISTORS. 1991 F04 Perhaps the most common op amp configuration is the noninverting amplifier. Figure 4 shows the textbook Figure 4. The LT1991 as a Classical Noninverting Op Amp 1991fh 12

LT1991 APPLICATIONS INFORMATION Table 1. Configuring the M Pins for Simple Noninverting Gains. The P Inputs are driven as shown in the examples on the next page M9, M3, M1 Connection Gain M9 M3 M1 1 Output Output Output 1.077 Output Output Ground 1.1 Output Float Ground 1.25 Float Output Ground 1.273 Output Ground Output 1.3 Output Ground Float 1.4 Output Ground Ground 2 Float Float Ground 2.5 Float Ground Output 2.8 Ground Output Output 3.25 Ground Output Float 3.5 Ground Output Ground 4 Float Ground Float 5 Float Ground Ground 5.5 Ground Float Output 7 Ground Ground Output 10 Ground Float Float 11 Ground Float Ground 13 Ground Ground Float 14 Ground Ground Ground 1991fh 13

LT1991 APPLICATIONS INFORMATION VS+ VS+ VS+ 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF VIN 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 VIN P9 4 P9 4 VIN P9 4 VS– VS– VS– GAIN = 1 GAIN = 2 GAIN = 3.25 VS+ VS+ VS+ 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 VS– VS– VS– VIN VIN VIN GAIN = 4 GAIN = 5 GAIN = 5.5 VS+ VS+ VS+ 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 VIN P9 4 VIN P9 4 P9 4 VS– VS– VS– VIN GAIN = 7 GAIN = 10 GAIN = 11 VS+ VS+ 8 8 M9 M9 9 7 9 7 M3 M3 10 VCC 10 VCC M1 M1 6 6 LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 VIN P9 4 P9 4 VS– VS– VIN GAIN = 13 GAIN = 14 1991 F05 Figure 5. Some Implementations of Classical Noninverting Gains Using the LT1991. High Input Z Is Maintained 1991fh 14

LT1991 APPLICATIONS INFORMATION Attenuation Using the P Input Resistors Table 2. Configuring the P Pins for Various Attenuations. Those Shown in Bold Are Functional Even When the Input Drive Attenuation happens as a matter of fact in difference Exceeds the Supplies. amplifier configurations, but it is also used for reducing P9, P3, P1, REF Connection peak signal level or improving input common mode range A P9 P3 P1 REF even in single ended systems. When signal conditioning 0.0714 Ground Ground Drive Ground indicates a need for attenuation, the LT1991 resistors are 0.0769 Ground Ground Drive Float ready at hand. The four precision resistors can provide 0.0909 Ground Float Drive Ground several attenuation levels, and these are tabulated in 0.1 Ground Float Drive Float Table 2 as a design reference. 0.143 Ground Ground Drive Drive 0.182 Ground Float Drive Drive 0.2 Float Ground Drive Ground VIN VIN 1 450k VINT 0.214 Ground Drive Ground Ground RA OKAY UP + TO ±60V 0.231 Ground Drive Float Ground VINT 2 150k 4pF 0.25 Float Ground Drive Float RG VINT = A • VIN 0.286 Ground Drive Drive Ground A = RG/(RA + RG) 3 50k 450k LT1991 0.308 Ground Drive Drive Float 5 0.357 Ground Drive Drive Drive CLASSICAL ATTENUATOR LT1991 ATTENUATING TO THE +INPUT BY 0.4 Float Ground Drive Drive DRIVING AND GROUNDING AND FLOATING INPUTS RA = 450k, RG = 50k, SO A = 0.1. 0.5 Float Float Drive Ground 1991 F06 0.6 Float Drive Ground Ground Figure 6. LT1991 Provides for Easy Attenuation to the Op Amp’s +Input. The P1 Input Can Be Taken Well Outside of the Supplies 0.643 Drive Ground Ground Ground 0.692 Drive Ground Float Ground Because the attenuations and the noninverting gains are set 0.714 Drive Ground Drive Ground independently, they can be combined. This provides high 0.75 Float Drive Float Ground gain resolution, about 340 unique gains between 0.077 0.769 Drive Ground Drive Float and 14, as plotted in Figure 7. This is too large a number 0.786 Drive Ground Drive Drive to tabulate, but the designer can calculate achievable gain 0.8 Float Drive Drive Ground by taking the vector product of the gains and attenuations 0.818 Drive Float Ground Ground in Tables 1 and 2, and seeking the best match. Average 0.857 Drive Drive Ground Ground gain resolution is 1.5%, with a worst-case of 7%. 0.9 Drive Float Float Ground 100 0.909 Drive Float Drive Ground 0.923 Drive Drive Float Ground 10 0.929 Drive Drive Drive Ground 1 Drive Drive Drive Drive N AI 1 G 0.1 0.01 0 50 100 150 200 250 300 350 COUNT 1991 F07 Figure 7. Over 346 Unique Gain Settings Achievable with the LT1991 by Combining Attenuation with Noninverting Gain 1991fh 15

LT1991 APPLICATIONS INFORMATION Inverting Configuration Table 3. Configuring the M Pins for Simple Inverting Gains The inverting amplifier, shown in Figure 8, is another clas- M9, M3, M1 Connection sical op amp configuration. The circuit is actually identical Gain M9 M3 M1 to the noninverting amplifier of Figure 4, except that V –0.077 Output Output Drive IN and GND have been swapped. The list of available gains –0.1 Output Float Drive is shown in Table 3, and some of the circuits are shown –0.25 Float Output Drive in Figure 9. Noise gain is 1+|Gain|, as is the usual case for –0.273 Output Drive Output inverting amplifiers. Again, for the best DC performance, –0.3 Output Drive Float match the source impedance seen by the op amp inputs. –0.4 Output Drive Drive –1 Float Float Drive RF –1.5 Float Drive Output –1.8 Drive Output Output –2.25 Drive Output Float RG VIN – –2.5 Drive Output Drive VOUT –3 Float Drive Float + VOUT = GAIN • VIN –4 Float Drive Drive GAIN = – RF/RG –4.5 Drive Float Output CLASSICAL INVERTING OP AMP CONFIGURATION. –6 Drive Drive Output YOU PROVIDE THE RESISTORS. –9 Drive Float Float –10 Drive Float Drive –12 Drive Drive Float VIN 8 50k 450k (DRIVE) –13 Drive Drive Drive 4pF 9 150k 10 450k – 6 VOUT 1 450k + 2 150k 4pF 3 50k 450k LT1991 5 CLASSICAL INVERTING OP AMP CONFIGURATION IMPLEMENTED WITH LT1991. RF = 225k, RG = 50k, GAIN = –4.5. GAIN IS ACHIEVED BY GROUNDING, FLOATING OR FEEDING BACK THE AVAILABLE RESISTORS TO ARRIVE AT DESIRED RF AND RG. WE PROVIDE YOU WITH <0.1% RESISTORS. 1991 F08 Figure 8. The LT1991 as a Classical Inverting Op Amp. Note the Circuit Is Identical to the Noninverting Amplifier, Except that V and Ground Have Been Swapped IN 1991fh 16

LT1991 APPLICATIONS INFORMATION VS+ VS+ VS+ 8 8 8 9 M9 7 9 M9 7 VIN 9 M9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN M1 6 VIN M1 6 M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 VS– VS– VS– GAIN = –0.25 GAIN = –1 GAIN = –2.25 VS+ VS+ VS+ 8 8 8 9 M9 7 9 M9 7 VIN 9 M9 7 VIN 10 M3 VCC 10 M3 VCC 10 M3 VCC M1 6 VIN M1 6 M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 VS– VS– VS– GAIN = –3 GAIN = –4 GAIN = –4.5 VS+ VS+ VS+ 8 8 8 VIN 9 M9 7 VIN 9 M9 7 VIN 9 M9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 VS– VS– VS– GAIN = –6 GAIN = –9 GAIN = –10 VS+ VS+ 8 8 VIN 9 M9 7 9 M9 7 M3 M3 10 VCC 10 VCC M1 6 VIN M1 6 LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 VS– VS– GAIN = –12 GAIN = –13 1991 F09 Figure 9. It Is Simple to Get Precision Inverting Gains with the LT1991. Input Impedance Varies from 45kΩ (Gain = –13) to 450kΩ (Gain = –1) 1991fh 17

LT1991 APPLICATIONS INFORMATION Difference Amplifiers RF The resistors in the LT1991 allow it to easily make differ- ence amplifiers also. Figure 10 shows the basic 4-resistor RG difference amplifier and the LT1991. A difference gain of VIN– – 3 is shown, but notice the effect of the additional dashed RG VOUT connections. By connecting the 450k resistors in paral- VIN+ + VOUT = GAIN • (VIN+ – VIN–) lel, the gain is reduced by a factor of 2. Of course, with RF GAIN = RF/RG so many resistors, there are many possible gains. Table 4 shows the difference gains and how they are achieved. CLASSICAL DIFFERENCE AMPLIFIER USING THE LT1991 Note that, as for inverting amplifiers, the noise gain is 1 more than the signal gain. 8 M9 50k 450k Table 4. Connections Giving Difference Gains for the LT1991 4pF Gain V + V – Output GND (REF) VIN– 9 M3 150k IN IN 0.077 P1 M1 M3, M9 P3, P9 10 M1 450k – PARALLEL 0.1 P1 M1 M9 P9 TO CHANGE 6 VOUT 0.25 P1 M1 M3 P3 RF, RG 1 P1 450k + 0.273 P3 M3 M1, M9 P1, P9 VIN+ 2 P3 150k 4pF 0.3 P3 M3 M9 P9 0.4 P1, P3 M1, M3 M9 P9 3 P9 50k 450k 5 1 P1 M1 LT1991 1.5 P3 M3 M1 P1 1.8 P9 M9 M1, M3 P1, P3 CLASSICAL DIFFERENCE AMPLIFIER IMPLEMENTED WITH LT1991. RF = 450k, RG = 150k, GAIN = 3. 2.25 P9 M9 M3 P3 ADDING THE DASHED CONNECTIONS CONNECTS THE 2.5 P1, P9 M1, M9 M3 P3 TWO 450k RESISTORS IN PARALLEL, SO RF IS REDUCED 3 P3 M3 TO 225k. GAIN BECOMES 225k/150k = 1.5. 1991 F10 4 P1, P3 M1, M3 Figure 10. Difference Amplifier Using the LT1991. Gain Is Set 4.5 P9 M9 M1 P1 Simply by Connecting the Correct Resistors or Combinations of Resistors. Gain of 3 Is Shown, with Dashed Lines Modifying 6 P3, P9 M3, M9 M1 P1 It to Gain of 1.5. Noise Gain Is Optimal 9 P9 M9 10 P1, P9 M1, M9 12 P3, P9 M3, M9 13 P1, P3, P9 M1, M3, M9 1991fh 18

LT1991 APPLICATIONS INFORMATION VS+ VS+ VS+ 89 M9 7 89 M9 7 VIN– 89 M9 7 M3 M3 M3 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 10 M1 VCC 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF 1 P1 REF 23 PP39 VEE4 5 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VS– VS– VS– GAIN = 0.25 GAIN = 1 GAIN = 2.25 VS+ VS+ VS+ VIN– 89 MM93 7 VIN– 89 MM93 7 VIN– 89 MM93 7 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VS– VS– VS– GAIN = 3 GAIN = 4 GAIN = 4.5 VS+ VS+ VS+ VIN– 8 M9 VIN– 8 M9 VIN– 8 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC M1 M1 M1 6 6 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF 1 P1 REF VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VS– VS– VS– GAIN = 6 GAIN = 9 GAIN = 10 VS+ VS+ VIN– 8 M9 VIN– 8 M9 9 7 9 7 M3 M3 10 VCC 10 VCC M1 M1 6 6 LT1991 OUT VOUT LT1991 OUT VOUT 1 P1 REF 1 P1 REF VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 VS– VS– GAIN = 12 GAIN = 13 1991 F11 Figure 11. Many Difference Gains Are Achievable Just by Strapping the Pins 1991fh 19

LT1991 APPLICATIONS INFORMATION 8 M9 50k 450k 4pF VIN– 9 M3 150k RF 10 M1 450k – CROSS- 6 VIN– RG – COUPLING 1 P1 450k + VOUT VIN+ RG + VOUT = GAIN • V(VOIUNT+ – VIN–) VIN+ 2 P3 150k 4pF RF GAIN = RF/RG 3 P9 50k 450k 5 LT1991 CLASSICAL DIFFERENCE AMPLIFIER IMPLEMENTED CLASSICAL DIFFERENCE AMPLIFIER WITH LT1991. RF = 450k, RG = 150k, GAIN = 3. GAIN CAN BE ADJUSTED BY "CROSS COUPLING." MAKING THE DASHED CONNECTIONS REDUCE THE GAIN FROM 3 T0 2. WHEN CROSS COUPLING, SEE WHAT IS CONNECTED TO THE VIN+ VOLTAGE. CONNECTING P3 AND M1 GIVES +3 –1 = 2. CONNECTIONS TO VIN– ARE SYMMETRIC: M3 AND P1. 1991 F12 Figure 12. Another Method of Selecting Difference Gain Is “Cross-Coupling.” The Additional Method Means the LT1991 Provides All Integer Gains from 1 to 13 Difference Amplifier: Additional Integer Gains Using VS+ VS+ Cross-Coupling VIN– 1890 MM93 VCC7 VIN– 1890 MM93 VCC7 Figure 12 shows the basic difference amplifier as well as M1 6 M1 6 the LT1991 in a difference gain of 3. But notice the effect 1 P1 LT1991REFOUT VOUT 1 P1 LT1991REFOUT VOUT of the additional dashed connections. This is referred to VIN+ 23 PP39 VEE4 5 VIN+ 23 PP39 VEE4 5 as “cross-coupling” and has the effect of reducing the VS– VS– differential gain from 3 to 2. Using this method, additional GAIN = 2 GAIN = 5 integer gains are achievable, as shown in Table 5 below, VS+ VS+ so that all integer gains from 1 to 13 are achieved with the VIN– 89 M9 7 VIN– 89 M9 7 LT1991. Note that the equations can be written by inspection 10 MM31 VCC 10 MM31 VCC 6 6 afrroem si mthpe lVy ItNh+e coopnpnoescitteio (nssw, aapn dP tfhoart M th aen VdI NM– fcoorn Pn)e. cNtiooinsse VIN+ 123 PPP139 VLTEE14991REF5OUT VOUTVIN+ 123 PPP139 VLTEE14991REF5OUT VOUT gain, bandwidth, and input impedance specifications for the VS– VS– various cases are also tabulated, as these are not obvious. GAIN = 7 GAIN = 8 Schematics are provided in Figure 13. VS+ VIN– 8 M9 9 7 Table 5. Connections Using Cross-Coupling. Note That Equations Can 10 MM31 VCC Be Written by Inspection of the VIN+ Column 1 P1 LT1991REFOUT 6 VOUT Gain VI N+ VI N– Equa tion NGoaiisne –3dkBH zBW TyRpI Nk+Ω TyRpI Nk–Ω VIN+ 23 PP39 VEE4 5 2 P3, M1 M3, P1 3 – 1 5 70 281 141 VS– 5 P9, M3, M1 M9, P3, P1 9 – 3 – 1 14 32 97 49 GAIN = 11 1991 F13 6* P9, M3 M9, P3 9 – 3 13 35 122 49 7 P9, P1, M3 M9, M1, P39 + 1 – 3 14 32 121 44 Figure 13. Integer Gain Difference 8 P9, M1 M9, P1 9 – 1 11 38 248 50 Amplifiers Using Cross-Coupling 11 P9, P3, M1 M9, M3, P19 + 3 – 1 14 32 242 37 *Gain of 6 is better implemented as shown previously, but is included here for completeness. 1991fh 20

LT1991 APPLICATIONS INFORMATION High Voltage CM Difference Amplifiers Table 6. HighV CM Connections Giving Difference Gains for the LT1991 This class of difference amplifier remains to be discussed. Max, Min V Figure 14 shows the basic circuit on the top. The effective EXT Noise (Substitute V – 1.2, CC input voltage range of the circuit is extended by the fact Gain V + V – R Gain V + 1 for V ) IN IN T EE LIM that resistors RT attenuate the common mode voltage seen 1 P1 M1 2 2 • VLIM - VREF by the op amp inputs. For the LT1991, the most useful 1 P1 M1 P3, M3 5 5 • V – V – 3 • V LIM REF TERM resistors for R are the M1 and P1 450kΩ resistors, be- G 1 P1 M1 P9, M9 11 11 • VLIM – VREF – 9 • VTERM cause they do not have diode clamps to the supplies and 1 P1 M1 P3||P9 14 14 • V – V – 12 • V LIM REF TERM therefore can be taken outside the supplies. As before, the M3||M9 input CM of the op amp is the limiting factor and is set by the voltage at the op amp +input, VINT. By superposition RF we can write: VCC VINT = VEXT • (RF||RT)/(RG + RF||RT) + VREF • (RG||RT)/ RG VIN– – (R + R ||R ) + V • (R ||R )/(R + R ||R ) F G T TERM F G T F G VIN+ RG + VOUT Solving for VEXT: (= VEXT) VOUT = GAIN • (VIN+ – VIN–) RT RT VEE GAIN = RF/RG V = (1 + R /(R ||R )) • (V – V • (R ||R )/ EXT G F T INT REF G T RF VREF (RF + RG||RT) – VTERM • (RF||RG)/(RT + RF||RG)) VTERM HIGH CM VOLTAGE DIFFERENCE AMPLIFIER Given the values of the resistors in the LT1991, this equa- INPUT CM TO OP AMP IS ATTENUATED BY tion has been simplified and evaluated, and the resulting RESISTORS RT CONNECTED TO VTERM. equations provided in Table 6. As before, substituting V – 1.2 and V + 1 for V will give the valid upper 12V 7 CC EE LIM and lower common mode extremes respectively. Following 8 M9 50k 450k are sample calculations for the case shown in Figure 14, 4pF 9 M3 150k right-hand side. Note that P9 and M9 are terminated so row 3 of Table 6 provides the equation: 10 M1 450k – MAX VEXT = 11 • (VCC – 1.2V) – VREF – 9 • VTERM 6 VOUT 1 P1 450k + = 11 • (10.8V) – 2.5 – 9 • 12 = 8.3V VIN– VIN+ 2 P3 150k 4pF and: INPUT CM RANGE = –60V TO 8.3V MIN VEXT = 11 • (VEE + 1V) – VREF – 9 • VTERM 3 P9 50k 450k REF 5 2.5V LT1991 = 11 • (1V) – 2.5 – 9 • 12 = –99.5V 4 but this exceeds the 60V absolute maximum rating of HIGH NEGATIVE CM VOLTAGE DIFFERENCE AMPLIFIER IMPLEMENTED WITH LT1991. the P1, M1 pins, so –60V becomes the de facto negative RF = 450k, RG = 450k, RT 50k, GAIN = 1 common mode limit. Several more examples of high CM VTERM = VCC = 12V, VREF = 2.5V, VEE = GROUND. 1991 F14 circuits are shown in Figures 15, 16, 17 for various supplies. Figure 14. Extending CM Input Range 1991fh 21

LT1991 APPLICATIONS INFORMATION 3V 3V 3V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 1.25V 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 3V VCM = 0.8V TO 2.35V VCM = 2V TO 3.6V VCM = –1V TO 0.6V VDM > 40mV VDM <–40mV 3V 3V 3V 3V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V P9 4 P9 4 P9 4 1.25V VCM = 0V TO 4V VCM = 3.8V TO 7.75V VCM = –5V TO –1.25V 3V 3V 3V 3V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V P9 4 P9 4 P9 4 1.25V VCM = –1.5V TO 7.2V VCM = 9.8V TO 18.55V VCM = –17.2V TO –8.45V 3V 3V 3V 3V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V 23 P3 VEE 5 1.25V P9 4 P9 4 P9 4 1.25V VCM = –2.25V TO 8.95V VCM = 12.75V TO 23.95V VCM = –23.2V TO –12V 1991 F15 Figure 15. Common Mode Ranges for Various LT1991 Configurations on V = 3V, 0V; with Gain = 1 S 1991fh 22

LT1991 APPLICATIONS INFORMATION 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 2.5V 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 3V VCM = –0.5V TO 5.1V VCM = 2V TO 7.6V VCM = –3V TO 2.6V VDM > 40mV VDM <–40mV 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V P9 4 P9 4 P9 4 2.5V VCM = –5V TO 9V VCM = 2.5V TO 16.5V VCM = –12.5V TO 1.5V 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V P9 4 P9 4 P9 4 2.5V VCM = –14V TO 16.8V VCM = 8.5V TO 39.3V VCM = –36.5V TO –5.7V 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V 23 P3 VEE 5 2.5V P9 4 P9 4 P9 4 2.5V VCM = –18.5V TO 20.7V VCM = 11.5V TO 50.7V VCM = –48.5V TO –9.3V 1991 F16 Figure 16. Common Mode Ranges for Various LT1991 Configurations on V = 5V, 0V; with Gain = 1 S 1991fh 23

LT1991 APPLICATIONS INFORMATION 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 VIN– 10 M1 VCC 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 –5V P9 4 –5V –5V –5V –5V VCM = –8V TO 7.6V VCM = –3V TO 12.6V VCM = –13V TO 2.6V VDM > 40mV VDM <–40mV 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 –5V –5V –5V –5V VCM = –20V TO 19V VCM = –5V TO 34V VCM = –35V TO 4V 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 –5V –5V –5V –5V VCM = –44V TO 41.8V VCM = 1V TO 60V VCM = –60V TO –3.2V 5V 5V 5V 5V 8 8 8 M9 M9 M9 9 7 9 7 9 7 M3 M3 M3 10 VCC 10 VCC 10 VCC VIN– M1 6 VIN– M1 6 VIN– M1 6 LT1991 OUT VOUT LT1991 OUT VOUT LT1991 OUT VOUT VIN+ 1 P1 REF VIN+ 1 P1 REF VIN+ 1 P1 REF 23 P3 VEE 5 23 P3 VEE 5 23 P3 VEE 5 P9 4 P9 4 P9 4 –5V –5V –5V –5V VCM = –56V TO 53.2V VCM = 4V TO 60V VCM = –60V TO –6.8V 1991 F17 Figure 17. Common Mode Ranges for Various LT1991 Configurations on V = ±5V, with Gain = 1 S 1991fh 24

LT1991 TYPICAL APPLICATIONS Micropower A = 10 Instrumentation Amplifier V VOUT 10 9 8 7 6 VM + 1/2 LT6011 – 4pF – + VP + LT1991 1/2 LT6011 – 4pF 1 2 3 4 5 1991 TA02 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699 Rev C) R = 0.125 0.40 ± 0.10 TYP 6 10 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 3.00 ±0.10 1.65 ± 0.10 2.15 ±0.05 (2 SIDES) PACKAGE (4 SIDES) (2 SIDES) PIN 1 NOTCH OUTLINE PIN 1 R = 0.20 OR TOP MARK 0.35 × 45° (SEE NOTE 6) CHAMFER (DD) DFN REV C 0310 5 1 0.25 ± 0.05 0.200 REF 0.75 ±0.05 0.25 ± 0.05 0.50 0.50 BSC BSC 2.38 ±0.10 2.38 ±0.05 0.00 – 0.05 (2 SIDES) (2 SIDES) BOTTOM VIEW—EXPOSED PAD RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 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 1991fh 25

LT1991 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661 Rev E) 0.889 ±0.127 (.035 ±.005) 5.23 3.20 – 3.45 (.206) (.126 – .136) MIN 3.00 ±0.102 0.305 ±0.038 0.50 (.118 ±.004) 0.497 ±0.076 (.0120 ±.0015) (.0197) (NOTE 3) (.0196 ±.003) 10 9 8 76 TYP BSC REF RECOMMENDED SOLDER PAD LAYOUT 3.00 ±0.102 4.90 ±0.152 DETAIL “A” (.193 ±.006) (.118 ±.004) 0.254 (NOTE 4) (.010) 0° – 6° TYP GAUGE PLANE 1 2 3 4 5 0.53 ±0.152 (.021 ±.006) 1.10 0.86 (.043) (.034) DETAIL “A” MAX REF 0.18 (.007) SEATING PLANE 0.17 – 0.27 0.1016 ±0.0508 (.007 – .011) (.004 ±.002) 0.50 TYP (.0197) MSOP (MS) 0307 REV E NOTE: BSC 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 1991fh 26

LT1991 REVISION HISTORY (Revision history begins at Rev H) REV DATE DESCRIPTION PAGE NUMBER H 5/12 Corrected specified temperature range for C-grade parts in the Order Information table. 2 Corrected V = –20V to 19V and V = –5V to 34V configurations in Figure 17. 24 CM CM Updated Related Parts Table 28 1991fh Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 27 However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LT1991 TYPICAL APPLICATION Bidirectional Current Source Single Supply AC Coupled Amplifier VS+ VS = 2.7V TO 36V 8 8 M9 M9 9 7 9 7 VIN– 10 MM31 6 1µF 10 MM31 6 VIN+ R2* 12 PP13 LT1991 5 R101k VCC 0.1µF 12 PP13 LT1991 5 VOUT 10k 3 3 P9 4 VIN P9 4 VS– ILOAD = VIN1+0 k–Ω VIN– GAIN = 12 *SHORT R2 FOR LOWEST OUTPUT BW = 7Hz TO 32kHz OFFSET CURRENT. INCLUDE R2 FOR HIGHEST OUTPUT IMPEDANCE. 1991 TA03 Ultra-Stable Precision Attenuator Analog Level Adaptor 5V 5V 8 M9 8 9 7 M9 M3 9 7 10 M3 M1 10 6 VIN 1 MP11 LT1991REF 6 VOUT = V1I3N ± 10VIN 12 PP13 LT1991REF5 0-4VOUT = 14V to 53V 23 P3 5 3 P9 4 P9 4 LT1790 –2.5 1µF –5V 5V 6 4 2 1991 TA04 1 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1990 High Voltage, Gain Selectable Difference Amplifier ±250V Common Mode, Micropower, Pin Selectable Gain = 1, 10 LT1996 Precision Gain Selectable Difference Amplifier Micropower, Pin Selectable Up to Gain = 118 LT1995 High Speed, Gain Selectable Difference Amplifier 30MHz, 1000V/µs, Pin Selectable Gain = –7 to 8 LT6010/LT6011/ Single/Dual/Quad 135µA 14nV/√Hz Rail-to-Rail Out Similar Op Amp Performance as Used in LT1991 Difference Amplifier LT6012 Precision Op Amp LT6013/LT6014 Single/Dual 145µA 8nV/√Hz Rail-to-Rail Out Lower Noise A ≥ 5 Version of LT1991 Type Op Amp V Precision Op Amp LTC6910-X Programmable Gain Amplifiers 3 Gain Configurations, Rail-to-Rail Input and Output LT1999 High Voltage Bidirectional Current Sense Amplifier CMRR > 80dB at 100kHz LT5400 Quad Matched Resistor Network 0.01% Matching, CMRR > 86dB 1991fh 28 Linear Technology Corporation LT 0512 REV H • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com  LINEAR TECHNOLOGY CORPORATION 2006

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: A nalog Devices Inc.: LT1991ACDD#TR LT1991AIDD#PBF LT1991HDD#PBF LT1991IDD#TRPBF LT1991IMS#TR LT1991AIMS#PBF LT1991CMS#TRPBF LT1991IMS LT1991IDD#TR LT1991ACDD LT1991ACDD#TRPBF LT1991ACMS#TR LT1991IMS#TRPBF LT1991CDD LT1991AIMS#TR LT1991ACMS LT1991AIMS#TRPBF LT1991HMS#TR LT1991IDD LT1991HDD#TR LT1991CMS LT1991HMS#PBF LT1991ACMS#PBF LT1991CDD#PBF LT1991ACMS#TRPBF LT1991CMS#PBF LT1991IDD#PBF LT1991IMS#PBF LT1991AIDD#TR LT1991ACDD#PBF LT1991AIDD#TRPBF LT1991HMS#TRPBF LT1991HDD#TRPBF LT1991HDD LT1991CMS#TR LT1991CDD#TR LT1991CDD#TRPBF LT1991HMS LT1991AIDD LT1991AIMS