LT1678CS8

LT1678/LT1679 Dual/Quad Low Noise, Rail-to-Rail, Precision Op Amps FEATURES ■ ■ DESCRIPTIO ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Rail-to-Rail Input and Output 100% Tested Low Voltage Noise: 3.9nV/√Hz Typ at 1kHz 5.5nV/√Hz Max at 1kHz Single Supply Operation from 2.7V to 36V Offset Voltage: 100µV Max Low Input Bias Current: 20nA Max High AVOL: 3V/µV Min, RL = 10k High CMRR: 100dB Min High PSRR: 106dB Min Gain Bandwidth Product: 20MHz Operating Temperature Range: – 40°C to 85°C Matching Specifications No Phase Inversion 8-Lead SO and 14-Lead SO Packages The LT ®1678/LT1679 are dual/quad rail-to-rail op amps offering both low noise and precision: 3.9nV/√Hz wideband noise, 1/f corner frequency of 4Hz and 90nV peak-to-peak 0.1Hz to 10Hz noise are combined with outstanding precision: 100µV maximum offset voltage, greater than 100dB common mode and power supply rejection and 20MHz gain bandwidth product. The LT1678/LT1679 bring precision as well as low noise to single supply applications as low as 3V. The input range exceeds the power supply by 100mV with no phase inversion while the output can swing to within 170mV of either rail. The LT1678/LT1679 are offered in the SO-8 and SO-14 packages. A full set of matching specifications are also provided, facilitating their use in matching dependent applications such as a two op amp instrumentation amplifier design. The LT1678/LT1679 are specified for supply voltages of ±15V, single 5V as well as single 3V. For a single amplifier with similiar performance, see the LT1677 data sheet. , LTC and LT are registered trademarks of Linear Technology Corporation. APPLICATIO S ■ ■ ■ ■ ■ ■ Strain Gauge Amplifiers Portable Microphones Battery-Powered Rail-to-Rail Instrumentation Low Noise Signal Processing Microvolt Accuracy Threshold Detection Infrared Detectors TYPICAL APPLICATIO 3 Instrumentation Amplifier with Shield Driver + 1/4 LT1679 1 1k RF 3.4k 5 30k 2 – GUARD INPUT + – GUARD + 8 1/4 LT1679 10 RG 100Ω 6 RG 100Ω + – 4 1/4 LT1679 11 –15V 7 OUTPUT 30k – 9 GAIN = 1000 13 VOLTAGE NOISE (50nV/DIV) 15V – 1/4 LT1679 14 RF 3.4k 16789 TA01 12 + 1k U 0.1Hz to 10Hz Voltage Noise VS = ±2.5V 0 2 4 6 TIME (sec) 8 10 16789 TA01b U U sn16789 16789fs 1 LT1678/LT1679 ABSOLUTE (Note 1) AXI U RATI GS Lead Temperature (Soldering, 10 sec.)................. 300°C Operating Temperature Range (Note 4) ............................................. – 40°C to 85°C Specified Temperature Range (Note 5) ............................................. – 40°C to 85°C Supply Voltage ...................................................... ± 18V Input Voltages (Note 2) ............ 0.3V Beyond Either Rail Differential Input Current (Note 2) ..................... ± 25mA Output Short-Circuit Duration (Note 3) ............ Indefinite Storage Temperature Range ................. – 65°C to 150°C PACKAGE/ORDER I FOR ATIO TOP VIEW OUT A 1 –IN A 2 +IN A 3 V– 4 A B 8V + ORDER PART NUMBER 7 OUT B 6 –IN B 5 +IN B LT1678CS8 LT1678IS8 S8 PART MARKING 1678 1678I S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 150°C, θJA = 190°C/ W Consult LTC Marketing for parts specified with wider operating temperature ranges. The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 3V, VCM = VO = 1.7V; VS = 5V, VCM = VO = 2.5V unless otherwise noted. SYMBOL VOS PARAMETER Input Offset Voltage CONDITIONS (Note 6) (Note 11) 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C VS =5V, VCM = VS + 0.1V VS =5V, VCM = VS – 0.3V, 0°C ≤ TA ≤ 70°C VS =5V, VCM = VS – 0.3V, – 40°C ≤ TA ≤ 85°C VS =5V, VCM = – 0.1V VS =5V, VCM = 0V, 0°C ≤ TA ≤ 70°C VS =5V, VCM = 0V, – 40°C ≤ TA ≤ 85°C ∆VOS ∆Temp IB Average Input Offset Drift (Note 10) Input Bias Current (Note 11) 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS VS = 5V, VCM = VS + 0.1V ● VS = 5V, VCM = VS – 0.3V, 0°C ≤ TA ≤ 70°C VS = 5V, VCM = VS – 0.3V, – 40°C ≤ TA ≤ 85°C ● VS = 5V, VCM = – 0.1V VS = 5V, VCM = 0V, 0°C ≤ TA ≤ 70°C VS = 5V, VCM = 0V, – 40°C ≤ TA ≤ 85°C ● ● 2 U U W WW U W TOP VIEW OUT A 1 –IN A 2 +IN A 3 V+ 4 +IN B 5 –IN B 6 OUT B 7 B C A D 14 OUT D 13 –IN D 12 +IN D 11 V – 10 +IN C 9 8 –IN C OUT C ORDER PART NUMBER LT1679CS LT1679IS S PACKAGE 14-LEAD PLASTIC SO TJMAX = 150°C, θJA = 160°C/ W MIN TYP 35 55 75 150 180 200 1.5 1.8 2.0 0.40 ±2 ±3 ±7 0.19 0.19 0.25 MAX 100 270 350 550 750 1000 30 45 50 3 ± 20 ± 35 ± 50 0.40 0.60 0.75 UNITS µV µV µV µV µV µV mV mV mV µV/°C nA nA nA µA µA µA µA µA µA ● ● –5 –8.4 –10 – 0.41 – 0.45 – 0.47 sn16789 16789fs LT1678/LT1679 The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 3V, VCM = VO = 1.7V; VS = 5V, VCM = VO = 2.5V unless otherwise noted. SYMBOL IOS PARAMETER Input Offset Current CONDITIONS (Note 6) (Note 11) 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ● ● ELECTRICAL CHARACTERISTICS MIN TYP 4 5 8 6 10 15 0.1 0.1 0.15 90 180 1600 4.4 6.6 19 3.9 5.3 9 1.2 0.3 MAX 25 35 55 30 40 65 1.6 2.0 2.4 UNITS nA nA nA nA nA nA µA µA µA nVP-P nVP-P nVP-P nV/√Hz nV/√Hz nV/√Hz VS = 5V, VCM = VS + 0.1V VS = 5V, VCM = VS – 0.3V, 0°C ≤ TA ≤ 70°C ● VS = 5V, VCM = VS – 0.3V, – 40°C ≤ TA ≤ 85°C ● VS = 5V, VCM = – 0.1V VS = 5V, VCM = 0V, 0°C ≤ TA ≤ 70°C VS = 5V, VCM = 0V, – 40°C ≤ TA ≤ 85°C en Input Noise Voltage 0.1Hz to 10Hz (Note 7) VCM = VS VCM = 0V fO = 10Hz VCM = VS, fO = 10Hz VCM = 0V, fO = 10Hz fO = 1kHz VCM = VS, fO = 1kHz VCM = 0V, fO = 1kHz in VCM RIN CIN CMRR PSRR AVOL Input Noise Current Density Input Voltage Range ● ● ● Input Noise Voltage Density (Note 8) 5.5 nV/√Hz nV/√Hz nV/√Hz pA/√Hz pA/√Hz fO = 10Hz fO = 1kHz – 0.1 0 VS + 0.1V VS – 0.3V 2 4.2 V V GΩ pF dB dB dB dB V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV V/µV Input Resistance Input Capacitance Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain Common Mode VS = 5V, VCM = 1.9V to 3.9V VS = 5V, VCM = 1.9V to 3.9V VS = 2.7V to 36V, VCM = VO = 1.7V VS = 3.1V to 36V, VCM = VO = 1.7V VS = 3V, RL = 10k, VO = 2.5V to 0.7V VS = 3V, RL = 2k, VO = 2.2V to 0.7V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C VS = 3V, RL = 600Ω, VO = 2.2V to 0.7V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C VS = 5V, RL = 10k, VO = 4.5V to 0.7V O°C < TA < 70°C –40 < TA < 85°C VS = 5V, RL = 2k, VO = 4.2V to 0.7V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C VS = 5V, RL = 600Ω, VO = 4.2V to 0.7V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C 98 92 100 98 0.6 0.3 0.5 0.4 0.4 0.20 0.15 0.10 1 0.6 0.3 0.7 0.6 0.5 0.6 0.5 0.4 ● ● ● ● ● ● ● ● ● ● ● ● ● 120 120 125 120 3 2 3 0.9 0.8 0.43 0.40 0.35 3.8 2 2 3.5 3.2 3.0 3.0 2.8 2.5 80 125 130 170 200 250 VOL Output Voltage Swing Low (Note 11) Above GND ISINK = 0.1mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ● ● mV mV mV sn16789 16789fs 3 LT1678/LT1679 The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = 3V, VCM = VO = 1.7V; VS = 5V, VCM = VO = 2.5V unless otherwise noted. SYMBOL VOL PARAMETER Output Voltage Swing Low (Note 11) CONDITIONS (Note 6) Above GND ISINK = 2.5mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Above GND ISINK = 10mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C VOH Output Voltage Swing High (Note 11) Below VS ISOURCE = 0.1mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Below VS ISOURCE = 2.5mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Below VS ISOURCE = 10mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ISC Output Short-Circuit Current (Note 3) VS = 3V ● ELECTRICAL CHARACTERISTICS MIN TYP 170 195 205 370 440 465 75 85 93 110 195 205 170 200 230 MAX 250 320 350 600 720 770 150 200 250 250 350 375 400 500 550 UNITS mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mA mA mA mA V/µs V/µs V/µs MHz MHz µs µs Ω Ω ● ● ● ● ● ● ● ● ● ● 15 13 18 14 4 3.5 3 13 12.5 22 19 29 25 6 5.8 5.5 20 19 1.4 2.4 100 1 VS = 5V ● SR Slew Rate (Note 13) AV = – 1, RL = 10k RL = 10k, 0°C ≤ TA ≤ 70°C RL = 10k, – 40°C ≤ TA ≤ 85°C fO = 100kHz fO = 100kHz 2V Step 0.1%, AV = +1 2V Step 0.01%, AV = +1 IOUT = 0 AV = 100, f = 10kHz ● ● ● GBW tS RO IS ∆VOS Gain Bandwidth Product (Note 11) Settling Time Open-Loop Output Resistance Closed-Loop Output Resistance Supply Current per Amplifier (Note 12) ● 2 2.5 35 55 75 ±2 ±3 ±7 94 88 96 94 110 110 120 120 3.4 3.8 150 400 525 ± 30 ± 55 ± 75 mA mA µV µV µV nA nA nA dB dB dB dB Offset Voltage Match (Notes 11, 15) Noninverting Bias Current Match (Notes 11, 15) Common Mode Rejection Match (Notes 11, 14, 15) Power Supply Rejection Match (Notes 11, 14, 15) 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C VS = 5V, VCM = 1.9V to 3.9V ● ● ● ● ● ∆IB+ ∆CMRR ∆PSRR VS = 2.7V to 36V, VCM = VO = 1.7V VS = 3.1V to 36V, VCM = VO = 1.7V ● sn16789 16789fs 4 LT1678/LT1679 The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ± 15V, VCM = VO = 0V unless otherwise noted. SYMBOL VOS PARAMETER Input Offset Voltage 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ∆VOS ∆Temp IB Average Input Offset Drift (Note 10) Input Bias Current 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C IOS Input Offset Current 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C en Input Noise Voltage 0.1Hz to 10Hz (Note 7) VCM = 15V VCM = – 15V fO = 10Hz VCM = 15V, fO = 10Hz VCM = – 15V, fO = 10Hz fO = 1kHz VCM = 15V, fO = 1kHz VCM = – 15V, fO = 1kHz in VCM RIN CIN CMRR PSRR AVOL Input Noise Current Density Input Voltage Range (Note 16) Input Resistance Input Capacitance Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain VCM = – 13.3V to 14V ● ● ● ● ● ● ● ● ELECTRICAL CHARACTERISTICS CONDITIONS (Note 6) MIN TYP 20 30 45 0.40 ±2 ±3 ±7 3 5 8 90 180 1600 4.4 6.6 19 3.9 5.3 9 1.2 0.3 MAX 150 350 420 3 ±20 ±35 ±50 25 35 55 UNITS µV µV µV µV/°C nA nA nA nA nA nA nVP-P nVP-P nVP-P nV/√Hz nV/√Hz nV/√Hz Input Noise Voltage Density 5.5 nV/√Hz nV/√Hz nV/√Hz pA/√Hz pA/√Hz fO = 10Hz fO = 1kHz ● – 13.3 2 4.2 100 96 106 100 3 2 1 0.8 0.5 0.4 130 124 130 125 7 6 4 1.7 1.4 1.1 14 V GΩ pF dB dB dB dB V/µV V/µV V/µV V/µV V/µV V/µV Common Mode VS = ±1.7V to ± 18V ● RL = 10k, VO = ±14V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C RL = 2k, VO = ±13.5V 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C ● ● ● ● sn16789 16789fs 5 LT1678/LT1679 The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VS = ± 15V, VCM = VO = 0V unless otherwise noted. SYMBOL VOL PARAMETER Output Voltage Swing Low CONDITIONS (Note 6) Above – VS ISINK = 0.1mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Above – VS ISINK = 2.5mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Above – VS ISINK = 10mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C VOH Output Voltage Swing High Below +VS ISOURCE = 0.1mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Below +VS ISOURCE = 2.5mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C Below +VS ISOURCE = 10mA 0°C ≤ TA ≤ 70°C – 40°C ≤ TA ≤ 85°C ISC SR Output Short-Circuit Current (Note 3) ● ELECTRICAL CHARACTERISTICS MIN TYP 110 125 130 170 195 205 370 440 450 80 90 100 110 120 120 200 250 250 MAX 200 230 260 280 350 380 600 700 750 150 200 250 200 300 350 450 500 550 UNITS mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mV mA mA V/µs V/µs V/µs MHz MHz % µs µs Ω Ω ● ● ● ● ● ● ● ● ● ● ● ● 20 15 4 3.5 3 13 12.5 35 28 6 5.8 5.5 20 19 0.00025 2.7 3.9 100 1 Slew Rate RL = 10k (Note 9) RL = 10k (Note 9) 0°C ≤ TA ≤ 70°C RL = 10k (Note 9) – 40°C ≤ TA ≤ 85°C fO = 100kHz fO = 100kHz RL = 2k, AV = 1, fO = 1kHz, VO = 20VP-P 10V Step 0.1%, AV = +1 10V Step 0.01%, AV = +1 IOUT = 0 AV = 100, f = 10kHz ● ● ● GBW THD tS RO IS Gain Bandwidth Product Total Harmonic Distortion Settling Time Open-Loop Output Resistance Closed-Loop Output Resistance Supply Current per Amplifier ● 2.5 3 132 5 30 45 ±2 ±3 ±7 96 92 100 96 120 115 123 120 3.5 4.5 225 525 630 ± 30 ± 55 ± 75 mA mA dB µV µV µV nA nA nA dB dB dB dB sn16789 16789fs Channel Separation ∆VOS Offset Voltage Match (Note 15) Noninverting Bias Current Match (Note 15) Common Mode Rejection Match (Notes 14, 15) Power Supply Rejection Match (Notes 14, 15) f = 10Hz, VO = ±10V, RL = 10k 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C 0°C ≤ TA ≤ 70°C –40°C ≤ TA ≤ 85°C VCM = – 13.3V to 14V VS = ±1.7V to ±18V ● ● ● ● ● ● ∆IB+ ∆CMRR ∆PSRR 6 LT1678/LT1679 ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: The inputs are protected by back-to-back diodes. Current limiting resistors are not used in order to achieve low noise. If differential input voltage exceeds ± 1.4V, the input current should be limited to 25mA. If the common mode range exceeds either rail, the input current should be limited to 10mA. Note 3: A heat sink may be required to keep the junction temperature below absolute maximum. Note 4: The LT1678C/LT1679C and LT1678I/LT1679I are guaranteed functional over the Operating Temperature Range of – 40°C to 85°C. Note 5: The LT1678C/LT1679C are guaranteed to meet specified performance from 0°C to 70°C. The LT1678C/LT1679C are designed, characterized and expected to meet specified performance from – 40°C to 85°C but is not tested or QA sampled at these temperatures. The LT1678I/ LT1679I are guaranteed to meet specified performance from – 40°C to 85°C. Note 6: Typical parameters are defined as the 60% yield of parameter distributions of individual amplifier; i.e., out of 100 LT1678/LT1679s, typically 60 op amps will be better than the indicated specification. Note 7: See the test circuit and frequency response curve for 0.1Hz to10Hz tester in the Applications Information section. Note 8: Noise is 100% tested at ±15V supplies. Note 9: Slew rate is measured in AV = – 1; input signal is ± 10V, output measured at ± 5V. Note 10: This parameter is not 100% tested. Note 11: VS = 5V limits are guaranteed by correlation to VS = 3V and VS = ±15V tests. Note 12: VS = 3V limits are guaranteed by correlation to VS = 5V and VS = ±15V tests. Note 13: Guaranteed by correlation to slew rate at VS = ±15V and GBW at VS = 3V and VS = ±15V tests. Note 14: ∆CMRR and ∆PSRR are defined as follows: 1. CMRR and PSRR are measured in µV/V on the individual amplifiers. 2. The difference is calculated between the matching sides in µV/V. 3. The result is converted to dB. Note 15: Matching parameters are the difference between amplifiers A and B on the LT1678 and between amplifiers A and D and B and C in the LT1679. Note 16: Input range guaranteed by the common mode rejection ratio test. TYPICAL PERFOR A CE CHARACTERISTICS Voltage Noise vs Frequency 100 VS = ±15V TA = 25°C VOLTAGE NOISE (50nV/DIV) 10 VCM = 14.5V VCM = 0V 1 0.1 1 10 100 FREQUENCY (Hz) 1000 16789 G01 0 2 4 6 TIME (sec) 8 10 16789 G02 VOLTAGE NOISE (50nV/DIV) NOISE VOLTAGE (nV/√Hz) UW 0.1Hz to 10Hz Voltage Noise VS = 5V, 0V 0.01Hz to 1Hz Voltage Noise VS = 5V, 0V 0 20 40 60 TIME (sec) 80 100 16789 G03 sn16789 16789fs 7 LT1678/LT1679 TYPICAL PERFOR A CE CHARACTERISTICS Voltage Noise vs Temperature 6 RMS VOLTAGE NOISE DENSITY (nV/√Hz) VS = ±15V VCM = 0V NOISE VOLTAGE (pA/√Hz) INPUT BIAS CURRENT (nA) 5 10Hz 4 1kHz 3 2 1 –50 –25 50 25 0 75 TEMPERATURE (°C) Input Bias Current vs Temperature 1400 1200 INPUT BIAS CURRENT (nA) VS = ±15V VCM = –14V CURRENT OUT OF DUT INPUT BIAS CURRENT (nA) OFFSET VOLTAGE (mV) 1000 800 600 400 200 0 –50 –25 25 0 50 75 TEMPERATURE (°C) 100 125 VCM = 14.7V CURRENT INTO DUT Warm-Up Drift vs Time 10 CHANGE IN OFFSET VOLTAGE (µV) VS = ±15V TA = 25°C 8 PERCENT OF UNITS (%) SO PACKAGE 6 20 15 10 5 0 VOLTAGE OFFSET (µV) 4 2 0 0 1 2 TIME (min) 3 8 UW 100 16789 G04 16789 G07 Current Noise vs Frequency 10 VS = ±15V TA = 25°C 16 14 12 10 8 6 4 2 0 –2 –4 125 0.1 0.01 0.1 1 FREQUENCY (kHz) 10 16789 G05 Input Bias Current vs Temperature VS = ±15V VCM = 0V VCM = 0V 1 VCM = 14.5V –6 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 16789 G06 Input Bias Current Over the Common Mode Range 900 700 500 300 100 –100 –300 –500 –700 –900 VCM = –15.2V 0 8 4 –16 –12 –8 –4 12 COMMON MODE INPUT VOLTAGE (V) 16 VCM = 14.1V VCM = –13.5V VCM = 14.5V VS = ±15V TA = 25°C 5 4 3 2 1 0 –1 –2 –3 –4 Offset Voltage Shift vs Common Mode 500 400 VOS IS REFERRED TO VCM = 0V 300 OFFSET VOLTAGE (µV) 200 100 0 –100 –200 INPUT BIAS CURRENT –5 –1.0 VS = ±1.5V TO ±15V TA = 25°C 5 TYPICAL PARTS 2.0 –0.8 –0.4 V + 0.4 – (V) VCM – V VCM – V+ (V) V– 1.0 16789 G09 –300 –400 –500 16789 G08 Distribution of Input Offset Voltage Drift (SO-8) 30 VS = 5V, 0V TA = – 40°C TO 85°C 25 111 PARTS (2 LOTS) 200 VOS vs Temperature of Representive Units VS = 5V, 0V VCM = 0V 100 0 –100 –200 4 16789 G10 –3.0 1.0 2.0 3.0 –2.0 –1.0 0 INPUT OFFSET VOLTAGE DRIFT (µV/°C) 16789 G11 –300 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 16789 G12 sn16789 16789fs LT1678/LT1679 TYPICAL PERFOR A CE CHARACTERISTICS Common Mode Range vs Temperature 5 4 3 SUPPLY CURRENT PER AMPLIFIER (mA) 400 300 COMMON MODE REJECTION RATIO (dB) VS = ±2.5V TO ±15V OFFSET VOLTAGE (mV) 2 1 0 –1 –2 –3 –4 –5 –1.0 25°C –55°C 125°C 25°C VOS IS REFERRED TO VCM = 0V 125°C V– 1.0 2.0 –0.8 –0.4 V – 0.4 VCM – VS+ (V) VCM – VS– (V) 16789 G09 Power Supply Rejection Ratio vs Frequency 160 POWER SUPPLY REJECTION RATIO (dB) OPEN LOOP VOLTAGE GAIN (V/µV) 140 120 100 VS = ±15V TA = 25°C RL = 2k 1 NEGATIVE SUPPLY 80 60 POSITIVE SUPPLY 40 20 0 0.001 0.01 0.1 1 10 FREQUENCY (kHz) 100 1000 OVERSHOOT (%) Phase Margin, Gain Bandwidth Product and Slew Rate vs Temperature PHASE MARGIN (DEG) 90 80 70 60 50 40 8 +SR –SR 4 –55 –35 –15 GAIN BANDWIDTH PRODUCT PHASE MARGIN VS = ±15V CL = 15pF AV = –1 RF = RG = 1k 30 25 20 15 10 SLEW RATE (V/µs) 6 5 25 45 65 85 105 125 TEMPERATURE (°C) 16789 G19 UW –55°C 0 16789 G16 Supply Current vs Supply Voltage 500 4.0 3.5 3.0 TA = 125°C 2.5 2.0 1.5 1.0 TA = 25°C TA = –55°C 160 140 120 100 80 60 40 20 Common Mode Rejection Ratio vs Frequency VS = ±15V TA = 25°C VCM = 0V OFFSET VOLTAGE (µV) 200 100 –100 –200 –300 –400 –500 0 ±5 ±10 ±15 SUPPLY VOLTAGE (V) ±20 16789 G14 0 10k 100k 1M FREQUENCY (Hz) 10M 16789 G15 Voltage Gain vs Supply Voltage 10 RL = 10k 60 % Overshoot vs Capacitive Load VS = ±15V RL = 2k TO 10k 50 AV = 1 TA = 25°C 40 30 20 10 0 10 100 CAPACITIVE LOAD (pF) 1000 16789 G18 RISING EDGE 0.1 0 TA = 25°C RL TO GND VCM = VO = VS/2 10 20 SUPPLY VOLTAGE (V) 30 16789 G17 FALLING EDGE Large Signal Transient Response GAIN BANDWIDTH PRODUCT, fO = 100kHz (MHz) 50mV 10V Small Signal Transient Response 0V –10V –50mV AVCL = –1 VS = ±15V 5µs/DIV 16789 G20 AVCL = 1 VS = ±15V CL = 15pF 0.5µs/DIV 16789 G21 sn16789 16789fs 9 LT1678/LT1679 TYPICAL PERFOR A CE CHARACTERISTICS Settling Time vs Output Step (Inverting) 6 5 VS = ±15V A V = –1 TA = 25°C 5k VIN – + VOUT 5k SETTLING TIME (µs) SETTLING TIME (µs) VOLTAGE GAIN (dB) 4 3 2 1 0.1% OF FULL SCALE 0.01% OF FULL SCALE 0.01% OF FULL SCALE 0.1% OF FULL SCALE 0 –10 –8 –6 –4 –2 0 2 4 OUTPUT STEP (V) Gain, Phase Shift vs Frequency 50 40 100 VS = ±15V VCM = 14.7V 80 CL = 10pF 50 40 VOLTAGE GAIN (dB) VOLTAGE GAIN (dB) PHASE 30 20 10 0 TA = –55°C TA = 25°C 60 40 20 0 OUTPUT VOLTAGE SWING (V) TA = 125°C TA = –55°C TA = 125°C TA = 25°C GAIN –10 0.1 1 10 FREQUENCY (MHz) Closed-Loop Output Impedance vs Frequency TOTAL HARMONIC DISTORTION + NOISE (%) 100 0.1 VS = ±15V OUTPUT IMPEDANCE (Ω) 10 1 TOTAL HARMONIC DISTORTION + NOISE (%) AV = 100 0.1 AV = 1 0.01 0.001 10 100 10k 1k FREQUENCY (Hz) 100k 1M 16789 G28 10 UW 6 8 16789 G22 16789 G25 Settling Time vs Output Step (Noninverting) 6 VS = ±15V AV = 1 5 TA = 25°C VIN – 2k + VOUT RL = 1k 2k Gain, Phase Shift vs Frequency 50 40 30 20 10 TA = 25°C 0 –10 TA = –55°C 0.1 1 10 FREQUENCY (MHz) GAIN 0 –20 100 16789 G24 PHASE TA = –55°C 100 VS = ±15V VCM = 0V CL = 10pF 80 TA = 25°C TA = 125°C 60 40 20 PHASE SHIFT (DEG) 4 3 2 0.1% OF 1 FULL SCALE 0 –10 –8 –6 0.01% OF FULL SCALE 0.01% OF FULL SCALE TA = 125°C 0.1% OF FULL SCALE 10 –4 –2 0 2 4 OUTPUT STEP (V) 6 8 10 16789 G23 Gain, Phase Shift vs Frequency 100 VS = ±15V VCM = –14V 80 CL = 10pF +VS 0 –0.1 –0.2 –0.3 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 1 10 FREQUENCY (MHz) –20 100 16789 G26 Output Voltage Swing vs Load Current VS = ±15V TA = –55°C TA = 125°C TA = 25°C PHASE SHIFT (DEG) –20 100 PHASE SHIFT (DEG) 30 20 10 0 PHASE TA = –55°C TA = 125°C 60 40 20 TA = 25°C GAIN TA = –55°C 0.1 TA = 25°C 0 TA = 125°C TA = 25°C TA = –55°C 8 10 –10 –VS 0 –10 –8 –6 –4 –2 0 2 4 6 OUTPUT CURRENT (mA) 16789 G27 Total Harmonic Distortion and Noise vs Frequency for Noninverting Gain ZL = 2k/15pF VS = ±15V VO = 20VP-P AV = 1, 10, 100 MEASUREMENT BANDWIDTH 0.01 = 10Hz TO 80kHz AV = 100 0.1 Total Harmonic Distortion and Noise vs Frequency for Noninverting Gain ZL = 2k/15pF VS = ±15V VO = 20VP-P AV = –1, –10, –100 MEASUREMENT BANDWIDTH 0.01 = 10Hz TO 80kHz AV = –100 0.001 AV = 1 0 AV = 1 0.0001 20 100 1k FREQUENCY (Hz) 10k 50k 16789 G29 0.001 AV = –10 AV = – 1 0.0001 20 100 1k FREQUENCY (Hz) 10k 50k 16789 G30 sn16789 16789fs LT1678/LT1679 APPLICATIO S I FOR ATIO Rail-to-Rail Operation To take full advantage of an input range that can exceed the supply, the LT1678/LT1679 are designed to eliminate phase reversal. Referring to the photographs shown in Figure 1, the LT1678/LT1679 are operating in the follower mode (AV = +1) at a single 3V supply. The output of the LT1678/LT1679 clips cleanly and recovers with no phase reversal. This has the benefit of preventing lock-up in servo systems and minimizing distortion components. Input = –0.5V to 3.5V 3 INPUT VOLTAGE (V) 2 1 Noise Testing 0 –0.5 50µs/DIV 16789 F01a LT1678 Output 3 OUTPUT VOLTAGE (V) 2 The 0.1Hz to 10Hz peak-to-peak noise of the LT1678/ LT1679 are measured in the test circuit shown (Figure 3). The frequency response of this noise tester (Figure 4) indicates that the 0.1Hz corner is defined by only one zero. The test time to measure 0.1Hz to 10Hz noise should not exceed ten seconds, as this time limit acts as an additional zero to eliminate noise contributions from the frequency band below 0.1Hz. Measuring the typical 90nV peak-to-peak noise performance of the LT1678/LT1679 requires special test precautions: 1 0 –0.5 50µs/DIV 16789 F01b Figure 1. Voltage Follower with Input Exceeding the Supply Voltage (VS = 3V) Unity-Gain Buffer Application When RF ≤ 100Ω and the input is driven with a fast, largesignal pulse (>1V), the output waveform will look as shown in the pulsed operation diagram (Figure 2). During the fast feedthrough-like portion of the output, the input protection diodes effectively short the output to the 1. The device should be warmed up for at least five minutes. As the op amp warms up, its offset voltage changes typically 3µV due to its chip temperature increasing 10°C to 20°C from the moment the power supplies are turned on. In the ten-second measurement interval these temperature-induced effects can easily exceed tens of nanovolts. 2. For similar reasons, the device must be well shielded from air currents to eliminate the possibility of thermoelectric effects in excess of a few nanovolts, which would invalidate the measurements. sn16789 16789fs – + U input and a current, limited only by the output short-circuit protection, will be drawn by the signal generator. With RF ≥ 500Ω, the output is capable of handling the current requirements (IL ≤ 20mA at 10V) and the amplifier stays in its active mode and a smooth transition will occur. As with all operational amplifiers when RF > 2k, a pole will be created with RF and the amplifier’s input capacitance, creating additional phase shift and reducing the phase margin. A small capacitor (20pF to 50pF) in parallel with RF will eliminate this problem. RF 6V/µs OUTPUT LT1678 16789 F02 W UU Figure 2. Pulsed Operation 11 LT1678/LT1679 APPLICATIO S I FOR ATIO 0.1µF 100k 10Ω GAIN (dB) * LT1678 2k + LT1001 4.7µF – VOLTAGE GAIN = 50,000 *DEVICE UNDER TEST NOTE: ALL CAPACITOR VALUES ARE FOR NONPOLARIZED CAPACITORS ONLY 24.3k 100k 0.1µF Figure 3. 0.1Hz to 10Hz Noise Test Circuit 3. Sudden motion in the vicinity of the device can also “feedthrough” to increase the observed noise. Current noise is measured in the circuit shown in Figure 5 and calculated by the following formula: 2⎤ ⎡ 2 ⎢ eno − 130nV • 101 ⎥ ⎦ in = ⎣ 1MΩ 101 ) ()( ( )( ) 100k 1/ 2 Figure 5. The LT1678/LT1679 achieve their low noise, in part, by operating the input stage at 100µA versus the typical 10µA of most other op amps. Voltage noise is inversely proportional while current noise is directly proportional to the square root of the input stage current. Therefore, the LT1678/LT1679’s current noise will be relatively high. At low frequencies, the low 1/f current noise corner frequency (≈ 200Hz) minimizes current noise to some extent. In most practical applications, however, current noise will not limit system performance. This is illustrated in the Total Noise vs Source Resistance plot (Figure 6) where: TOTAL NOISE DENSITY (nV/√Hz) 12 + 500k – 100Ω 500k LT1678 eno 16789 F05 U 100 90 80 70 60 50 40 30 0.01 16789 F03 W UU + – 4.3k 22µF SCOPE ×1 RIN = 1M 110k 2.2µF 0.1 1 10 FREQUENCY (Hz) 100 16789 F04 Figure 4. 0.1Hz to 10Hz Peak-to-Peak Noise Tester Frequency Response Total Noise = [(op amp voltage noise)2 + (resistor noise)2 + (current noise RS)2]1/2 Three regions can be identified as a function of source resistance: (i) RS ≤ 400Ω. Voltage noise dominates (ii) 400Ω ≤ RS ≤ 50k at 1kHz Resistor Noise 400Ω ≤ RS ≤ 8k at 10Hz Dominates (iii) RS > 50k at 1kHz Current Noise RS > 8k at 10Hz Dominates Clearly the LT1678/LT1679 should not be used in region (iii), where total system noise is at least six times higher than the voltage noise of the op amp, i.e., the low voltage noise specification is completely wasted. In this region the LT1113 or LT1169 are better choices. 1000 R R SOURCE RESISTANCE = 2R VS = ± 15V TA = 25°C 100 AT 1kHz AT 10Hz 10 RESISTOR NOISE ONLY 1 0.1 1 10 SOURCE RESISTANCE (kΩ) 100 16789 F06 Figure 6. Total Noise vs Source Resistance sn16789 16789fs LT1678/LT1679 APPLICATIO S I FOR ATIO Rail-to-Rail Input The input common mode range for the LT1678/LT1679 can exceed the supplies by at least 100mV. As the common mode voltage approaches the positive rail (+VS – 0.7V), the tail current for the input pair (Q1, Q2) is reduced, which prevents the input pair from saturating (refer to the Simplified Schematic). The voltage drop across the load resistors RC1, RC2 is reduced to less than 200mV, degrading the slew rate, bandwidth, voltage noise, offset voltage and input bias current (the cancellation is shut off). When the input common mode range goes below 1.5V above the negative rail, the NPN input pair (Q1, Q2) shuts off and the PNP input pair (Q8, Q9) turns on. The offset voltage, input bias current, voltage noise and bandwidth are also degraded. The graph of Offset Voltage Shift vs Common Mode shows where the knees occur by displaying the change in offset voltage. The change-over points are temperature dependent; see the graph Common Mode Range vs Temperature. RL = 600Ω RL = 1k INPUT VOLTAGE (50µV/DIV) RL = 10k TA = 25°C VS = ±15V RL CONNECTED TO 0V MEASURED ON TEKTRONIX 577 CURVE TRACER –15 –10 –5 0 5 10 15 OUTPUT VOLTAGE (V) 16789 F07 Figure 7. Voltage Gain Split Supply U Rail-to-Rail Output The rail-to-rail output swing is achieved by using transistor collectors (Q28, Q29 referring to the Simplified Schematic) instead of customary class A-B emitter followers for the output stage. The output NPN transistor (Q29) sinks the current necessary to move the output in the negative direction. The change in Q29’s base emitter voltage is reflected directly to the gain node (collectors of Q20 and Q16). For large sinking currents, the delta VBE of Q29 can dominate the gain. Figure 7 shows the change in input voltage for a change in output voltage for different load resistors connected between the supplies. The gain is much higher for output voltages above ground (Q28 sources current) since the change in base emitter voltage of Q28 is attenuated by the gain in the PNP portion of the output stage. Therefore, for positive output swings (output sourcing current) there is hardly any change in input voltage for any load resistance. Highest gain and best linearity are achieved when the output is sourcing current, which is the case in single supply operation when the load is ground referenced. Figure 8 shows gains for both sinking and sourcing load currents for a worst-case load of 600Ω. VOLTAGE GAIN SINGLE SUPPLY VS = 5V RL = 600Ω MEASURED ON TEKTRONIX 577 CURVE TRACER RL TO 0V INPUT VOLTAGE (10µV/DIV) RL TO 5V 0 1 2 3 OUTPUT VOLTAGE (V) 4 5 16789 F08 W UU Figure 8. Voltage Gain Single Supply sn16789 16789fs 13 LT1678/LT1679 W Q35 SI PLIFIED SCHE ATIC Q17 Q18 R2 50Ω 100µA R1 500Ω C1 40pF + Q4 Q7 R19 2k R20 2k Q20 Q10 Q6 Q11 C2 80pF + OUT Q12 Q5 Q27 C3 40pF Q23 R3 100Ω D4 D1 Q3 D2 100µA D3 160µA Q31 + –IN Q19 Q1A Q1B Q2A Q2B IA R9 200Ω 50µA Q9 IC ID IB Q22 50µA Q15 Q14 Q16 Q25 Q30 Q26 R54 100Ω Q29 R23A 10k R30 2k R26 Q38 100Ω R23B 10k R15 1k R14 1k R16 1k R25 1k R29 10Ω R8 200Ω Q13 ×2 Q21 Q24 Q8 R13 100Ω R21 100Ω R24 100Ω IA, IB = 0µA VCM > 1.5V ABOVE –VS IC = 200µA VCM < 0.7V BELOW +VS ID = 100µA VCM < 0.7V BELOW +VS 200µA VCM < 1.5V ABOVE –VS 50µA VCM > 0.7V BELOW +VS 0µA VCM > 0.7V BELOW +VS 16789 SS + +IN C4 20pF –VS W + 14 +VS R32 1.5k R34 2k Q34 Q28 RC1 6k 200µA Q32 C10 81pF RC2 6k sn16789 16789fs LT1678/LT1679 PACKAGE DESCRIPTIO .050 BSC 8 .245 MIN .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) 0°– 8° TYP NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) .050 BSC N 14 13 .245 MIN 1 .030 ±.005 TYP 2 3 RECOMMENDED SOLDER PAD LAYOUT 1 .010 – .020 × 45° (0.254 – 0.508) 2 3 4 5 6 7 .008 – .010 (0.203 – 0.254) .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 7 6 5 .045 ±.005 .160 ±.005 .228 – .244 (5.791 – 6.197) .150 – .157 (3.810 – 3.988) NOTE 3 1 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) .016 – .050 (0.406 – 1.270) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC SO8 0303 S Package 14-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .337 – .344 (8.560 – 8.738) NOTE 3 12 11 10 9 8 .045 ±.005 N .160 ±.005 .228 – .244 (5.791 – 6.197) N/2 N/2 .150 – .157 (3.810 – 3.988) NOTE 3 .053 – .069 (1.346 – 1.752) 0° – 8° TYP .004 – .010 (0.101 – 0.254) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC S14 0502 sn16789 16789fs 15 LT1678/LT1679 TYPICAL APPLICATIO Bridge Reversal Eliminates 1/f Noise and Offset Drift of a Low Noise, Non-autozeroed, Bipolar Amplifier. Circuit Gives 14nV Noise Level or 19 Effective Bits Over a 10mV Span VREF 3 4 5,6,7,8 2 5V φ1 1 350Ω 350Ω 350Ω 350Ω 100Ω 0.1% VREF 100k 3 4 5,6,7,8 1 2 2X SILICONIX Si9801 φ2 RELATED PARTS PART NUMBER LT1028/LT1128 LT1115 LT1124/LT1125 LT1126/LT1127 LT1226 LT1498/LT1499 LT1677 LT1792 LT1793 LT1806 LT1881/LT1882 LT1884/LT1885 DESCRIPTION Ultralow Noise Precision Op Amps Ultralow Noise, Low distortion Audio Op Amp Dual/Quad Low Noise, High Speed Precision Op Amps Dual/Quad Decompensated Low Noise, High Speed Precision Op Amps Low Noise, Very High Speed Op Amp 10MHz, 5V/µs, Dual/Quad Rail-to-Rail Input and Output Op Amps Single Version of LT1678/LT1679 Low Noise, Precision JFET Input Op Amp Low Noise, Picoampere Bias Current Op Amp Low Noise, 325MHz Rail-to-Rail Input and Output Op Amp Dual/Quad Rail-to-Rail Output Picoamp Input Precision Op Amps Dual/Quad Rail-to-Rail Output Picoamp Input Precision Op Amps COMMENTS Lowest Noise 0.85nV/√Hz 0.002% THD, Max Noise 1.2nV/√Hz Similar to LT1007 Similar to LT1037 1GHz, 2.6nV/√Hz, Gain of 25 Stable Precision C-LoadTM Stable Rail-to-Rail 3.2nV/√Hz 4.2nV/√Hz, 10fA/√Hz 6nV/√Hz, 1fA/√Hz, IB = 10pA Max 3.5nV/√Hz CLOAD to 1000pF, IB = 200pA Max 2.2MHz Bandwidth, 1.2V/µs SR sn16789 16789fs C-Load is a trademark of Linear Technology Corporation. 16 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com + 100k + – – U 7V LT1461-5 10µF 0.1µF VREF 1/2 LT1678 0.047µF 10Ω REF+ 1k 0.1% 1µF 1k 0.1% 1µF REF – 10Ω 100Ω 100Ω IN+ LTC2440 IN– 0.047µF 1/2 LT1678 φ1 φ2 ≈2s 16789 TA02 LT/TP 0104 1K • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2003