LT1468IN8

FEATURES n n n n n n n n n n n n n n LT1468 90MHz, 22V/µs 16-Bit Accurate Operational Amplifier DESCRIPTION The LT®1468 is a precision high speed operational amplifier with 16-bit accuracy and 900ns settling to 150μV for 10V signals. This unique blend of precision and AC performance makes the LT1468 the optimum choice for high accuracy applications such as DAC current-to-voltage conversion and ADC buffers. The initial accuracy and drift characteristics of the input offset voltage and inverting input bias current are tailored for inverting applications. The 90MHz gain bandwidth ensures high open-loop gain at frequency for reducing distortion. In noninverting applications such as an ADC buffer, the low distortion and DC accuracy allow full 16-bit AC and DC performance. The 22V/μs slew rate of the LT1468 improves large-signal performance in applications such as active filters and instrumentation amplifiers compared to other precision op amps. The LT1468 is manufactured on a complementary bipolar process. It is available in a space saving 3mm × 3mm leadless package, as well as small outline and DIP packages. L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 90MHz Gain Bandwidth, f = 100kHz 22V/μs Slew Rate Settling Time: 900ns (AV = –1, 150μV, 10V Step) Low Distortion, – 96.5dB for 100kHz, 10VP-P Maximum Input Offset Voltage: 75μV Maximum Input Offset Voltage Drift: 2μV/°C Maximum (–) Input Bias Current: 10nA Minimum DC Gain: 1000V/mV Minimum Output Swing into 2k: ±12.8V Unity Gain Stable Input Noise Voltage: 5nV/√Hz Input Noise Current: 0.6pA/√Hz Total Input Noise Optimized for 1k < RS < 20k Specified at ±5V and ±15V APPLICATIONS n n n n n n 16-Bit DAC Current-to-Voltage Converter Precision Instrumentation ADC Buffer Low Distortion Active Filters High Accuracy Data Acquisition Systems Photodiode Amplifiers TYPICAL APPLICATION Total Harmonic Distortion vs Frequency 16-Bit DAC I-to-V Converter TOTAL HARMONIC DISTORTION (dB) –80 VS = ±15V AV = 2 RL = 2k VOUT = 10VP-P –90 20pF DAC INPUTS 16 6k – LT1468 –100 2k VOUT 50pF LTC®1597 –110 + OPTIONAL NOISE FILTER OFFSET: VOS + IB (6kΩ) < 1LSB SETTLING TIME TO 150μV = 1.7μs SETTLING LIMITED BY 6k AND 20pF TO COMPENSATE DAC OUTPUT CAPACITANCE 1468 TA01 –120 –130 100 1k 10k FREQUENCY (Hz) 100k 1468 TA02 1468fa 1 LT1468 ABSOLUTE MAXIMUM RATINGS (Note 1) Total Supply Voltage (V+ to V –).................................36V Maximum Input Current (Note 2) ...........................10mA Output Short-Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range ................. –40°C to 85°C Specified Temperature Range (Note 4) .... –40°C to 85°C Junction Temperature ........................................... 150°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C PIN CONFIGURATION TOP VIEW NULL 1 NULL 1 –IN 2 +IN 3 V – TOP VIEW 8 DNC* V+ OUT NULL 8 DNC* V+ OUT NULL + – 7 6 5 –IN 2 +IN 3 V– 4 N8 PACKAGE 8-LEAD PDIP + – 7 6 5 4 DD PACKAGE 8-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 150°C, θJA = 43°C/W EXPOSED PAD IS INTERNALLY CONNECTED TO V– S8 PACKAGE 8-LEAD PLASTIC SO *DO NOT CONNECT TJMAX = 150°C, θJA = 130°C/W (N8) TJMAX = 150°C, θJA = 190°C/W (S8) ORDER INFORMATION LEAD FREE FINISH LT1468CN8#PBF LT1468IN8#PBF LT1468CS8#PBF LT1468IS8#PBF LT1468ACDD#PBF LT1468AIDD#PBF LT1468CDD#PBF LT1468IDD#PBF LEAD BASED FINISH LT1468CN8 LT1468IN8 LT1468CS8 LT1468IS8 TAPE AND REEL NA NA LT1468CS8#TRPBF LT1468IS8#TRPBF LT1468ACDD#TRPBF LT1468AIDD#TRPBF LT1468CDD#TRPBF LT1468IDD#TRPBF TAPE AND REEL NA NA LT1468CS8#TR LT1468IS8#TR PART MARKING LT1468CN8 LT1468IN8 1468 1468I LDJX LDJX LDJX LDJX PART MARKING LT1468CN8 LT1468IN8 1468 1468I PACKAGE DESCRIPTION 8-Lead PDIP 8-Lead PDIP 8-Lead Plastic Small Outline 8-Lead Plastic Small Outline 8-Lead (3mm × 3mm) Plastic DFN 8-Lead (3mm × 3mm) Plastic DFN 8-Lead (3mm × 3mm) Plastic DFN 8-Lead (3mm × 3mm) Plastic DFN PACKAGE DESCRIPTION 8-Lead PDIP 8-Lead PDIP 8-Lead Plastic Small Outline 8-Lead Plastic Small Outline SPECIFIED TEMPERATURE RANGE 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C SPECIFIED TEMPERATURE RANGE 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. 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/ 1468fa 2 LT1468 ELECTRICAL CHARACTERISTICS SYMBOL VOS PARAMETER Input Offset Voltage N8, S8 LT1468A, DD Package LT1468, DD Package IOS IB– IB + The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCM = 0V unless otherwise noted. CONDITIONS VSUPPLY ±15V ± 5V ±15V ± 5V ±15V ± 5V ±5V to ±15V ±5V to ±15V ±5V to ±15V 0.1Hz to 10Hz f = 10kHz f = 10kHz VCM = ±12.5V Differential ±5V to ±15V ±5V to ±15V ±5V to ±15V ±15V ±15V ±15V ±15V ±5V ±15V ±5V VCM = ±12.5V VCM = ±2.5V VS = ±4.5V to ±15V VOUT = ±12.5V, RL = 10k VOUT = ±12.5V, RL = 2k VOUT = ±2.5V, RL = 10k VOUT = ±2.5V, RL = 2k RL = 10k RL = 2k RL = 10k RL = 2k VOUT = ±12.5V VOUT = ±2.5V VOUT = 0V, VIN = ±0.2V AV = –1, RL = 2k (Note 5) 10V Peak, (Note 6) 3V Peak, (Note 6) f = 100kHz, RL = 2k AV = 2, VO = 10VP-P, f = 1kHz AV = 2, VO = 10VP-P, f = 100kHz AV = 1, 10% to 90%, 0.1V AV = 1, 0.1V AV = 1, 50% VIN to 50% VOUT, 0.1V ±15V ±15V ±5V ±5V ±15V ±15V ± 5V ±5V ±15V ±5V ±15V ±15V ± 5V ±15V ±5V ±15V ±5V ±15V ±15V ±15V ±5V ±15V ±5V ±15V ±5V 60 55 ±15V ±5V 96 96 100 1000 500 1000 500 ±13.0 ±12.8 ±3.0 ±2.8 ±15 ±15 ±25 15 11 12.5 2.5 100 50 MIN TYP 30 50 30 50 100 150 13 3 –10 0.3 5 0.6 240 150 4 13.5 3.5 –14.3 –4.3 110 112 112 9000 5000 6000 3000 ±13.6 ±13.5 ±3.6 ±3.5 ±22 ±22 ±40 22 17 350 900 90 88 0.00007 0.0015 11 12 30 35 9 10 –12.5 –2.5 MAX 75 175 75 175 200 300 50 ±10 ±40 UNITS μV μV μV μV μV μV nA nA nA μVP-P nV/√Hz pA/√Hz MΩ kΩ pF V V V V dB dB dB V/mV V/mV V/mV V/mV V V V V mA mA mA V/μs V/μs kHz kHz MHz MHz % % ns ns % % ns ns Input Offset Current Inverting Input Bias Current Noninverting Input Bias Current Input Noise Voltage Input Noise Voltage Input Noise Voltage Input Resistance Input Capacitance Input Voltage Range + Input Voltage Range – en in RIN CIN CMRR PSRR AVOL Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain VOUT Output Swing IOUT ISC SR Output Current Short-Circuit Current Slew Rate Full-Power Bandwidth GBW THD tr, tf Gain Bandwidth Total Harmonic Distortion Rise Time, Fall Time Overshoot Propagation Delay 1468fa 3 LT1468 ELECTRICAL CHARACTERISTICS SYMBOL ts PARAMETER Settling Time The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCM = 0V unless otherwise noted. CONDITIONS 10V Step, 0.01%, AV = –1 10V Step, 150μV, AV = –1 5V Step, 0.01%, AV = –1 AV = 1, f = 100kHz VSUPPLY ±15V ±15V ±5V ±15V ±15V ±5V MIN TYP 760 900 770 0.02 3.9 3.6 5.2 5.0 MAX UNITS ns ns ns Ω mA mA RO IS Output Resistance Supply Current The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted. SYMBOL VOS PARAMETER Input Offset Voltage CONDITIONS N8, S8 LT1468A, DD Package LT1468, DD Package Input VOS Drift IOS IB– IB + VSUPPLY ±15V ± 5V ±15V ± 5V ±15V ± 5V ±5V to ±15V ±5V to ±15V ±5V to ±15V ±5V to ±15V ± 5V to ±15V ±5V to ±15V ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● MIN TYP MAX 150 250 150 250 300 400 UNITS μV μV μV μV μV μV μV/°C nA pA/°C nA pA/°C nA dB dB dB V/mV V/mV V/mV V/mV V V V V mA mA mA V/μs V/μs MHz MHz (Note 7) 0.7 60 2.0 65 ±15 Input Offset Current Input Offset Current Drift Inverting Input Bias Current Negative Input Current Drift Noninverting Input Bias Current Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain VCM = ±12.5V VCM = ±2.5V VS = ±4.5V to ±15V VOUT = ±12.5V, RL = 10k VOUT = ±12.5V, RL = 2k VOUT = ±2.5V, RL = 10k VOUT = ±2.5V, RL = 2k RL = 10k RL = 2k RL = 10k RL = 2k VOUT = ±12.5V VOUT = ±2.5V VOUT = 0V, VIN = ±0.2V AV = –1, RL = 2k (Note 5) f = 100kHz, RL = 2k 40 ±50 94 94 98 500 250 500 250 ±12.9 ±12.7 ±2.9 ±2.7 ±12.5 ±12.5 ±17 13 9 55 50 6.5 6.3 CMRR PSRR AVOL ±15V ±5V ±15V ±15V ±5V ±5V ±15V ±15V ±5V ±5V ±15V ±5V ±15V ±15V ±5V ±15V ± 5V ±15V ±5V VOUT Output Swing IOUT ISC SR GBW IS Output Current Short-Circuit Current Slew Rate Gain Bandwidth Supply Current mA mA 1468fa 4 LT1468 ELECTRICAL CHARACTERISTICS SYMBOL VOS PARAMETER Input Offset Voltage N8, S8 LT1468A, DD Package LT1468, DD Package Input VOS Drift IOS IB– IB + The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. –40°C ≤ TA ≤ 85°C, VCM = 0V unless otherwise noted. CONDITIONS VSUPPLY ±15V ± 5V ±15V ± 5V ±15V ± 5V ±5V to ±15V ±5V to ±15V ±5V to ±15V ±5V to ±15V ±5V to ±15V ±5V to ±15V VCM = ±12.5V VCM = ±2.5V VS = ±4.5V to ±15V VOUT = ±12V, RL = 10k VOUT = ±10V, RL = 2k VOUT = ±2.5V, RL = 10k VOUT = ±2.5V, RL = 2k RL = 10k RL = 2k RL = 10k RL = 2k VOUT = ±12.5V VOUT = ±2.5V VOUT = 0V, VIN = ±0.2V AV = –1, RL = 2k (Note 5) f = 100kHz, RL = 2k ±15V ±15V ±5V ±5V ±15V ±15V ±5V ±5V ±15V ±5V ±15V ±15V ±5V ±15V ±5V ±15V ±5V ±15V ±5V ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● MIN TYP MAX 230 330 230 330 400 500 UNITS μV μV μV μV μV μV μV/°C nA pA/°C nA pA/°C nA dB dB dB V/mV V/mV V/mV V/mV V V V V mA mA mA V/μs V/μs MHz MHz (Note 7) 0.7 120 2.5 80 ±30 Input Offset Current Input Offset Current Drift Inverting Input Bias Current Negative Input Current Drift Noninverting Input Bias Current Common Mode Rejection Ratio Power Supply Rejection Ratio Large-Signal Voltage Gain 80 ±60 92 92 96 300 150 300 150 ±12.8 ±12.6 ±2.8 ±2.6 ±7 ±7 ±12 9 6 45 40 7.0 6.8 CMRR PSRR AVOL VOUT Output Swing IOUT ISC SR GBW IS Output Current Short-Circuit Current Slew Rate Gain Bandwidth Supply Current mA mA 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: The inputs are protected by back-to-back diodes and two 100Ω series resistors. If the differential input voltage exceeds 0.7V, the input current should be limited to 10mA. Input voltages outside the supplies will be clamped by ESD protection devices and input currents should also be limited to 10mA. Note 3: A heat sink may be required to keep the junction temperature below absolute maximum when the output is shorted indefinitely. Note 4: The LT1468C is guaranteed to meet specified performance from 0°C to 70°C and is designed, characterized and expected to meet these extended temperature limits, but is not tested at – 40°C and at 85°C. The LT1468I is guaranteed to meet the extended temperature limits. Note 5: Slew rate is measured between ±8V on the output with ±12V input for ±15V supplies and ±2V on the output with ±3V input for ±5V supplies. Note 6: Full power bandwidth is calculated from the slew rate measurement: FPBW = SR/2πVP Note 7: This parameter is not 100% tested. 1468fa 5 LT1468 TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Supply Voltage and Temperature 7 6 COMMON MODE RANGE (V) SUPPLY CURRENT (mA) 125°C 5 4 25°C 3 –55°C 2 1 0 5 10 15 SUPPLY VOLTAGE (±V) 20 1468 G01 Input Common Mode Range vs Supply Voltage V+ –0.5 –1.0 –1.5 –2.0 TA = 25°C ΔVOS < 100μV INPUT BIAS CURRENT (nA) 80 60 40 20 0 –20 –40 –60 0 3 9 12 6 SUPPLY VOLTAGE (±V) 15 18 1468 G02 Input Bias Current vs Input Common Mode Voltage VS = ±15V TA = 25°C IB– IB+ 2.0 1.5 1.0 0.5 V– –80 –15 –10 –5 5 10 0 INPUT COMMON MODE VOLTAGE (V) 15 1468 G03 Input Bias Current vs Temperature 30 VS = ±15V INPUT VOLTAGE NOISE (nV/√Hz) 20 INPUT BIAS CURRENT (nA) 10 0 –10 –20 –30 –40 –50 –25 IB+ IB– 1000 Input Noise Spectral Density 10 VS = ±15V TA = 25°C AV = 101 RS = 100k FOR in 1 INPUT CURRENT NOISE (pA/√Hz) 0.1Hz to 10Hz Voltage Noise VS = ±15V 100 in en 10 0.1 1 50 25 75 0 TEMPERATURE (°C) 100 125 1 10 100 1k FREQUENCY (Hz) 10k 0.01 100k 1468 G05 VOLTAGE NOISE (100nV/DIV) TIME (1s/DIV) 1468 G06 1468 G04 Warm-Up Drift vs Time 5 0 OFFSET VOLTAGE DRIFT (μV) OPEN-LOOP GAIN (dB) –5 –10 –15 –20 –25 –30 –35 –40 0 20 40 60 80 100 120 TIME AFTER POWER UP (s) 140 1468 G07 Open-Loop Gain vs Resistive Load 140 TA = 25°C VS = ±15V OPEN-LOOP GAIN (dB) VS = ±5V 160 150 135 130 125 120 115 110 10 100 1k LOAD RESISTANCE (Ω) 10k 1468 G08 Open-Loop Gain vs Temperature RL = 2k VS = ±15V 140 130 VS = ±5V 120 110 100 90 –50 –25 N8 ±5V S0-8 ±5V N8 ±15V S0-8 ±15V 50 25 75 0 TEMPERATURE (°C) 100 125 1468 G09 1468fa 6 LT1468 TYPICAL PERFORMANCE CHARACTERISTICS Output Voltage Swing vs Supply Voltage V+ –1 OUTPUT VOLTAGE SWING (V) –2 –3 –4 4 3 2 1 V – –1.0 OUTPUT VOLTAGE SWING (V) –1.5 –2.0 –2.5 OUTPUT SHORT-CIRCUIT CURRENT (mA) RL = 2k RL = 10k V+ –0.5 Output Voltage Swing vs Load Current VS = ±15V 60 25°C –40°C 85°C 55 50 45 40 35 30 25 20 15 Output Short-Circuit Current vs Temperature VS = ±15V VIN = ±0.2V SOURCE SINK 2.5 2.0 1.5 1.0 40°C 25°C RL = 2k TA = 25°C 0 RL = 10k 5 10 15 SUPPLY VOLTAGE (±V) 20 1468 G10 85°C V– 0.5 –20 –15 –10 –5 0 10 5 OUTPUT CURRENT (mA) 15 20 10 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 125 1468 G11 1468 G12 Settling Time to 0.01% vs Output Step, VS = ± 15V 10 8 6 OUTPUT STEP (V) 4 2 0 –2 –4 –6 –8 –10 0 200 AV = 1 AV = –1 VS = ±15V RL = 1k 5 AV = –1 AV = 1 OUTPUT STEP (V) 4 3 2 1 0 –1 –2 –3 –4 1000 1468 G13 Settling Time to 0.01% vs Output Step, VS = ± 5V 10 VS = ±5V RL = 1k 8 AV = 1 AV = –1 OUTPUT STEP (V) 6 4 2 0 –2 –4 –6 –8 –10 400 600 700 500 SETTLING TIME (ns) 800 1468 G14 Settling Time to 150μV vs Output Step VS = ±15V AV = –1 RF = RG = 2k CF = 8pF AV = 1 AV = –1 600 800 400 SETTLING TIME (ns) –5 300 0 200 600 800 400 SETTLING TIME (ns) 1000 1468 G15 Gain Bandwidth and Phase Margin vs Supply Voltage 98 96 GAIN BANDWIDTH (MHz) 94 92 90 88 GAIN BANDWIDTH 86 84 82 0 10 5 15 SUPPLY VOLTAGE (±V) 20 1468 G17 Gain Bandwidth and Phase Margin vs Temperature 44 104 102 GAIN BANDWIDTH (MHz) 100 98 96 94 92 90 88 86 84 –55 –25 50 25 0 75 TEMPERATURE (°C) 100 VS = 5V GAIN BANDWIDTH VS = 15V VS = ±5V PHASE MARGIN 46 44 OUTPUT IMPEDANCE (Ω) VS = ±15V 42 PHASE MARGIN (DEG) 40 38 36 34 32 30 28 26 125 10 100 42 Output Impedance vs Frequency VS = ±15V TA = 25°C AV = 100 1 AV = 10 0.1 AV = 1 TA = 25°C AV = –1 RF = RG = 5.1k CF = 5pF RL = 2k PHASE MARGIN 40 38 36 34 32 30 28 PHASE MARGIN (DEG) 0.01 0.001 10k 100k 1M 10M FREQUENCY (Hz) 100M 1468 G19 1468 G18 1468fa 7 LT1468 TYPICAL PERFORMANCE CHARACTERISTICS Gain and Phase vs Frequency 70 60 PHASE 50 GAIN (dB) 40 30 GAIN 20 10 0 TA = 25°C AV = –1 RF = RG = 5.1k CF = 5pF RL = 2k 100k ±15V –20 ±5V –40 –60 100M 1468 G16 Power Supply Rejection Ratio vs Frequency 100 80 160 POWER SUPPLY REJECTION RATIO (dB) 140 120 100 80 60 40 20 0 100 1k 10k 1M 100k FREQUENCY (Hz) 10M 100M 1468 G20 Common Mode Rejection Ratio vs Frequency 120 COMMON MODE REJECTION RATIO (dB) 100 80 60 40 20 0 100 VS = ±15V TA = 25°C VS = ±15V TA = 25°C +PSRR –PSRR ±15V ±5V 60 PHASE (DEG) 40 20 0 –10 10k 1M 10M FREQUENCY (Hz) 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M 1468 G21 Frequency Response vs Supply Voltage, AV = 1 5 4 3 2 GAIN (dB) GAIN (dB) 1 0 –1 –2 –3 –4 –5 100k 1M 10M FREQUENCY (Hz) 100M 1468 G22 Frequency Response vs Supply Voltage, AV = – 1 5 14 RF = RG = 2k ±5V ±15V GAIN (dB) 12 10 8 6 4 2 0 TA = 25°C AV = –1 RL = 2k CF = 5pF 1M 10M FREQUENCY (Hz) 100M 1468 G23 Frequency Response vs Capacitive Load, AV = 1 VS = ±15V TA = 25°C AV = 1 NO RL 100pF 50pF 20pF 10pF TA = 25°C AV = 1 RL = 2k ±5V ±15V 4 3 2 1 0 –1 –2 –3 –4 RF = RG = 5.1k ±5V ±15V –2 –4 –6 100k 1M 10M FREQUENCY (Hz) 100M 1468 G24 –5 100k Frequency Response vs Capacitive Load, AV = – 1 14 12 10 8 GAIN (dB) 6 4 2 0 –2 –4 –6 100k 1M 10M FREQUENCY (Hz) 100M 1468 G25 Slew Rate vs Supply Voltage 30 TA = 25°C 28 AV = –1 RL = 2k 45 40 –SR 35 SLEW RATE (V/μs) Slew Rate vs Temperature VS = ±15V AV = –1 RL = 2k –SR 30 25 20 15 10 +SR SLEW RATE (V/μs) VS = ±15V TA = 25°C AV = –1 RF = RG = 5.1k CF = 5pF NO RL 200pF 300pF 26 24 22 20 18 16 14 0 10 5 15 SUPPLY VOLTAGE (±V) 20 1468 G26 +SR 100pF 50pF 5 –50 –25 0 75 50 25 TEMPERATURE (°C) 100 125 1468 G27 1468fa 8 LT1468 TYPICAL PERFORMANCE CHARACTERISTICS Total Harmonic Distortion + Noise vs Frequency 0.010 VS = ±15V TA = 25°C RL = 600Ω VO = 20VP-P NOISE BW = 80kHz –50 OUTPUT VOLTAGE SWING (VP-P) –60 ±5V THD + NOISE (dB) –70 –80 –90 ±15V Total Harmonic Distortion + Noise vs Amplitude 30 25 20 Undistorted Output Swing vs Frequency, ± 15V AV = 1 THD + NOISE (%) 0.001 AV = 10 AV = 1 MEASUREMENT LIMIT AV = –1 15 10 5 0 –100 0.0001 20 100 1k FREQUENCY (Hz) 10k 20k 1468 G28 –110 0.01 TA = 25°C AV = 10 RL = 600Ω f = 10kHz NOISE BW = 80kHz 0.1 1 OUTPUT SIGNAL (VRMS) 10 1468 G29 VS = ±15V RL = 2k 1 10 100 FREQUENCY (kHz) 1000 1468 G30 Small-Signal Transient, AV = 1 Small-Signal Transient, AV = – 1 10 9 OUTPUT VOLTAGE SWING (VP-P) 8 7 6 5 4 3 2 1 0 Undistorted Output Swing vs Frequency, ± 5V VS = ±5V RL = 2k AV = 1 AV = –1 VS = ±15V 1468 G31 VS = ±15V 1468 G32 1 10 100 FREQUENCY (kHz) 1000 1468 G33 Large-Signal Transient, AV = 1 Large-Signal Transient, AV = – 1 100 TOTAL NOISE VOLTAGE (nV/√Hz) Total Noise vs Unmatched Source Resistance VS = ±15V TA = 25°C f = 10kHz 10 TOTAL NOISE RESISTOR NOISE ONLY 1 RS + – VS = ±15V 1468 G34 VS = ±15V 1468 G35 0.1 10 100 1k 10k SOURCE RESISTANCE, RS (Ω) 100k 1468 G36 1468fa 9 LT1468 APPLICATIONS INFORMATION The LT1468 may be inserted directly into many operational amplifier applications improving both DC and AC performance, provided that the nulling circuitry is removed. The suggested nulling circuit for the LT1468 is shown below. Offset Nulling V+ 3 contacts to the inputs can exceed the inherent drift of the amplifier. Air currents over device leads should be minimized, package leads should be short, and the two input leads should be as close together as possible and maintained at the same temperature. Make no connection to Pin 8. This pin is used for factory trim of the inverting input current. + LT1468 76 4 0.1μF 2.2μF 2 – 5 1 100k 0.1μF 2.2μF The parallel combination of the feedback resistor and gain setting resistor on the inverting input can combine with the input capacitance to form a pole that can cause peaking or even oscillations. For feedback resistors greater than 2k, a feedback capacitor of the value: CF > (RG)(CIN/RF) should be used to cancel the input pole and optimize dynamic performance. For applications where the DC noise gain is one, and a large feedback resistor is used, CF should be greater than or equal to CIN. An example would be a DAC I-to-V converter as shown on the front page of this data sheet where the DAC can have many tens of pF of output capacitance. Another example would be a gain of –1 with 5k resistors; a 5pF to 10pF capacitor should be added across the feedback resistor. The frequency response in a gain of –1 is shown in the Typical Performance curves with 2k and 5.1k resistors with a 5pF feedback capacitor. Nulling Input Capacitance RF CF V– 1468 AI01 Layout and Passive Components The LT1468 requires attention to detail in board layout in order to maximize DC and AC performance. For best AC results (for example fast settling time) use a ground plane, short lead lengths, and RF-quality bypass capacitors (0.01μF to 0.1μF) in parallel with low ESR bypass capacitors (1μF to 10μF tantalum). For best DC performance, use “star” grounding techniques, equalize input trace lengths and minimize leakage (i.e., 1.5GΩ of leakage between an input and a 15V supply will generate 10nA—equal to the maximum IB– specification.) Board leakage can be minimized by encircling the input circuitry with a guard ring operated at a potential close to that of the inputs. For inverting configurations tie the ring to ground, in noninverting connections tie the ring to the inverting input (note the input capacitance will increase which may require a compensating capacitor as discussed below.) Microvolt level error voltages can also be generated in the external circuitry. Thermocouple effects caused by temperature gradients across dissimilar metals at the RG CIN VIN – LT1468 VOUT + 1468 AI02 1468fa 10 LT1468 APPLICATIONS INFORMATION Input Considerations Each input of the LT1468 is protected with a 100Ω series resistor and back-to-back diodes across the bases of the input devices. If the inputs can be pulled apart, the input current should be limited to less than 10mA with an external series resistor. Each input also has two ESD clamp diodes—one to each supply. If an input is driven above the supply, limit the current with an external resistor to less than 10mA. The LT1468 employs bias current cancellation at the inputs. The inverting input current is trimmed at zero common mode voltage to minimize errors in inverting applications such as I-to-V converters. The noninverting input current is not trimmed and has a wider variation and therefore a larger maximum value. As the input offset current can be greater than either input current, the use of balanced source resistance is NOT recommended as it actually degrades DC accuracy and also increases noise. The input bias currents vary with common mode voltage as shown in the Typical Performance Characteristics. The cancellation circuitry was not designed to track this common mode voltage because the settling time would have been adversely affected. The LT1468 inputs can be driven to the negative supply and to within 0.5V of the positive supply without phase reversal. As the input moves closer than 0.5V to the positive supply, the output reverses phase. Total Input Noise The curve of Total Noise vs Unmatched Source Resistance in the Typical Performance Characteristics shows that with source resistance below 1k, the voltage noise of the amplifier dominates. In the 1k to 20k region the increase in noise is due to the source resistance. Above 20k the input current noise component is larger than the resistor noise. Capacitive Loading The LT1468 drives capacitive loads of up to 100pF in unity gain and 300pF in a gain of –1. When there is a need to drive a larger capacitive load, a small series resistor should be inserted between the output and the load. In addition, a capacitor should be added between the output and the inverting input as shown in Driving Capacitive Loads. Settling Time The LT1468 is a single stage amplifier with an optimal thermal layout that leads to outstanding settling performance. Measuring settling, even at the 12-bit level is very challenging, and at the 16-bit level requires a great deal of subtlety and expertise. Fortunately, there are two excellent Linear Technology reference sources for settling measurements, Application Notes 47 and 74. Appendix B of AN47 is a vital primer on 12-bit settling measurements, and AN74 extends the state of the art while concentrating on settling time with a 16-bit current output DAC input. Input Stage Protection Driving Capacitive Loads RF CF RO ≥ (1 + RF/RG)/(2πCL5MHz) RF ≥ 10RO CF = (2RO/RF)CL RO LT1468 VOUT CL 1468 AI04 R1 100Ω +IN Q1 Q2 R2 100Ω –IN 1468 AI03 RG – VIN + 1468fa 11 LT1468 APPLICATIONS INFORMATION The 150μV settling curve in the Typical Performance Characteristics is measured using the Differential Amplifier method of AN74 followed by a clamped, nonsaturating gain of 100. The total gain of 500 allows a resolution of 100μV/DIV with an oscilloscope setting of 0.05V/DIV The settling of the DAC I-to-V converter on the front page was measured using the exact methods of AN74. The optimum nulling of the DAC output capacitance requires 20pF across the 6k feedback resistor. The theoretical limit for 16-bit settling is 11.1 times this RC time constant or 1.33μs. The actual settling time is 1.7μs at the output of the LT1468. The LT1468 is the fastest Linear Technology amplifier in this application. The optional noise filter adds a slight delay of 100ns, but reduces the noise bandwidth to 1.6MHz which increases the output resolution for 16-bit accuracy. Distortion The LT1468 has outstanding distortion performance as shown in the Typical Performance curves of Total Harmonic Distortion + Noise vs Frequency and Amplitude. The high open-loop gain and inherently balanced architecture reduce errors to yield 16-bit accuracy to frequencies as high as 100kHz. An example of this performance is the Typical Application titled 100kHz Low Distortion Bandpass Filter. This circuit is useful for cleaning up the output of a high performance signal generator such as the B & K type 1051 or HP3326A. Another key application for LT1468 is buffering the input to a 16-bit A/D converter. In a gain of 1 or 2 this straightforward circuit provides uncorrupted AC and DC levels to the converter, while buffering the A/D input sampleand-hold circuit from high source impedance which can reduce the maximum sampling rate. The front page graph shows better than 16-bit distortion for a gain of 2 with a 10VP-P output. SIMPLIFIED SCHEMATIC V+ I1 I2 Q8 +IN Q1 Q2 –IN Q5 Q6 Q7 Q3 Q4 BIAS C Q11 I5 Q10 Q9 OUT I3 V– I4 I6 1468 SS 1468fa 12 LT1468 PACKAGE DESCRIPTION DD Package 8-Lead Plastic DFN (3mm × 3mm) (LTC DWG # 05-08-1698) 0.675 ± 0.05 3.5 ± 0.05 1.65 ± 0.05 2.15 ± 0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 5 0.38 ± 0.10 8 3.00 ± 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) 1.65 ± 0.10 (2 SIDES) (DD) DFN 1203 0.200 REF 0.75 ± 0.05 4 0.25 ± 0.05 2.38 ± 0.10 (2 SIDES) 1 0.50 BSC 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 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 TOP AND BOTTOM OF PACKAGE 1468fa 13 LT1468 PACKAGE DESCRIPTION N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) .400* (10.160) MAX 8 7 6 5 .255 ± .015* (6.477 ± 0.381) 1 .300 – .325 (7.620 – 8.255) 2 3 4 .130 ± .005 (3.302 ± 0.127) .045 – .065 (1.143 – 1.651) .008 – .015 (0.203 – 0.381) +.035 .325 –.015 .065 (1.651) TYP .120 (3.048) .020 MIN (0.508) MIN .018 ± .003 (0.457 ± 0.076) N8 1002 ( 8.255 +0.889 –0.381 ) .100 (2.54) BSC INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) NOTE: 1. DIMENSIONS ARE 1468fa 14 LT1468 PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) .050 BSC .045 ±.005 8 .189 – .197 (4.801 – 5.004) NOTE 3 7 6 5 .245 MIN .160 ±.005 .228 – .244 (5.791 – 6.197) .150 – .157 (3.810 – 3.988) NOTE 3 .030 ±.005 TYP RECOMMENDED SOLDER PAD LAYOUT .010 – .020 × 45° (0.254 – 0.508) .008 – .010 (0.203 – 0.254) .016 – .050 (0.406 – 1.270) NOTE: 1. DIMENSIONS IN 0°– 8° TYP 1 2 3 4 .053 – .069 (1.346 – 1.752) .004 – .010 (0.101 – 0.254) 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) .014 – .019 (0.355 – 0.483) TYP .050 (1.270) BSC SO8 0303 1468fa 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. 15 LT1468 TYPICAL APPLICATIONS Instrumentation Amplifier R5 1.1k R2 5k R1 50k C1 10pF R4 50k C2 2pF 2k 10pF 16-Bit ADC Buffer 2k – LT1468 200Ω LTC1605 1000pF 33.2k CAP 2.2μF 16 BITS – LT1468 R3 5k VIN + – LT1468 VOUT 1468 TA03 1468 TA04 – VIN + + + GAIN = [R4/R3][1 + (1/2)(R2/R1 + R3/R4) + (R2 + R3)/R5] = 102 TRIM R5 FOR GAIN TRIM R1 FOR COMMON MODE REJECTION BW = 480kHz 100kHz Low Distortion Bandpass Filter 1000pF 22.1k 11k VIN 121Ω 1000pF – LT1468 VOUT RL + 100kHz Distortion SIGNAL LEVEL 1VRMS 2VRMS 3.5VRMS 1VRMS 2VRMS 3.5VRMS RL 1M 1M 1M 2k 2k 2k 2ND HARMONIC –106dB –105dB –106dB –103dB –99dB –96.5dB 3RD HARMONIC –103dB –105dB –104dB –103dB –103dB –102dB 1468 TA05 fO = 100kHz Q=7 AV = –1 RELATED PARTS PART NUMBER LT1167 LTC1595/LTC1596 LTC1597 LTC1604 LTC1605 LT1469 LT1800 LT6220 LT1722 LTC6244HV DESCRIPTION Precision Instrumentation Amplifier 16-Bit Serial Multiplying IOUT DACs 16-Bit Parallel Multiplying IOUT DAC 16-Bit, 333ksps Sampling ADC Single 5V, 16-Bit, 100ksps Sampling ADC Dual 90MHz 16-Bit Accurate Op Amp COMMENTS Single Resistor Gain Set, 0.04% Max Gain Error, 10ppm Max Gain Nonlinearity ±1LSB Max INL/DNL, Low Glitch, DAC8043 16-Bit Upgrade ±1LSB Max INL/DNL, Low Glitch, On-Chip Bipolar Resistors ± 2.5V Input, SINAD = 90dB, THD = –100dB Low Power, ±10V Inputs, Parallel/Byte Interface Dual Version of LT1468 80MHz, 25V/μs Low Power Rail-to-Rail Precision Op Amp VS ≤ ±5V, ICC = 1.6mA, VOS ≤ 350μV 60MHz, 20V/μs Low Power Rail-to-Rail Precision Op Amp VS ≤ ±5V, ICC = 0.9mA, VOS ≤ 350μV 200MHz, 70V/μs Low Noise Precision Op Amp Dual 50MHz, Low Noise, Precision CMOS Op Amp VS ≤ ±5V, en = 3.8nV/√Hz, –85dBc at 1MHz VS ≤ ±5V, VOS ≤ 100μV, IB ≤ 75pA 1468fa 16 Linear Technology Corporation (408) 432-1900 ● FAX: (408) 434-0507 ● LT 0808 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 www.linear.com © LINEAR TECHNOLOGY CORPORATION 1998