LT1351 250µA, 3MHz, 200V/µs Operational Amplifier U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ The LT ®1351 is a low power, high speed, high slew rate operational amplifier with outstanding AC and DC performance. The LT1351 features lower supply current, lower input offset voltage, lower input bias current and higher DC gain than devices with comparable bandwidth. The circuit combines the slewing performance of a current feedback amplifier in a true operational amplifier with matched high impedance inputs. The high slew rate ensures that the large-signal bandwidth is not degraded. The amplifier is a single gain stage with outstanding settling characteristics which make the circuit an ideal choice for data acquisition systems. The output drives a 1kΩ load to ±13V with ±15V supplies and a 500Ω load to ±3.4V on ±5V supplies. The amplifier is also stable with any capacitive load which makes it useful in buffer or cable driver applications. 3MHz Gain Bandwidth 200V/µs Slew Rate 250µA Supply Current Available in Tiny MSOP Package C-LoadTM Op Amp Drives All Capacitive Loads Unity-Gain Stable Power Saving Shutdown Feature Maximum Input Offset Voltage: 600µV Maximum Input Bias Current: 50nA Maximum Input Offset Current: 15nA Minimum DC Gain, RL = 2k: 30V/mV Input Noise Voltage: 14nV/√Hz Settling Time to 0.1%, 10V Step: 700ns Settling Time to 0.01%, 10V Step: 1.25µs Minimum Output Swing into 1k: ±13V Minimum Output Swing into 500Ω: ±3.4V Specified at ±2.5V, ±5V and ±15V The LT1351 is a member of a family of fast, high performance amplifiers using this unique topology and employing Linear Technology Corporation’s advanced complementary bipolar processing. For dual and quad amplifier versions of the LT1351 see the LT1352/LT1353 data sheet. For higher bandwidth devices with higher supply current see the LT1354 through LT1365 data sheets. Singles, duals and quads of each amplifier are available. U APPLICATIONS ■ ■ ■ ■ ■ ■ Battery-Powered Systems Wideband Amplifiers Buffers Active Filters Data Acquisition Systems Photodiode Amplifiers , LTC and LT are registered trademarks of Linear Technology Corporation. C-Load is a trademark of Linear Technology Corporation. U TYPICAL APPLICATION Instrumentation Amplifier R1 50k R2 5k – LT1351 – VIN + R5 1.1k Large-Signal Response R4 50k R3 5k – LT1351 VOUT + + 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 = 30kHz 1351 TA01 AV = –1 1351 TA02 1 LT1351 W W U W ABSOLUTE MAXIMUM RATINGS Total Supply Voltage (V + to V –) .............................. 36V Differential Input Voltage (Transient Only, Note 1) ... ±10V Input Voltage .......................................................... ±VS Output Short-Circuit Duration (Note 2) ........... Indefinite Operating Temperature Range ................ – 40°C to 85°C Specified Temperature Range (Note 6) .....– 40°C to 85°C Maximum Junction Temperature (See Below) Plastic Package ................................................ 150°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C U W U PACKAGE/ORDER INFORMATION TOP VIEW NULL –IN +IN V– 1 2 3 4 8 7 6 5 NULL V+ VOUT SHDN MS8 PACKAGE 8-LEAD PLASTIC MSOP ORDER PART NUMBER LT1351CMS8 MS8 PART MARKING TJMAX = 150°C, θJA = 250°C/ W LTBT ORDER PART NUMBER TOP VIEW NULL 1 8 NULL – IN 2 7 V+ +IN 3 6 VOUT V– 4 5 SHDN N8 PACKAGE 8-LEAD PDIP LT1351CN8 LT1351CS8 S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SO 1351 TJMAX = 150°C, θJA = 130°C/ W (N8) TJMAX = 150°C, θJA = 190°C/ W (S) Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER VOS Input Offset Voltage IOS TA = 25°C, VCM = 0V unless otherwise noted. CONDITIONS TYP MAX UNITS ±15V ±5V ±2.5V 0.2 0.2 0.3 0.6 0.6 0.8 mV mV mV Input Offset Current ±2.5V to ±15V 5 15 nA IB Input Bias Current ±2.5V to ±15V 20 50 nA en Input Noise Voltage f = 10kHz ±2.5V to ±15V 14 nV/√Hz in Input Noise Current f = 10kHz ±2.5V to ±15V 0.5 pA/√Hz RIN Input Resistance VCM = ±12V Differential 600 20 MΩ MΩ CIN Input Capacitance ±15V 3 pF Positive Input Voltage Range ±15V ±5V ±2.5V 13.5 3.5 1.0 V V V Negative Input Voltage Range ±15V ±5V ±2.5V CMRR Common Mode Rejection Ratio VCM = ±12V VCM = ±2.5V VCM = ±0.5V PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 2 VSUPPLY ±15V ±15V ±15V ±5V ±2.5V MIN 300 12.0 2.5 0.5 – 13.5 – 3.5 – 1.0 – 12.0 – 2.5 – 0.5 V V V 80 78 68 94 86 77 dB dB dB 90 106 dB LT1351 ELECTRICAL CHARACTERISTICS TA = 25°C, VCM = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VSUPPLY MIN TYP AVOL Large-Signal Voltage Gain VOUT IOUT VOUT = ±12V, RL = 5k VOUT = ±10V, RL = 2k VOUT = ±10V, RL = 1k VOUT = ±2.5V, RL = 5k VOUT = ±2 .5V, RL = 2k VOUT = ±2.5V, RL = 1k VOUT = ±1V, RL = 5k ±15V ±15V ±15V ±5V ±5V ±5V ±2.5V 40 30 20 30 25 15 20 80 60 40 60 50 30 40 Output Swing RL = 5k, VIN = ±10mV RL = 2k, VIN = ±10mV RL = 1k, VIN = ±10mV RL = 1k, VIN = ±10mV RL= 500Ω, VIN = ±10mV RL = 5k, VIN = ±10mV ±15V ±15V ±15V ±5V ±5V ±2.5V 13.5 13.4 13.0 3.5 3.4 1.3 14.0 13.8 13.4 4.0 3.8 1.7 ±V ±V ±V ±V ±V ±V Output Current VOUT = ±13V VOUT = ±3.4V ±15V ±5V 13.0 6.8 13.4 7.6 mA mA ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V 30 45 mA SR Slew Rate AV = – 1, RL = 5k (Note 3) ±15V ±5V 120 30 200 50 V/µs V/µs Full-Power Bandwidth 10V Peak (Note 4) 3V Peak (Note 4) ±15V ±5V 3.2 2.6 MHz MHz GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V ± 5V ± 2.5V 3.0 2.7 2.5 MHz MHz MHz t r , tf Rise Time, Fall Time AV = 1, 10% to 90%, 0.1V ±15V ±5V 46 53 ns ns Overshoot AV = 1, 0.1V ±15V ±5V 13 16 % % Propagation Delay 50% VIN to 50% VOUT, 0.1V ±15V ±5V 41 52 ns ns ts Settling Time 10V Step, 0.1%, AV = – 1 10V Step, 0.01%, AV = – 1 5V Step, 0.1%, AV = – 1 5V Step, 0.01%, AV = – 1 ±15V ±15V ±5V ±5V 700 1250 950 1400 ns ns ns ns RO Output Resistance AV = 1, f = 20kHz ±15V 1.5 Ω ISHDN Shutdown Input Current SHDN = VEE + 0.1V SHDN = VCC ±15V ±15V – 10 0.1 250 220 10 330 300 SHDN = VEE + 0.1V ±15V ±5V ±5V µA µA µA TYP MAX UNITS IS Supply Current 2.0 1.8 MAX UNITS V/mV V/mV V/mV V/mV V/mV V/mV V/mV 2 µA µA 0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted. SYMBOL PARAMETER VOS Input Offset Voltage Input VOS Drift CONDITIONS VSUPPLY MIN ±15V ±5V ±2.5V (Note 5) ±2.5V to ±15V 0.8 0.8 1.0 3 mV mV mV 8 µV/°C IOS Input Offset Current ±2.5V to ±15V 20 nA IB Input Bias Current ±2.5V to ±15V 75 nA 3 LT1351 ELECTRICAL CHARACTERISTICS 0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VSUPPLY MIN CMRR Common Mode Rejection Ratio VCM = ±12V VCM = ±2.5V VCM = ±0.5V ±15V ±5V ±2.5V 78 77 67 dB dB dB PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 89 dB AVOL Large-Signal Voltage Gain VOUT = ±12V, RL = 5k VOUT = ±10V, RL = 2k VOUT = ±2.5V, RL = 5k VOUT = ±2 .5V, RL = 2k VOUT = ±2.5V, RL = 1k VOUT = ±1V, RL = 5k ±15V ±15V ±5V ±5V ±5V ±2.5V 25 20 20 15 10 15 V/mV V/mV V/mV V/mV V/mV V/mV VOUT Output Swing RL = 5k, VIN = ±10mV RL = 2k, VIN = ±10mV RL = 1k, VIN = ±10mV RL = 1k, VIN = ±10mV RL= 500Ω, VIN = ±10mV RL = 5k, VIN = ±10mV ±15V ±15V ±15V ±5V ±5V ±2.5V 13.4 13.3 12.0 3.4 3.3 1.2 ±V ±V ±V ±V ±V ±V IOUT Output Current VOUT = ±12V VOUT = ±3.3V ±15V ±5V 12.0 6.6 mA mA ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V 24 mA SR Slew Rate AV = – 1, RL = 5k (Note 3) ±15V ±5V 100 21 V/µs V/µs GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V ± 5V 1.8 1.6 MHz MHz ISHDN Shutdown Input Current SHDN = VEE + 0.1V SHDN = VCC ±15V ±15V SHDN = VEE + 0.1V ±15V ±5V ±5V IS Supply Current TYP MAX – 20 3 UNITS µA µA 380 355 µA µA µA MAX UNITS 1.0 1.0 1.2 mV mV mV 20 – 40°C ≤ TA ≤ 85°C, VCM = 0V unless otherwise noted (Note 6). SYMBOL PARAMETER VOS Input Offset Voltage CONDITIONS VSUPPLY MIN TYP ±15V ±5V ±2.5V 8 µV/°C IOS Input Offset Current ±2.5V to ±15V 30 nA IB Input Bias Current ±2.5V to ±15V 100 nA CMRR Common Mode Rejection Ratio VCM = ±12V VCM = ±2.5V VCM = ±0.5V PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V AVOL Large-Signal Voltage Gain VOUT = ±12V, RL = 5k VOUT = ±10V, RL = 2k VOUT = ±2.5V, RL = 5k VOUT = ±2 .5V, RL = 2k VOUT = ±2.5V, RL = 1k VOUT = ±1V, RL = 5k Input VOS Drift 4 (Note 5) ±2.5V to ±15V ±15V ±5V ±2.5V ±15V ±15V ±5V ±5V ±5V ±2.5V 3 76 76 66 dB dB dB 87 dB 20 15 15 10 8 10 V/mV V/mV V/mV V/mV V/mV V/mV LT1351 ELECTRICAL CHARACTERISTICS – 40°C ≤ TA ≤ 85°C, VCM = 0V unless otherwise noted (Note 6). SYMBOL PARAMETER CONDITIONS VSUPPLY MIN VOUT Output Swing RL = 5k, VIN = ±10mV RL = 2k, VIN = ±10mV RL = 1k, VIN = ±10mV RL = 1k, VIN = ±10mV RL= 500Ω, VIN = ±10mV RL = 5k, VIN = ±10mV ±15V ±15V ±15V ±5V ±5V ±2.5V 13.3 13.2 10.0 3.3 3.2 1.1 ±V ±V ±V ±V ±V ±V IOUT Output Current VOUT = ±10V VOUT = ±3.2V ±15V ±5V 10.0 6.4 mA mA ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V 20 mA SR Slew Rate AV = – 1, RL = 5k (Note 3) ±15V ±5V 50 15 V/µs V/µs GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V ± 5V 1.6 1.4 MHz MHz ISHDN Shutdown Input Current SHDN = VEE + 0.1V SHDN = VCC ±15V ±15V SHDN = VEE + 0.1V ±15V ±5V ±5V IS Supply Current Note 1: Differential inputs of ±10V are appropriate for transient operation only, such as during slewing. Large, sustained differential inputs will cause excessive power dissipation and may damage the part. See Input Considerations in the Applications Information section of this data sheet for more details. Note 2: A heat sink may be required to keep the junction temperature below absolute maximum when the output is shorted indefinitely. Note 3: 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. TYP MAX UNITS µA µA – 30 5 µA µA µA 390 380 30 Note 4: Full-power bandwidth is calculated from the slew rate measurement: FPBW = (Slew Rate)/2πVP. Note 5: This parameter is not 100% tested. Note 6: The LT1351 is designed, characterized and expected to meet these extended temperature limits, but is not tested at – 40°C and at 85°C. Guaranteed I grade parts are available; consult factory. U W TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Supply Voltage and Temperature Input Common Mode Range vs Supply Voltage V+ 350 30 TA = 25°C ∆VOS = 1mV –0.5 125°C 250 25°C 200 – 55°C 150 TA = 25°C VS = ±15V –1.0 INPUT BIAS CURRENT (nA) COMMON MODE RANGE (V) 300 SUPPLY CURRENT (µA) Input Bias Current vs Input Common Mode Voltage –1.5 –2.0 2.0 1.5 1.0 20 IB = IB+ + IB– 2 10 0 –10 0.5 100 V– 0 10 5 15 SUPPLY VOLTAGE (± V) 20 1351 G01 0 15 10 5 SUPPLY VOLTAGE (± V) 20 1351 G02 –20 –15 10 –5 0 5 –10 INPUT COMMON MODE VOLTAGE (V) 15 1351 G03 5 LT1351 U W TYPICAL PERFORMANCE CHARACTERISTICS 100 VS = ±15V IB+ + IB– IB = 2 INPUT VOLTAGE NOISE (nV/√Hz) 32 Open-Loop Gain vs Resistive Load 28 24 20 16 12 8 110 10 TA = 25°C TA = 25°C VS = ±15V AV = 101 RS = 100k INPUT CURRENT NOISE (pA/√Hz) INPUT BIAS CURRENT (nA) 36 Input Noise Spectral Density en 1 10 in VS = ±15V 100 OPEN-LOOP GAIN (dB) Input Bias Current vs Temperature 40 VS = ±5V 90 80 70 4 50 25 0 75 TEMPERATURE (°C) 100 125 1 10 1k 100 FREQUENCY (Hz) 1351 G04 Output Voltage Swing vs Load Current V+ 97 96 95 RL = 1k –2 –3 TA = 25°C VIN = ±10mV 3 RL = 1k 2 1 94 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 RL = 2k 0 5 10 10 8 2 0 –2 –4 10mV –8 125 1351 G10 6 1mV VS = ±15V AV = 1 OUTPUT FILTER: 1.6MHz LPF –10 100 – 40°C – 40°C 25°C 85°C 15 0.7 0.8 0.9 20 6 1mV 4 –6 30 25°C 85°C 1.0 8 1 1.1 1.2 1.3 1.4 1.5 1.6 SETTLING TIME (µs) 1351 G11 OUTPUT STEP (V) SOURCE 50 25 75 0 TEMPERATURE (°C) 1.5 10 10mV 35 25 –50 –25 2.0 – 40°C 85°C Settling Time vs Output Step (Inverting) 6 40 –2.0 25°C 1351 G09 55 OUTPUT STEP (V) OUTPUT SHORT-CIRCUIT CURRENT (mA) VS = ±15V 45 – 40°C –1.5 Settling Time vs Output Step (Noninverting) SINK 85°C 1351 G08 Output Short-Circuit Current vs Temperature 50 25°C –1.0 V– –20 –15 –10 – 5 0 10 5 OUTPUT CURRENT (mA) 20 15 SUPPLY VOLTAGE (V) VS = ±5V VIN = 10mV 0.5 V– 125 1351 G07 60 – 0.5 RL = 2k –1 98 10k 1351 G06 V+ OUTPUT VOLTAGE SWING (V) OPEN-LOOP GAIN (dB) 99 1k LOAD RESISTANCE (Ω) Output Voltage Swing vs Supply Voltage VS = ±15V VO = ±12V RL = 5k 100 10 1351 G05 Open-Loop Gain vs Temperature 100 60 0.1 10k 1 OUTPUT VOLTAGE SWING (V) 0 –50 –25 4 2 10mV 1mV 0 –2 –4 –6 –8 10mV VS = ±15V AV = –1 RG = RF = 2k CF = 5pF RL = 2k 1mV –10 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 SETTLING TIME (µs) 1351 G12 LT1351 U W TYPICAL PERFORMANCE CHARACTERISTICS Gain and Phase vs Frequency 120 VS = ±5V 100 60 VS = ±5V 40 30 GAIN 20 20 10 0 0 –20 –10 –40 100M 1k 10k 100k 1M FREQUENCY (Hz) 10M 8 100 80 VS = ±15V PHASE (DEG) 40 TA = 25°C VS = ±15V 6 AV = 100 AV = 10 10 1 0.1 10k 1k 100k 1M FREQUENCY (Hz) 4.00 VS = ±5V 46 3 3.75 PHASE MARGIN 44 10M 42 3.25 40 38 2.00 –50 –25 5 TA = 25°C AV = 1 RL = 5k 3 2 1 0 –1 VS = ±5V 34 –3 32 –4 ±15V ±5V ±2.5V –2 3.75 44 3.50 42 3.25 40 3.00 38 36 2.75 GAIN BANDWIDTH 2.50 34 32 2.25 30 2.00 0 15 10 5 SUPPLY VOLTAGE (± V) 20 1351 G19 POWER SUPPLY REJECTION RATIO (dB) 46 PHASE MARGIN PHASE MARGIN (DEG) GAIN BANDWIDTH (MHz) 120 48 4.00 –2 ±15V ±5V ±2.5V –5 10k 10M 100k 1M FREQUENCY (Hz) 10M 1351 G18 Common Mode Rejection Ratio vs Frequency Power Supply Rejection Ratio vs Frequency 50 TA = 25°C –1 1351 G17 Gain Bandwidth and Phase Margin vs Supply Voltage 4.25 0 –3 100k 1M FREQUENCY (Hz) 1351 G16 4.50 TA = 25°C AV = –1 RL = RG = 5k –4 –5 10k 30 125 4 1 36 100 10M Frequency Response vs Supply Voltage (AV = – 1) 2 VS = ±15V 50 25 0 75 TEMPERATURE (°C) 100k 1M FREQUENCY (Hz) 1351 G15 GAIN (dB) GAIN BANDWIDTH (MHz) 3.50 GAIN (dB) 4 PHASE MARGIN (DEG) 5 48 2.25 –10 10k Frequency Response vs Supply Voltage (AV = 1) 50 2.50 C = 10pF –2 1351 G14 VS = ±15V 2.75 0 –8 0.01 4.25 3.00 C = 1000pF 2 –4 Gain Bandwidth and Phase Margin vs Temperature GAIN BANDWIDTH C = 5000pF C = 500pF C = 100pF –6 1351 G13 4.50 TA = 25°C VS = ±15V AV = –1 RFB = RG = 5k 4 AV = 1 GAIN (dB) VS = ±15V 10 1000 TA = 25°C VS = ±15V 100 80 – PSRR = +PSRR 60 40 20 0 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 1351 G20 120 COMMON MODE REJECTION RATIO (dB) PHASE 50 GAIN (dB) TA = 25°C AV = –1 RF = RG = 5k OUTPUT IMPEDANCE (Ω) 70 60 Frequency Response vs Capacitive Load Output Impedance vs Frequency 100 TA = 25°C VS = ±15V 80 60 40 20 0 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 1351 G21 7 LT1351 U W TYPICAL PERFORMANCE CHARACTERISTICS Slew Rate vs Supply Voltage TA = 25°C AV = –1 RF = RG = 5k SR = (SR+ + SR – )/2 Slew Rate vs Input Level 150 VS = ±15V 150 100 VS = ±5V 50 50 TA = 25°C VS = ±15V AV = –1 RFB = RG = 5k SR = (SR+ + SR – )/2 175 SLEW RATE (V/µs) 100 200 AV = –1 RF = RG = RL = 5k SR = (SR+ + SR – )/2 200 SLEW RATE (V/µs) 150 SLEW RATE (V/µs) Slew Rate vs Temperature 250 200 125 100 75 50 25 0 0 0 –50 –25 15 5 10 SUPPLY VOLTAGE (±V) 50 0 75 25 TEMPERATURE (°C) 1351 G22 AV = 1 20 15 10 5 AV = 1 10 100 1k 10k FREQUENCY (Hz) 0 10k 100k 100k FREQUENCY (Hz) 90 4 3 3RD HARMONIC – 60 –70 2ND HARMONIC 70 60 50 Capacitive Load Handling 90 80 VSHDN = VEE + 0.2 VSHDN = VEE + 0.1 40 30 FREQUENCY (Hz) 1351 G28 0 –50 –25 1M 100 TA = 25°C VS = ±15V RL = 5k 70 AV = 1 60 50 40 AV = –1 30 20 VSHDN = VEE 10 10 1M 100k FREQUENCY (Hz) 1351 G27 VS = ±15V 20 – 80 VS = ± 5V RL = 5k THD = 1% 0 10k 1M 80 SUPPLY CURRENT (µA) HARMONIC DISTORTION (dB) 100 – 50 AV = –1 5 Shutdown Supply Current vs Temperature VS = ±15V AV = 1 RL = 5k VO = 2VP-P AV = 1 6 1351 G26 2nd and 3rd Harmonic Distortion vs Frequency 8 7 1 1351 G25 – 90 100k 8 2 VS = ±15V RL = 5k THD = 1% OVERSHOOT (%) 0.001 OUTPUT VOLTAGE (VP-P) OUTPUT VOLTAGE (VP-P) TOTAL HARMONIC DISTORTION (%) AV = –1 24 9 25 0.01 20 10 AV = –1 0.1 8 16 12 INPUT LEVEL (VP-P) Undistorted Output Swing vs Frequency (±5V) 30 TA = 25°C VS = ±15V RL = 5k VO = 2VP-P 4 0 1351 G24 Undistorted Output Swing vs Frequency (±15V) 1 – 40 0 125 1351 G23 Total Harmonic Distortion vs Frequency – 30 100 50 25 0 75 TEMPERATURE (°C) 100 125 1351 G29 0 10p 100p 1n 10n 0.1µ CAPACITIVE LOAD (F) 1µ 1351 G30 LT1351 U W TYPICAL PERFORMANCE CHARACTERISTICS Small-Signal Transient (AV = 1) Small-Signal Transient (AV = – 1) 1351 G31 Small-Signal Transient (AV = – 1, CL = 1000pF) 1351 G32 Large-Signal Transient (AV = 1) Large-Signal Transient (AV = – 1) 1351 G34 1351 G33 Large-Signal Transient (AV = 1, CL = 10,000pF) 1351 G35 1351 G36 U U W U APPLICATIONS INFORMATION The LT1351 may be inserted directly into many high speed amplifier applications improving both DC and AC performance, provided that the nulling circuitry is removed. The suggested nulling circuit for the LT1351 is shown in Figure 1. V+ 3 0.1µF + 7 LT1351 2 6 4 – 8 1 0.1µF 100k V– 1351 F01 Figure 1. Offset Nulling Layout and Passive Components The LT1351 amplifier is easy to apply and tolerant of less than ideal layouts. For maximum performance (for example fast settling time) use a ground plane, short lead lengths and RF-quality bypass capacitors (0.01µF to 0.1µF). For high drive current applications use low ESR bypass capacitors (1µF to 10µF tantalum). For details see Design Note 50. 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 which can cause peaking or even oscillations. For feedback resistors greater than 10k, a parallel capacitor of value, CF > (RG)(CIN/RF) should be used to cancel the input pole and optimize dynamic performance. For applications where the DC 9 LT1351 U W U U APPLICATIONS INFORMATION noise gain is one and a large feedback resistor is used, CF should be greater than or equal to CIN. An example would be an I-to-V converter as shown in the Typical Applications section. Capacitive Loading The LT1351 is stable with any capacitive load. As the capacitive load increases, both the bandwidth and phase margin decrease so there will be peaking in the frequency domain and in the transient response. Graphs of Frequency Response vs Capacitive Load, Capacitive Load Handling and the transient response photos clearly show these effects. Shutdown The LT1351 has a Shutdown pin for conserving power. When this pin is open or 2V above the negative supply the part operates normally. When pulled down to V – the supply current will drop to about 10µA. The current out of the Shutdown pin is also typically 10µA. In shutdown the amplifier output is not isolated from the inputs so the LT1351 cannot be used in multiplexing applications using the shutdown feature. A level shift application is shown in the Typical Applications section so that a ground-referenced logic signal can control the Shutdown pin. Input Considerations Circuit Operation Each of the LT1351 inputs is the base of an NPN and a PNP transistor whose base currents are of opposite polarity and provide first-order bias current cancellation. Because of variation in the matching of NPN and PNP beta, the polarity of the input bias current can be positive or negative. The offset current does not depend on NPN/PNP beta matching and is well controlled. The use of balanced source resistance at each input is recommended for applications where DC accuracy must be maximized. The LT1351 circuit topology is a true voltage feedback amplifier that has the slewing behavior of a current feedback amplifier. The operation of the circuit can be understood by referring to the simplified schematic. The inputs can withstand transient differential input voltages up to 10V without damage and need no clamping or source resistance for protection. Differential inputs, however, generate large supply currents (tens of mA) as required for high slew rates. If the device is used with sustained differential inputs, the average supply current will increase, excessive power dissipation will result and the part may be damaged. The part should not be used as a comparator, peak detector or other open-loop application with large, sustained differential inputs. Under normal, closed-loop operation, an increase of power dissipation is only noticeable in applications with large slewing outputs and is proportional to the magnitude of the differential input voltage and the percent of the time that the inputs are apart. Measure the average supply current for the application in order to calculate the power dissipation. 10 The inputs are buffered by complementary NPN and PNP emitter followers which drive R1, a 1k resistor. The input voltage appears across the resistor generating currents which are mirrored into the high impedance node and compensation capacitor CT. Complementary followers form an output stage which buffers the gain node from the load. The output devices Q19 and Q22 are connected to form a composite PNP and composite NPN. The bandwidth is set by the input resistor and the capacitance on the high impedance node. The slew rate is determined by the current available to charge the capacitance. This current is the differential input voltage divided by R1, so the slew rate is proportional to the input. Highest slew rates are therefore seen in the lowest gain configurations. For example, a 10V output step in a gain of 10 has only a 1V input step whereas the same output step in unity gain has a 10 times greater input step. The curve of Slew Rate vs Input Level illustrates this relationship. Capacitive load compensation is provided by the RC, CC network which is bootstrapped across the output stage. When the amplifier is driving a light load the network has no effect. When driving a capacitive load (or a low value LT1351 U U W U APPLICATIONS INFORMATION resistive load) the network is incompletely bootstrapped and adds to the compensation at the high impedance node. The added capacitance slows down the amplifier and a zero is created by the RC combination, both of which improve the phase margin. The design ensures that even for very large load capacitances the total phase lag can never exceed 180 degrees (zero phase margin) and the amplifier remains stable. W W SI PLIFIED SCHE ATIC V+ R2 Q11 Q10 Q12 C1 R3 Q21 Q20 R6 Q9 –IN Q7 R1 Q3 1k Q5 Q17 Q1 Q2 Q6 Q8 Q19 RC CC +IN OUTPUT Q18 Q4 R7 Q22 Q13 C2 CT Q15 Q14 Q16 Q23 Q24 R4 V– R5 1351 SS U TYPICAL APPLICATIONS 20kHz, 4th Order Butterworth Filter 4.64k 5.49k 470pF 220pF 4.64k 13.3k VIN 2200pF – 5.49k 11.3k LT1351 + 4700pF – LT1351 VOUT + 1351 TA03 11 LT1351 U TYPICAL APPLICATIONS Shutdown Circuit 3 + 6 LT1351 2 1N4148 1M SHDN G S SST177 D – G 1M 5 S SST177 D V– 1351 TA04 DAC I-to-V Converter 10pF DAC INPUTS 12 5k – LT1351 565A TYPE V VOS + IOS (5kΩ) + OUT < 0.5LSB AVOL 12 VOUT + 5k 1351 TA05 LT1351 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 ± 0.004* (3.00 ± 0.102) 8 7 6 5 0.118 ± 0.004** (3.00 ± 0.102) 0.192 ± 0.004 (4.88 ± 0.10) 1 2 3 0.040 ± 0.006 (1.02 ± 0.15) 0.007 (0.18) 4 0.034 ± 0.004 (0.86 ± 0.102) 0° – 6° TYP 0.021 ± 0.006 (0.53 ± 0.015) SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) TYP 0.006 ± 0.004 (0.15 ± 0.102) MSOP (MS8) 1197 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 13 LT1351 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.400* (10.160) MAX 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 8.255 +0.889 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.100 ± 0.010 (2.540 ± 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 14 0.130 ± 0.005 (3.302 ± 0.127) 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 ± 0.003 (0.457 ± 0.076) N8 1197 LT1351 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 2 3 4 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) 0.050 (1.270) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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. SO8 0996 15 LT1351 U TYPICAL APPLICATION Low Power Sample-and-Hold – – LTC201 LT1351 VIN + LT1351 + VOUT 2000pF DROOP: 20nA/2000pF = 10mV/ms ACQUISITION TIME: 10V, 0.1% = 2µs CHARGE INJECTION ERROR: 8pC/2000pF = 4mV 1351 TA06 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1352/LT1353 Dual/Quad 250µA, 3MHz, 200V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads LT1354 1mA, 12MHz, 400V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads 16 Linear Technology Corporation 1351fa LT/TP 0498 REV A 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1996