LT1360 50MHz, 800V/µs Op Amp U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 50MHz Gain Bandwidth 800V/µs Slew Rate 5mA Maximum Supply Current 9nV/√Hz Input Noise Voltage Unity-Gain Stable C-LoadTM Op Amp Drives All Capacitive Loads 1mV Maximum Input Offset Voltage 1µA Maximum Input Bias Current 250nA Maximum Input Offset Current ±13V Minimum Output Swing into 500Ω ±3.2V Minimum Output Swing into 150Ω 4.5V/mV Minimum DC Gain, RL=1k 60ns Settling Time to 0.1%, 10V Step 0.2% Differential Gain, AV=2, RL=150Ω 0.3° Differential Phase, AV=2, RL=150Ω Specified at ±2.5V, ±5V, and ±15V The LT1360 is a high speed, very high slew rate operational amplifier with excellent DC performance. The LT1360 features reduced supply current, lower input offset voltage, lower input bias current and higher DC gain than devices with comparable bandwidth. The circuit topology is a voltage feedback amplifier with the slewing characteristics of a current feedback amplifier. The amplifier is a single gain stage with outstanding settling characteristics which makes the circuit an ideal choice for data acquisition systems. The output drives a 500Ω load to ±13V with ±15V supplies and a 150Ω load to ±3.2V on ±5V supplies. The amplifier is also capable of driving any capacitive load which makes it useful in buffer or cable driver applications. The LT1360 is a member of a family of fast, high performance amplifiers using this unique topology and employing Linear Technology Corporation’s advanced bipolar complementary processing. For dual and quad amplifier versions of the LT1360 see the LT1361/LT1362 data sheet. For 70MHz amplifiers with 6mA of supply current per amplifier see the LT1363 and LT1364/LT1365 data sheets. For lower supply current amplifiers with bandwidths of 12MHz and 25MHz see the LT1354 through LT1359 data sheets. Singles, duals and quads of each amplifier are available. U APPLICATIO S ■ ■ ■ ■ ■ Wideband Amplifiers Buffers Active Filters Video and RF Amplification Cable Drivers Data Acquisition Systems , LTC and LT are registered trademarks of Linear Technology Corporation. C-Load is a trademark of Linear Technology Corporation. U ■ TYPICAL APPLICATIO AV = –1 Large-Signal Response Two Op Amp Instrumentation Amplifier R5 220Ω R1 10k R4 10k R2 1k R3 1k – – LT1360 – + LT1360 VOUT + VIN + ( R4 1 R2 R3 R2 + R3 GAIN = 1 + + + R5 R3 2 R1 R4 TRIM R5 FOR GAIN TRIM R1 FOR COMMON-MODE REJECTION BW = 500kHz ) = 102 1360 TA02 1360 TA01 1 LT1360 W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) Total Supply Voltage (V + to V –) ............................... 36V Differential Input Voltage (Transient Only) (Note 2)................................... ±10V Input Voltage ............................................................ ±VS Output Short Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range (Note 8) ...–40°C to 85°C Specified Temperature Range (Note 9) ....–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 W U U PACKAGE/ORDER INFORMATION TOP VIEW NULL 1 8 NULL –IN 2 7 V+ +IN 3 6 VOUT V– 4 5 NC ORDER PART NUMBER LT1360CN8 ORDER PART NUMBER TOP VIEW NULL 1 8 NULL –IN 2 7 V+ +IN 3 6 VOUT V– 4 5 NC N8 PACKAGE, 8-LEAD PDIP S8 PACKAGE, 8-LEAD PLASTIC SO TJMAX = 150°C, θJA = 130°C/ W TJMAX = 150°C, θJA = 190°C/ W LT1360CS8 S8 PART MARKING 1360 Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS TA = 25°C, VCM = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VSUPPLY TYP MAX UNITS VOS Input Offset Voltage (Note 4) ±15V ±5V ±2.5V 0.3 0.3 0.4 1.0 1.0 1.2 mV mV mV IOS Input Offset Current ±2.5V to ±15V 80 250 nA IB Input Bias Current ±2.5V to ±15V 0.3 1.0 en Input Noise Voltage f = 10kHz ±2.5V to ±15V 9 nV/√Hz in Input Noise Current f = 10kHz ±2.5V to ±15V 0.9 pA/√Hz RIN Input Resistance VCM = ±12V ±15V 50 MΩ Input Resistance Differential ±15V 5 MΩ ±15V 3 pF 13.4 3.4 1.1 V V V CIN Input Capacitance + ±15V ±5V ±2.5V Input Voltage Range – ±15V ±5V ±2.5V Input Voltage Range CMRR Common Mode Rejection Ratio VCM = ±12V VCM = ±2.5V VCM = ±0.5V PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 2 ±15V ±5V ±2.5V MIN 20 12.0 2.5 0.5 –13.2 –3.2 –0.9 –12.0 –2.5 –0.5 µA V V V 86 79 68 92 84 74 dB dB dB 93 105 dB LT1360 ELECTRICAL CHARACTERISTICS TA = 25°C, VCM = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS VSUPPLY MIN TYP AVOL Large-Signal Voltage Gain VOUT = ±12V, RL = 1k VOUT = ±10V, RL = 500Ω VOUT = ±2.5V, RL = 500Ω VOUT = ±2.5V, RL = 150Ω VOUT = ±1V, RL = 500Ω VOUT Output Swing IOUT Output Current MAX UNITS ±15V ±15V ±5V ±5V ±2.5V 4.5 3.0 3.0 1.5 2.5 9.0 6.5 6.4 4.2 5.2 V/mV V/mV V/mV V/mV V/mV RL = 1k, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 150Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV ±15V ±15V ±5V ±5V ±2.5V 13.5 13.0 3.5 3.2 1.3 13.9 13.6 4.0 3.8 1.7 ±V ±V ±V ±V ±V VOUT = ±13V VOUT = ±3.2V ±15V ±5V 26 21 34 29 mA mA ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V 40 54 mA SR Slew Rate AV = –2, (Note 5) ±15V ±5V 600 250 800 350 V/µs V/µs Full Power Bandwidth 10V Peak, (Note 6) 3V Peak, (Note 6) ±15V ±5V 12.7 18.6 MHz MHz GBW Gain Bandwidth f = 1MHz ±15V ±5V ±2.5V 50 37 32 MHz MHz MHz tr , tf Rise Time, Fall Time AV = 1, 10%-90%, 0.1V ±15V ±5V 3.1 4.3 ns ns Overshoot AV = 1, 0.1V ±15V ±5V 35 27 % % Propagation Delay 50% VIN to 50% VOUT, 0.1V ±15V ±5V 5.2 6.4 ns ns Settling Time 10V Step, 0.1%, AV = –1 10V Step, 0.01%, AV = –1 5V Step, 0.1%, AV = –1 ±15V ±15V ±5V 60 90 65 ns ns ns Differential Gain f = 3.58MHz, AV = 2, RL = 150Ω ±15V ±5V ±15V ±5V 0.20 0.20 0.04 0.02 % % % % ±15V ±5V ±15V ±5V 0.40 0.30 0.07 0.26 Deg Deg Deg Deg ±15V 1.4 ±15V ±5V 4.0 3.8 ts f = 3.58MHz, AV = 2, RL = 1k Differential Phase f = 3.58MHz, AV = 2, RL = 150Ω f = 3.58MHz, AV = 2, RL = 1k RO Output Resistance IS Supply Current AV = 1, f = 1MHz Ω 5.0 4.8 mA mA 3 LT1360 ELECTRICAL CHARACTERISTICS 0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted. The ● denotes the specifications which apply over the temperature range SYMBOL PARAMETER CONDITIONS VSUPPLY VOS Input Offset Voltage (Note 4) ±15V ±5V ±2.5V ● ● ● MIN Input VOS Drift (Note 7) ±2.5V to ±15V ● TYP 9 MAX UNITS 1.5 1.5 1.7 mV mV mV 12 µV/°C IOS Input Offset Current ±2.5V to ±15V ● 350 nA IB Input Bias Current ±2.5V to ±15V ● 1.5 µA CMRR Common Mode Rejection Ratio ±15V ±5V ±2.5V ● ● ● PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V ● 91 dB AVOL Large-Signal Voltage Gain VOUT = ±12V, RL = 1k VOUT = ±10V, RL = 500Ω VOUT = ±2.5V, RL = 500Ω VOUT = ±2.5V, RL = 150Ω VOUT = ±1V, RL = 500Ω ±15V ±15V ±5V ±5V ±2.5V ● ● ● ● ● 3.6 2.4 2.4 1.0 2.0 V/mV V/mV V/mV V/mV V/mV VOUT Output Swing RL = 1k, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 150Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV ±15V ±15V ±5V ±5V ±2.5V ● ● ● ● ● 13.4 12.8 3.4 3.1 1.2 ±V ±V ±V ±V ±V IOUT Output Current VOUT = ±12.8V VOUT = ±3.1V ±15V ±5V ● ● 25 20 mA mA VCM = ±12V VCM = ±2.5V VCM = ±0.5V 84 77 66 dB dB dB ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V ● 32 mA SR Slew Rate AV = –2, (Note 5) ±15V ±5V ● ● 475 185 V/µs V/µs IS Supply Current ±15V ±5V ● ● 4 5.8 5.6 mA mA LT1360 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the temperature range – 40°C ≤ TA ≤ 85°C, VCM = 0V unless otherwise noted. (Note 9) SYMBOL VOS PARAMETER Input Offset Voltage CONDITIONS (Note 4) VSUPPLY ±15V ±5V ±2.5V ● ● ● MIN Input VOS Drift (Note 7) TYP MAX 2.0 2.0 2.2 UNITS mV mV mV ±2.5V to ±15V ● 12 µV/°C IOS Input Offset Current ±2.5V to ±15V ● 400 nA IB Input Bias Current ±2.5V to ±15V ● 1.8 µA CMRR Common Mode Rejection Ratio ±15V ±5V ±2.5V ● ● ● PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V ● 90 dB AVOL Large-Signal Voltage Gain VOUT = ±12V, RL = 1k VOUT = ±10V, RL = 500Ω VOUT = ±2.5V, RL = 500Ω VOUT = ±2.5V, RL = 150Ω VOUT = ±1V, RL = 500Ω ±15V ±15V ±5V ±5V ±2.5V ● ● ● ● ● 2.5 1.5 1.5 0.6 1.3 V/mV V/mV V/mV V/mV V/mV VOUT Output Swing RL = 1kΩ, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV RL = 150Ω, VIN = ±40mV RL = 500Ω, VIN = ±40mV ±15V ±15V ±5V ±5V ±2.5V ● ● ● ● ● 13.4 12.0 3.4 3.0 1.2 ±V ±V ±V ±V ±V IOUT Output Current VOUT = ±12.0V VOUT = ±3.0V ±15V ±5V ● ● 24 20 mA mA ISC Short-Circuit Current VOUT = 0V, VIN = ±3V ±15V ● 30 mA SR Slew Rate AV = –2, (Note 5) ±15V ±5V ● ● 450 175 V/µs V/µs IS Supply Current ±15V ±5V ● ● VCM = ±12V VCM = ±2.5V VCM = ±0.5V Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: 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 3: A heat sink may be required to keep the junction temperature below absolute maximum when the output is shorted indefinitely. Note 4: Input offset voltage is pulse tested and is exclusive of warm-up drift. Note 5: Slew rate is measured between ±10V on the output with ±6V input for ±15V supplies and ±2V on the output with ±1.75V input for ±5V supplies. 9 84 77 66 dB dB dB 6.0 5.8 mA mA Note 6: Full power bandwidth is calculated from the slew rate measurement: FPBW = SR/2πVP. Note 7: This parameter is not 100% tested. Note 8: The LT1360C is guaranteed functional over the operating temperature range of –40°C to 85°C. Note 9: The LT1360C is guaranteed to meet specified performance from 0°C to 70°C. The LT1360C is designed, characterized and expected to meet specified performance from – 40°C to 85°C, but is not tested or QA sampled at these temperatures. For guaranteed I-grade parts, consult the factory. 5 LT1360 U W TYPICAL PERFORMANCE CHARACTERISTICS Supply Current vs Supply Voltage and Temperature 0.6 V+ 6 TA = 25°C ∆VOS < 1mV – 0.5 125°C 4 25°C 3 –55°C 2 –1.5 –2.0 2.0 1.5 1.0 V– 5 10 15 SUPPLY VOLTAGE (±V) 0 20 5 10 15 SUPPLY VOLTAGE (±V) 0.5 0.4 0.3 0.2 0.1 VS = ±15V TA = 25°C AV = 101 RS = 100k in 10 en 1 1 –25 0 25 50 75 TEMPERATURE (°C) 100 10 125 100 10 76 75 74 Output Voltage Swing vs Load Current – 0.5 –2 RL = 500Ω –3 3 RL = 500Ω 2 RL = 1k V– –25 0 25 50 75 TEMPERATURE (°C) 100 125 1360 G07 10k 1360 G06 RL = 1k 1 73 100 1k LOAD RESISTANCE (Ω) V+ –1 OUTPUT VOLTAGE SWING (V) OPEN-LOOP GAIN (dB) 60 TA = 25°C 77 6 65 V+ 78 72 –50 70 Output Voltage Swing vs Supply Voltage 81 79 VS = ±5V 75 1360 G05 Open-Loop Gain vs Temperature RL = 1k VO = ±12V VS = ±15V VS = ±15V 80 0.1 100k 1k 10k FREQUENCY (Hz) 1360 G04 80 TA = 25°C OUTPUT VOLTAGE SWING (V) 0 –50 INPUT VOLTAGE NOISE (nV/√Hz) INPUT BIAS CURRENT (µA) 85 10 100 INPUT CURRENT NOISE (pA/√Hz) 15 Open-Loop Gain vs Resistive Load Input Noise Spectral Density VS = ±15V IB+ + IB– IB = ———— 2 –10 –5 0 5 10 INPUT COMMON MODE VOLTAGE (V) 1360 G03 Input Bias Current vs Temperature 0.6 0.2 1360 G02 1360 G01 0.7 0.3 0 –15 20 OPEN-LOOP GAIN (dB) 0 0.4 0.1 0.5 1 VS = ±15V TA = 25°C IB+ + IB– IB = ———— 2 0.5 –1.0 INPUT BIAS CURRENT (µA) COMMON MODE RANGE (V) 5 SUPPLY CURRENT (mA) Input Bias Current vs Input Common Mode Voltage Input Common Mode Range vs Supply Voltage 0 5 10 15 SUPPLY VOLTAGE (±V) 20 1360 G08 VS = ±5V VIN = 100mV 85°C –1.0 25°C –1.5 – 40°C –2.0 – 40°C 2.0 1.5 25°C 1.0 85°C 0.5 V– – 50 – 40 –30 –20 –10 0 10 20 30 40 50 OUTPUT CURRENT (mA) 1360 G09 LT1360 U W TYPICAL PERFORMANCE CHARACTERISTICS Output Short-Circuit Current vs Temperature Gain and Phase vs Frequency 70 100 VS = ±5V 65 120 PHASE 60 55 SOURCE 50 SINK 45 10 50 AV = 1 1 VS = ±15V TA = 25°C 35 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 0.01 10k 125 40 60 VS = ±5V 30 100k 1M 10M FREQUENCY (Hz) 20 20 0 TA = 25°C AV = –1 RF = RG = 1k 0 –10 10k 100M 40 VS = ±5V 10 0.1 40 80 VS = ±15V GAIN GAIN (dB) OUTPUT IMPEDANCE (Ω) 60 100 VS = ±15V AV = 10 AV = 100 PHASE (DEG) OUTPUT SHORT-CIRCUIT CURRENT (mA) 70 Output Impedance vs Frequency 100k 100M 1M 10M FREQUENCY (Hz) 1360 G10 1360 G14 1360 G11 Settling Time vs Output Step (Noninverting) Settling Time vs Output Step (Inverting) 6 8 10mV 6 1mV 4 OUTPUT STEP (V) 4 2 0 –2 –4 70 2 0 –2 –4 10mV 1mV –8 20 40 60 80 SETTLING TIME (ns) 0 100 20 40 60 80 SETTLING TIME (ns) Gain Bandwidth and Phase Margin vs Temperature 5 45 4 40 3 30 60 GAIN BANDWIDTH VS = ±15V 0 25 50 75 TEMPERATURE (°C) 25 20 15 GAIN BANDWIDTH VS = ±5V –25 38 36 100 32 100 30 0 5 10 15 SUPPLY VOLTAGE (±V) 20 1360 G15 Frequency Response vs Supply Voltage (AV = –1) 5 TA = 25°C AV = 1 RL = 1k 4 3 ±15V 2 1 0 –1 –2 ±5V 2 ±5V –2 –3 5 –4 –4 ±2.5V 1M 10M FREQUENCY (Hz) ±15V 0 –1 –3 –5 100k TA = 25°C AV = –1 RF = RG = 1k 1 10 0 125 1360 G16 34 GAIN BANDWIDTH GAIN (dB) 35 GAIN (dB) PHASE MARGIN VS = ±15V 50 PHASE MARGIN (DEG) GAIN BANDWIDTH (MHz) PHASE MARGIN VS = ±5V 30 –50 40 50 Frequency Response vs Supply Voltage (AV = 1) 70 40 42 1360 G13 1360 G12 50 60 30 –10 0 44 1mV –8 –10 46 PHASE MARGIN 40 –6 –6 48 TA = 25°C 10mV 1mV 10mV 50 PHASE MARGIN (DEG) VS = ±15V AV = –1 RF = 1k CF = 3pF GAIN BANDWIDTH (MHz) VS = ±15V AV = 1 RL = 1k 8 OUTPUT STEP (V) 80 10 10 80 Gain Bandwidth and Phase Margin vs Supply Voltage 100M 1360 G17 –5 100k ±2.5V 1M 10M FREQUENCY (Hz) 100M 1360 G18 7 LT1360 U W TYPICAL PERFORMANCE CHARACTERISTICS Frequency Response vs Capacitive Load 12 C = 500pF 6 C = 100pF 4 C = 50pF 2 0 C=0 –2 –4 –6 –8 1M 10M FREQUENCY (Hz) – PSRR 80 60 40 20 0 100 100M VS = ±15V TA = 25°C +PSRR 10k 100k 1M FREQUENCY (Hz) 10M SLEW RATE (V/µs) 600 400 1600 700 VS = ±15V 600 500 VS = ± 5V 400 0 0 25 50 75 TEMPERATURE (°C) 100 1000 800 600 0 125 2 4 6 8 10 12 14 16 18 INPUT LEVEL (VP-P) Undistorted Output Swing vs Frequency (±5V) Undistorted Output Swing vs Frequency (±15V) 10 AV = –1 OUTPUT VOLTAGE (VP-P) 25 AV = 1 20 0.0001 1k 10k FREQUENCY (Hz) 100k 1360 G25 AV = 1 15 10 5 20 1360 G24 30 100 1200 1360 G23 0.01 10 1400 0 –25 1360 G22 Total Harmonic Distortion vs Frequency 100M 200 200 – 50 15 AV = –1 10M 400 300 200 TA = 25°C VO = 3VRMS RL = 500Ω 100k 1M FREQUENCY (Hz) TA = 25°C VS = ±15V AV = –1 RF = RG = 1k SR + + SR – SR = ————— 2 1800 OUTPUT VOLTAGE (VP-P) SLEW RATE (V/µs) 800 10k Slew Rate vs Input Level AV = –2 SR + + SR – SR = ————— 2 800 1000 0.001 20 2000 900 1200 5 10 SUPPLY VOLTAGE (±V) 40 1360 G21 SLEW RATE (V/µs) TA = 25°C AV = –1 RF = RG = 1k SR+ + SR – SR = ————— 2 0 60 1k 100M 1000 1400 80 Slew Rate vs Temperature Slew Rate vs Supply Voltage 1600 100 1360 G20 2000 1800 VS = ±15V TA = 25°C 0 1k 1360 G19 TOTAL HARMONIC DISTORTION (%) COMMON-MODE REJECTION RATIO (dB) 8 POWER SUPPLY REJECTION RATIO (dB) VOLTAGE MAGNITUDE (dB) 120 100 C = 1000pF VS = ±15V TA = 25°C AV = –1 10 8 Common Mode Rejection Ratio vs Frequency Power Supply Rejection Ratio vs Frequency VS = ±15V RL = 1k AV = 1, 1% MAX DISTORTION AV = –1, 2% MAX DISTORTION 0 100k 1M FREQUENCY (Hz) 1360 G26 AV = 1 6 4 2 10M AV = –1 8 VS = ±5V RL = 1k 2% MAX DISTORTION 0 100k 1M FREQUENCY (Hz) 10M 1360 G27 LT1360 U W TYPICAL PERFORMANCE CHARACTERISTICS –40 0.50 VS = ±15V VO = 2VP-P RL = 500Ω AV = 2 0.25 3RD HARMONIC DIFFERENTIAL GAIN –50 DIFFERENTIAL PHASE (DEG) HARMONIC DISTORTION (dB) –30 –60 –70 2ND HARMONIC –80 –90 100k 200k 400k 1M 2M FREQUENCY (Hz) 4M 10M 0 0.40 0.36 DIFFERENTIAL PHASE 0.32 0.28 ±5 ±10 SUPPLY VOLTAGE (V) 50 ±15 0 10p 100p 1000p 0.01µ 0.1µ CAPACITIVE LOAD (F) 1µ 1360 G30 1360 G29 1360 TA31 Small-Signal Transient (AV = –1, CL = 500pF) 1360 TA32 1360 TA33 Large-Signal Transient (AV = 1, CL = 10,000pF) Large-Signal Transient (AV = –1) 1360 TA34 AV = –1 AV = 1 Small-Signal Transient (AV = –1) Large-Signal Transient (AV = 1) VS = ±15V TA = 25°C AV = 2 RL = 150Ω TA = 25°C 1360 G28 Small-Signal Transient (AV = 1) Capacitive Load Handling 100 OVERSHOOT (%) Differential Gain and Phase vs Supply Voltage DIFFERENTIAL GAIN (%) 2nd and 3rd Harmonic Distortion vs Frequency 1360 TA35 1360 TA36 9 LT1360 U U W U APPLICATIONS INFORMATION The LT1360 may be inserted directly into AD817, AD847, EL2020, EL2044, and LM6361 applications improving both DC and AC performance, provided that the nulling circuitry is removed. The suggested nulling circuit for the LT1360 is shown below. Offset Nulling V+ 3 7 + 6 LT1360 2 4 – 8 1 10k V– 1360 AI01 Capacitive Loading The LT1360 is stable with any capacitive load. This is accomplished by sensing the load induced output pole and adding compensation at the amplifier gain node. 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 as shown in the typical performance curves.The photo of the smallsignal response with 500pF load shows 60% peaking. The large-signal response with a 10,000pF load shows the output slew rate being limited to 5V/µs by the short-circuit current. Coaxial cable can be driven directly, but for best pulse fidelity a resistor of value equal to the characteristic impedance of the cable (i.e., 75Ω) should be placed in series with the output. The other end of the cable should be terminated with the same value resistor to ground. Layout and Passive Components 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 oscillations. For feedback resistors greater than 5kW, a parallel capacitor of value CF > RG x CIN/RF should be used to cancel the input pole and optimize dynamic performance. For unity-gain applications where a large feedback resistor is used, CF should be greater than or equal to CIN. 10 2 AV = 2 RF = RG = 500Ω RL = 150Ω 0 GAIN (dB) The LT1360 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). Sockets should be avoided when maximum frequency performance is required, although low profile sockets can provide reasonable performance up to 50MHz. For more details see Design Note 50. Cable Driver Frequency Response VS = ±15V VS = ±10V VS = ±2.5V VS = ±5V –2 IN –4 + LT1360 – 510Ω –6 75Ω OUT 75Ω 510Ω –8 1 10 FREQUENCY (MHz) 100 1360 AI02 LT1360 U W U U APPLICATIONS INFORMATION Input Considerations Power Dissipation Each of the LT1360 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 LT1360 combines high speed and large output drive in a small package. Because of the wide supply voltage range, it is possible to exceed the maximum junction temperature under certain conditions. Maximum junction temperature (TJ) is calculated from the ambient temperature (TA) and power dissipation (PD) as follows: 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. LT1360CN8: TJ = TA + (PD x 130°C/W) LT1360CS8: TJ = TA + (PD x 190°C/W) Worst case power dissipation occurs at the maximum supply current and when the output voltage is at 1/2 of either supply voltage (or the maximum swing if less than 1/2 supply voltage). Therefore PDMAX is: PDMAX = (V+ – V–)(ISMAX) + (V+/2)2/RL Example: LT1360CS8 at 70°C, VS = ±15V, RL = 250W PDMAX = (30V)(5.8mA) + (7.5V)2/250W = 399mW TJMAX = 70°C + (399mW)(190°C/W) = 146°C 11 LT1360 U W U U APPLICATIONS INFORMATION Circuit Operation The LT1360 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 are buffered by complementary NPN and PNP emitter followers which drive a 500Ω resistor. The input voltage appears across the resistor generating currents which are mirrored into the high impedance node. Complementary followers form an output stage which buffers the gain node from the load. 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 gain node 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. The LT1360 is tested for slew rate in a gain of –2 so higher slew rates can be expected in gains of 1 and –1, and lower slew rates in higher gain configurations. The RC network across the output stage is bootstrapped when the amplifier is driving a light or moderate load and has no effect under normal operation. When driving a capacitive load (or a low value resistive load) the network 12 is incompletely bootstrapped and adds to the compensation at the high impedance node. The added capacitance slows down the amplifier which improves the phase margin by moving the unity-gain frequency away from the pole formed by the output impedance and the capacitive load. The zero created by the RC combination adds phase to ensure that even for very large load capacitances, the total phase lag can never exceed 180 degrees (zero phase margin) and the amplifier remains stable. Comparison to Current Feedback Amplifiers The LT1360 enjoys the high slew rates of Current Feedback Amplifiers (CFAs) while maintaining the characteristics of a true voltage feedback amplifier. The primary differences are that the LT1360 has two high impedance inputs and its closed loop bandwidth decreases as the gain increases. CFAs have a low impedance inverting input and maintain relatively constant bandwidth with increasing gain. The LT1360 can be used in all traditional op amp configurations including integrators and applications such as photodiode amplifiers and I-to-V converters where there may be significant capacitance on the inverting input. The frequency compensation is internal and not dependent on the value of the feedback resistor. For CFAs, the feedback resistance is fixed for a given bandwidth and capacitance on the inverting input can cause peaking or oscillations. The slew rate of the LT1360 in noninverting gain configurations is also superior in most cases. LT1360 W W SI PLIFIED SCHE ATIC V+ R1 500Ω +IN RC OUT –IN C V– CC 1360 SS01 13 LT1360 U PACKAGE DESCRIPTION Dimension 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 (2.54) BSC *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 1098 LT1360 U PACKAGE DESCRIPTION Dimension 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) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 (0.406 – 1.270) 0.014 – 0.019 (0.355 – 0.483) 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 2 3 4 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) BSC 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 1298 15 LT1360 U TYPICAL APPLICATIONS Photodiode Preamp with AC Coupling Loop 1pF 1N5712 1N5712 10k VS = ±5V f–3dB = 100KHz, 5.5MHz iPD – VOUT LT1360 SFH205 + 10k 2k 2k 300pF 1µF 10k –5V – 5.1k – 1/2 LT1358 + 1/2 LT1358 + 1360 TA03 1MHz, 4th Order Butterworth Filter 909Ω 1.1k 47pF 22pF 909Ω 2.67k VIN – 1.1k 2.21k LT1360 220pF + – LT1360 470pF VOUT + 1360 TA04 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1361/LT1362 Dual and Quad 50MHz, 800V/µs Op Amps Dual and Quad Versions of LT1360 LT1363 70MHz, 1000V/µs Op Amp Faster Version of LT1360, VOS = 1.5mV, IS = 6.3mA LT1357 25MHz, 600V/µs Op Amp Lower Power Version of LT1360, VOS = 0.6mV, IS = 2mA LT1812 100MHz, 750V/µs Op Amp Low Voltage, Low Power LT1360, VOS = 1mV, IS = 3mA 16 Linear Technology Corporation 1360fa LT/TP 0400 2K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1994