LT1230CS

LT1229/LT1230 Dual and Quad 100MHz Current Feedback Amplifiers FEATURES s s s s s s s s s s s DESCRIPTIO 100MHz Bandwidth 1000V/µs Slew Rate Low Cost 30mA Output Drive Current 0.04% Differential Gain 0.1° Differential Phase High Input Impedance: 25MΩ, 3pF Wide Supply Range: ±2V to ±15V Low Supply Current: 6mA Per Amplifier Inputs Common Mode to Within 1.5V of Supplies Outputs Swing Within 0.8V of Supplies The LT1229/LT1230 dual and quad 100MHz current feedback amplifiers are designed for maximum performance in small packages. Using industry standard pinouts, the dual is available in the 8-pin miniDIP and the 8-pin SO package while the quad is in the 14-pin DIP and 14-pin SO. The amplifiers are designed to operate on almost any available supply voltage from 4V (±2V) to 30V (±15V). These current feedback amplifiers have very high input impedance and make excellent buffer amplifiers. They maintain their wide bandwidth for almost all closed-loop voltage gains. The amplifiers drive over 30mA of output current and are optimized to drive low impedance loads, such as cables, with excellent linearity at high frequencies. The LT1229/LT1230 are manufactured on Linear Technology’s proprietary complementary bipolar process. For a single amplifier like these see the LT1227 and for better DC accuracy see the LT1223. APPLICATI s s s s S Video Instrumentation Amplifiers Cable Drivers RGB Amplifiers Test Equipment Amplifiers TYPICAL APPLICATI Video Loop Through Amplifier R G1 3.01k R F1 750Ω R G2 187Ω R F2 750Ω 10 0 Loop Through Amplifier Frequency Response NORMAL SIGNAL –10 GAIN (dB) – 3.01k VIN – 1/2 LT1229 – 3.01k VIN+ 1/2 LT1229 VOUT –20 –30 –40 –50 –60 10 100 1k 10k 100k 1M 10M 100M LT1229 • TA02 + + 1% RESISTORS WORST CASE CMRR = 22dB TYPICALLY = 38dB VOUT = G (VIN+ – VIN – ) R F1 = RF2 COMMON-MODE SIGNAL 12.1k 12.1k BNC INPUTS HIGH INPUT RESISTANCE DOES NOT LOAD CABLE EVEN WHEN POWER IS OFF R G1 = (G – 1) RF2 R F2 RG2 = G–1 TRIM CMRR WITH RG1 LT1229 • TA01 U FREQUENCY (Hz) UO UO 1 LT1229/LT1230 ABSOLUTE AXI U RATI GS Storage Temperature Range ................. –65°C to 150°C Junction Temperature Plastic Package .............................................. 150°C Ceramic Package ............................................ 175°C Lead Temperature (Soldering, 10 sec.)................. 300°C Supply Voltage ...................................................... ± 18V Input Current ...................................................... ± 15mA Output Short Circuit Duration (Note 1) ......... Continuous Operating Temperature Range LT1229C, LT1230C ............................... 0°C to 70°C LT1229M, LT1230M ....................... –55°C to 125°C PACKAGE/ORDER I FOR ATIO TOP VIEW OUT A –IN A +IN A V– 1 2 A 3 4 B 6 5 –IN B +IN B 8 7 V+ OUT B ORDER PART NUMBER LT1229MJ8 LT1229CJ8 LT1229CN8 LT1229CS8 S8 PART MARKING 1229 N8 PACKAGE J8 PACKAGE 8-LEAD CERAMIC DIP 8-LEAD PLASTIC DIP S8 PACKAGE 8-LEAD PLASTIC SOIC LT1124 • POI01 TJ MAX = 175°C, θJA = 100°C/W (J8) TJ MAX = 150°C, θJA = 100°C/W (N8) TJ MAX = 150°C, θJA = 150°C/W (S8) Each Amplifier, VCM = 0V, ± 5V ≤ VS = ± 15V, pulse tested unless otherwise noted. SYMBOL VOS PARAMETER Input Offset Voltage Input Offset Voltage Drift IIN+ IIN– en +in –in RIN CIN Noninverting Input Current Inverting Input Current Input Noise Voltage Density Noninverting Input Noise Current Density Inverting Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range VS = ±15V, TA = 25°C q ELECTRICAL CHARACTERISTICS CONDITIONS TA = 25°C q q TA = 25°C q TA = 25°C q f = 1kHz, RF = 1k, RG = 10Ω, RS = 0Ω f = 1kHz, RF = 1k, RG = 10Ω, RS = 10k f = 1kHz VIN = ±13V, VS = ±15V VIN = ± 3V, VS = ±5V q q VS = ± 5V, TA = 25°C q CMRR Common-Mode Rejection Ratio VS = ±15V, VCM = ±13V, TA = 25°C VS = ± 15V, VCM = ± 12V VS = ± 5V, VCM = ±3V, TA = 25°C VS = ± 5V, VCM = ± 2V 2 U U W WW U W TOP VIEW OUT A 1 2 3 4 5 6 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 LT1230MJ LT1230CJ LT1230CN LT1230CS –IN A +IN A V+ +IN B –IN B OUT B J PACKAGE N PACKAGE 14-LEAD CERAMIC DIP 14-LEAD PLASTIC DIP S PACKAGE 14-LEAD PLASTIC SOIC LT1229 • POI02 TJ MAX = 175°C, θJA = 80°C/W (J) TJ MAX = 150°C, θJA = 70°C/W (N) TJ MAX = 150°C, θJA = 110°C/W (S) MIN TYP ±3 10 ± 0.3 ±10 3.2 1.4 32 MAX ± 10 ±15 ±3 ±10 ± 50 ±100 UNITS mV mV µV/°C µA µA µA µA nV/√Hz pA/√Hz pA/√Hz MΩ MΩ pF V V V V dB dB dB dB 2 2 ±13 ±12 ±3 ±2 55 55 55 55 25 25 3 ±13.5 ± 3.5 69 69 q q LT1229/LT1230 Each Amplifier, VCM = 0V, ± 5V ≤ VS = ± 15V, pulse tested unless otherwise noted. SYMBOL PARAMETER Inverting Input Current Common-Mode Rejection CONDITIONS VS = ±15V, VCM = ±13V, TA = 25°C VS = ± 15V, VCM = ±12V VS = ± 5V, VCM = ± 3V, TA = 25°C VS = ± 5V, VCM = ±2V VS = ± 2V to ±15V, TA = 25°C VS = ± 3V to ±15V VS = ± 2V to ±15V, TA = 25°C VS = ± 3V to ±15V VS = ± 2V to ±15V, TA = 25°C VS = ± 3V to ±15V VS = ±15V, VOUT = ±10V, RL = 1k VS = ± 5V, VOUT = ±2V, RL = 150Ω VS = ±15V, VOUT = ±10V, RL = 1k VS = ± 5V, VOUT = ±2V, RL = 150Ω VS = ±15V, RL = 400Ω, TA = 25°C q q ELECTRICAL CHARACTERISTICS MIN TYP 2.5 2.5 MAX 10 10 10 10 UNITS µA/V µA/V µA/V µA/V dB dB q q q PSRR Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection 60 60 80 10 0.1 50 50 5 5 nA/V nA/V µA/V µA/V dB dB kΩ kΩ V V V V q q q q q AV ROL VOUT Large-Signal Voltage Gain, (Note 2) Transresistance, ∆VOUT/∆IIN–, (Note 2) Maximum Output Voltage Swing, (Note 2) 55 55 100 100 ±12 ±10 ±3 ±2.5 30 65 65 200 200 ±13.5 ±3.7 65 6 125 9.5 11 VS = ± 5V, RL = 150Ω, TA = 25°C q IOUT IS SR SR tr BW tr Maximum Output Current Supply Current, (Note 3) Slew Rate, (Notes 4 and 6) Slew Rate Rise Time, (Notes 5 and 6) Small-Signal Bandwidth Small-Signal Rise Time Propagation Delay Small-Signal Overshoot RL = 0Ω, TA = 25°C VOUT = 0V, Each Amplifier, TA = 25°C q mA mA mA V/µs V/µs TA = 25°C VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 400Ω TA = 25°C VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 100Ω 0.1%, VOUT = 10V, RF =1k, RG= 1k, RL =1k VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 1k VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 1k VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 150Ω VS = ±15V, RF = 750Ω, RG= 750Ω, RL = 150Ω 300 700 2500 10 100 3.5 3.5 15 45 0.01 0.01 0.04 0.1 20 ns MHz ns ns % ns % Deg % Deg ts Settling Time Differential Gain, (Note 7) Differential Phase, (Note 7) Differential Gain, (Note 7) Differential Phase, (Note 7) The q denotes specifications which apply over the operating temperature range. Note 1: A heat sink may be required depending on the power supply voltage and how many amplifiers are shorted. Note 2: The power tests done on ±15V supplies are done on only one amplifier at a time to prevent excessive junction temperatures when testing at maximum operating temperature. Note 3: The supply current of the LT1229/LT1230 has a negative temperature coefficient. For more information see the application information section. Note 4: Slew rate is measured at ± 5V on a ±10V output signal while operating on ±15V supplies with RF = 1k, RG = 110Ω and RL = 400Ω. The slew rate is much higher when the input is overdriven and when the amplifier is operated inverting, see the applications section. Note 5: Rise time is measured from 10% to 90% on a ± 500mV output signal while operating on ±15V supplies with RF = 1k, RG = 110Ω and RL = 100Ω. This condition is not the fastest possible, however, it does guarantee the internal capacitances are correct and it makes automatic testing practical. Note 6: AC parameters are 100% tested on the ceramic and plastic DIP packaged parts (J and N suffix) and are sample tested on every lot of the SO packaged parts (S suffix). Note 7: NTSC composite video with an output level of 2VP. 3 LT1229/LT1230 TYPICAL PERFOR A CE CHARACTERISTICS Voltage Gain and Phase vs Frequency, Gain = 6dB 8 7 6 GAIN PHASE 0 45 90 –3dB BANDWIDTH (MHz) VOLTAGE GAIN (dB) 5 4 3 2 1 0 –1 –2 0.1 VS = ±15V RL = 100Ω RF = 750Ω 1 10 100 LT1229 • TPC01 135 180 225 120 100 80 60 40 20 0 0 2 4 6 8 10 12 RF = 500Ω RF = 750Ω RF = 1k –3dB BANDWIDTH (MHz) FREQUENCY (MHz) Voltage Gain and Phase vs Frequency, Gain = 20dB 22 21 20 VOLTAGE GAIN (dB) PHASE –3dB BANDWIDTH (MHz) 19 18 17 16 15 14 13 12 0.1 VS = ±15V RL = 100Ω RF = 750Ω 1 10 100 LT1229 • TPC04 135 180 225 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 RF = 250Ω RF = 500Ω RF = 750Ω RF = 1k RF = 2k –3dB BANDWIDTH (MHz) GAIN FREQUENCY (MHz) Voltage Gain and Phase vs Frequency, Gain = 40dB 42 41 40 PHASE 0 45 90 –3dB BANDWIDTH (MHz) 39 38 37 36 35 34 33 32 0.1 VS = ±15V RL = 100Ω RF = 750Ω 1 10 100 LT1229 • TPC07 135 180 225 12 10 8 6 4 2 0 0 2 4 6 8 10 –3dB BANDWIDTH (MHz) GAIN VOLTAGE GAIN (dB) FREQUENCY (MHz) 4 UW – 3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 100Ω 180 160 140 PEAKING ≤ 0.5dB PEAKING ≤ 5dB 180 160 140 120 100 80 60 40 20 0 14 16 18 – 3dB Bandwidth vs Supply Voltage, Gain = 2, RL = 1k RF = 500Ω RF = 750Ω PHASE SHIFT (DEG) PHASE SHIFT (DEG) PEAKING ≤ 0.5dB PEAKING ≤ 5dB RF = 1k RF = 2k RF = 2k 0 2 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE (±V) LT1229 • TPC02 SUPPLY VOLTAGE (±V) LT1229 • TPC03 – 3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 100Ω 0 45 90 – 3dB Bandwidth vs Supply Voltage, Gain = 10, RL = 1k 180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 RF = 2k RF = 250Ω RF = 500Ω RF = 750Ω RF = 1k PEAKING ≤ 0.5dB PEAKING ≤ 5dB 180 160 140 PEAKING ≤ 0.5dB PEAKING ≤ 5dB SUPPLY VOLTAGE (±V) LT1229 • TPC05 SUPPLY VOLTAGE (±V) LT1229 • TPC06 – 3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 100Ω 18 16 14 RF = 500Ω RF = 1k RF = 2k 18 16 14 12 10 8 6 4 2 0 12 14 16 18 – 3dB Bandwidth vs Supply Voltage, Gain = 100, RL = 1kΩ RF = 500Ω PHASE SHIFT (DEG) RF = 1k RF = 2k 0 2 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE (±V) LT1229 • TPC08 SUPPLY VOLTAGE (±V) LT1229 • TPC09 LT1229/LT1230 TYPICAL PERFOR A CE CHARACTERISTICS Maximum Capacitance Load vs Feedback Resistor 10000 TOTAL HARMONIC DISTORTION (%) CAPACITIVE LOAD (pF) 1000 VS = ± 5V DISTORTION (dBc) 100 VS = ±15V 10 RL = 1k PEAKING ≤ 5dB GAIN = 2 1 0 1 2 3 LT1229 • TPC10 FEEDBACK RESISTOR (kΩ) Input Common-Mode Limit vs Temperature V+ OUTPUT SATURATION VOLTAGE (V) –0.5 –0.5 –1.0 RL = ∞ ± 2V ≤ VS ≤ ±18V COMMON MODE RANGE (V) –1.0 –1.5 –2.0 V + = 2V TO 18V OUTPUT SHORT CIRCUIT CURRENT (mA) 2.0 1.5 1.0 0.5 V– – 50 –25 0 25 50 75 100 125 TEMPERATURE (°C) LT1229 • TPC13 V – = –2V TO –18V Spot Noise Voltage and Current vs Frequency 100 80 SPOT NOISE (nV/√Hz OR pA/√Hz) 60 POSITIVE 40 OUTPUT IMPEDANCE (Ω) –in POWER SUPPLY REJECTION (dB) 10 en +in 1 10 100 1k 10k FREQUENCY (Hz) UW LT1229 • TPC16 Total Harmonic Distortion vs Frequency 0.10 VS = ±15V RL = 400Ω RF = RG = 750Ω –20 2nd and 3rd Harmonic Distortion vs Frequency VS = ±15V VO = 2VP-P RL = 100Ω RF = 750Ω AV = 10dB –30 2ND –40 3RD –50 0.01 VO = 7VRMS VO = 1VRMS –60 0.001 10 100 1k FREQUENCY (Hz) LT1229 • TPC11 10k 100k –70 1 10 FREQUENCY (MHz) LT1229 • TPC12 100 Output Saturation Voltage vs Temperature V+ 70 Output Short-Circuit Current vs Junction Temperature 60 50 1.0 0.5 V– –50 –25 40 0 25 50 75 100 125 LT1229 • TPC14 30 –50 –25 0 25 50 75 100 125 150 175 LT1229 • TPC15 TEMPERATURE (°C) TEMPERATURE (°C) Power Supply Rejection vs Frequency 100 VS = ±15V RL = 100Ω RF = RG = 750Ω Output Impedance vs Frequency VS = ±15V 10 1.0 RF = RG = 2k 0.1 RF = RG = 750Ω NEGATIVE 20 0.01 100k 0 10k 100k 1M FREQUENCY (Hz) 10M 100M 0.001 10k 100k 1M FREQUENCY (Hz) 10M 100M LT1229 • TPC17 LT1229 • TPC18 5 LT1229/LT1230 TYPICAL PERFOR A CE CHARACTERISTICS Settling Time to 10mV vs Output Step 10 8 6 OUTPUT STEP (V) NONINVERTING INVERTING SUPPLY CURRENT (mA) OUTPUT STEP (V) 4 2 0 –2 –4 –6 –8 –10 0 20 40 60 80 100 SETTLING TIME (ns) LT1229 • TPC19 VS = ±15V RF = RG = 1k NONINVERTING INVERTING SI PLIFIED SCHE ATIC One Amplifier V+ +IN 6 UW Settling Time to 1mV vs Output Step 10 8 6 4 2 0 –2 –4 –6 –8 –10 0 4 8 12 16 20 SETTLING TIME (µs) LT1229 • TPC20 Supply Current vs Supply Voltage 10 9 8 NONINVERTING INVERTING –55°C 25°C 125°C 7 6 5 4 3 2 175°C VS = ±15V RF = RG = 1k INVERTING NONINVERTING 1 0 0 2 4 6 8 10 12 14 16 18 SUPPLY VOLTAGE (±V) LT1229 • TPC21 W W –IN VOUT V– LT1229 • TA03 LT1229/LT1230 APPLICATI S I FOR ATIO The LT1229/LT1230 are very fast dual and quad current feedback amplifiers. Because they are current feedback amplifiers, they maintain their wide bandwidth over a wide range of voltage gains. These amplifiers are designed to drive low impedance loads such as cables with excellent linearity at high frequencies. Feedback Resistor Selection The small-signal bandwidth of the LT1229/LT1230 is set by the external feedback resistors and the internal junction capacitors. As a result, the bandwidth is a function of the supply voltage, the value of the feedback resistor, the closed-loop gain and load resistor. The characteristic curves of Bandwidth versus Supply Voltage are done with a heavy load (100Ω) and a light load (1k) to show the effect of loading. These graphs also show the family of curves that result from various values of the feedback resistor. These curves use a solid line when the response has less than 0.5dB of peaking and a dashed line when the response has 0.5dB to 5dB of peaking. The curves stop where the response has more than 5dB of peaking. Small-Signal Rise Time with RF = RG = 750Ω, VS = ±15V, and RL = 100Ω LT1229 • TA04 At a gain of two, on ±15V supplies with a 750Ω feedback resistor, the bandwidth into a light load is over 160MHz without peaking, but into a heavy load the bandwidth reduces to 100MHz. The loading has so much effect because there is a mild resonance in the output stage that enhances the bandwidth at light loads but has its Q reduced by the heavy load. This enhancement is only useful at low gain settings; at a gain of ten it does not boost the bandwidth. At unity gain, the enhancement is so effective the value of the feedback resistor has very little effect. At very high closed-loop gains, the bandwidth is GAIN (dB) U limited by the gain bandwidth product of about 1GHz. The curves show that the bandwidth at a closed-loop gain of 100 is 10MHz, only one tenth what it is at a gain of two. Capacitance on the Inverting Input Current feedback amplifiers want resistive feedback from the output to the inverting input for stable operation. Take care to minimize the stray capacitance between the output and the inverting input. Capacitance on the inverting input to ground will cause peaking in the frequency response (and overshoot in the transient response), but it does not degrade the stability of the amplifier. The amount of capacitance that is necessary to cause peaking is a function of the closed-loop gain taken. The higher the gain, the more capacitance is required to cause peaking. We can add capacitance from the inverting input to ground to increase the bandwidth in high gain applications. For example, in this gain of 100 application, the bandwidth can be increased from 10MHz to 17MHz by adding a 2200pF capacitor. VIN W U UO + 1/2 LT1229 VOUT – RF 510Ω RG 5.1Ω LT1229 • TA05 CG Boosting Bandwidth of High Gain Amplifier with Capacitance on Inverting Input 49 46 43 40 37 34 31 28 25 22 19 1 10 FREQUENCY (MHz) LT1229 • TA06 C G = 4700pF C G = 2200pF CG = 0 100 7 LT1229/LT1230 APPLICATI S I FOR ATIO U amplifier at 150°C is less than 7mA and typically is only 4.5mA. The power in the IC due to the load is a function of the output voltage, the supply voltage and load resistance. The worst case occurs when the output voltage is at half supply, if it can go that far, or its maximum value if it cannot reach half supply. For example, let’s calculate the worst case power dissipation in a video cable driver operating on ±12V supplies that delivers a maximum of 2V into 150Ω. VO (MAX ) Pd (MAX ) = 2 VS IS (MAX ) + VS – VO (MAX ) RL Capacitive Loads The LT1229/LT1230 can drive capacitive loads directly when the proper value of feedback resistor is used. The graph Maximum Capacitive Load vs Feedback Resistor should be used to select the appropriate value. The value shown is for 5dB peaking when driving a 1k load at a gain of 2. This is a worst case condition; the amplifier is more stable at higher gains and driving heavier loads. Alternatively, a small resistor (10Ω to 20Ω) can be put in series with the output to isolate the capacitive load from the amplifier output. This has the advantage that the amplifier bandwidth is only reduced when the capacitive load is present, and the disadvantage that the gain is a function of the load resistance. Power Supplies The LT1229/LT1230 amplifiers will operate from single or split supplies from ± 2V (4V total) to ±15V (30V total). It is not necessary to use equal value split supplies, however, the offset voltage and inverting input bias current will change. The offset voltage changes about 350µV per volt of supply mismatch, the inverting bias current changes about 2.5µA per volt of supply mismatch. Power Dissipation The LT1229/LT1230 amplifiers combine high speed and large output current drive into very small packages. Because these amplifiers work over a very wide supply range, it is possible to exceed the maximum junction temperature under certain conditions. To ensure that the LT1229 and LT1230 remain within their absolute maximum ratings, we must calculate the worst case power dissipation, define the maximum ambient temperature, select the appropriate package and then calculate the maximum junction temperature. The worst case amplifier power dissipation is the total of the quiescent current times the total power supply voltage plus the power in the IC due to the load. The quiescent supply current of the LT1229/LT1230 has a strong negative temperature coefficient. The supply current of each 8 W U UO ( ) 2V 150Ω = 0.168 + 0.133 = 0.301W per Amp Now if that is the dual LT1229, the total power in the package is twice that, or 0.602W. We now must calculate how much the die temperature will rise above the ambient. The total power dissipation times the thermal resistance of the package gives the amount of temperature rise. For the above example, if we use the SO8 surface mount package, the thermal resistance is 150°C/W junction to ambient in still air. Pd (MAX ) = 2 × 12 V × 7mA + 12 V – 2 V × Temperature Rise = Pd (MAX) RθJA = 0.602W × 150°C/W = 90.3°C The maximum junction temperature allowed in the plastic package is 150°C. Therefore, the maximum ambient allowed is the maximum junction temperature less the temperature rise. Maximum Ambient = 150°C – 90.3°C = 59.7°C Note that this is less than the maximum of 70°C that is specified in the absolute maximum data listing. If we must use this package at the maximum ambient we must lower the supply voltage or reduce the output swing. As a guideline to help in the selection of the LT1229/ LT1230 the following table describes the maximum supply voltage that can be used with each part in cable driving applications. ( ) LT1229/LT1230 APPLICATI Assumptions: 1. The maximum ambient is 70°C for the commercial parts (C suffix) and 125°C for the full temperature parts (M suffix). 2. The load is a double-terminated video cable, 150Ω. 3. The maximum output voltage is 2V (peak or DC). 4. The thermal resistance of each package: J8 is 100°C/W N8 is 100°C/W S8 is 150°C/W J is 80°/W N is 70°/W S is 110°/W LT1229 • TA07 S I FOR ATIO Maximum Supply Voltage for 75Ω Cable Driving Applications at Maximum Ambient Temperature PART LT1229MJ8 LT1229CJ8 LT1229CN8 LT1229CS8 LT1230MJ LT1230CJ LT1230CN LT1230CS PACKAGE Ceramic DIP Ceramic DIP Plastic DIP Plastic SO8 Ceramic DIP Ceramic DIP Plastic DIP Plastic SO14 MAX POWER AT TA 0.500W @ 125°C 1.050W @ 70°C 0.800W @ 70°C 0.533W @ 70°C 0.625W @ 125°C 1.313W @ 70°C 1.143W @ 70°C 0.727W @ 70°C MAX SUPPLY VS < ±10.1 VS < ±18.0 VS < ±15.6 VS < ±10.6 VS < ±6.6 VS < ±13.0 VS < ±11.4 VS < ±7.6 Slew Rate The slew rate of a current feedback amplifier is not independent of the amplifier gain the way it is in a traditional op amp. This is because the input stage and the output stage both have slew rate limitations. The input stage of the LT1229/LT1230 amplifiers slew at about 100V/µs before they become nonlinear. Faster input signals will turn on the normally reverse-biased emitters on the input transistors and enhance the slew rate significantly. This enhanced slew rate can be as much as 2500V/µs. The output slew rate is set by the value of the feedback resistors and the internal capacitance. At a gain of ten with a 1k feedback resistor and ±15V supplies, the output slew rate is typically 700V/µ s and – 1000V/ µ s. There is no input stage enhancement because of the high gain. U Large-Signal Response, AV = 2, RF = RG = 750Ω W U UO Larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced. Large-Signal Response, AV = 10, RF = 1k, RG = 110Ω LT1229 • TA08 Settling Time The characteristic curves show that the LT1229/LT1230 amplifiers settle to within 10mV of final value in 40ns to 55ns for any output step up to 10V. The curve of settling to 1mV of final value shows that there is a slower thermal contribution up to 20µs. The thermal settling component comes from the output and the input stage. The output contributes just under 1mV per volt of output change and the input contributes 300µV per volt of input change. Fortunately, the input thermal tends to cancel the output thermal. For this reason the noninverting gain of two configurations settles faster than the inverting gain of one. 9 LT1229/LT1230 APPLICATI S I FOR ATIO Crosstalk and Cascaded Amplifiers The amplifiers in the LT1229/LT1230 do not share any common circuitry. The only thing the amplifiers share is the supplies. As a result, the crosstalk between amplifiers is very low. In a good breadboard or with a good PC board layout the crosstalk from the output of one amplifier to the input of another will be over 100dB down, up to 100kHz and 65dB down at 10MHz. The following curve shows the crosstalk from the output of one amplifier to the input of another. Amplifier Crosstalk vs Frequency 120 OUTPUT TO INPUT CROSSTALK (dB) 110 100 90 80 70 60 50 10 100 1k 10k 100k VS = ±15V AV = 10 RS = 50Ω RL = 100Ω 1M 10M 100M LT1229 • TA12 FREQUENCY (Hz) TYPICAL APPLICATI S (the sync pulses). R4, R5 and R6 set the amplifier up with a gain of two and bias the output so the bottom of the sync pulses are at 1.1V. The maximum input then drives the output to 3.9V. 5V R1 3k 2N3904 R2 2k C1 1µF VIN C2 1µF C4 1000µF VOUT R4 1.5k C3 47µF Single 5V Supply Cable Driver for Composite Video This circuit amplifies standard 1V peak composite video input (1.4VP-P) by two and drives an AC coupled, doubly terminated cable. In order for the output to swing 2.8VP-P on a single 5V supply, it must be biased accurately. The average DC level of the composite input is a function of the luminance signal. This will cause problems if we AC couple the input signal into the amplifier because a rapid change in luminance will drive the output into the rails. To prevent this we must establish the DC level at the input and operate the amplifier with DC gain. The transistor’s base is biased by R1 and R2 at 2V. The emitter of the transistor clamps the noninverting input of the amplifier to 1.4V at the most negative part of the input R3 150k R5 750Ω 1/2 LT1229 – R6 510Ω 10 + U The high frequency crosstalk between amplifiers is caused by magnetic coupling between the internal wire bonds that connect the IC chip to the package lead frame. The amount of crosstalk is inversely proportional to the load resistor the amplifier is driving, with no load (just the feedback resistor) the crosstalk improves 18dB. The curve shows the crosstalk of the LT1229 amplifier B output (pin 7) to the input of amplifier A. The crosstalk from amplifier A’s output (pin 1) to amplifier B is about 10dB better. The crosstalk between all of the LT1230 amplifiers is as shown. The LT1230 amplifiers that are separated by the supplies are a few dB better. When cascading amplifiers the crosstalk will limit the amount of high frequency gain that is available because the crosstalk signal is out of phase with the input signal. This will often show up as unusual frequency response. For example: cascading the two amplifiers in the LT1229, each set up with 20dB of gain and a –3dB bandwidth of 65MHz into 100Ω will result in 40dB of gain, BUT the response will start to drop at about 10MHz and then flatten out from 20MHz to 30MHz at about 0.5dB down. This is due to the crosstalk back to the input of the first amplifier. For best results when cascading amplifiers use the LT1229 and drive amplifier B and follow it with amplifier A. + + R7 75Ω R8 10k LT1229 • TA11 W UO U UO LT1229/LT1230 TYPICAL APPLICATI UO 5V S Single Supply AC Coupled Amplifiers Inverting 5V 4.7µF Noninverting 4.7µF 10kΩ 0.1µF VIN 10k + + 10k 1/2 LT1229 VOUT 0.1µF 10kΩ 1/2 LT1229 – 4.7µF – 4.7µF RS 51Ω 510Ω 51Ω AV = 510Ω VIN 510Ω 10 RS + 51Ω BW = 600Hz TO 50MHz AV = 11 BW = 600Hz TO 50MHz LT1229 • TA09 PACKAGE DESCRIPTIO 0.290 – 0.320 (7.366 – 8.128) Dimensions in inches (millimeters) unless otherwise noted. 0.405 (10.287) MAX 8 7 6 5 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.005 (0.127) MIN J8 Package 8-Lead Ceramic DIP 0.008 – 0.018 (0.203 – 0.460) 0.385 ± 0.025 (9.779 ± 0.635) 0° – 15° 0.038 – 0.068 (0.965 – 1.727) 0.014 – 0.026 (0.360 – 0.660) 0.025 (0.635) RAD TYP 1 2 3 0.125 3.175 0.100 ± 0.010 MIN (2.540 ± 0.254) 0.055 (1.397) MAX 0.300 – 0.320 (7.620 – 8.128) 0.045 – 0.065 (1.143 – 1.651) 0.130 ± 0.005 (3.302 ± 0.127) 0.400 (10.160) MAX 8 7 6 5 N8 Package 8-Lead Plastic DIP 0.009 – 0.015 (0.229 – 0.381) 0.065 (1.651) TYP 0.125 (3.175) MIN 0.020 (0.508) MIN ( +0.025 0.325 –0.015 +0.635 8.255 –0.381 ) 0.045 ± 0.015 (1.143 ± 0.381) 0.100 ± 0.010 (2.540 ± 0.254) 1 2 3 0.018 ± 0.003 (0.457 ± 0.076) 0.189 – 0.197 (4.801 – 5.004) 0.010 – 0.020 × 45° (0.254 – 0.508) 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 0.228 – 0.244 (5.791 – 6.197) 0.150 – 0.157 (3.810 – 3.988) 8 7 6 5 S8 Package 8-Lead Plastic SOIC 0°– 8° TYP 0.008 – 0.010 (0.203 – 0.254) 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) 0.050 (1.270) BSC 1 2 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. + VOUT U + + + LT1229 • TA10 0.220 – 0.310 (5.588 – 7.874) 4 J8 0392 0.250 ± 0.010 (6.350 ± 0.254) 4 N8 0392 3 4 SO8 0392 11 LT1229/LT1230 PACKAGE DESCRIPTIO 0.290 – 0.320 (7.366 – 8.128) 0.008 – 0.018 (0.203 – 0.460) 0.385 ± 0.025 (9.779 ± 0.635) 0° – 15° 1 0.038 – 0.068 (0.965 – 1.727) 0.014 – 0.026 (0.360 – 0.660) 0.100 ± 0.010 (2.540 ± 0.254) 0.125 (3.175) MIN 0.098 (2.489) MAX 2 3 4 5 6 7 0.300 – 0.325 (7.620 – 8.255) 0.015 (0.380) MIN 0.130 ± 0.005 (3.302 ± 0.127) 0.009 – 0.015 (0.229 – 0.381) +0.025 0.325 –0.015 +0.635 8.255 –0.381 ( ) 0.075 ± 0.015 (1.905 ± 0.381) 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) 0.004 – 0.010 (0.101 – 0.254) 0.228 – 0.244 (5.791 – 6.197) 0° – 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 U Dimensions in inches (millimeters) unless otherwise noted. J Package 14-Lead Ceramic DIP 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.005 (0.127) MIN 0.785 (19.939) MAX 14 13 12 11 10 9 8 0.025 (0.635) RAD TYP 0.220 – 0.310 (5.588 – 7.874) J14 0392 N Package 14-Lead Plastic DIP 0.065 (1.651) TYP 14 13 12 0.770 (19.558) MAX 11 10 9 8 0.045 – 0.065 (1.143 – 1.651) 0.260 ± 0.010 (6.604 ± 0.254) 0.018 ± 0.003 (0.457 ± 0.076) 0.100 ± 0.010 (2.540 ± 0.254) 1 0.125 (3.175) MIN 2 3 4 5 6 7 N14 0392 S Package 14-Lead Plastic SOIC 0.337 – 0.344 (8.560 – 8.738) 14 13 12 11 10 9 8 0.050 (1.270) TYP 0.150 – 0.157 (3.810 – 3.988) 1 2 3 4 5 6 7 SO14 0392 LT/GP 1092 5K REV A © LINEAR TECHNOLOGY CORPORATION 1992