LT1189C

LT1189 Low Power Video Difference Amplifier FEATURES s s s s s s s s s s s DESCRIPTIO Differential or Single-Ended Gain Block (Adjustable) –3dB Bandwidth, AV = ± 10 35MHz Slew Rate 220V/µs Low Supply Current 13mA Output Current ± 20mA CMRR at 10MHz 48dB LT1193 Pin Out Low Cost Single 5V Operation Drives Cables Directly Output Shutdown The LT1189 is a difference amplifier optimized for operation on ± 5V, or a single 5V supply, and gain ≥ 10. This versatile amplifier features uncommitted high input impedance (+) and (–) inputs, and can be used in differential or single-ended configurations. Additionally, a second set of inputs give gain adjustment and DC control to the difference amplifier. The LT1189’s high slew rate, 220V/µs, wide bandwidth, 35MHz, and ± 20mA output current require only 13mA of supply current. The shutdown feature reduces the power dissipation to a mere 15mW, and allows multiple amplifiers to drive the same cable. The LT1189 is a low power, gain of 10 stable version of the popular LT1193, and is available in 8-pin miniDIPs and SO packages. For lower gain applications see the LT1187 data sheet. APPLICATI s s s s S Line Receivers Video Signal Processing Cable Drivers Tape and Disc Drive Systems TYPICAL APPLICATI Cable Sense Amplifier for Loop Through Connections with DC Adjust VIN 5V 3 CABLE VDC 2 1 8 – LT1189 + – 4 –5V 909Ω Closed-Loop Gain vs Frequency 50 VS = ±5V RL = 1k 40 VOLTAGE GAIN (dB) + 7 6 VOUT 30 20 10 100Ω 0 0.1 LT1189 • TA01 U 1 10 FREQUENCY (MHz) 100 LT1189 • TA02 UO UO 1 LT1189 ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO TOP VIEW +/REF –IN +IN V– 1 2 3 4 8 7 6 5 –/FB V+ OUT S/D Total Supply Voltage (V + to V –) ............................. 18V Differential Input Voltage ........................................ ± 6V Input Voltage .......................................................... ± VS Output Short Circuit Duration (Note 1) ........ Continuous Operating Temperature Range LT1189M ..................................... – 55°C to 150°C LT1189C............................................. 0°C to 70°C Junction Temperature (Note 2) Plastic Package (CN8,CS8) ......................... 150°C Ceramic Package (CJ8,MJ8) ....................... 175°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec.)................ 300°C ORDER PART NUMBER LT1189MJ8 LT1189CJ8 LT1189CN8 LT1189CS8 S8 PART MARKING 1189 J8 PACKAGE N8 PACKAGE 8-LEAD HERMETIC DIP 8-LEAD PLASTIC DIP S8 PACKAGE 8-LEAD PLASTIC SOIC LT1189 • POI01 TJMAX = 175°C, θJA = 100°C/W (J8) TJMAX = 150°C, θJA = 100°C/W (N8) TJMAX = 150°C, θJA = 150°C/W (S8) +5V ELECTRICAL CHARACTERISTICS – SYMBOL VOS IOS IB en in RIN CIN VIN LIM CMRR PSRR VOUT PARAMETER Input Offset Voltage Input Offset Current Input Bias Current Input Noise Voltage Input Noise Current Input Resistance Input Capacitance Input Voltage Limit Input Voltage Range Common-Mode Rejection Ratio Power Supply Rejection Ratio Output Voltage Swing TA = 25°C, (Note 3) VS = ± 5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open. CONDITIONS Either Input, (Note 4) SOIC Package Either Input Either Input fO = 10kHz fO = 10kHz Differential Either Input (Note 5) –2.5 VCM = – 2.5V to 3.5V VS = ± 2.375V to ± 8V VS = ± 5V, RL = 1k, AV = 50 VS = ± 8V, RL = 1k, AV = 50 VS = ± 8V, RL = 300Ω, AV = 50, (Note 3) GE SR FPBW BW tr, tf tPD ts Diff AV Diff Ph IS Gain Error Slew Rate Full Power Bandwidth Small Signal Bandwidth Rise Time, Fall Time Propagation Delay Overshoot Settling Time Differential Gain Differential Phase Supply Current Shutdown Supply Current Pin 5 at V – VO = ±1.0V, AV = 10 (Note 6, 10) VO = 2VP-P, (Note 7) AV = 10 AV = 50, VO = ±1.5V, 20% to 80% (Note 10) RL= 1k, VO = ±125mV, 50% to 50% VO = ± 50mV 3V Step, 0.1%, (Note 8) RL = 1k, AV = 10, (Note 9) RL = 1k, AV = 10, (Note 9) 35 80 75 ± 3.8 ± 6.7 ± 6.4 150 105 90 ± 4.0 ±7.0 ± 6.8 1.0 220 35 35 50 12 10 1 0.6 0.75 13 0.8 16 1.5 75 3.5 % V/µs MHz MHz ns ns % µs % DEGP-P mA mA MIN LT1189M/C TYP MAX 1.0 3.0 1.0 4.0 0.2 ± 0.5 30 1.25 30 2.0 ±170 3.5 1.0 ±2.0 UNITS mV mV µA µA nV/√Hz pA/√Hz kΩ pF mV V dB dB V 2 U W U U WW W LT1189 +5V ELECTRICAL CHARACTERISTICS – SYMBOL IS/D ton toff PARAMETER Shutdown Pin Current Turn On Time Turn Off Time CONDITIONS Pin 5 at V – Pin 5 from V – to Ground, RL = 1k Pin 5 from Ground to V –, RL = 1k TA = 25°C, (Note 3) VS = ± 5V, VREF = 0V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to ground, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open. MIN LT1189M/C TYP MAX 5 500 600 25 UNITS µA ns ns 5V ELECTRICAL CHARACTERISTICS + – SYMBOL VOS IOS IB CMRR VOUT SR BW IS IS/D PARAMETER Input Offset Voltage Input Offset Current Input Bias Current Input Voltage Range Common-Mode Rejection Ratio Output Voltage Swing Slew Rate Small-Signal Bandwidth Supply Current Shutdown Supply Current Shutdown Pin Current Pin 5 at V – Pin 5 at V – CONDITIONS TA = 25°C, (Note 3) VS = 5V, VS = 0V, VREF = 2.5V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to VREF, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open. MIN LT1189M/C TYP MAX 1.0 1.0 0.2 ± 0.5 2.0 VCM = 2.0V to 3.5V RL = 300Ω to Ground (Note 3) VO = 1.5V to 3.5V AV = 10 VOUT High VOUT Low 80 3.6 100 4.0 0.15 175 30 12 0.8 5 15 1.5 25 0.4 V/µs MHz mA mA µA 3.0 5.0 1.0 ± 2.0 3.5 UNITS mV mV µA µA V dB V Either Input, (Note 4) SOIC Package Either Input Either Input +5V ELECTRICAL CHARACTERISTICS –55°C ≤ TA ≤ 125°C, (Note 3) – V = ± 5V, V = 0V, R = 900Ω from pins 6 to 8, R = 100Ω from pin 8 to ground, R = R + R S REF FB1 FB2 L FB1 FB2 = 1k, CL ≤ 10pF, pin 5 open. LT1189M TYP MAX 1.0 10 0.2 ± 0.5 7.5 1.5 ± 3.5 3.5 105 90 ± 4.0 ± 7.0 ± 6.6 1.0 13 0.8 5 6.0 17 1.5 25 % mA mA µA UNITS mV µV/°C µA µA V dB dB V SYMBOL VOS ∆VOS /∆T IOS IB CMRR PSRR VOUT PARAMETER Input Offset Voltage Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range Common-Mode Rejection Ratio Power Supply Rejection Ratio Output Voltage Swing CONDITIONS Either Input, (Note 4) Either Input Either Input MIN –2.5 VCM = – 2.5V to 3.5V VS = ±2.375V to ± 8V VS = ± 5V, RL = 1k, AV = 50 VS = ± 8V, RL = 1k, AV = 50 VS = ± 8V, RL = 300Ω, AV = 50, (Note 3) 80 65 ± 3.7 ± 6.6 ± 6.4 GE IS IS/D Gain Error Supply Current Shutdown Supply Current Shutdown Pin Current VO = ±1V, AV = 10, RL = 1k Pin 5 at V –, (Note 11) Pin 5 at V – 3 LT1189 +5V ELECTRICAL CHARACTERISTICS 0°C ≤ TA ≤ 70°C, (Note 3) – V = ± 5V, V = 0V, R = 900Ω from pins 6 to 8, R = 100Ω from pin 8 to ground, R = R S REF FB1 FB2 L FB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open. MIN LT1189C TYP MAX 1.0 1.0 5.0 0.2 ± 0.5 –2.5 80 70 ± 3.7 ± 6.6 ± 6.4 105 90 ± 4.0 ± 7.0 ± 6.6 1.0 13 0.8 5 3.5 17 1.5 25 % mA mA µA 3.0 6.0 1.5 ± 3.5 3.5 UNITS mV mV µV/°C µA µA V dB dB V SYMBOL VOS ∆VOS /∆T IOS IB CMRR PSRR VOUT PARAMETER Input Offset Voltage (Note 4) Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range Common-Mode Rejection Ratio Power Supply Rejection Ratio Output Voltage Swing CONDITIONS Either Input SOIC Package Either Input Either Input VCM = – 2.5V to 3.5V VS = ± 2.375V to ± 8V VS = ± 5V, RL = 1k, AV = 50 VS = ± 8V, RL = 1k, AV = 50 VS = ± 8V, RL = 300Ω, AV = 50, (Note 3) GE IS IS/D Gain Error Supply Current Shutdown Supply Current Shutdown Pin Current VO = ± 1V, AV = 10, RL = 1k Pin 5 at V –, (Note 11) Pin 5 at V – 5V ELECTRICAL CHARACTERISTICS + – SYMBOL VOS ∆VOS /∆T IOS IB CMRR VOUT IS IS/D PARAMETER Input Offset Voltage, (Note 4) Input VOS Drift Input Offset Current Input Bias Current Input Voltage Range Common-Mode Rejection Ratio Output Voltage Swing Supply Current Shutdown Supply Current Shutdown Pin Current Either Input Either Input CONDITIONS Either Input 0°C ≤ TA ≤ 70°C, (Note 3) VS = + 5V, VS = 0V, VREF = 2.5V, RFB1 = 900Ω from pins 6 to 8, RFB2 = 100Ω from pin 8 to VREF, RL = RFB1 + RFB2 = 1k, CL ≤ 10pF, pin 5 open. MIN LT1189C TYP MAX 1.0 5.0 0.2 ± 0.5 2.0 VCM = 2.0V to 3.5V RL = 300Ω to Ground (Note 3) Pin 5 at V, (Note 11) Pin 5 at V – VOUT High VOUT Low 80 3.5 100 4.0 0.15 12 0.8 5 0.4 16 1.5 25 mA mA µA 1.5 ± 3.5 3.5 3.0 UNITS mV µV/°C µA µA V dB V Note 1: A heat sink may be required to keep the junction temperature below absolute maximum when the output is shorted continuously. Note 2: TJ is calculated from the ambient temperature T A and power dissipation PD according to the following formulas: LT1189MJ8, LT1189CJ8: TJ = TA + (PD × 100°C/W) LT1189CN8: TJ = TA + (PD × 100°C/W) LT1189CS8: TJ = TA + (PD × 150°C/W) Note 3: When RL = 1k is specified, the load resistor is RFB1 + RFB2, but when RL = 300 Ω is specified, then an additional 430 Ω is added to the output such that (RFB1 + RFB2) in parallel with 430Ω is RL = 300Ω. Note 4: VOS measured at the output (pin 6) is the contribution from both input pair, and is input referred. Note 5: VIN LIM is the maximum voltage between –V IN and +VIN (pin 2 and pin 3) for which the output can respond. Note 6: Slew rate is measured between ±1V on the output, with a VIN step of ±0.5V, AV = 10 and RL = 1k. Note 7: Full power bandwidth is calculated from the slew rate measurement: FPBW = SR/2πVp. Note 8: Settling time measurement techniques are shown in “Take the Guesswork Out of Settling Time Measurements,” EDN, September 19, 1985. Note 9: NTSC (3.58MHz). Note 10: AC parameters are 100% tested on the ceramic and plastic DIP packaged parts (J8 and N8 suffix) and are sample tested on every lot of the SO packaged parts (S8 suffix). Note 11: See Application section for shutdown at elevated temperatures. Do not operate shutdown above T J > 125°C. 4 LT1189 TYPICAL PERFOR A CE CHARACTERISTICS Input Bias Current vs Common-Mode Voltage 3.0 VS = ±5V 2.5 INPUT BIAS CURRENT (µA) INPUT BIAS CURRENT (nA) 2.0 1.5 –55°C 1.0 0.5 0 25°C 125°C COMMON-MODE RANGE (V) – 0.5 – 5 – 4 –3 –2 –1 0 1 2 3 COMMON-MODE VOLTAGE (V) 4 5 Equivalent Input Noise Voltage vs Frequency 180 160 140 120 100 80 60 40 20 0 10 100 1k 10k FREQUENCY (Hz) 100k V S = ±5V T A = 25°C RS = 0Ω EQUIVALENT INPUT NOISE CURRENT (pA/√Hz) EQUIVALENT INPUT NOISE VOLTAGE (nV/√Hz) 200 8 6 4 2 0 10 100 1k 10k FREQUENCY (Hz) 100k SUPPLY CURRENT (mA) Shutdown Supply Current vs Temperature 6.0 SHUTDOWN SUPPLY CURRENT (mA) VS = ±5V 5.0 –1.4 GAIN ERROR (%) 4.0 3.0 2.0 1.0 VS/D = –VEE + 0.6V VS/D = –VEE + 0.4V VS/D = –VEE + 0.2V –1.6 –1.8 –2.0 –2.2 OPEN-LOOP GAIN (kV/V) VS/D = –VEE 0 –50 –25 0 25 75 50 TEMPERATURE (°C) 100 125 –2.4 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 0 –50 –25 25 75 0 50 TEMPERATURE (°C) 100 125 UW LT1189 • TPC01 Input Bias Current vs Temperature 100 VS = ± 5V 0 +IB Common-Mode Voltage vs Temperature V+ –0.5 –1.0 –1.5 –2.0 V + = 1.8V TO 9V –100 IOS –200 –IB 2.0 1.5 1.0 0.5 V– – 50 –25 V + = –1.8V TO –9V –300 –400 –50 –25 0 25 75 50 TEMPERATURE (°C) 100 125 0 25 50 75 TEMPERATURE (°C) 100 125 LT1189 • TPC02 LT1189 • TPC03 Equivalent Input Noise Current vs Frequency 12 10 VS = ± 5V TA = 25°C RS = 100k 16 Supply Current vs Supply Voltage 14 –55°C 25°C 12 125°C 10 8 0 2 4 6 8 ±SUPPLY VOLTAGE (V) 10 LT1189 • TPC04 LT1189 • TPC05 LT1189 • TPC06 Gain Error vs Temperature –1.2 VS = ± 5V VOUT = ±1V AV = 10 RL = 1k 16 14 12 10 8 6 4 2 Open-Loop Gain vs Temperature VS = ± 5V VO = ± 3V RL = 1k RL = 500Ω LT1189 • TPC07 LT1189 • TPC08 LT1189 • TPC09 5 LT1189 TYPICAL PERFOR A CE CHARACTERISTICS Gain, Phase vs Frequency 100 80 PHASE VS = ± 5V TA = 25°C RL = 1k 100 80 OPEN-LOOP VOLTAGE GAIN (kV/V) GAIN BANDWIDTH PRODUCT (MHz) VOLTAGE GAIN (dB) 60 40 20 0 –20 100k GAIN 1M 10M FREQUENCY (Hz) Gain Bandwidth Product and Phase Margin vs Temperature 250 GAIN BANDWIDTH PRODUCT (MHz) COMMON-MODE REJECTION RATIO (dB) OUTPUT IMPEDANCE (Ω ) VS = ±5V R L = 1k AV = 20dB PHASE MARGIN (DEG) 200 GAIN BANDWIDTH PRODUCT 150 PHASE MARGIN 100 –50 –25 25 75 0 50 TEMPERATURE (°C) Power Supply Rejection Ratio vs Frequency 80 OUTPUT SHORT CIRCUIT CURRENT (mA) POWER SUPPLY REJECTION RATIO (dB) OUTPUT SATURATION VOLTAGE (V) 60 VS = ± 5V TA = 25°C VRIPPLE = ± 300mV 40 +PSRR –PSRR 20 0 –20 1k 10k 1M 100k FREQUENCY (Hz) 10M 100M 6 UW 100M LT1189 • TPC11 Open-Loop Voltage Gain vs Load Resistance 30 VS = ± 5V VO = ± 3V TA = 25°C 20 250 Gain Bandwidth Product vs Supply Voltage AV = 20dB TA = – 55°C PHASE MARGIN (DEG) 60 40 20 0 –20 200 TA = 25°C TA = 125°C 150 10 0 100 100 1k LOAD RESISTANCE (Ω) 10k LT1189• TPC10 0 2 4 8 6 ±SUPPLY VOLTAGE (V) 10 LT1189 • TPC12 Output Impedance vs Frequency 85 100 VS = ± 5V TA = 25°C AV = 10 75 10 Common-Mode Rejection Ratio vs Frequency 90 80 70 60 50 40 30 100k VS = ± 5V TA = 25°C RL = 1k 65 1 100 55 125 0.1 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M 1M 10M FREQUENCY (Hz) 100M LT1189 • TPC15 LT1189 • TPC13 LT1189 • TPC14 Output Short Circuit Current vs Temperature 36 VS = ± 5V 35 34 33 32 31 30 –50 V+ – 0.7 –0.8 –0.9 –1.0 –1.1 0.5 0.4 0.3 0.2 ± Output Swing vs Supply Voltage 125°C 25°C –55°C RL = 1k ±1.8V ≤ VS ≤ ± 9V 125°C 25°C –55°C –25 50 0 25 75 TEMPERATURE (°C) 100 125 0.1 V– 0 2 4 6 8 ±SUPPLY VOLTAGE (V) 10 LT1189 • TPC16 LT1189 • TPC17 LT1189 • TPC18 LT1189 TYPICAL PERFOR A CE CHARACTERISTICS Output Voltage Swing vs Load Resistance 5 VS = ± 5V –SLEW RATE OUTPUT VOLTAGE SWING (V) 3 TA = – 55°C TA = 25°C TA = 25°C SLEW RATE (V/µs) 1 –1 TA = 25°C –3 –5 10 100 LOAD RESISTANCE (Ω) 1000 LT1189 • TPC19 Output Voltage Step vs Settling Time, AV = 10 4 VS = ± 5V TA = 25°C RL = 1k 0 –10 DISTORTION (dBc) OUTPUT VOLTAGE STEP (V) 2 0 –2 10mV –4 100 140 180 220 260 SETTLING TIME (ns) Large-Signal Transient Reponse AV = 10, RL = 1k, +SR = 223V/µs, –SR = 232V/µs LT1189 • TPC23 UW Slew Rate vs Temperature 300 +SLEW RATE 250 TA = – 55°C TA = 25°C VS = ± 5V RL = 1k VO = ± 2V AV = 10 200 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 LT1189 • TPC20 Harmonic Distortion vs Output Level VS = ±5V TA = 25°C RL = 1k f = 10MHz AV = 10 10mV –20 –30 –40 –50 –60 HD3 HD2 300 340 0 3 1 2 OUTPUT VOLTAGE (VP-P) 4 LT1189 • TPC22 LT1189 • TPC21 Small-Signal Transient Reponse AV = 10, RL = 1k, tr = 9.40ns LT1189 • TPC24 7 LT1189 APPLICATI S I FOR ATIO U Power Supply Bypassing The LT1189 is quite tolerant of power supply bypassing. In some applications a 0.1µF ceramic disc capacitor placed 1/2 inch from the amplifier is all that is required. In applications requiring good settling time, it is important to use multiple bypass capacitors. A 0.1µF ceramic disc in parallel with a 4.7µF tantalum is recommended. Calculating the Output Offset Voltage Both input stages contribute to the output offset voltage at pin 6. The feedback correction forces balance in the input stages by introducing an Input VOS at pin 8. The complete expression for the output offset voltage is: VOUT = (VOS + IOS(RS) + IB(RREF)) × (RFB + RG)/RG + IB(RFB) RS represents the input source resistance, typically 75Ω, and RREF represents finite source impedance from the DC reference voltage, for VREF grounded, RREF = 0Ω the IOS is normally a small contributor and the expression simplifies to: VOUT = VOS(RFB + RG)/RG + IB(RFB) If RFB is limited to 1k, the last term of the equation contributes only 2mV since IB is less than 2µA. RFB + RG RG 6 VOUT The primary use of the LT1189 is in converting high speed differential signals to a single-ended output. The LT1189 video difference amplifier has two uncommitted high input impedance (+) and (–) inputs. The amplifier has another set of inputs which can be used for reference and feedback. Additionally, this set of inputs give gain adjust, and DC control to the differential amplifier. The voltage gain of the LT1189 is set like a conventional operational amplifier. Feedback is applied to pin 8, and it is optimized for gains of 10 or greater. The amplifier can be operated singleended by connecting either the (+) or (–) inputs to the +/REF (pin 1). The voltage gain is set by the resistors: (RFB + RG)/RG. Like the single-ended case, the differential voltage gain is set by the external resistors: (RFB + RG)/RG. The maximum input differential signal for which the output will respond is approximately ±170mV. S/D 5 VIN V+ V IN V+ 5 3 7 + 2 – LT1189 1 +/REF 8 –/FB 4 V– RFB RFB + RG RG S/D 3 7 + 2 – LT1189 1 +/REF 8 –/FB 4 V– RFB AV = + 6 VOUT RG S/D V+ 5 3 7 + 2 – LT1189 1 +/REF 8 –/FB 4 V– RFB RFB + RG RG VIN DIFF VIN 6 VIN DIFF VOUT V IN RG RG VO = (VIN DIFF + VIN) VO = ( 8 W RG U UO AV = – 7 V+ 6 S/D V+ 5 3 7 + 2 – LT1189 1 +/REF 8 –/FB 4 V– RFB RFB + RG RG RFB 6 VOUT Q1 3 Q2 RE 300 Q3 Q4 RE 300 8 RG + RS 2 – RS + 1 REF RREF 345µA 350µA 4 V– LT1189 • AI02 (V IN DIFF – ( R (V G RFB IN LT1189 • AI01 Figure 1. Simplified Input Stage Schematic LT1189 APPLICATI S I FOR ATIO Instrumentation Amplifier Rejects High Voltage Instrumentation amplifiers are often used to process slowly varying outputs from transducers. With the LT1189 it is easy to make an instrumentation amplifier that can respond to rapidly varying signals. Attenuation resistors in front of the LT1189 allow very large common-mode signals to be rejected while maintaining good frequency response. The input common-mode and differential-mode signals are reduced by 100:1, while the closed-loop gain is set to be 100, thereby maintaining unity-gain input to output. The unique topology allows for frequency response boost by adding 150pF to pin 8 as shown. 3.5MHz Instrumentation Amplifier Rejects 120VP-P 5V 2 1 10k* 100* 3 8 VOLTAGE GAIN (dB) 10k* VIN VCM 120VP-P 100* + REF 7 LT1189 4 –5V 10k 6 – FB 150pF * 0.1% RESISTORS WORST CASE CMRR = 48dB 100Ω LT1189 • AI03 Output of Instrumentation Amplifier with 1MHz Square Wave Riding on 120VP-P at the Input LT1189 • AI04 U High Voltage Instrumentation Amplifier Response 20 0 DIFFERENTIAL-MODE RESPONSE –20 –40 COMMON-MODE RESPONSE – 60 100k 1M 10M FREQUENCY (Hz) 100M LT1189 • AI05 W U UO Operating with Low Closed-Loop Gain The LT1189 has been optimized for closed-loop gains of 10 or greater. The amplifier can be operated at much lower closed-loop gains with the aid of a capacitor CFB across the feedback resistor, (feedback zero). This capacitor lowers the closed-loop 3dB bandwidth. The bandwidth cannot be made arbitrarily low because CFB is a short at high frequency and the amplifier will appear configured unity-gain. As an approximate guideline, make BW × AVCL = 200MHz. This expression expands to: A VCL = 200MHz 2π(RFB )(C FB ) or: C FB = A VCL (200MHz)(2π)(RFB ) The effect of the feedback zero on the transient and frequency response is shown for AV = 4. 9 LT1189 APPLICATI 30 S I FOR ATIO Closed-Loop Voltage Gain vs Frequency CLOSED-LOOP VOLTAGE GAIN (dB) 20 CFB = 0pF 10 CFB = 5pF 0 VS = ± 5V TA = 25°C AV = 4 RFB = 900Ω RG = 300Ω 1M 10M FREQUENCY (Hz) 100M LT1189 • AI06 –10 –20 100k Small-Signal Transient Response AV = 4, RFB = 910Ω, RG = 300Ω LT1189 • AI07 Small-Signal Transient Response AV = 4, RFB = 910Ω, RG = 300Ω, CFB = 5pF LT1189 • AI08 10 U Reducing the Closed-Loop Bandwidth Although it is possible to reduce the closed-loop bandwidth by using a feedback zero, instability can occur if the bandwidth is made too low. An alternate technique is to do differential filtering at the input of the amplifier. This technique filters the differential input signal, and the differential noise, but does not filter common-mode noise. Common-mode noise is rejected by the LT1189’s CMRR. 10MHz Bandwidth Limited Amplifier R1 110Ω SIG eND C1 68pF 5V 3 2 1 8 R2 110Ω 100Ω + – LT1189 REF FB 4 –5V 909Ω AV = 10 f –3dB = VOUT = 1 2π(R1 + R2)C1 SIG + eND eNCM + CMR FILTER LT1189 • AI09 W U UO 7 6 VOUT eNCM Using the Shutdown Feature The LT1189 has a unique feature that allows the amplifier to be shutdown for conserving power, or for multiplexing several amplifiers onto a common cable. The amplifier will shutdown by taking pin 5 to V –. In shutdown, the amplifier dissipates 15mW while maintaining a true high impedance output state of about 20kΩ in parallel with the feedback resistors. For MUX applications, the amplifiers may be configured inverting, non-inverting, or differential. When the output is loaded with as little as 1kΩ from the amplifier’s feedback resistors, the amplifier shuts off in 600ns. This shutoff can be under the control of HC CMOS operating between 0V and – 5V. LT1189 APPLICATI S I FOR ATIO 1MHz Sine Wave Gated Off with Shutdown Pin SHUTDOWN VOUT AV = 10, RFB = 900Ω, RG = 100Ω LT1189 • AI10 TYPICAL APPLICATI Differential Receiver MUX for Power Down Applications 15k 1.5k 15k 1.5k CMOS IN CHANNEL SELECT 1k 3 2 CABLE 1 1k –5V 15k 1.5k 15k 1.5k 3 + 2 – VDC 1 REF 8 FB 5 5V 7 LT1189 4 –5V 1k 100Ω 1% RESISTORS WORST CASE CMRR = 28dB TYPICALLY 35dB LT1189 • TA03 CABLE 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. U The ability to maintain shutoff is shown on the curve Shut down Supply Current vs Temperature in the Typical Performance Characteristics section. At very high elevated temperature it is important to hold the shutdown pin close to the negative supply to keep the supply current from increasing. + – 5 5V 7 LT1189 4 –5V 6 VDC 1 REF 8 FB 1k 100Ω 74HC04 74HC04 VOUT 6 W UO U UO 11 LT1189 SI PLIFIED SCHE ATIC 7 V+ VBIAS VBIAS +3 C FF –2 +V +V 5 S/D 1 +/REF 8 –/FB * SUBSTRATE DIODE, DO NOT FORWARD BIAS PACKAGE DESCRIPTIO 0.290 – 0.320 (7.366 – 8.128) J8 Package 8-Lead Hermetic DIP 0.008 – 0.018 (0.203 – 0.460) 0.385 ± 0.025 (9.779 ± 0.635) 0.300 – 0.320 (7.620 – 8.128) N8 Package 8-Lead Plastic DIP 0.009 – 0.015 (0.229 – 0.381) ( +0.025 0.325 –0.015 +0.635 8.255 –0.381 ) 0.010 – 0.020 × 45° (0.254 – 0.508) S8 Package 8-Lead Plastic SOIC 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 U W W CM 6 VOUT * 4 V– LT1189 • SS Dimensions in inches (millimeters) unless otherwise noted. 0.405 (10.287) MAX 8 7 6 5 CORNER LEADS OPTION (4 PLCS) 0.200 (5.080) MAX 0.015 – 0.060 (0.381 – 1.524) 0.005 (0.127) MIN 0.023 – 0.045 (0.58 – 1.14) HALF LEAD OPTION 0° – 15° 0.045 – 0.065 (1.14 – 1.65) FULL LEAD OPTION 0.025 (0.635) RAD TYP 1 2 3 0.220 – 0.310 (5.588 – 7.874) 4 0.045 – 0.065 (1.14 – 1.65) 0.014 – 0.026 (0.360 – 0.660) 0.125 3.175 0.100 ± 0.010 MIN (2.540 ± 0.254) 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 0.065 (1.651) TYP 0.125 (3.175) MIN 0.020 (0.508) MIN 0.250 ± 0.010 (6.350 ± 0.254) 0.045 ± 0.015 (1.143 ± 0.381) 0.100 ± 0.010 (2.540 ± 0.254) 1 2 3 4 0.018 ± 0.003 (0.457 ± 0.076) 0.189 – 0.197 (4.801 – 5.004) 0.053 – 0.069 (1.346 – 1.752) 0.004 – 0.010 (0.101 – 0.254) 0.228 – 0.244 (5.791 – 6.197) 8 7 6 5 0.008 – 0.010 (0.203 – 0.254) 0.014 – 0.019 (0.355 – 0.483) 0.050 (1.270) BSC 0.150 – 0.157 (3.810 – 3.988) 1 2 3 4 BA/LT/GP 0293 10K REV 0 © LINEAR TECHNOLOGY CORPORATION 1993