DESCRIPTIO TYPICAL APPLICATION. LT1207 Dual 250mA/60MHz Current Feedback Amplifier APPLICATIO S

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1 LT27 Dual 25mA/6MHz Current Feedback Amplifier FEATRES 25mA Minimum Output Drive Current 6MHz Bandwidth, A V = 2, R L = Ω 9V/µs Slew Rate, A V = 2, R L = 5Ω.2% Differential Gain, A V = 2, R L = 3Ω.7 Differential Phase, A V = 2, R L = 3Ω High Input Impedance: MΩ Shutdown Mode: I S < 2µA per Amplifier Stable with C L =,pf APPLICATIO S ADSL/HDSL Drivers Video Amplifiers Cable Drivers RGB Amplifiers Test Equipment Amplifiers Buffers DESCRIPTIO The LT 27 is a dual version of the LT26 high speed current feedback amplifier. Like the LT26, each CFA in the dual has excellent video characteristics: 6MHz bandwidth, 25mA minimum output drive current, V/µs minimum slew rate, low differential gain (.2% typ) and low differential phase (.7 typ). The LT27 includes a pin for an optional compensation network which stabilizes the amplifier for heavy capacitive loads. Both amplifiers have thermal and current limit circuits which protect against fault conditions. These capabilities make the LT27 well suited for driving difficult loads such as cables in video or digital communication systems. Operation is fully specified from ±5V to ±5V supplies. Supply current is typically 2mA per amplifier. Two micropower shutdown controls place each amplifier in a high impedance low current mode, dropping supply current to 2µA per amplifier. For reduced bandwidth applications, supply current can be lowered by adding a resistor in series with the Shutdown pin. The LT27 is manufactured on Linear Technology's complementary bipolar process and is available in a low thermal resistance 6-lead SO package., LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATION 5V HDSL Driver V IN SHDN A /2 LT27 72Ω.µF* 62Ω 2.2µF** L 5k 2Ω 72Ω 72Ω 5k SHDN B /2 LT27 62Ω *CERAMIC ** TANTALM L = TRANSPOWER SMPT38 OR SIMILAR DEVICE 5V.µF* 2.2µF** 27 TA

2 LT27 ABSOLTE AXI RATI GS W W W Supply Voltage... ±8V Input Current per Amplifier... ±5mA Output Short-Circuit Duration (Note )... Continuous Specified Temperature Range (Note 2)... C to 7 C Operating Temperature Range... C to 85 C Junction Temperature... 5 C Storage Temperature Range C to 5 C Lead Temperature (Soldering, sec)... 3 C PACKAGE/ORDER I FOR TOP VIEW V 6 V IN A 2 5 OT A IN A 3 V A SHDN A 3 COMP A IN B 5 2 OT B IN B 6 V B SHDN B 7 COMP B V 8 9 V S PACKAGE 6-LEAD PLASTIC SO θ JA = C/W (NOTE 3) W ATIO ORDER PART NMBER LT27CS Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS V CM =, ±5V V S ±5V, pulse tested, V SHDN A = V, V SHDN B = V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX NITS V OS Input Offset Voltage T A = 25 C ±3 ± mv ±5 mv Input Offset Voltage Drift µv/ C I IN Noninverting Input Current T A = 25 C ±2 ±5 µa ±2 µa I IN Inverting Input Current T A = 25 C ± ±6 µa ± µa e n Input Noise Voltage Density f = khz, R F =, R G = Ω, R S = Ω 3.6 nv/ Hz i n Input Noise Current Density f = khz, R F =, R G = Ω, R S = k 2 pa/ Hz i n Input Noise Current Density f = khz, R F =, R G = Ω, R S = k 3 pa/ Hz R IN Input Resistance V IN = ±2V,.5 MΩ V IN = ±2V, V S = ±5V.5 5 MΩ C IN Input Capacitance 2 pf Input Voltage Range ±2 ±3.5 V V S = ±5V ±2 ±3.5 V CMRR Common Mode Rejection Ratio, V CM = ±2V db V S = ±5V, V CM = ±2V 5 6 db Inverting Input Current, V CM = ±2V. µa/v Common Mode Rejection V S = ±5V, V CM = ±2V. µa/v PSRR Power Supply Rejection Ratio V S = ±5V to ±5V 6 77 db 2

3 LT27 ELECTRICAL CHARACTERISTICS V CM =, ±5V V S ±5V, pulse tested, V SHDN A = V, V SHDN B = V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX NITS Noninverting Input Current V S = ±5V to ±5V 3 5 na/v Power Supply Rejection Inverting Input Current V S = ±5V to ±5V.7 5 µa/v Power Supply Rejection A V Large-Signal Voltage Gain, V OT = ±V, R L = 5Ω 55 7 db V S = ±5V, V OT = ±2V, R L = 25Ω db R OL Transresistance, V OT / I IN, V OT = ±V, R L = 5Ω 26 kω V S = ±5V, V OT = ±2V, R L = 25Ω 75 2 kω V OT Maximum Output Voltage Swing, R L = 5Ω, T A = 25 C ±.5 ±2.5 V ±. V V S = ±5V, R L = 25Ω, T A = 25 C ±2.5 ±3. V ±2. V I OT Maximum Output Current R L = Ω ma I S Supply Current per Amplifier, V SHDN = V, T A = 25 C 2 3 ma 35 ma Supply Current per Amplifier,, T A = 25 C 2 7 ma R SHDN = 5 (Note ) Positive Supply Current, V SHDN A = 5V, V SHDN B = 5V 2 µa per Amplifier, Shutdown Output Leakage Current, Shutdown, V SHDN = 5V, V OT = V µa SR Slew Rate (Note 5) A V = 2, T A = 25 C 9 V/µs Differential Gain (Note 6), R F = 56Ω, R G = 56Ω, R L = 3Ω.2 % Differential Phase (Note 6), R F = 56Ω, R G = 56Ω, R L = 3Ω.7 DEG BW Small-Signal Bandwidth, Peaking.5dB 6 MHz R F = R G = 62Ω, R L = Ω, Peaking.5dB 52 MHz R F = R G = 69Ω, R L = 5Ω, Peaking.5dB 3 MHz R F = R G = 698Ω, R L = 3Ω, Peaking.5dB 27 MHz R F = R G = 825Ω, R L = Ω The denotes specifications which apply for C T A 7 C. Note : Applies to short circuits to ground only. A short circuit between the output and either supply may permanently damage the part when operated on supplies greater than ±V. Note 2: Commercial grade parts are designed to operate over the temperature range of C to 85 C but are neither tested nor guaranteed beyond C to 7 C. Industrial grade parts tested over C to 85 C are available on special request. Consult factory. Note 3: Thermal resistance θ JA varies from C/W to 6 C/W depending upon the amount of PC board metal attached to the device. θ JA is specified for a 25mm 2 test board covered with 2oz copper on both sides. Note : R SHDN is connected between the Shutdown pin and ground. Note 5: Slew rate is measured at ±5V on a ±V output signal while operating on ±5V supplies with R F =.5k, R G =.5k and R L = Ω. Note 6: NTSC composite video with an output level of 2V. 3

4 LT27 S ALL-SIG AL BA DWIDTH W I S = 2mA per Amplifier Typical, Peaking.dB 3dB BW.dB BW A V R L R F R G (MHz) (MHz) V S = ±5V, R SHDN = Ω I S = ma per Amplifier Typical, Peaking.dB 3dB BW.dB BW A V R L R F R G (MHz) (MHz) V S = ±5V, R SHDN =.2k I S = 5mA per Amplifier Typical, Peaking.dB 3dB BW.dB BW A V R L R F R G (MHz) (MHz) V S = ±5V, R SHDN = dB BW.dB BW A V R L R F R G (MHz) (MHz), R SHDN = Ω dB BW.dB BW A V R L R F R G (MHz) (MHz), R SHDN = 6.k dB BW.dB BW A V R L R F R G (MHz) (MHz), R SHDN =

5 LT27 TYPICAL PERFOR A CE CHARACTERISTICS W 3dB BANDWIDTH (MHz) Bandwidth vs Supply Voltage PEAKING.5dB PEAKING 5dB R F = 7Ω R F = 56Ω A V = 2 R L = Ω R F = 68Ω R F = 75Ω R F =.5k R F = SPPLY VOLTAGE (±V) 3dB BANDWIDTH (MHz) Bandwidth vs Supply Voltage PEAKING.5dB PEAKING 5dB R F = 56Ω R F = 75Ω R F = R F = 2k A V = 2 R L = Ω SPPLY VOLTAGE (±V) FEEDBACK RESISTOR (Ω) k Bandwidth and Feedback Resistance vs Capacitive Load for.5db Peak BANDWIDTH FEEDBACK RESISTOR A V = 2 R L = C COMP =.µf CAPACITIVE LOAD (pf) 3dB BANDWIDTH (MHz) LT27 TPC LT27 TPC2 LT27 TPC3 3dB BANDWIDTH (MHz) Bandwidth vs Supply Voltage PEAKING.5dB PEAKING 5dB R F =39Ω A V = R L = Ω R F = 33Ω R F = 7Ω R F = 68Ω R F =.5k SPPLY VOLTAGE (±V) 3dB BANDWIDTH (MHz) Bandwidth vs Supply Voltage PEAKING.5dB PEAKING 5dB A V = R L = Ω R F = 56Ω R F = 68Ω R F = R F =.5k SPPLY VOLTAGE (±V) FEEDBACK RESISTOR (Ω) k Bandwidth and Feedback Resistance vs Capacitive Load for 5dB Peak BANDWIDTH FEEDBACK RESISTOR A V = 2 R L = C COMP =.µf k CAPACITIVE LOAD (pf) 3dB BANDWIDTH (MHz) LT27 TPC LT27 TPC5 LT27 TPC6 DIFFERENTIAL PHASE (DEG) Differential Phase vs Supply Voltage 5 R F = R G = 56Ω A V = 2 N PACKAGE R L = 5Ω R L = 3Ω R L = 5Ω R L = 5Ω SPPLY VOLTAGE (±V) LT27 TPC7 DIFFERENTIAL GAIN (%) Differential Gain vs Supply Voltage 5 R L = 5Ω R L = 3Ω R L = 5Ω R L = 5Ω SPPLY VOLTAGE (±V) R F = R G = 56Ω A V = 2 N PACKAGE LT27 TPC8 SPOT NOISE (nv/ Hz OR pa/ Hz) Spot Noise Voltage and Current vs Frequency i n e n i n k k FREQENCY (Hz) LT27 TPC9 5

6 LT27 TYPICAL PERFOR A CE CHARACTERISTICS W SPPLY CRRENT PER AMPLIFIER (ma) Supply Current vs Supply Voltage 2 V SHDN = V T 22 J = C 2 T J = 25 C 8 6 T J = 85 C T J = 25 C 2 SPPLY CRRENT PER AMPLIFIER (ma) Supply Current vs Ambient Temperature, V S = ±5V R SD = Ω R SD =.2k R SD = 22. A V = R L = SPPLY CRRENT PER AMPLIFIER (ma) Supply Current vs Ambient Temperature, R SD = Ω R SD = 6.k R SD = 2 A V = R L = SPPLY VOLTAGE (±V) TEMPERATRE ( C) TEMPERATRE ( C) LT27 TPC LT27 TPC LT27 TPC2 SPPLY CRRENT PER AMPLIFIER (ma) Supply Current vs Shutdown Pin Current SHTDOWN PIN CRRENT (µa) COMMON MODE RANGE (V) V V 5 Input Common Mode Limit vs Junction Temperature TEMPERATRE ( C) OTPT SHORT-CIRCIT CRRENT (A) Output Short-Circuit Current vs Junction Temperature SORCING SINKING TEMPERATRE ( C) LT27 TPC3 LT27 TPC LT27 TPC5 OTPT SATRATION VOLTAGE (V) V Output Saturation Voltage vs Junction Temperature R L = 2k R L = 5Ω R L = 5Ω R L = 2k POWER SPPLY REJECTION (db) Power Supply Rejection Ratio vs Frequency NEGATIVE POSITIVE R L = 5Ω R F = R G = SPPLY CRRENT PER AMPLIFIER (ma) Supply Current vs Large-Signal Output Frequency (No Load) A V = 2 R L = V OT = 2V P-P V TEMPERATRE ( C) LT27 TPC6 k k M M M FREQENCY (Hz) LT27 TPC7 k k M M FREQENCY (Hz) LT27 TPC8 6

7 LT27 TYPICAL PERFOR A CE CHARACTERISTICS W OTPT IMPEDANCE (Ω). Output Impedance vs Frequency I O = ma R SHDN = 2 R SHDN = Ω OTPT IMPEDANCE (Ω) k k Output Impedance in Shutdown vs Frequency A V = R F = DISTORTION (dbc) nd and 3rd Harmonic Distortion vs Frequency V O = 2V P-P R L = Ω R L = 3Ω 2nd 3rd 2nd 3rd. k M M M FREQENCY (Hz) LT27 TPC9 k M M M FREQENCY (Hz) LT27 TPC FREQENCY (MHz) LT27 TPC2 3rd ORDER INTERCEPT (dbm) rd Order Intercept vs Frequency R L = 5Ω R F = 59Ω R G = 6.9Ω Test Circuit for 3rd Order Intercept /2 LT27 59Ω 65Ω MEASRE INTERCEPT AT P O LT27 TPC23 5Ω P O FREQENCY (MHz) 25 3 LT27 TPC22 7

8 LT27 SI PLIFIED SCHE ATIC W W V TO ALL CRRENT SORCES Q5 Q Q2 D Q Q8 Q Q6 Q5 Q7.25k IN V IN Q9 V 5Ω C C R C COMP OTPT SHTDOWN V V Q2 Q3 Q8 Q6 Q Q D2 Q7 Q3 /2 LT27 CRRENT FEEDBACK AMPLIFIER LT27 SS V APPLICATI 8 O S I FOR W ATIO The LT27 is a dual current feedback amplifier with high output current drive capability. The device is stable with large capacitive loads and can easily supply the high currents required by capacitive loads. The amplifier will drive low impedance loads such as cables with excellent linearity at high frequencies. Feedback Resistor Selection The optimum value for the feedback resistors is a function of the operating conditions of the device, the load impedance and the desired flatness of response. The Typical AC Performance tables give the values which result in the highest.db and.5db bandwidths for various resistive loads and operating conditions. If this level of flatness is not required, a higher bandwidth can be obtained by use of a lower feedback resistor. The characteristic curves of Bandwidth vs Supply Voltage indicate feedback resistors for peaking up to 5dB. These curves use a solid line when the response has less than.5db of peaking and a dashed line when the response has.5db to 5dB of peaking. The curves stop where the response has more than 5dB of peaking. For resistive loads, the COMP pin should be left open (see section on capacitive loads). Capacitive Loads Each amplifier in the LT27 includes an optional compensation network for driving capacitive loads. This network eliminates most of the output stage peaking associated with capacitive loads, allowing the frequency response to be flattened. Figure shows the effect of the network on a 2pF load. Without the optional compensation, there is a 5dB peak at MHz caused by the effect of the capacitance on the output stage. Adding a.µf bypass capacitor between the output and the COMP pins connects the compensation and completely eliminates the peaking. A lower value feedback resistor can now be used, resulting in a response which is flat to.35db to 3MHz.

9 LT27 APPLICATI VOLTAGE GAIN (db) O S I FOR W R F =.2k COMPENSATION R F = 2k NO COMPENSATION R F = 2k COMPENSATION ATIO FREQENCY (MHz) Figure. LT27 F The network has the greatest effect for C L in the range of pf to pf. The graph of Maximum Capacitive Load vs Feedback Resistor can be used to select the appropriate value of the feedback resistor. The values shown are for.5db and 5dB peaking at a gain of 2 with no resistive load. This is a worst-case condition, as the amplifier is more stable at higher gains and with some resistive load in parallel with the capacitance. Also shown is the 3dB bandwidth with the suggested feedback resistor vs the load capacitance. Although the optional compensation works well with capacitive loads, it simply reduces the bandwidth when it is connected with resistive loads. For instance, with a 3Ω load, the bandwidth drops from 55MHz to 35MHz when the compensation is connected. Hence, the compensation was made optional. To disconnect the optional compensation, leave the COMP pin open. typically µa. Each Shutdown pin is referenced to the positive supply through an internal bias circuit (see the Simplified Schematic). An easy way to force shutdown is to use open drain (collector) logic. The circuit shown in Figure 2 uses a 7C9 buffer to interface between 5V logic and the LT27. The switching time between the active and shutdown states is less than µs. A 2k pull-up resistor speeds up the turn-off time and insures that the amplifier is completely turned off. Because the pin is referenced to the positive supply, the logic used should have a breakdown voltage of greater than the positive supply voltage. No other circuitry is necessary as the internal circuit limits the Shutdown pin current to about 5µA. Figure 3 shows the resulting waveforms. ENABLE V IN 5V 7C96 /2 LT27 SHDN 5V 5V R F 5V 2k LT27 F2 Figure 2. Shutdown Interface R G V OT Shutdown/Current Set If the shutdown feature is not used, the Shutdown pins must be connected to ground or V. Each amplifier has a separate Shutdown pin which can be used to either turn off the amplifier, which reduces the amplifier supply current to less than 2µA, or to control the supply current in normal operation. The supply current in each amplifier is controlled by the current flowing out of the Shutdown pin. When the Shutdown pin is open or driven to the positive supply, the amplifier is shut down. In the shutdown mode, the output looks like a pf capacitor and the supply current is ENABLE VOT A V = R F = 825Ω R L = 5Ω R P = 2k V IN = V P-P Figure 3. Shutdown Operation LT27 F3 For applications where the full bandwidth of the amplifier is not required, the quiescent current may be reduced by connecting a resistor from the Shutdown pin to ground. 9

10 LT27 APPLICATI O S I FOR W ATIO The amplifier s supply current will be approximately times the current in the Shutdown pin. The voltage across the resistor in this condition is V 3V BE. For example, a 6k resistor will set the amplifier s supply current to ma with. The photos (Figures a and b) show the effect of reducing the quiescent supply current on the large-signal response. The quiescent current can be reduced to 5mA in the inverting configuration without much change in response. In noninverting mode, however, the slew rate is reduced as the quiescent current is reduced. and for higher gains in the noninverting mode, the signal amplitude on the input pins is small and the overall slew rate is that of the output stage. The input stage slew rate is related to the quiescent current and will be reduced as the supply current is reduced. The output slew rate is set by the value of the feedback resistors and the internal capacitance. Larger feedback resistors will reduce the slew rate as will lower supply voltages, similar to the way the bandwidth is reduced. The photos (Figures 5a, 5b and 5c) show the large-signal response of the LT27 or various gain configurations. The slew rate varies from 86V/µs for a gain of, to V/µs for a gain of. When the LT27 is used to drive capacitive loads, the available output current can limit the overall slew rate. In the fastest configuration, the LT27 is capable of a slew rate of over V/ns. The current required to slew a capacitor R F = 75Ω R L = 5Ω I Q = 5mA, ma, 2mA LT27 Fa Figure a. Large-Signal Response vs I Q, A V = R F = 825Ω R L = 5Ω LT27 F5a Figure 5a. Large-Signal Response, A V = R F = 75Ω R L = 5Ω I Q = 5mA, ma, 2mA LT27 Fb Figure b. Large-Signal Response vs I Q, A V = 2 Slew Rate nlike a traditional op amp, the slew rate of a current feedback amplifier is not independent of the amplifier gain configuration. There are slew rate limitations in both the input stage and the output stage. In the inverting mode, R F = RG = 75Ω R L = 5Ω LT27 F5b Figure 5b. Large-Signal Response, A V =

11 LT27 APPLICATI O S I FOR W ATIO Capacitance on the Inverting Input Current feedback amplifiers require 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. R F = 75Ω R L = 5Ω LT27 F5c Figure 5c. Large-Signal Response, A V = 2 at this rate is ma per picofarad of capacitance, so,pf would require A! The photo (Figure 6) shows the large-signal behavior with C L =,pf. The slew rate is about 6V/µs, determined by the current limit of 6mA. R F = RG = 3k R L = LT27 F6 Figure 6. Large-Signal Response, C L =,pf Differential Input Signal Swing The differential input swing is limited to about ±6V by an ESD protection device connected between the inputs. In normal operation, the differential voltage between the input pins is small, so this clamp has no effect; however, in the shutdown mode the differential swing can be the same as the input swing. The clamp voltage will then set the maximum allowable input voltage. To allow for some margin, it is recommended that the input signal be less than ±5V when the device is shut down. Power Supplies The LT27 will operate from single or split supplies from ±5V (V total) to ±5V (3V 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 5µV per volt of supply mismatch. The inverting bias current can change as much as 5µA per volt of supply mismatch, though typically the change is less than.5µa per volt. Thermal Considerations Each amplifier in the LT27 includes a separate thermal shutdown circuit which protects against excessive internal (junction) temperature. If the junction temperature exceeds the protection threshold, the amplifier will begin cycling between normal operation and an off state. The cycling is not harmful to the part. The thermal cycling occurs at a slow rate, typically ms to several seconds, which depends on the power dissipation and the thermal time constants of the package and heat sinking. Raising the ambient temperature until the device begins thermal shutdown gives a good indication of how much margin there is in the thermal design. Heat flows away from the amplifier through the package s copper lead frame. Heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Experiments have shown that the heat spreading copper layer does not need to be electrically connected to the tab of the device. The PCB material can be very effective at transmitting heat between the pad area attached to the tab of the device and a ground or power plane layer either inside or on the opposite side of the board. Although the actual thermal resistance of the PCB material is high, the length/area ratio of the thermal

12 LT27 APPLICATI O S I FOR W ATIO resistance between the layer is small. Copper board stiffeners and plated through holes can also be used to spread the heat generated by the device. Table lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 3/32" FR- board with 2oz copper. This data can be used as a rough guideline in estimating thermal resistance. The thermal resistance for each application will be affected by thermal interactions with other components as well as board size and shape. Table. Fused 6-Lead SO Package COPPER AREA (2oz) TOTAL THERMAL RESISTANCE TOPSIDE BACKSIDE COPPER AREA (JNCTION-TO-AMBIENT) 25 sq. mm 25 sq. mm 5 sq. mm C/W sq. mm 25 sq. mm 35 sq. mm 6 C/W 6 sq. mm 25 sq. mm 3 sq. mm 8 C/W 8 sq. mm 25 sq. mm 268 sq. mm 9 C/W 8 sq. mm sq. mm 8 sq. mm 56 C/W 8 sq. mm 6 sq. mm 78 sq. mm 58 C/W 8 sq. mm 3 sq. mm 8 sq. mm 59 C/W 8 sq. mm sq. mm 28 sq. mm 6 C/W 8 sq. mm sq. mm 8 sq. mm 6 C/W THERMAL RESISTANCE ( C/W) COPPER AREA (mm 2 ) LT27 F7 Figure 7. Thermal Resistance vs Total Copper Area (Top Bottom) Calculating Junction Temperature The junction temperature can be calculated from the equation: T J = (P D )(θ JA ) T A where: T J = Junction Temperature T A = Ambient Temperature P D = Device Dissipation θ JA = Thermal Resistance (Junction-to-Ambient) As an example, calculate the junction temperature for the circuit in Figure 8 assuming a 7 C ambient temperature. The device dissipation can be found by measuring the supply currents, calculating the total dissipation and then subtracting the dissipation in the load and feedback network. 33Ω 5V I /2 LT27 SHDN 5V 37.5mA.µF The dissipation for each amplifier is: P D = (37.5mA)(3V) (2V) 2 /( ) =.837W The total dissipation is P D =.67W. When a 25 sq mm PC board with 2oz copper on top and bottom is used, the thermal resistance is C/W. The junction temperature T J is: T J = (.67W)( C/W) 7 C = 37 C The maximum junction temperature for the LT27 is 5 C, so the heat sinking capability of the board is adequate for the application. If the copper area on the PC board is reduced to 28mm 2 the thermal resistance increases to 6 C/W and the junction temperature becomes: T J = (.67W)(6 C/W) 7 C = 7 C Which is above the maximum junction temperature indicating that the heat sinking capability of the board is inadequate and should be increased. 2pF Figure 8. Thermal Calculation Example f = 2MHz 2V 2V LT26 F7 2

13 LT27 TYPICAL APPLICATIO S Gain of Eleven High Current Amplifier V IN LT97 5pF /2 LT27 COMP SHDN.µF OT 33Ω 3k k OTPT OFFSET: < 5µV SLEW RATE: 2V/µs BANDWIDTH: MHz STABLE WITH C L < nf LT27 TA2 Gain of Ten Buffered Line Driver 5V µf LT5 µf 5V µf /2 LT27 SHDN.µF OTPT R L 5V 68pF µf 56Ω 5V 56Ω 99Ω Ω LT27 TA3 R L = 32Ω V O = 5V RMS THD NOISE =.9% AT Hz =.% AT 2kHz SMALL-SIGNAL.dB BANDWIDTH = 6kHz 3

14 LT27 TYPICAL APPLICATIO S CMOS Logic to Shutdown Interface Distribution Amplifier 5V /2 LT27 SHDN 2k V IN 75Ω /2 LT27 SHDN R F 75Ω 75Ω 75Ω CABLE LT27 TA5 75Ω 5V k 5V 2N39 LT27 TA R G 75Ω Buffer A V = Differential Output Driver V IN /2 LT27 COMP SHDN.µF* R F ** V OT *OPTIONAL, SE WITH CAPACITIVE LOADS ** VALE OF R F DEPENDS ON SPPLY VOLTAGE AND LOADING. SELECT FROM TYPICAL AC PERFORMANCE TABLE OR DETERMINE EMPIRICALLY V IN /2 LT27.µF LT27 TA6 5Ω V OT Differential Input Differential Output Power Amplifier (A V = ) /2 LT27 /2 LT27.µF LT27 TA7 V IN V OT /2 LT27 LT27 TA8

15 LT27 TYPICAL APPLICATIO S Paralleling Both CFAs for Guaranteed 5mA Output Drive Current V IN /2 LT27 3Ω VOT /2 LT27 3Ω LT27 TA9 PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. S Package 6-Lead Plastic Small Outline (Narrow.5) (LTC DWG # 5-8-6) * (9.8.8) ( ).5.57** ( ).8. (.23.25)..2 (.25.58) 5 8 TYP ( ) (..25) *DIMENSION DOES NOT INCLDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED.6" (.52mm) PER SIDE ** DIMENSION DOES NOT INCLDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED." (.25mm) PER SIDE..9 ( ).5 (.27) TYP 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 circuits as described herein will not infringe on existing patent rights. S

16 LT27 TYPICAL APPLICATION CCD Clock Driver. Two 3rd Order Gaussian Filters Produce Clean CCD Clock Signals 5pF CCD ARRAY LOAD CLOCK INPT CLK Q 7HC7 D Q pf 9pF 2V /2 LT27.µF Ω 33pF 5Ω 5pF CLOCK INPT 5 pf 9pF /2 LT27 V.µF Ω 33pF 5 LT27 TA DRIVER OTPT 5Ω RELATED PARTS PART NMBER DESCRIPTION COMMENTS LT26 Single 25mA/6MHz Current Feedback Amplifier Single Version of LT27, 9V/µs Slew Rate,.2% Differential Gain,.7 Differential Phase, with A V = 2 and R L = 3Ω, Stable with C L =,pf, Shutdown Control Reduces Supply Current to 2µA LT2 Single A/3MHz Current Feedback Amplifier Higher Output Current Version of LT26 LT229/LT23 Dual/Quad MHz Current Feedback Amplifiers Low Cost CFA for Video Applications, V/µs Slew Rate, 3mA Output Drive Current,.% Differential Gain,. Differential Phase, with A V = 2 and R L = 5Ω, 9.5mA Max Supply Current per Op Amp, ±2V to ±5V Supply Range LT36/LT36/LT362 Single/Dual/Quad 5MHz, 8V/µs, Fast Settling Voltage Feedback Amplifier, 6ns Settling Time to.%, C-Load TM Op Amps V Step, 5mA Max Supply Current per Op Amp, 9nV Hz Input Noise Voltage, Drives All Capacitive Loads, mv Max V OS,.2% Differential Gain,.3 Differential Phase with A V = 2 and R L = 5Ω C-Load is a trademark of Linear Technology Corporation 6 LT/GP 96 K PRINTED IN SA Linear Technology Corporation 63 McCarthy Blvd., Milpitas, CA (8) 32-9 FAX: (8) 3-57 TELEX: LINEAR TECHNOLOGY CORPORATION 996