LT1207 Dual 250mA/60MHz Current Feedback Amplifier FEATURES DESCRIPTIOU n 250mA Minimum Output Drive Current The LT®1207 is a dual version of the LT1206 high speed n 60MHz Bandwidth, A = 2, R = 100W current feedback amplifier. Like the LT1206, each CFA in V L n 900V/m s Slew Rate, A = 2, R = 50W the dual has excellent video characteristics: 60MHz band- V L n 0.02% Differential Gain, A = 2, R = 30W width, 250mA minimum output drive current, 400V/m s V L n 0.17(cid:176) Differential Phase, A = 2, R = 30W minimum slew rate, low differential gain (0.02% typ) and V L n High Input Impedance: 10MW low differential phase (0.17(cid:176) typ). The LT1207 includes a n Shutdown Mode: I < 200m A per Amplifier pin for an optional compensation network which stabi- S n Stable with C = 10,000pF lizes the amplifier for heavy capacitive loads. Both ampli- L fiers have thermal and current limit circuits which protect APPLICATIOU S against fault conditions. These capabilities make the LT1207 well suited for driving difficult loads such as cables in video n ADSL/HDSL Drivers or digital communication systems. n Video Amplifiers n Cable Drivers Operation is fully specified from – 5V to – 15V supplies. n RGB Amplifiers Supply current is typically 20mA per amplifier. Two n Test Equipment Amplifiers micropower shutdown controls place each amplifier in a n Buffers high impedance low current mode, dropping supply current to 200m A per amplifier. For reduced bandwidth applications, supply current can be lowered by adding a resistor in series with the Shutdown pin. The LT1207 is manufactured on Linear Technology's complementary bipolar process and is available in a low thermal resistance 16-lead SO package. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIONU HDSL Driver 5V + 0.1µF*(cid:13) 2.2µF**(cid:13) (cid:13) (cid:13) VIN + SHDN A 1/2 LT1207 62Ω – L1 720Ω 15k 240Ω 720Ω 720Ω – *(cid:13)CERAMIC(cid:13) SHDN B 62Ω **TANTALUM(cid:13) 1/2 LT1207 L1 =(cid:9)TRANSPOWER SMPT–308 (cid:13) 15k + (cid:9) OR SIMILAR DEVICE –5V 0.1µF*(cid:13) +2.2µF**(cid:13) (cid:13) (cid:13) 1207 • TA01 1

LT1207 ABSOLUTE WAXIWUW RATIUGS PACKAGE/ORDER IUFORWATIOU Supply Voltage ..................................................... – 18V ORDER PART Input Current per Amplifier............................... – 15mA TOP VIEW NUMBER Output Short-Circuit Duration (Note 1)....... Continuous V+(cid:13) 1(cid:13) 16(cid:13) V+(cid:13) Specified Temperature Range (Note 2)...... 0(cid:176) C to 70(cid:176) C –IN A(cid:13) 2(cid:13) 15(cid:13) OUT A(cid:13) LT1207CS Operating Temperature Range............... –40(cid:176) C to 85(cid:176) C +IN A(cid:13) 3(cid:13) 14(cid:13) V– A(cid:13) Junction Temperature......................................... 150(cid:176) C SHDN A(cid:13) 4(cid:13) 13(cid:13) COMP A(cid:13) –IN B(cid:13) 5(cid:13) 12(cid:13) OUT B(cid:13) Storage Temperature Range.................–65(cid:176) C to 150(cid:176) C Lead Temperature (Soldering, 10 sec)................. 300(cid:176) C +IN B(cid:13) 6(cid:13) 11(cid:13) V– B(cid:13) SHDN B(cid:13) 7(cid:13) 10(cid:13) COMP B(cid:13) V+ 8 9 V+(cid:13) (cid:13) S PACKAGE(cid:13) 16-LEAD PLASTIC SO q JA = 40(cid:176)C/W (NOTE 3) Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS V = 0, – 5V £ V £ – 15V, pulse tested, V = 0V, V = 0V, unless otherwise noted. CM S SHDN A SHDN B SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Offset Voltage T = 25(cid:176) C – 3 – 10 mV OS A l – 15 mV Input Offset Voltage Drift l 10 m V/(cid:176) C I + Noninverting Input Current T = 25(cid:176) C – 2 – 5 m A IN A l – 20 m A I – Inverting Input Current T = 25(cid:176) C – 10 – 60 m A IN A l – 100 m A e Input Noise Voltage Density f = 10kHz, R = 1k, R = 10W , R = 0W 3.6 nV/(cid:214) Hz n F G S +i Input Noise Current Density f = 10kHz, R = 1k, R = 10W , R = 10k 2 pA/(cid:214) Hz n F G S –i Input Noise Current Density f = 10kHz, R = 1k, R = 10W , R = 10k 30 pA/(cid:214) Hz n F G S R Input Resistance V = – 12V, V = – 15V l 1.5 10 MW IN IN S V = – 2V, V = – 5V l 0.5 5 MW IN S C Input Capacitance V = – 15V 2 pF IN S Input Voltage Range V = – 15V l – 12 – 13.5 V S V = – 5V l – 2 – 3.5 V S CMRR Common Mode Rejection Ratio V = – 15V, V = – 12V l 55 62 dB S CM V = – 5V, V = – 2V l 50 60 dB S CM Inverting Input Current V = – 15V, V = – 12V l 0.1 10 m A/V S CM Common Mode Rejection V = – 5V, V = – 2V l 0.1 10 m A/V S CM PSRR Power Supply Rejection Ratio V = – 5V to – 15V l 60 77 dB S 2

LT1207 ELECTRICAL CHARACTERISTICS V = 0, – 5V £ V £ – 15V, pulse tested, V = 0V, V = 0V, unless otherwise noted. CM S SHDN A SHDN B SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Noninverting Input Current V = – 5V to – 15V l 30 500 nA/V S Power Supply Rejection Inverting Input Current V = – 5V to – 15V l 0.7 5 m A/V S Power Supply Rejection A Large-Signal Voltage Gain V = – 15V, V = – 10V, R = 50W l 55 71 dB V S OUT L V = – 5V, V = – 2V, R = 25W l 55 68 dB S OUT L R Transresistance, D V /D I – V = – 15V, V = – 10V, R = 50W l 100 260 kW OL OUT IN S OUT L V = – 5V, V = – 2V, R = 25W l 75 200 kW S OUT L V Maximum Output Voltage Swing V = – 15V, R = 50W , T = 25(cid:176) C – 11.5 – 12.5 V OUT S L A l – 10.0 V V = – 5V, R = 25W , T = 25(cid:176) C – 2.5 – 3.0 V S L A l – 2.0 V I Maximum Output Current R = 1W l 250 500 1200 mA OUT L I Supply Current per Amplifier V = – 15V, V = 0V, T = 25(cid:176) C 20 30 mA S S SHDN A l 35 mA Supply Current per Amplifier, V = – 15V, T = 25(cid:176) C 12 17 mA S A R = 51k (Note 4) SHDN Positive Supply Current V = – 15V, V = 15V, V = 15V l 200 m A S SHDN A SHDN B per Amplifier, Shutdown Output Leakage Current, Shutdown V = – 15V, V = 15V, V = 0V l 10 m A S SHDN OUT SR Slew Rate (Note 5) A = 2, T = 25(cid:176) C 400 900 V/m s V A Differential Gain (Note 6) V = – 15V, R = 560W , R = 560W , R = 30W 0.02 % S F G L Differential Phase (Note 6) V = – 15V, R = 560W , R = 560W , R = 30W 0.17 DEG S F G L BW Small-Signal Bandwidth V = – 15V, Peaking £ 0.5dB 60 MHz S R = R = 620W , R = 100W F G L V = – 15V, Peaking £ 0.5dB 52 MHz S R = R = 649W , R = 50W F G L V = – 15V, Peaking £ 0.5dB 43 MHz S R = R = 698W , R = 30W F G L V = – 15V, Peaking £ 0.5dB 27 MHz S R = R = 825W , R = 10W F G L The l denotes specifications which apply for 0(cid:176) C £ T £ 70(cid:176) C. Note 3: Thermal resistance q varies from 40(cid:176) C/W to 60(cid:176) C/W depending A JA Note 1: Applies to short circuits to ground only. A short circuit between upon the amount of PC board metal attached to the device. q JA is specified the output and either supply may permanently damage the part when for a 2500mm2 test board covered with 2oz copper on both sides. operated on supplies greater than – 10V. Note 4: R is connected between the Shutdown pin and ground. SHDN Note 2: Commercial grade parts are designed to operate over the Note 5: Slew rate is measured at – 5V on a – 10V output signal while temperature range of –40(cid:176) C to 85(cid:176) C but are neither tested nor guaranteed operating on – 15V supplies with R = 1.5k, R = 1.5k and R = 400W . F G L beyond 0(cid:176) C to 70(cid:176) C. Industrial grade parts tested over –40(cid:176) C to 85(cid:176) C are Note 6: NTSC composite video with an output level of 2V. available on special request. Consult factory. 3

LT1207 SW ALL-SIGU AL BAU DWIDTH I = 20mA per Amplifier Typical, Peaking £ 0.1dB S –3dB BW –0.1dB BW –3dB BW –0.1dB BW A R R R (MHz) (MHz) A R R R (MHz) (MHz) V L F G V L F G V = – 5V, R = 0W V = – 15V, R = 0W S SHDN S SHDN –1 150 562 562 48 21.4 –1 150 681 681 50 19.2 30 649 649 34 17 30 768 768 35 17 10 732 732 22 12.5 10 887 887 24 12.3 1 150 619 – 54 22.3 1 150 768 – 66 22.4 30 715 – 36 17.5 30 909 – 37 17.5 10 806 – 22.4 11.5 10 1k – 23 12 2 150 576 576 48 20.7 2 150 665 665 55 23 30 649 649 35 18.1 30 787 787 36 18.5 10 750 750 22.4 11.7 10 931 931 22.5 11.8 10 150 442 48.7 40 19.2 10 150 487 536 44 20.7 30 511 56.2 31 16.5 30 590 64.9 33 17.5 10 649 71.5 20 10.2 10 768 84.5 20.7 10.8 I = 10mA per Amplifier Typical, Peaking £ 0.1dB S –3dB BW –0.1dB BW –3dB BW –0.1dB BW AV RL RF RG (MHz) (MHz) AV RL RF RG (MHz) (MHz) VS = – 5V, RSHDN = 10.2k VS = – 15V, RSHDN = 60.4k –1 150 576 576 35 17 –1 150 634 634 41 19.1 30 681 681 25 12.5 30 768 768 26.5 14 10 750 750 16.4 8.7 10 866 866 17 9.4 1 150 665 – 37 17.5 1 150 768 – 44 18.8 30 768 – 25 12.6 30 909 – 28 14.4 10 845 – 16.5 8.2 10 1k – 16.8 8.3 2 150 590 590 35 16.8 2 150 649 649 40 18.5 30 681 681 25 13.4 30 787 787 27 14.1 10 768 768 16.2 8.1 10 931 931 16.5 8.1 10 150 301 33.2 31 15.6 10 150 301 33.2 33 15.6 30 392 43.2 23 11.9 30 402 44.2 25 13.3 10 499 54.9 15 7.8 10 590 64.9 15.3 7.4 I = 5mA per Amplifier Typical, Peaking £ 0.1dB S –3dB BW –0.1dB BW –3dB BW –0.1dB BW A R R R (MHz) (MHz) A R R R (MHz) (MHz) V L F G V L F G V = – 5V, R = 22.1k V = – 15V, R = 121k S SHDN S SHDN –1 150 604 604 21 10.5 –1 150 619 619 25 12.5 30 715 715 14.6 7.4 30 787 787 15.8 8.5 10 681 681 10.5 6.0 10 825 825 10.5 5.4 1 150 768 – 20 9.6 1 150 845 – 23 10.6 30 866 – 14.1 6.7 30 1k – 15.3 7.6 10 825 – 9.8 5.1 10 1k – 10 5.2 2 150 634 634 20 9.6 2 150 681 681 23 10.2 30 750 750 14.1 7.2 30 845 845 15 7.7 10 732 732 9.6 5.1 10 866 866 10 5.4 10 150 100 11.1 16.2 5.8 10 150 100 11.1 15.9 4.5 30 100 11.1 13.4 7.0 30 100 11.1 13.6 6 10 100 11.1 9.5 4.7 10 100 11.1 9.6 4.5 4

LT1207 TYPICAL PERFORW AU CE CHARACTERISTICS Bandwidth and Feedback Resistance Bandwidth vs Supply Voltage Bandwidth vs Supply Voltage vs Capacitive Load for 0.5dB Peak 100 50 10k 100 90 PPEEAAKKIINNGG ££ 05.d5BdB(cid:13) RAVL == 21(cid:13)00W PPEEAAKKIINNGG ££ 05.d5BdB(cid:13) RAVL == 21(cid:13)0W BANDWIDTH 80 40 WIDTH (MHz) 657000 RF = 470W RF = 560W RF = 680W WIDTH (MHz) 30 RRFF == 576500WW WESISTOR () 1k 10 –3dB BANDW –3dB BAND 342000 RF =R F7 5=0 1Wk –3dB BAND 2100 RFR =F 1=k 2k FEEDBACK R RFAEVLE ==D 2¥B(cid:13)A(cid:13)CK RESISTOR IDTH (MHz) 10 VS = – 15V(cid:13) RF = 1.5k CCOMP = 0.01m F 0 0 100 1 4 6 8 10 12 14 16 18 4 6 8 10 12 14 16 18 1 10 100 1000 10000 SUPPLY VOLTAGE (– V) SUPPLY VOLTAGE (– V) CAPACITIVE LOAD (pF) LT1207 • TPC01 LT1207 • TPC02 LT1207 • TPC03 Bandwidth and Feedback Resistance Bandwidth vs Supply Voltage Bandwidth vs Supply Voltage vs Capacitive Load for 5dB Peak 100 50 10k(cid:13) 100 90 PPEEAAKKIINNGG ££ 05.d5BdB(cid:13) RAVL == 1100(cid:13)0W PPEEAAKKIINNGG ££ 05.d5BdB(cid:13) RAVL == 1100(cid:13)W BANDWIDTH 80 40 (cid:13) WIDTH (MHz) 657000 RF =390W RF = 330W WIDTH (MHz) 30 RF = 560W WESISTOR () 1k(cid:13) 10 –3dB BANDW –3dB BAND 342000 RRFF == 467800WW –3dB BAND 2100 RRRFFF === 6118k.50kW FEEDBACK R (cid:13)(cid:13) FEEDBACK RESISTOR RAVL == +¥ 2(cid:13)(cid:13) IDTH (MHz) 10 VS = – 15V(cid:13) RF = 1.5k CCOMP = 0.01m F 0 0 10000 1 4 6 8 10 12 14 16 18 4 6 8 10 12 14 16 18 1 10 100 1k 10k SUPPLY VOLTAGE (– V) SUPPLY VOLTAGE (– V) CAPACITIVE LOAD (pF) LT1207 • TPC04 LT1207 • TPC05 LT1207 • TPC06 Differential Phase Differential Gain Spot Noise Voltage and Current vs Supply Voltage vs Supply Voltage vs Frequency 0.50 0.10 100 RF = RG = 560W G)0.40 RL = 15W 0.08 RL = 15W ANV P =A C2K(cid:13) AGE Hz) –in DE %) (cid:214)A/ E ( N ( R p DIFFERENTIAL PHAS000...123000 ANRV FP ==A CR2K(cid:13)GA =G 5E60W RRLL == 3500WW DIFFERENTIAL GAI000...000246 RL = 30W RL = 50W (cid:214)POT NOISE (nV/Hz O 10 einn RL = 150W RL = 150W S 0 0 1 5 7 9 11 13 15 5 7 9 11 13 15 10 100 1k 10k 100k SUPPLY VOLTAGE (– V) SUPPLY VOLTAGE (– V) FREQUENCY (Hz) LT1207 • TPC07 LT1207 • TPC08 LT1207 • TPC09 5

LT1207 TYPICAL PERFORW AU CE CHARACTERISTICS Supply Current vs Supply Current vs Supply Current vs Supply Voltage Ambient Temperature, V = – 5V Ambient Temperature, V = – 15V S S 24 25 25 R (mA) 22 VSHDN = 0V TJ = –40˚C R (mA) 20 RSD = 0W RAVL == 1¥ (cid:13) R (mA) 20 RSD = 0W RAVL == 1¥ (cid:13) E E E LIFI 20 LIFI LIFI R AMP 18 TJ = 25˚C R AMP 15 R AMP 15 E E E ENT P 16 TJ = 85˚C ENT P 10 RSD = 10.2k ENT P 10 RSD = 60.4k R R R R R R LY CU 14 TJ = 125˚C LY CU 5 RSD = 22.1k LY CU 5 RSD = 121k PP 12 PP PP U U U S S S 10 0 0 4 6 8 10 12 14 16 18 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 SUPPLY VOLTAGE (– V) TEMPERATURE (°C) TEMPERATURE (°C) LT1207 • TPC10 LT1207 • TPC11 LT1207 • TPC12 Supply Current Input Common Mode Limit Output Short-Circuit Current vs Shutdown Pin Current vs Junction Temperature vs Junction Temperature 20 V+ 1.0 SUPPLY CURRENT PER AMPLIFIER (mA) 11111426488620 VS = – 15V COMMON MODE RANGE (V)––––12211010........00050555 (cid:13)OUTPUT SHORT-CIRCUIT CURRENT (A) 000000......765984 SINSKOINUGRCING 0 V– 0.3 0 100 200 300 400 500 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 SHUTDOWN PIN CURRENT (m A) TEMPERATURE (°C) TEMPERATURE (°C) LT1207 • TPC13 LT1207 • TPC14 LT1207 • TPC15 Output Saturation Voltage Power Supply Rejection Ratio Supply Current vs Large-Signal vs Junction Temperature vs Frequency Output Frequency (No Load) V+ 70 60 OUTPUT SATURATION VOLTAGE (V) ––––24432131 VS = – 15V RRRRLLLL ==== 2552k00kWW POWER SUPPLY REJECTION (dB) 465312000000 NPOEGSAITTIIVVEE VRRSLF === R–50G1W 5=V(cid:13) 1(cid:13)k UPPLY CURRENT PER AMPLIFIER (mA) 45320000 RVAVVSOL U===T 2–¥=(cid:13)1 (cid:13)250VV(cid:13)P-P S V– 0 10 –50 –25 0 25 50 75 100 125 10k 100k 1M 10M 100M 10k 100k 1M 10M TEMPERATURE (°C) FREQUENCY (Hz) FREQUENCY (Hz) LT1207 • TPC16 LT1207 • TPC17 LT1207 • TPC18 6

LT1207 TYPICAL PERFORW AU CE CHARACTERISTICS Output Impedance in Shutdown 2nd and 3rd Harmonic Distortion Output Impedance vs Frequency vs Frequency vs Frequency 100 100k –30 VS = – 15V(cid:13) AV = 1(cid:13) VS = – 15V(cid:13) IO = 0mA RF = 1k(cid:13) VO = 2VP-P ) 10 RSHDN = 121k )10k VS = – 15V –40 RL = 10W 2nd WPEDANCE ( 1 RSHDN = 0W WPEDANCE ( 1k TION (dBc)––5600 23nrdd M M R T I T I TO UTPU0.1 UTPU100 DIS–70 RL = 30W 3rd O O –80 0.01 10 –90 100k 1M 10M 100M 100k 1M 10M 100M 1 2 3 4 5 6 7 8 910 FREQUENCY (MHz) FREQUENCY (Hz) FREQUENCY (Hz) LT1207 • TPC19 LT1207 • TPC20 LT1207 • TPC21 3rd Order Intercept vs Frequency Test Circuit for 3rd Order Intercept 60 RVSL == –501W5V(cid:13)(cid:13) + Bm) 50 RRFG == 56940.9WW(cid:13) 1/2 LT1207 PO T (d – P RCE 40 590W (cid:13) TE (cid:13) N ER I 30 65W (cid:13) 50W (cid:13) ORD (cid:13)MEASURE INTERCEPT AT PO (cid:13) 3rd 20 LT1207 • TPC23 10 0 5 10 15 20 25 30 FREQUENCY (MHz) LT1207 • TPC22 7

LT1207 SIW PLIFIED SCHEW ATIC V+ TO ALL(cid:13) CURRENT(cid:13) Q5 SOURCES Q10 Q2 D1 Q11 Q18 Q1 Q6 Q15 Q17 Q9 V– 1.25k V– 50W +IN –IN CC RC COMP OUTPUT V+ SHUTDOWN V+ Q12 Q3 Q8 Q16 Q14 Q4 D2 Q13 Q7 V(cid:16)– 1/2 LT1207 CURRENT FEEDBACK AMPLIFIER LT1207 • SS APPLICATIOUS IUFORWATIOU The LT1207 is a dual current feedback amplifier with high line when the response has 0.5dB to 5dB of peaking. The output current drive capability. The device is stable with curves stop where the response has more than 5dB of large capacitive loads and can easily supply the high peaking. currents required by capacitive loads. The amplifier will For resistive loads, the COMP pin should be left open (see drive low impedance loads such as cables with excellent section on capacitive loads). linearity at high frequencies. Capacitive Loads Feedback Resistor Selection Each amplifier in the LT1207 includes an optional com- The optimum value for the feedback resistors is a function pensation network for driving capacitive loads. This net- of the operating conditions of the device, the load imped- work eliminates most of the output stage peaking associ- ance and the desired flatness of response. The Typical AC ated with capacitive loads, allowing the frequency re- Performance tables give the values which result in the sponse to be flattened. Figure 1 shows the effect of the highest 0.1dB and 0.5dB bandwidths for various resistive network on a 200pF load. Without the optional compensa- loads and operating conditions. If this level of flatness is tion, there is a 5dB peak at 40MHz caused by the effect of not required, a higher bandwidth can be obtained by use the capacitance on the output stage. Adding a 0.01m F of a lower feedback resistor. The characteristic curves of bypass capacitor between the output and the COMP pins Bandwidth vs Supply Voltage indicate feedback resistors connects the compensation and completely eliminates the for peaking up to 5dB. These curves use a solid line when peaking. A lower value feedback resistor can now be used, the response has less than 0.5dB of peaking and a dashed resulting in a response which is flat to 0.35dB to 30MHz. 8

LT1207 APPLICATIOUS IUFORWATIOU 12 typically 100m A. Each Shutdown pin is referenced to the VS = – 15V 10 positive supply through an internal bias circuit (see the 8 RF = 1.2k(cid:13) Simplified Schematic). An easy way to force shutdown is COMPENSATION B) 6 to use open drain (collector) logic. The circuit shown in d AIN ( 4 Figure 2 uses a 74C904 buffer to interface between 5V GE G 2 NO COMPENSRAFT =IO 2Nk(cid:13) logic and the LT1207. The switching time between the A 0 LT active and shutdown states is less than 1m s. A 24k pull-up VO –2 RF = 2k(cid:13) COMPENSATION resistor speeds up the turn-off time and insures that the –4 amplifier is completely turned off. Because the pin is –6 referenced to the positive supply, the logic used should –8 1 10 100 have a breakdown voltage of greater than the positive FREQUENCY (MHz) supply voltage. No other circuitry is necessary as the LT1207 • F01 internal circuit limits the Shutdown pin current to about Figure 1. 500m A. Figure 3 shows the resulting waveforms. The network has the greatest effect for C in the range of L 15V 0pF to 1000pF. The graph of Maximum Capacitive Load vs Feedback Resistor can be used to select the appropriate VIN + 1/2 LT1207 VOUT value of the feedback resistor. The values shown are for SHDN – 0.5dB and 5dB peaking at a gain of 2 with no resistive load. This is a worst-case condition, as the amplifier is more stable –15V RF at higher gains and with some resistive load in parallel with the capacitance. Also shown is the –3dB bandwidth with the 15V RG suggested feedback resistor vs the load capacitance. 5V 24k ENABLE Although the optional compensation works well with 74C906 LT1207 • F02 capacitive loads, it simply reduces the bandwidth when it is connected with resistive loads. For instance, with a 30W Figure 2. Shutdown Interface load, the bandwidth drops from 55MHz to 35MHz when the compensation is connected. Hence, the compensation was made optional. To disconnect the optional compensa- tion, leave the COMP pin open. Shutdown/Current Set OUT V 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 E L B A used to either turn off the amplifier, which reduces the N E amplifier supply current to less than 200m A, or to control the supply current in normal operation. AV = 1 RPU = 24k LT1207 • F3 RF = 825W VIN = 1VP-P The supply current in each amplifier is controlled by the RL = 50W Figure 3. Shutdown Operation current flowing out of the Shutdown pin. When the Shut- down pin is open or driven to the positive supply, the For applications where the full bandwidth of the amplifier amplifier is shut down. In the shutdown mode, the output is not required, the quiescent current may be reduced by looks like a 40pF capacitor and the supply current is connecting a resistor from the Shutdown pin to ground. 9

LT1207 APPLICATIOUS IUFORWATIOU The amplifier’s supply current will be approximately 40 and for higher gains in the noninverting mode, the signal times the current in the Shutdown pin. The voltage across amplitude on the input pins is small and the overall slew the resistor in this condition is V+ – 3V . For example, a rate is that of the output stage. The input stage slew rate BE 60k resistor will set the amplifier’s supply current to 10mA is related to the quiescent current and will be reduced as with V = – 15V. the supply current is reduced. The output slew rate is set S by the value of the feedback resistors and the internal The photos (Figures 4a and 4b) show the effect of reducing capacitance. Larger feedback resistors will reduce the the quiescent supply current on the large-signal response. slew rate as will lower supply voltages, similar to the way The quiescent current can be reduced to 5mA in the the bandwidth is reduced. The photos (Figures 5a, 5b and inverting configuration without much change in response. 5c) show the large-signal response of the LT1207 or In noninverting mode, however, the slew rate is reduced various gain configurations. The slew rate varies from as the quiescent current is reduced. 860V/m s for a gain of 1, to 1400V/m s for a gain of –1. When the LT1207 is used to drive capacitive loads, the available output current can limit the overall slew rate. In the fastest configuration, the LT1207 is capable of a slew rate of over 1V/ns. The current required to slew a capacitor RF = 750W IQ = 5mA, 10mA, 20mA LT1207 • F04a RL = 50W VS = – 15V Figure 4a. Large-Signal Response vs I , A = –1 Q V RF = 825W VS = – 15V LT1207 • F05a RL = 50W Figure 5a. Large-Signal Response, A = 1 V RF = 750W IQ = 5mA, 10mA, 20mA LT1207 • F04b RL = 50W VS = – 15V Figure 4b. Large-Signal Response vs I , A = 2 Q V Slew Rate Unlike 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 RRFL == R50GW = 750W VS = – 15V LT1207 • F05b input stage and the output stage. In the inverting mode, Figure 5b. Large-Signal Response, A = –1 V 10

LT1207 APPLICATIOUS IUFORWATIOU 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 invert- ing 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. Power Supplies RF = 750W LT1207 • F05c The LT1207 will operate from single or split supplies from RL = 50W – 5V (10V total) to – 15V (30V total). It is not necessary to Figure 5c. Large-Signal Response, A = 2 V use equal value split supplies, however the offset voltage and inverting input bias current will change. The offset voltage changes about 500m V per volt of supply mis- at this rate is 1mA per picofarad of capacitance, so match. The inverting bias current can change as much as 10,000pF would require 10A! The photo (Figure 6) shows 5m A per volt of supply mismatch, though typically the the large-signal behavior with C = 10,000pF. The slew L rate is about 60V/m s, determined by the current limit of change is less than 0.5m A per volt. 600mA. Thermal Considerations Each amplifier in the LT1207 includes a separate thermal shutdown circuit which protects against excessive inter- nal (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 10ms 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 VS = – 15V RL = ¥ LT1207 • F06 shutdown gives a good indication of how much margin RF = RG = 3k there is in the thermal design. Figure 6. Large-Signal Response, C = 10,000pF L Heat flows away from the amplifier through the package’s Differential Input Signal Swing copper lead frame. Heat sinking is accomplished by using The differential input swing is limited to about – 6V by an the heat spreading capabilities of the PC board and its copper traces. Experiments have shown that the heat ESD protection device connected between the inputs. In spreading copper layer does not need to be electrically normal operation, the differential voltage between the connected to the tab of the device. The PCB material can input pins is small, so this clamp has no effect; however, be very effective at transmitting heat between the pad area in the shutdown mode the differential swing can be the attached to the tab of the device and a ground or power same as the input swing. The clamp voltage will then set plane layer either inside or on the opposite side of the the maximum allowable input voltage. To allow for some board. Although the actual thermal resistance of the PCB margin, it is recommended that the input signal be less than – 5V when the device is shut down. material is high, the length/area ratio of the thermal 11

LT1207 APPLICATIOUS IUFORWATIOU resistance between the layer is small. Copper board stiff- where: eners and plated through holes can also be used to spread T = Junction Temperature J the heat generated by the device. T = Ambient Temperature A Table 1 lists thermal resistance for several different board P = Device Dissipation D sizes and copper areas. All measurements were taken in q = Thermal Resistance (Junction-to-Ambient) JA still air on 3/32" FR-4 board with 2oz copper. This data can be used as a rough guideline in estimating thermal resis- As an example, calculate the junction temperature for the tance. The thermal resistance for each application will be circuit in Figure 8 assuming a 70(cid:176) C ambient temperature. affected by thermal interactions with other components as The device dissipation can be found by measuring the well as board size and shape. supply currents, calculating the total dissipation and then subtracting the dissipation in the load and feedback Table 1. Fused 16-Lead SO Package network. COPPER AREA (2oz) TOTAL THERMAL RESISTANCE TOPSIDE BACKSIDE COPPER AREA (JUNCTION-TO-AMBIENT) 15V 2500 sq. mm 2500 sq. mm 5000 sq. mm 40(cid:176) C/W I 37.5mA 1000 sq. mm 2500 sq. mm 3500 sq. mm 46(cid:176) C/W + 600 sq. mm 2500 sq. mm 3100 sq. mm 48(cid:176) C/W 12V 1/2 LT1207 180 sq. mm 2500 sq. mm 2680 sq. mm 49(cid:176) C/W 330W SHDN –12V 180 sq. mm 1000 sq. mm 1180 sq. mm 56(cid:176) C/W – 0.01m F f = 2MHz 1k 200pF 180 sq. mm 600 sq. mm 780 sq. mm 58(cid:176) C/W –15V 180 sq. mm 300 sq. mm 480 sq. mm 59(cid:176) C/W 1k LT1206 • F07 180 sq. mm 100 sq. mm 280 sq. mm 60(cid:176) C/W Figure 8. Thermal Calculation Example 180 sq. mm 0 sq. mm 180 sq. mm 61(cid:176) C/W The dissipation for each amplifier is: 70(cid:13) P = (37.5mA)(30V) – (12V)2/(1k||1k) = 0.837W 60(cid:13) D W) °E (C/ 50(cid:13) The total dissipation is PD = 1.674W. When a 2500 sq mm C PC board with 2oz copper on top and bottom is used, the N A 40(cid:13) SIST thermal resistance is 40(cid:176) C/W. The junction temperature TJ is: L RE 30(cid:13) T = (1.674W)(40(cid:176) C/W) + 70(cid:176) C = 137(cid:176) C A J RM 20(cid:13) HE The maximum junction temperature for the LT1207 is T 10(cid:13) 150(cid:176) C, so the heat sinking capability of the board is 0(cid:13) adequate for the application. 0 1000 2000 3000 4000 5000 (cid:13) COPPER AREA (mm2) If the copper area on the PC board is reduced to 280mm2 LT1207 • F07 the thermal resistance increases to 60(cid:176) C/W and the junc- Figure 7. Thermal Resistance vs Total Copper Area tion temperature becomes: (Top + Bottom) T = (1.674W)(60(cid:176) C/W) + 70(cid:176) C = 170(cid:176) C J Calculating Junction Temperature Which is above the maximum junction temperature indi- The junction temperature can be calculated from the cating that the heat sinking capability of the board is equation: inadequate and should be increased. T = (P )(q ) + T J D JA A 12

LT1207 TYPICAL APPLICATIOU S Gain of Eleven High Current Amplifier VIN + 1/2 LT1207 LT1097 + – COMP OUT SHDN – 0.01m F 500pF 330W 3k 10k OUTPUT OFFSET: <500m V(cid:13) LT1207 • TA02 1k SLEW RATE: 2V/m s(cid:13) BANDWIDTH: 4MHz(cid:13) STABLE WITH CL < 10nF Gain of Ten Buffered Line Driver 15V 1m F 15V 1m F + + + LT1115 + OUTPUT – 1/2 LT1207 1m F+ – SHDN 0.01m F RL –15V 1m F 68pF + –15V 560W 560W 909W LT1207 • TA03 100W RL = 32W (cid:13) VO = 5VRMS(cid:13) THD + NOISE = 0.0009% AT 1kHz(cid:13) (cid:9) = 0.004% AT 20kHz(cid:13) SMALL-SIGNAL 0.1dB BANDWIDTH = 600kHz 13

LT1207 TYPICAL APPLICATIOU S CMOS Logic to Shutdown Interface Distribution Amplifier 15V VIN + 75W 75W CABLE 75W 1/2 LT1207 + SHDN – 1/2 LT1207 24k RF 75W – SHDN 75W LT1207 • TA05 5V –15V LT1207 • TA04 RG 10k 75W 2N3904 Buffer A = 1 Differential Output Driver V VIN + 1/2 LT1207 VIN +1/2 LT1207 + COMP VOUT *(cid:13)OPTIONAL, USE WITH CAPACITIVE LOADS(cid:13) – SHDN 0.01m F* **VVOALLUTAEG OEF ARNFD D LEOPEANDDINSG O. NS ESLUEPCPTL (cid:13)Y(cid:13) – 0.01µF FROM TYPICAL AC PERFORMANCE (cid:13) TABLE OR DETERMINE EMPIRICALLY 1k RF** LT1207 • TA06 500Ω VOUT 1k 1k – Differential Input—Differential Output Power Amplifier (A = 4) V – 1/2 LT1207 + 0.01µF + + 1/2 LT1207 + LT1207 • TA07 – 1k VIN 1k VOUT 1k – – 1/2 LT1207 – + LT1207 • TA08 14

LT1207 TYPICAL APPLICATIOU S Paralleling Both CFAs for Guaranteed 500mA Output Drive Current VIN + 3Ω 1/2 LT1207 VOUT – 1k 1k + 3Ω 1/2 LT1207 – 1k LT1207 • TA09 1k PACKAGE DESCRIPTIOU Dimensions in inches (millimeters) unless otherwise noted. S Package 16-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.386 – 0.394*(cid:13) (9.804 – 10.008) 16 15 14 13 12 11 10 9 0.228 – 0.244(cid:13) 0.150 – 0.157**(cid:13) (5.791 – 6.197) (3.810 – 3.988) 1 2 3 4 5 6 7 8 0.010 – 0.020(cid:13) · 45(cid:176) 0.053 – 0.069(cid:13) (0.254 – 0.508) (1.346 – 1.752) 0.004 – 0.010(cid:13) 0.008 – 0.010(cid:13) (0.203 – 0.254) 0° – 8° TYP (0.101 – 0.254) 0.014 – 0.019(cid:13) 0.050(cid:13) 0.016 – 0.050(cid:13) (0.355 – 0.483) (1.270)(cid:13) 0.406 – 1.270 TYP S16 0695 *(cid:13)DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH (cid:13) (cid:13)SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE(cid:13) **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD (cid:13) FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE(cid:13) (cid:13) (cid:13) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 15 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of circuits as described herein will not infringe on existing patent rights.

LT1207 TYPICAL APPLICATIONU CCD Clock Driver. Two 3rd Order Gaussian Filters Produce Clean CCD Clock Signals 45pF CCD ARRAY LOAD 20V CLOCK(cid:13) CLK(cid:13) Q(cid:13) 1k 1k 1k + INPUT 10Ω 74HC74 100pF 91pF 1/2 LT1207 D Q – 3300pF 0.01µF 1k 510Ω 45pF 1k 1k 1k + 10Ω 100pF 91pF 1/2 LT1207 CLOCK(cid:13) 5(cid:13) – 3300pF INPUT 0 0.01µF –10V 1k 15(cid:13) LT1207 • TA10 DRIVER(cid:13) 510Ω OUTPUT 0 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1206 Single 250mA/60MHz Current Feedback Amplifier Single Version of LT1207, 900V/m s Slew Rate, 0.02% Differential Gain, 0.17(cid:176) Differential Phase, with A = 2 and R = 30W , Stable with V L C = 10,000pF, Shutdown Control Reduces Supply Current to 200m A L LT1210 Single 1A/30MHz Current Feedback Amplifier Higher Output Current Version of LT1206 LT1229/LT1230 Dual/Quad 100MHz Current Feedback Amplifiers Low Cost CFA for Video Applications, 1000V/m s Slew Rate, 30mA Output Drive Current, 0.04% Differential Gain, 0.1(cid:176) Differential Phase, with A = 2 and R = 150W , 9.5mA Max Supply Current per V L Op Amp, – 2V to – 15V Supply Range LT1360/LT1361/LT1362 Single/Dual/Quad 50MHz, 800V/m s, Fast Settling Voltage Feedback Amplifier, 60ns Settling Time to 0.1%, C-LoadTM Op Amps 10V Step, 5mA Max Supply Current per Op Amp, 9nV(cid:214) Hz Input Noise Voltage, Drives All Capacitive Loads, 1mV Max V , 0.2% Differential OS Gain, 0.3(cid:176) Differential Phase with A = 2 and R = 150W V L C-Load is a trademark of Linear Technology Corporation 16 Linear Technology Corporation LT/GP 0196 10K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l F AX: (408) 434-0507 l TELEX: 499-3977 ª LINEAR TECHNOLOGY CORPORATION 1996

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