LT1070IK

FEATURES s s s s s s s s s s LT1070/LT1071 5A and 2.5A High Efficiency Switching Regulators DESCRIPTIO The LT ®1070/LT1071 are monolithic high power switching regulators. They can be operated in all standard switching configurations including buck, boost, flyback, forward, inverting and “Cuk”. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1070/LT1071 to be built in a standard 5-pin T0-220 power package. This makes it extremely easy to use and provides “bust proof” operation similar to that obtained with 3-pin linear regulators. The LT1070/LT1071 operate with supply voltages from 3V to 60V, and draw only 6mA quiescent current. They can deliver load power up to 100W with no external power devices. By utilizing current mode switching techniques, they provide excellent AC and DC load and line regulation. The LT1070/LT1071 have many unique features not found even on the vastly more difficult to use low power control chips presently available. They use adaptive antisat switch drive to allow very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 50µA typical for standby operation. Totally isolated and regulated outputs can be generated by using the optional “flyback regulation mode” built into the LT1070/LT1071, without the need for optocouplers or extra transformer windings. , LTC and LT are registered trademarks of Linear Technology Corporation. Wide Input Voltage Range: 3V to 60V Low Quiescent Current: 6mA Internal 5A Switch (2.5A for LT1071) Very Few External Parts Required Self Protected Against Overloads Operates in Nearly All Switching Topologies Shutdown Mode Draws Only 50µA Supply Current Flyback Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin TO-220 Package Can be Externally Synchronized (Consult Factory) APPLICATIO S s s s s s s s Logic Supply 5V at 10A 5V Logic to ±15V Op Amp Supply Off-Line Converter Up to 200W Battery Upconverter Power Inverter (+ to –) or (– to +) Fully Floating Multiple Outputs For Lower Current Applications, See the LT1072 USER NOTE: This data sheet is only intended to provide specifications, graphs and a general functional description of the LT1070/LT1071. Application circuits are included to show the capability of the LT1070/LT1071. A complete design manual (AN19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1071 by factoring in the lower switch current rating. A second Application Note, AN25, which details off-line applications is available. TYPICAL APPLICATIO Boost Converter (5V to 12V) L2 10µH OUTPUT FILTER D1 VIN C3* 100µF VSW C3 100µF Maximum Output Power* 100 80 BOOST POWER (W)** 5V L1** 150µH 60 + LT1070 GND VC FB R3 1k C1 1µF *REQUIRED IF INPUT LEADS ≥ 2" **PULSE ENGINEERING 92113 + 12V 1A C2 1000µF R1 10.7k 1% 40 ISOLATED 20 BUCK/BOOST VO = 5V 0 0 10 30 20 INPUT VOLTAGE (V) 40 50 1070/71 TA02 R2 1.24k 1% 1070/71 TA01 *ROUGH GUIDE ONLY. BUCK MODE POUT = 5A • VOUT. SPECIAL TOPOLOGIES DELIVER MORE POWER **DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071 10701fe U U U BUCK/BOOST VO = 30V FLYBACK 1 LT1070/LT1071 ABSOLUTE MAXIMUM RATINGS Supply Voltage LT1070/LT1071 (Note 2) .................................... 40V LT1070HV/LT1071HV (Note 2) .......................... 60V Switch Output Voltage LT1070/LT1071 .................................................. 65V LT1070HV/LT1071HV ........................................ 75V Feedback Pin Voltage (Transient, 1ms) ................ ±15V PACKAGE/ORDER INFORMATION BOTTOM VIEW VSW 1 2 3 VC ORDER PART NUMBER CASE IS GND 4 VIN FB K PACKAGE 4-LEAD TO-3 METAL CAN TJMAX = 100°C, θJA = 35°C/ W, QJC = 2°C (LT1070C, I) TJMAX = 150°C, θJA = 35°C/ W, QJC = 2°C (LT1070M) TJMAX = 100°C, θJA = 35°C/ W, QJC = 4°C (LT1071C, I) TJMAX = 150°C, θJA = 35°C/ W, QJC = 4°C (LT1071M) LT1070CK LT1070HVCK LT1070HVMK LT1070IK LT1070MK LT1071CK LT1071HVCK LT1071HVMK LT1071MK OBSOLETE PACKAGE Consider the T5 Package for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified. SYMBOL VREF IB gm PARAMETER Reference Voltage Feedback Input Current Error Amplifier Transconductance Error Amplifier Source or Sink Current Error Amplifier Clamp Voltage Reference Voltage Line Regulation AV IQ Error Amplifier Voltage Gain Minimum Input Voltage Supply Current Control Pin Threshold Normal/Flyback Threshold on Feedback Pin 3V ≤ VIN ≤ VMAX, VC = 0.6V Duty Cycle = 0 q CONDITIONS Measured at Feedback Pin, VC = 0.8V q VFB = VREF q ∆IC = ± 25µA q VC = 1.5V q Hi Clamp, VFB = 1V Lo Clamp, VFB = 1.5V 3V ≤ VIN ≤ VMAX, VC = 0.8V 0.9V ≤ VC ≤ 1.4V q q 2 U U W WW U W (Note 1) Operating Junction Temperature Range Commercial (Operating) ....................... 0°C to 100°C Commercial (Short Circuit)................... 0°C to 125°C Industrial ......................................... – 40°C to 125°C Military (OBSOLETE) ................. – 55°C to 150°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C ORDER PART NUMBER FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD PLASTIC TO-220 VIN VSW GND FB VC TJMAX = 100°C, θJA = 75°C/ W, QJC = 2°C (LT1070C, I) TJMAX = 100°C, θJA = 75°C/ W, QJC = 4°C (LT1071C) LT1070CT LT1070HVCT LT1070HVIT LT1070IT LT1071CT LT1071HVCT LT1071HVIT LT1071IT MIN 1.224 1.214 TYP 1.244 1.244 350 MAX 1.264 1.274 750 1100 6000 7000 350 400 2.30 0.52 0.03 UNITS V V nA nA µmho µmho µA µA V V %/V V/V V mA V V V 10701fe 3000 2400 150 120 1.80 0.25 500 4400 200 0.38 800 2.6 6 3.0 9 1.08 1.25 0.54 0.8 0.6 0.4 0.9 0.45 LT1070/LT1071 The q denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = VREF, output pin open unless otherwise specified. SYMBOL VFB PARAMETER Flyback Reference Voltage Change in Flyback Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and Sink Current BV Output Switch Breakdown Voltage CONDITIONS IFB = 50µA q ELECTRICAL CHARACTERISTICS MIN 15 14 4.5 150 q q q q q q TYP 16.3 6.8 0.01 300 32 40 90 90 0.15 0.30 8 4 MAX 17.6 18.0 8.5 0.03 650 70 70 UNITS V V V %/V µmho µA µA V V 0.05 ≤ IFB ≤ 1mA IFB = 50µA, 3V ≤ VIN ≤ VMAX (Note 3) ∆IC = ±10µA VC = 0.6V, IFB = 50µA (Source) VC = 0.6V, IFB = 50µA (Sink) 3V ≤ VIN ≤ VMAX, ISW = 1.5mA (LT1070/LT1071) (LT1070HV/LT1071HV) LT1070 LT1071 LT1070 LT1071 Duty Cycle ≤ 50%, TJ ≥ 25°C Duty Cycle ≤ 50%, TJ < 25°C Duty Cycle = 80% (Note 5) Duty Cycle ≤ 50%, TJ ≥ 25°C Duty Cycle ≤ 50%, TJ < 25°C Duty Cycle = 80% (Note 5) q q q q q q 15 25 65 75 VSAT Output Switch “On” Resistance (Note 4) Control Voltage to Switch Current Transconductance 0.24 0.50 Ω Ω A/V A/V ILIM Switch Current Limit (LT1070) 5 5 4 2.5 2.5 2.0 25 35 33 90 40 92 1.5 100 10 11 10 5.0 5.5 5.0 35 45 47 97 250 250 300 A A A A A A mA/A kHz kHz % µs µA mV mV Switch Current Limit (LT1071) ∆IIN ∆ISW f DC (Max) Supply Current Increase During Switch “On” Time Switching Frequency q Maximum Switch Duty Cycle Flyback Sense Delay Time Shutdown Mode Supply Current Shutdown Mode Threshold Voltage 3V ≤ VIN ≤ VMAX, VC = 0.05V 3V ≤ VIN ≤ VMAX q 100 50 150 Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Minimum switch “on” time for the LT1070/LT1071 in current limit is ≈1µs. This limits the maximum input voltage during short-circuit conditions, in the buck and inverting modes only, to ≈ 35V. Normal (unshorted) conditions are not affected. Mask changes are being implemented which will reduce minimum “on” time to ≤ 1µs, increasing maximum short-circuit input voltage above 40V. If the present LT1070/LT1071 (contact factory for package date code) is being operated in the buck or inverting mode at high input voltages and short-circuit conditions are expected, a resistor must be placed in series with the inductor, as follows: The value of the resistor is given by: R= t • f • VIN – VF – RL ILIMIT t = Minimum “on” time of LT1070/LT1071 in current limit, ≈ 1µs f = Operating frequency (40kHz) VF = Forward voltage of external catch diode at ILIMIT ILIMIT = Current limit of LT1070 (≈ 8A), LT1071 (≈ 4A) RL = Internal series resistance of inductor Note 3: VMAX = 55V for LT1070HV and LT1071HV to avoid switch breakdown. Note 4: Measured with VC in hi clamp, VFB = 0.8V. ISW = 4A for LT1070 and 2A for LT1071. Note 5: For duty cycles (DC) between 50% and 80%, minimum guaranteed switch current is given by ILIM = 3.33 (2 – DC) for the LT1070 and ILIM = 1.67 (2 – DC) for the LT1071. 10701fe 3 LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS Switch Current Limit vs Duty Cycle 16 14 FOR LT1071, DIVIDE VERTICAL SCALE BY 2 SWITCH CURRENT (A) 12 8 6 4 2 0 0 – 55°C 125°C 25°C 93 92 91 90 –75 – 50 – 25 0 25 50 75 100 125 150 JUNCTION TEMPERATURE (°C) 1070/71 G02 TIME (µs) 10 DUTY CYCLE (%) 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) 1070/71 G01 Minimum Input Voltage 2.9 1.6 SWITCH SATURATION VOLTAGE (V) SWITCH CURRENT = 5A MINIMUM INPUT VOLTAGE (V) 2.8 2.7 2.6 SWITCH CURRENT = 0A 2.5 2.4 2.3 –75 – 50 – 25 1.0 0.8 0.6 0.4 0.2 0 0 1 100°C 25°C – 55°C FLYBACK VOLTAGE (V) 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G04 Line Regulation 5 REFERENCE VOLTAGE CHANGE (mV) 4 1.250 1.248 REFERENCE VOLTAGE (V) 3 2 1 0 –1 –2 –3 –4 –5 0 10 TJ = 150°C TJ = 25°C TJ = – 55°C 1.246 1.244 1.242 1.240 1.238 1.236 1.234 – 75 – 50 – 25 40 39 FEEDBACK BIAS CURRENT (nA) 30 40 20 INPUT VOLTAGE (V) 4 UW 50 60 1070/71 G07 Maximum Duty Cycle 96 95 94 2.2 2.0 1.8 1.6 1.4 1.2 Flyback Blanking Time 1.0 –75 – 50 – 25 0 25 50 75 100 125 150 JUNCTION TEMPERATURE (°C) 1070/71 G03 Switch Saturation Voltage 1.4 1.2 FOR LT1071, DIVIDE CURRENT BY 2 150°C 23 22 21 20 19 18 17 16 4 5 2 3 6 SWITCH CURRENT (A) 7 8 15 – 75 – 50 – 25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G06 RFEEDBACK = 500Ω RFEEDBACK = 1k RFEEDBACK = 10k 1070/71 G05 Reference Voltage vs Temperature 42 SWITCHING FREQUENCY 41 800 700 600 500 400 300 200 100 Feedback Bias Current vs Temperature SWITCHING FREQUENCY (kHz) REFERENCE V0LTAGE 38 37 36 35 34 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G08 0 – 75 – 50 – 25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G09 10701fe LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS Driver Current* vs Switch Current 160 140 DRIVER CURRENT (mA) 13 12 11 10 9 8 ISWITCH ≤ 10mA 100 80 TJ = – 55°C 60 40 20 0 0 1 2 3 4 SWITCH CURRENT (A) 5 1070/71 G10 SUPPLY CURRENT (µA) INPUT CURRENT (mA) 120 TJ ≥ 25°C *AVERAGE LT1070 POWER SUPPLY CURRENT IS FOUND BY MULTIPLYING DRIVER CURRENT BY DUTY CYCLE, THEN ADDING QUIESCENT CURRENT Normal/Flyback Mode Threshold on Feedback Pin 500 490 FEEDBACK PIN VOLTAGE (mV) 480 470 460 450 440 430 420 410 400 –50 –25 0 FEEDBACK PIN CURRENT (AT THRESHOLD) FEEDBACK PIN VOLTAGE (AT THRESHOLD) –24 –22 FEEDBACK PIN CURRENT (µA) –20 –18 –16 –14 –12 –10 –8 –6 –4 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G13 TRANSCONDUCTANCE (µmho) SUPPLY CURRENT (µA) Shutdown Thresholds 400 350 CURRENT (OUT OF VC PIN) – 400 –350 11 10 IDLE SUPPLY CURRENT (mA) VC PIN VOLTAGE (mV) 300 250 200 VOLTAGE 150 100 50 VC VOLTAGE IS REDUCED UNTIL REGULATOR CURRENT DROPS BELOW 300µA –300 –250 –200 –150 –100 – 50 FEEDBACK VOLTAGE (mV) 0 – 75 – 50 – 25 0 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G16 UW Supply Current vs Input Voltage* 16 15 14 TJ = 25°C 90% DUTY CYCLE 160 140 120 100 Supply Current vs Supply Voltage (Shutdown Mode) TJ = 25°C VC = 50mV 80 60 40 20 0 0 10 VC = 0 V 20 40 30 SUPPLY VOLTAGE (V) 50 60 50% DUTY CYCLE 10% DUTY CYCLE 0% DUTY CYCLE 0 10 30 40 20 INPUT VOLTAGE (V) 50 60 7 6 1070/71 G11 1070/71 G12 *UNDER VERY LOW OUTPUT CURRENT CONDITIONS, DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH 10% OR LESS Shutdown Mode Supply Current 200 180 160 140 120 100 80 60 40 20 0 0 10 20 30 40 50 60 70 80 90 100 VC PIN VOLTAGE (mV) 1070/71 G14 Error Amplifier Transconductance 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 –75 – 50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G14 gm = ∆I (VC PIN) ∆V (FB PIN) TJ = 150°C – 55°C ≤ TJ ≤ 125°C Idle Supply Current vs Temperature VC = 0.6V Feedback Pin Clamp Voltage 500 450 400 350 300 250 200 150 100 50 0 – 55°C 25°C 150°C 9 8 7 6 5 4 3 2 1 –75 – 50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 1070/71 G14 VC PIN CURRENT (µA) VSUPPLY = 60V VSUPPLY = 3V 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FEEDBACK CURRENT (mA) 1070/71 G18 10701fe 5 LT1070/LT1071 TYPICAL PERFORMANCE CHARACTERISTICS Switch “Off” Characteristics 1000 900 800 TRANSCONDUCTANCE (µmho) SWITCH CURRENT (µA) VC PIN CURRENT (µA) 700 600 500 400 300 200 100 0 0 10 20 30 40 50 60 70 80 90 100 SWITCH VOLTAGE (V) 1070/71 G19 VSUPPLY = 3V 15V 40V 55V BLOCK DIAGRAM VIN 2.3V REG 40kHz OSC MODE SELECT COMP FB 1.24V REF OPERATION The LT1070/LT1071 is a current mode switcher. This means that switch duty cycle is directly controlled by switch current rather than by output voltage. Referring to the Block Diagram, the switch is turned “on” at the start of each oscillator cycle. It is turned “off” when switch current reaches a predetermined level. Control of output voltage is obtained by using the output of a voltage sensing error amplifier to set current trip level. This technique has several advantages. First, it has immediate response to input voltage variations, unlike ordinary switchers which have notoriously poor line transient response. Second, it reduces the 90° phase shift at 10701fe 6 UW + – VC Pin Characteristics 300 200 100 0 –100 – 200 – 300 – 400 0 0.5 2.0 1.5 1.0 VC PIN VOLTAGE (V) 2.5 VFB = 1.5V (CURRENT INTO VC PIN) TJ = 25°C 7000 6000 5000 4000 3000 2000 1000 0 –1000 Transconductance of Error Amplifier – 30 θ 0 30 gm 60 90 120 150 180 1k 10k 100k 1M FREQUENCY (Hz) 210 10M 1070/71 G21 PHASE (°) VFB = 0.8V (CURRENT OUT OF VC PIN) 1070/71 G20 W 16V SWITCH OUT FLYBACK ERROR AMP LOGIC DRIVER 5A, 75V SWITCH ANTISAT ERROR AMP VC + SHUTDOWN CIRCUIT 0.15V CURRENT AMP GAIN ≈ 6 0.02Ω (0.04Ω LT1071) – 1070/71 BD U LT1070/LT1071 OPERATION midfrequencies in the energy storage inductor. This greatly simplifies closed-loop frequency compensation under widely varying input voltage or output load conditions. Finally, it allows simple pulse-by-pulse current limiting to provide maximum switch protection under output overload or short-circuit conditions. A low dropout internal regulator provides a 2.3V supply for all internal circuitry of the LT1070/LT1071. This low dropout design allows input voltage to vary from 3V to 60V with virtually no change in device performance. A 40kHz oscillator is the basic clock for all internal timing. It turns “on” the output switch via the logic and driver circuitry. Special adaptive antisat circuitry detects onset of saturation in the power switch and adjusts driver current instantaneously to limit switch saturation. This minimizes driver dissipation and provides very rapid turn-off of the switch. A 1.2V bandgap reference biases the positive input of the error amplifier. The negative input is brought out for output voltage sensing. This feedback pin has a second function; when pulled low with an external resistor, it programs the LT1070/LT1071 to disconnect the main error amplifier output and connects the output of the flyback amplifier to the comparator input. The LT1070/ LT1071 will then regulate the value of the flyback pulse with respect to the supply voltage. This flyback pulse is directly proportional to output voltage in the traditional transformer coupled flyback topology regulator. By regulating the amplitude of the flyback pulse, the output voltage can be regulated with no direct connection between input and output. The output is fully floating up to the breakdown voltage of the transformer windings. Multiple floating outputs are easily obtained with additional windings. A special delay network inside the LT1070/ LT1071 ignores the leakage inductance spike at the leading edge of the flyback pulse to improve output regulation. The error signal developed at the comparator input is brought out externally. This pin (VC) has four different functions. It is used for frequency compensation, current limit adjustment, soft starting and total regulator shutdown. During normal regulator operation this pin sits at a voltage between 0.9V (low output current) and 2.0V (high output current). The error amplifiers are current output (gm) types, so this voltage can be externally clamped for adjusting current limit. Likewise, a capacitor coupled external clamp will provide soft start. Switch duty cycle goes to zero if the VC pin is pulled to ground through a diode, placing the LT1070/LT1071 in an idle mode. Pulling the VC pin below 0.15V causes total regulator shutdown, with only 50µA supply current for shutdown circuitry biasing. See AN19 for full application details. TYPICAL APPLICATIONS Driving High Voltage FET (for Off-Line Applications, See AN25) VIN VSW 10V TO 20V + LT1070/LT1071 GND 30AT 1070/71 TA03 17/0701 U U (Note that maximum output currents are divided by 2 for the LT1071) Driving High Voltage NPN C1 D2 G D1 D S Q1 R2** R1* Q1 D1 VIN VSW *SETS IB(ON) **SETS IB(OFF) LT1070/LT1071 GND 1070/71 TA16 10701fe 7 LT1070/LT1071 TYPICAL APPLICATIONS OPTIONAL INPUT FILTER L3 VIN D3 VIN C3 2.2µF L2 4µH VSW OPTIONAL OUTPUT FILTER R1 3.74k GND VC FB R3 470Ω C1 1µF D1 *REQUIRED IF INPUT LEADS ≥2" **PULSE ENGINEERING 92112 R2 1.24k D2 1N914 C5 200µF + LT1070 100µF + C5* + – VIN 8 U (Note that maximum output currents are divided by 2 for the LT1071) Negative Buck Converter + L1** 200µH D1 VIN C3 100µF VSW C2 1000µF R1 4.64k LOAD – 5.2V 4.5A + LT1070 Q1 2N3906 FB C1 R3 R2 1.24k OPTIONAL OUTPUT FILTER L2 4µH 1070/71 TA12 GND VC + C4 200µF VIN – 20V *REQUIRED IF INPUT LEADS ≥ 2" **PULSE ENGINEERING 92113 Positive Buck Converter + C2 1µF L1** 100µH R4 10Ω 5V 4.5A 100mA MINIMUM 1070/71 TA14 r + C4 1000µF Negative Current Boosted Buck Converter + R1 R5 C3 T1 1:N D1 Q1 2N3906 R4 12k R1 = VOUT – 0.6V 1mA C1 MINIMUM LOAD = 10mA – VOUT 5V 10A • VIN VSW • LT1070 GND VC FB R3 C2 1070/71 TA13 R2 1.24k 10701fe LT1070/LT1071 TYPICAL APPLICATIONS VIN 28V + R3 680Ω C5* 100µF C1 0.33µF 6 V+ V – LM308 COMP 3 4 8 200pF *REQUIRED IF INPUT LEADS ≥ 2" Negative to Positive Buck/Boost Converter L2 L1** 150µH OPTIONAL OUTPUT FILTER D1 VIN C4* 100µF L3 GND OPTIONAL INPUT FILTER VIN – 12V *REQUIRED IF INPUT LEADS ≥ 2" **PULSE ENGINEERING 92113 VC VSW C2 1000µF C3 D3† 1N4001 + LT1070 + Q1 R1 11.3k VOUT 12V 2A 5µF + C4 FB R3 2.2k C1 0.22µF R2 1.24k 1070/71 TA05 – + U (Note that maximum output currents are divided by 2 for the LT1071) Positive Current Boosted Buck Converter 470Ω 2W D2 VSW C3 0.47µF R6 470Ω C6 0.002µF • • VIN 1:N LT1070 R2 1k GND VC FB VIN 7 2 R7 1.24k N ≈ 0.25 D1 R5 5k R4 1.24k VOUT 5V 10A C2 5000µF 1070/71 TA19 R1 5k + Positive to Negative Buck/Boost Converter R5† 470Ω 1W †TO AVOID START-UP VIN VSW LT1070 PROBLEMS FOR INPUT VOLTAGES BELOW 10V, VIN 10V TO 30V CONNECT ANODE OF D3 TO VIN AND REMOVE R5. C5* C1 MAY BE REDUCED FOR 100µF LOWER OUTPUT CURRENTS. C1 ≈ (500µF)(IOUT) FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO 0.3µF D2 R1 R4 AND REDUCE R6 TO 100Ω. 1N914 10.7k 47Ω GND VC FB R3 5k C1 0.1µF R2 1.24k + C1† C3 2µF 1000µF D1 + R6 470Ω VOUT – 12V 2A 1070/71 TA09 L1** 200µH *REQUIRED IF INPUT LEADS ≥ 2" **PULSE ENGINEERING 92113 10701fe 9 LT1070/LT1071 TYPICAL APPLICATIONS R4 680Ω 1W D2 VIN VIN 15V Voltage Boosted Boost Converter C3 0.68µF TOTAL INDUCTANCE = 4mH INTERLEAVE PRIMARY AND SECONDARY FOR LOW LEAKAGE INDUCTANCE VOUT 100V 300mA + LT1070 VSW R1 98k GND VC FB R3 10k C2 0.047µF R2 1.24k + Negative Boost Regulator D2 VIN VSW C4* 470µF + LT1070 R1 27k + GND VC FB R3 3.3k C2 0.22µF R2 1.24k VIN –15V L1 200µH *REQUIRED IF INPUT LEADS ≥ 2" External Current Limit VIN VSW VX LT1070/LT1071 R2 = 2V D1 R1 500Ω R2 1070/71 TA04 LT1070/LT1071 + VIN GND R1 1k Q1 C1 1000pF RS VC FB C2 10 U D1 (Note that maximum output currents are divided by 2 for the LT1071) Current Boosted Boost Converter R4 C3 I N D1 1 L1 N=5 D2 VIN VIN 16V TO 24V VOUT 28V 4A + LT1070 VSW R1 27k + C1 FB R3 C2 R2 1.24k GND VC C1 200µF 1070/71 TA10 1070/71 TA11 Negative Input/Negative Output Flyback Converter • • Q1 2N3906 R1* LT1070/LT1071 – VOUT GND VC FB R5 V  – 1.6V *R1 = OUT 200µA R4 1.24k 1070/71 TA17 C3 R6 R3 1k R2 5k VIN VSW + C3 10µF T1 1:N + C1 C1 1000µF RO (MINIMUM LOAD) + D1 VOUT –28V 1A C2 – VIN 1070/71 TA15 External Current Limit GND VC NOTE THAT THE LT1070/LT1071 GND PIN IS NO LONGER COMMON TO VIN– 1070/71 TA06 10701fe LT1070/LT1071 TYPICAL APPLICATIONS VIN 20V TO 30V R4 C3 0.47µF D2 VIN VSW N = 1/3 R1 3.74k 0 IPRI N 0 IPRI R2 1.24k 0 IPRI + C4* 100µF LT1070 FB GND VC R3 1.5k C2 0.15µF *REQUIRED IF INPUT LEADS ≥ 2" PACKAGE DESCRIPTION K Package 4-Lead TO-3 Metal Can (Reference LTC DWG # 05-08-1311) 0.320 – 0.350 (8.13 – 8.89) 0.760 – 0.775 (19.30 – 19.69) 0.060 – 0.135 (1.524 – 3.429) 0.390 – 0.415 (9.906 – 10.541) 0.147 – 0.155 (3.734 – 3.937) DIA 0.230 – 0.270 (5.842 – 6.858) 0.460 – 0.500 (11.684 – 12.700) 0.570 – 0.620 (14.478 – 15.748) 0.330 – 0.370 (8.382 – 9.398) 0.700 – 0.728 (17.78 – 18.491) 0.620 (15.75) TYP 0.165 – 0.180 (4.191 – 4.572) 0.420 – 0.480 (10.67 – 12.19) 0.038 – 0.043 (0.965 – 1.09) 1.177 – 1.197 (29.90 – 30.40) 0.655 – 0.675 (16.64 – 19.05) 0.151 – 0.161 (3.84 – 4.09) DIA 2 PLC 0.167 – 0.177 (4.24 – 4.49) R 72° 18° 0.490 – 0.510 (12.45 – 12.95) R 0.470 TP P.C.D. OBSOLETE PACKAGE 10701fe 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 U (Note that maximum output currents are divided by 2 for the LT1071) Flyback Converter VSNUB L2 10µH OPTIONAL FILTER D1 C4 200µF VOUT 5V 6A C1 2000µF VIN 0V VOUT + VF c 0V d ∆I IPRI PRIMARY CURRENT (N)(VIN) SECONDARY VOLTAGE AREA “c” = AREA “d” TO MAINTAIN ZERO DC VOLTS ACROSS SECONDARY CLAMP TURN-ON SPIKE a b + VF V PRIMARY FLYBACK VOLTAGE = OUT N LT1070/LT1071 SWITCH VOLTAGE AREA “a” = AREA “b” TO MAINTAIN ZERO DC VOLTS ACROSS PRIMARY • 1N + • SECONDARY CURRENT LT1070 SWITCH CURRENT SNUBBER DIODE CURRENT (I )(L ) t = PRI L VSNUB 1070/71 TA08 T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) 0.045 – 0.055 (1.143 – 1.397) SEATING PLANE 0.152 – 0.202 0.260 – 0.320 (3.861 – 5.131) (6.60 – 8.13) 0.095 – 0.115 (2.413 – 2.921) 0.155 – 0.195* (3.937 – 4.953) 0.013 – 0.023 (0.330 – 0.584) BSC 0.067 (1.70) 0.028 – 0.038 (0.711 – 0.965) 0.135 – 0.165 (3.429 – 4.191) T5 (TO-220) 0399 * MEASURED AT THE SEATING PLANE K4(TO-3) 1098 11 LT1070/LT1071 TYPICAL APPLICATIONS +V + IN 5V C5* 100µF LT1070/LT1071 FB GND VC *REQUIRED IF INPUT LEADS ≥ 2" VIN 20V TO 30V GND RELATED PARTS PART NUMBER LT1074/LT1076 LT1170/LT1171/ LT1172 LT1370/LT1371 LT1374/LT1376 LT1765 DESCRIPTION High Voltage Switching Regulators 100kHz High Efficiency Switching Regulators 500kHz High Efficiency Switching Regulators 100kHz High Efficiency Switching Regulators 1.25MHz, 3A, Step-Down Regulator 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 q FAX: (408) 434-0507 q U (Note that maximum output currents are divided by 2 for the LT1071) Totally Isolated Converter OPTIONAL OUTPUT FILTER D1 1:N R4 1.5k C3 0.47µF L1 10µF 15V • + N C1 500µF C4 500µF + COM L2 10µF C5 200µF C6 200µF N VIN VSW N = 0.875 = 7:8 FOR VOUT = 15V + + • –15V ≈ 16V SWITCH VOLTAGE 500Ω VIN 0V R2 tOFF tON VOUT 0V VF (DIODE FORWARD VOLTAGE) SECONDARY VOLTAGE 1070/71 TA07 C2 5k 0.01µF (N)(VIN) Forward Converter T1 R4 C2 D3 VSW D4 R1 3.74k D1 N L1 70µH VOUT 5V 6A C1 2000µF • I M • + D2 VIN • LT1070 VC FB Q1 R3 C3 R6 C4 330Ω R5 1Ω R2 1.24k 1070/71 TA18 COMMENTS 40V Input (60V for HV Versions), 100kHz, 5A and 2A 40V Input (65V for HV Versions), 5A/2.5A/1.25A Internal Switch 35V, 6A/3A Internal Switch 25V Input, 4.5A/1.5A Internal Switch 25V Input, TSSOP-16E, SO8 Package 10701fe LT/CPI 0202 1.5K REV E • PRINTED IN USA www.linear.com © LINEAR TECHNOLOGY CORPORATION 1989