LT1268B/LT1268 7.5A, 150kHz Switching Regulators DESCRIPTIO FEATURES n Wide Input Voltage Range: 3.5V to 30V The LT1268B and LT1268 are monolithic high power n Low Quiescent Current: 7mA switching regulators. Identical to the popular LT1070, n Internal 7.5A Switch except for switching frequency (150kHz) and higher n Very Few External Parts Required switch current, they can be operated in all standard n Self-Protected Against Overloads switching configurations including buck, boost, flyback, n Available in Standard and Surface Mount and inverting. A high current, high efficiency switch is 5-Pin Packages included on the die along with all oscillator, control, and n Can Be Externally Synchronized protection circuitry. Integration of all functions allows (See LT1072 Data Sheet) the LT1268 to be built in standard 5-pin power packages. This makes it extremely easy to use and provides bust PPLICATI S A proof operations similar to that obtained with 3-pin linear regulators. n High Efficiency Boost Converter n PC Power Supply with Multiple Outputs The LT1268 operate with supply voltages from 3.5V to n Battery Upconverter 30V and draw only 7mA quiescent current. By utilizing n Negative-to-Positive Converter current mode switching techniques, it provides excellent AC and DC load and line regulation. USER NOTE: This data sheet is only intended to provide specifications, graphs, and a general functional The LT1268 use an adaptive anti-sat switch drive to allow description of the LT1268B/LT1268. Application circuits are included to show the capability of the LT1268B/LT1268. A complete design manual (AN19) should be obtained to assist in developing new very wide ranging load currents with no loss in efficiency. 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 An externally activated shutdown mode reduces total components. The manual can also be used for the LT1268B/LT1268 factoring in the higher switch current rating and higher operating frequency. supply current to 100m A typical for standby operation. TYPICAL APPLICATI Boost Regulator with 5.3V 1% Output Efficiency of 5.3V Boost Converter D1 100 L1 L2 MBR1035 8m H, 5A* 2m H, 5A** V V IN OUT 4.7V TO 5.3V 1% 5.3V 3.75A V = 5.3V IN 90 D2, D3 C3 1N4001 V = 4.7V C5 IN R1 390m F 0.02 V = 5V IN 4.043k 16V 0.1% V V IN SW 80 C4 C1 220m F 390m F LT1268B FB 16V 16V CASE GND V C 70 R2 C2 1.24k 0.068 0.1% R3 60 220W 0 1 2 3 4 LT1268 TA01 LOAD CURRENT (A) *COILTRONICS CTX8-5-52 LT1268 TA02 **COILTRONICS CTX2-5-52 OPTIONAL. D2 AND D3 ARE USED TO INCREASE UNDERVOLTAGE LOCKOUT FROM 2.7V TO 4V. 1 EFFICIENCY (%) + + + UO UO ULT1268B/LT1268 ABSOLUTEXAI U RATI GS PACKAGE/ORDER I FOR ATIO Supply Voltage ....................................................... 30V FRONT VIEW ORDER PART Switch Output Voltage ............................................ 60V 5 V IN NUMBER 4 V SW Feedback Pin Voltage (Transient, 1ms) ................ 15V 3 GND Operating Junction Temperature Range 2 FB LT1268CQ 1 V C Operating............................................... 0 C to 125 C LT1268BCQ Q PACKAGE Short-Circuit......................................... 0 C to 140 C 5-LEAD DD Storage Temperature Range ................. 65 C to 150 C T = 125 C, q = 2 C/W, q = See Notes 5 and 6 JMAX JC JA Lead Temperature (Soldering, 10 sec).................. 300 C FRONT VIEW ORDER PART V 5 IN NUMBER V 4 SW 3 GND FB 2 LT1268CT V 1 C LT1268BCT T PACKAGE 5-LEAD TO-220 T = 125 C, q = 2 C/W, q = 50 C/W JMAX JC JA Consult factory for Industrial and Military parts ELECTRICAL CHARACTERISTICS V = 15V, V = 0.5V, V = V , switch pin open, unless otherwise noted. IN C FB REF SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Reference Voltage Measured at LT1268B 1.235 1.244 1.253 V REF Feedback Pin (Note 4) l 1.224 1.244 1.264 V Reference Voltage LT1268 1.224 1.244 1.264 V l 1.214 1.244 1.274 V I Feedback Input Current V = V 350 750 nA B FB REF l 1100 nA g Error Amplifier Transconductance D I = 25m A 3000 4400 6000 m mho m C l 2400 7000 m mho Error Amplifier Source or Sink Current V = 1.5V 150 200 350 m A C l 120 400 m A Error Amplifier Clamp Voltage Hi Clamp, V = 1V 1.80 2.30 V FB Lo Clamp, V = 1.5V 0.25 0.38 0.52 V FB Reference Voltage Line Regulation 3V V V , V = 0.8V l 0.03 %/V IN MAX C A Error Amplifier Voltage Gain 0.9V V 1.4V 500 800 V/V V C Minimum Input Voltage l 2.8 3.0 V I Supply Current 3V V V , V = 0.6V 7 10 mA Q IN MAX C Control Pin Threshold Duty Cycle = 0 0.7 0.9 1.08 V l 0.5 1.25 V BV Output Switch Breakdown Voltage 3V V V , I = 1.5mA l 60 75 V IN MAX SW V Output Switch-ON Resistance T 100 C 0.12 0.18 W SAT J (Note 1, 3) T 125 C 0.22 W J Control Voltage to Switch 12 A/V Current Transconductance I Switch Current Limit (Note 3, 6) Duty Cycle = 50%, T 100 C l 7.50 15 A LIM J Duty Cycle = 65%, T 100 C l 6.50 14 A J 2 U WU U W W W