LT1082 1A High Voltage, Efficiency Switching Voltage Regulator FEATURES DESCRIPTIO n Wide Input Voltage Range: 3V to 75V The LT 1082 is a monolithic high voltage switching n High Switch Voltage: 100V regulator. It can be operated in all standard switching n Low Quiescent Current: 4.5mA configurations including buck, boost, flyback, forward, n and inverting. A 1A high efficiency switch is included on Internal 1A Switch n the die along with all oscillator, control, and protection Shutdown Mode Draws Only 120m A Supply Current n circuitry. Isolated Flyback Regulation Mode for Fully Floating Outputs The LT1082 operates with supply voltages from 3V to 75V, n Can Be Externally Synchronized switch voltage up to 100V and draws only 4.5mA quies- n Available in MiniDIP and TO-220 Packages cent current. It can deliver load power up to 20W with no n Same Pinout as LT1072 external power devices. By utilizing current-mode switch- U ing techniques, it provides excellent AC and DC load and APPLICATIO S line regulation. n Telecom 5V Supply at 0.7A from 48V An externally activated shutdown mode reduces total n 90V Supply at 120mA from 15V supply current to 120m A typical for standby operation. n All Applications Using LT1072 (See Below for Totally isolated and regulated outputs can be generated by Specification Differences) using the optional isolated flyback regulation mode built into the LT1082, without the need for optocouplers or LT1082 and LT1072 Major Specification Differences extra transformer windings. LT1082C LT1072HV V 3V to 75V 3V to 60V IN The LT1082 has a unique feature to provide high voltage 100V 75V V SW short-circuit protection. When the FB pin is pulled down to Switch Current Limit 1A 1.25A 0.6V and the current out of the pin reaches approximately Quiescent Current 4.5mA 6mA 350m A, the switching frequency will shift down from Operating Frequency 60kHz 40kHz Flyback Reference Voltage 16.2 + 0.6 (35kW /R ) 16 + 0.35 (7kW /R ) 60kHz to 12kHz. FB FB USER NOTE: This data sheet is only intended to provide specifications, graphs, and a general The LT1082 is nearly identical to the lower voltage LT1072. functional description of the LT1082. Application circuits are included to show the capability of the LT1082. A complete design manual (AN19) and Switcher CAD (LTC Switching Power Supply Design For the major differences in specifications, see the table on Program) 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 the left. complete formulas for calculating the values of these components. The manual can also be used for the LT1082 by factoring in the lower switch current rating. , LTC and LT are registered trademarks of Linear Technology Corporation TYPICAL APPLICATIO Telecom 5V Supply Maximum Output Current vs Input Voltage Negative-to-Positive Telecom 5V Supply NOTE: MAXIMUM OUTPUT 1.0 *D1 **250m H CURRENT IS A FUNCTION OF f = 45kHz V OUT INPUT VOLTAGE. SEE THE I LIMIT = 1.07A 5V, 0.7A SW 0.9 L=550m H + GRAPH ON THE RIGHT. 470m F 3.83k L=450m H 10V L=350m H CHEMI-CON V V IN 0.8 SW Q1 L=250m H SXE SERIES 33m F 2N5401 + LT1082 80V 0.7 CHEMI-CON FB SXE SERIES GND V MOTOROLA MUR110 (100V, 1A) C * L=150m H 0.6 69 TURNS OF 28 AWG WIRE ON A ** 1.1k MICROMETALS T60 TYPE 52 CORE. NOTE: THIS CORE IS LOW COST, BUT 0.5 4.7k HAS HIGHER CORE LOSS AND IS LARGER 0.01m F L=100m H THAN NECESSARY FOR LOWER CURRENT 0.22m F APPLICATIONS. FOR SMALLER INDUCTORS 0.4 20V OR HIGHER EFFICIENCY, USE A LOW LOSS 0 10 20 30 40 50 60 70 80 90 TO 70V CORE SUCH AS MAGNETICS INC. KOOL Mm INPUT VOLTAGE (V) 1082 TA01 OR MOLYPERMALLOY. 1082 TA02 sn1082 1082fas 1 MAXIMUM OUTPUT CURRENT (A) U ULT1082 (Note 1) ABSOLUTEXAI U RATI GS Supply Voltage ....................................................... 75V Operating Junction Temperature Range Switch Output Voltage .......................................... 100V LT1082M (OBSOLETE) ............... 55 C to 150 C Feedback Pin Voltage (Transient, 1ms) ................ 15V LT1082I ........................................... 40 C to 125 C Storage Temperature Range ................ 65 C to 150 C LT1082C ............................................... 0 C to 100 C Lead Temperature (Soldering, 10 sec)................. 300 C PACKAGE/ORDER I FOR ATIO TOP VIEW FRONT VIEW FRONT VIEW GND 1 8 E2 5 V 5 V IN IN V 2 V 7 C SW 4 V 4 SW V SW 3 GND 3 GND FB 3 6 E1 2 FB 2 FB NC V 1 V 4 5 1 IN C V C Q PACKAGE T PACKAGE N8 PACKAGE 5-LEAD DD 5-LEAD TO-220 8-LEAD PLASTIC DIP T = 100 C, q = 90 C/W (CN8) JMAX JA T = 100 C, q = 40 C/W (CQ) T = 100 C, q = 75 C/W, q = 8 C/W (CT) JMAX JA JMAX JA JC T = 125 C, q = 90 C/W (IN8) JMAX JA T = 125 C, q = 40 C/W (IQ) T = 125 C, q = 75 C/W, q = 8 C/W (IT) JMAX JA JMAX JA JC NOTE: q VARIES FROM 25 C/W TO 50 C/W ORDER PART NUMBER JA DEPENDING ON BOARD COMPOSITION. LT1082CN8 ORDER PART NUMBER ORDER PART NUMBER LT1082IN8 J8 PACKAGE LT1082CQ LT1082CT 8-LEAD CERAMIC DIP T = 150 C, q = 100 C/W (MJ8) JMAX JA LT1082IQ LT1082IT LT1082MJ8 OBSOLETE PACKAGE Consider the Q Package for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. V = 15V, V = 0.5V, V = V , output pin open, unless otherwise A IN C FB REF specified. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 V REF V = 0.8V l 1.214 1.244 1.274 V C I Feedback Input Current V = V 350 750 nA B FB REF l 1100 nA g Error Amplifier D I = 25m A 3000 4400 6000 m mho m C Transconductance l 2400 7000 m mho Error Amplifier Source or V = 1.5V 150 200 400 m A C Sink Current l 120 400 m A Error Amplifier Clamp Hi Clamp, V = 1V 1.8 2.3 V FB Voltage Lo Clamp, V = 1.5V 0.12 0.22 0.36 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 350 650 V/V V C Minimum Input Voltage l 2.6 3.0 V sn1082 1082fas 2 U WU U W W W