LT1680 High Power DC/DC Step-Up Controller FEATURES DESCRIPTIO n The LT 1680 is a high power, current mode switching High Voltage: Operation Up to 60V n power supply controller optimized for boost topologies. High Current: N-Channel Drive Handles Up to The IC drives an N-channel MOSFET switch for DC/DC 10,000pF Gate Capacitance n converter applications up to 60V input. A high current gate Programmable Average Current Limiting drive output handles up to 10,000pF gate capacitance, n 5V Reference Output with 10mA External enabling the construction of high power DC/DC convert- Loading Capability ers. Current sense common mode range up to 60V allows n Fixed Frequency Current Mode Operation current sensing to be referenced to the input supply, n Oscillator Synchronizable Up to 200kHz eliminating the need for sense blanking circuits. n Undervoltage Lockout with Hysteresis n Programmable Start Inhibit for Power Supply The LT1680 incorporates programmable average current Sequencing and Protection limiting allowing accurate limiting of DC current in the n User Adjustable Slope Compensation magnetics, independent of ripple current . User adjustable slope compensation provides stable operation at duty U cycles up to 90%. APPLICATIO S The LT1680 operating frequency is programmable and n High Power Single Board Systems can be synchronized up to 200kHz. Minimum off-time n Distributed Power Converters operation provides switch protection. The IC also incorpo- n Industrial Control Systems rates a soft start feature that is gated by both shutdown n and undervoltage lockout conditions. Lead-Acid Battery Back-Up Systems n , LTC and LT are registered trademarks of Linear Technology Corporation. Automotive and Heavy Equipment TYPICAL APPLICATIO 12V to 48V, 250W Boost Converter 12V IN 10V TO 15V R SENSE C2 24A (DC) Efficiency vs Output Power 0.005W 1m F 100 C IN V = 48V + OUT 680m F R LT1680 CT L1 25V C 15k CT 25m H 1 16 95 4 1nF SL/ADJ 5V REF 2 15 + C SYNC T C12 3 14 C3 220pF 90 1m F I 12V AVG IN M1 C4 0.22m F 4 13 SS GATE IRFZ44 5 12 3 85 C 4.7nF V PGND VC C R9 6 11 100k R 4.7k SGND RUN/SHDN VC MBR0520 7 10 80 V SENSE FB 8 9 C11 1nF + D1 V SENSE REF R7 R6 MBR20100CT 75 C6 0.1m F V 2k 75k 2 OUT 0 50 100 150 200 250 48V C OUTPUT POWER (W) OUT 5.2A + 680m F 1680 TA02 L1: Kool Mm , 18T 14 ON 77314-A7 63V Kool Mm IS A REGISTERED TRADEMARK OF MAGNETICS, INC. 3 1680 TA01 1 EFFICIENCY (%) U ULT1680 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW ORDER PART Power Supply Voltage (12V ) .................. 0.3V to 20V IN NUMBER SL/ADJ 1 16 5V REF Sense Amplifier Input Common Mode ...... 0.3V to 60V C 2 15 SYNC T LT1680CN GATE Pin Voltage....................... 0.3V to 12V + 0.3V IN I 3 14 12V AVG IN LT1680CSW RUN/SHDN Pin Voltage ......................... 0.3V to 12V IN SS 4 13 GATE LT1680IN All Other Pin Voltages ................................. 0.3V to 7V V 5 12 PGND C LT1680ISW 5V Reference Output Current ............................... 65mA SGND 6 11 RUN/SHDN Operating Ambient Temperature Range V 7 10 SENSE FB + V 8 9 SENSE LT1680C .................................................. 0 C to 70 C REF LT1680I .............................................. 40 C to 85 C N PACKAGE SW PACKAGE 16-LEAD PDIP 16-LEAD PLASTIC SO WIDE Storage Temperature Range ................ 65 C to 150 C T = 125 C, q = 75 C/ W (N) JMAX JA Lead Temperature (Soldering, 10 sec)................. 300 C T = 125 C, q = 90 C/ W (SW) JMAX JA Consult factory 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. A 12V = 12V, V = 2V, V = V = 1.25V, C = 3000pF, unless otherwise noted. IN VC FB REF GATE SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply and Protection I DC Active Supply Current (Note 2) Gate Output On l 15 22 mA 12VIN Gate Output Off 12 mA DC Standby Supply Current V < 0.5V l 150 250 m A RUN V Shutdown Rising Threshold l 1.15 1.25 1.35 V RUN/SHDN V Shutdown Threshold Hysteresis 25 mV SSHYST I Soft Start Charge Current l 58 14 m A SS V Undervoltage Lockout Threshold - Falling l 8.20 9.00 9.75 V UVLO Undervoltage Lockout Threshold - Rising l 9.35 9.95 V Undervoltage Lockout Hysteresis l 200 350 mV 5V Reference V 5V Reference Voltage Line, Load and Temperature l 4.75 5 5.25 V REF5 5V Reference Line Regulation 10V 12V 15V l 3 5 mV/V IN I 5V Reference Load Range - DC l 10 mA REF5 Pulse l 20 mA 5V Reference Load Regulation 0 I 20mA l 1.25 2 V/A REF5 I 5V Reference Short-Circuit Current 45 mA SC Error Amplifier V Error Amplifier Reference Voltage Measured at Feedback Pin 1.242 1.250 1.258 V FB l 1.235 1.265 V I Feedback Input Current V = V l 0.1 0.5 1.0 m A FB FB REF g Error Amplifier Transconductance l 1200 2000 3200 m mho m A Error Amplifier Voltage Gain l 1500 3000 V/V V I Error Amplifier Source Current l 200 275 m A VC Error Amplifier Sink Current V V = 500mV l 280 400 m A FB REF V Absolute V Clamp Voltage Measured at V Pin 3.5 V VC C C 2 U WWW