LT1618 Constant-Current/ Constant-Voltage 1.4MHz Step-Up DC/DC Converter FEATURES DESCRIPTIO Accurate Input/Output Current Control: 5% Over The LT 1618 step-up DC/DC converter combines a tradi- Temperature tional voltage feedback loop and a unique current feedback Accurate Output Voltage Control: 1% loop to operate as a constant-current, constant-voltage Wide V Range: 1.6V to 18V source. This fixed frequency, current mode switcher oper- IN 1.4MHz Switching Frequency ates from a wide input voltage range of 1.6V to 18V, and High Output Voltage: Up to 35V the high switching frequency of 1.4MHz permits the use of Low V Switch: 200mV at 1A tiny, low profile inductors and capacitors. The current CESAT Available in (3mm 3mm 0.8mm) 10-Pin DFN and sense voltage is set at 50mV and can be adjusted using the 10-Pin MSOP Packages I pin. ADJ U Available in the 10-Pin (3mm 3mm) Exposed Pad DFN APPLICATIO S and 10-pin MSOP packages, the LT1618 provides a com- plete solution for constant-current applications. LED Backlight Drivers , LTC and LT are registered trademarks of Linear Technology Corporation. USB Powered Boost/SEPIC Converters Input Current Limited Boost/SEPIC Converters Battery Chargers TYPICAL APPLICATIO USB to 12V Boost Converter (with Selectable 100mA/500mA Input Current Limit) L1 D1 10H 0.1 Efficiency Curve V IN V OUT 5V 12V 90 2 7 85 ISN SW C1 R1 3 4.7F ISP 909k LT1618 80 1 8 C2 V FB IN 4.7F 3.3V 75 9 R2 SHDN OFF ON 107k 0V I V GND ADJ C 20k 70 4 510 65 3.3V 2k 100mA 500mA 13k 0V 10nF 60 140 0 20 40 60 80 100 120 160 LOAD CURRENT (mA) C1: TAIYO YUDEN JMK212BJ475 1618 TA01a 1618 TA01b C2: TAIYO YUDEN EMK316BJ475 D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-100 sn1618 1618fas 1 EFFICIENCY (%) U ULT1618 ABSOLUTE AXI U RATI GS (Note 1) V , SHDN Voltage ................................................... 18V Junction Temperature........................................... 125C IN SW Voltage .............................................................. 36V Operating Temperature Range (Note 2) .. 40C to 85C ISP, ISN Voltage ...................................................... 36V Storage Temperature Range I Voltage ............................................................... 6V MSOP ............................................... 65C to 150C ADJ FB Voltage .............................................................. 1.5V DFN ................................................. 65C to 125C V Voltage .............................................................. 1.5V Lead Temperature (Soldering, 10 sec) (MSOP) .... 300C C UUW PACKAGE/ORDER I FOR ATIO TOP VIEW ORDER PART ORDER PART NUMBER NUMBER TOP VIEW FB 1 10 V C FB 1 10 V ISN 2 9 SHDN C ISN 2 9 SHDN LT1618EDD LT1618EMS 11 ISP 3 8 V IN ISP 3 8 V IN I 4 7 SW I 4 7 SW ADJ ADJ GND 5 6 NC GND 5 6 SW DD PART MS PART MS PACKAGE DD PACKAGE 10-LEAD PLASTIC MSOP MARKING MARKING 10-LEAD (3mm 3mm) PLASTIC DFN T = 125C, = 160C/W JMAX JA T = 125C, = 43C/W, = 3C/W JMAX JA JC LAFQ LTNH EXPOSED PAD (PIN 11) IS GND AND MUST BE SOLDERED TO PCB Consult LTC marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 1.6V, V = 1.6V, unless otherwise noted. A IN SHDN PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage 1.6 18 V Quiescent Current V = 1.6V, Not Switching 1.8 2.7 mA SHDN V = 0V 0.1 1 A SHDN Reference Voltage Measured at FB Pin 1.250 1.263 1.276 V 1.243 1.263 1.283 V Reference Voltage Line Regulation 1.6V < V < 18V 0.01 0.03 %/V IN FB Pin Bias Current V = 1.263V, V = 1.8V 2 12 nA FB IN Error Amplifier Voltage Gain 180 V/V Error Amplifier Transconductance I = 5A 160 mho C Error Amplifier Sink Current V = 1.35V, V = 1V 15 A FB C Error Amplifier Source Current V = 1.10V, V = 1V 30 A FB C Current Sense Voltage (ISP, ISN) V = 0V, V = 0V 47.5 50 52.5 mV FB IADJ ISP, ISN Pin Bias Currents (Note 3) V = 1.85V, V = 1.80V, V = 0V 50 80 A ISP ISN IADJ (ISP, ISN) Common Mode Minimum Voltage 1.8 V Switching Frequency V = 1V 1.25 1.4 1.6 MHz FB V = 0V 550 kHz FB Maximum Switch Duty Cycle 88 92 % Switch Current Limit (Note 4) 1.5 2.1 2.8 A sn1618 1618fas 2 U WWW