LT1946 1.2MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start FEATURES DESCRIPTIO 1.5A, 36V Internal Switch The LT 1946 is a fixed frequency step-up DC/DC converter 1.2MHz Switching Frequency containing an internal 1.5A, 36V switch. Capable of gener- Integrated Soft-Start Function ating 8V at 430mA from a 3.3V input, the LT1946 is ideal Output Voltage Up to 34V for large TFT-LCD panel power supplies. The LT1946 Low V Switch: 300mV at 1.5A (Typ) switches at 1.2MHz, allowing the use of tiny, low profile CESAT 8V at 430mA from a 3.3V Input inductors and low value ceramic capacitors. Loop com- Small 8-Lead MSOP Package pensation can be either internal or external, giving the user flexibility in setting loop compensation and allowing opti- U mized transient response with low ESR ceramic output APPLICATIO S capacitors. Soft-start is controlled with an external capaci- tor, which determines the input current ramp rate during TFT-LCD Bias Supplies start-up. GPS Receivers DSL Modems The 8-lead MSOP package and high switching frequency Local Power Supplies ensure a low profile overall solution less than 1.2mm high. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATIO Efficiency 90 D1 4.7H V OUT V IN 85 8V 3.3V 430mA 80 V SW IN 28.7k OFF ON SHDN 75 LT1946 2.2F 70 FB V 20F C 49.9k SS COMP GND 65 5.23k 60 470pF 100nF 55 1946 F01 C1: 2.2F, X5R OR X7R, 6.3V C2: 2 10F, X5R OR X7R, 10V 50 0 100 200 400 500 300 D1: MICROSEMI UPS120 OR EQUIVALENT L1: TDK RLF5018T-4R7M1R4 LOAD CURRENT (mA) 1946 F01b Figure 1. 3.3V to 8V, 430mA Step-Up DC/DC Converter 1946fb 1 EFFICIENCY (%) U ULT1946 ABSOLUTE AXI U RATI GS (Note 1) V Voltage ............................................................. 16V Maximum Junction Temperature ......................... 125C IN SW Voltage ............................................... 0.4V to 36V Operating Temperature Range (Note 2) .. 40C to 85C FB Voltage ............................................................. 2.5V Storage Temperature Range ................ 65C to 150C SHDN Voltage ......................................................... 16V Lead Temperature (Soldering, 10 sec)................. 300C Current Into FB Pin .............................................. 1mA UUW PACKAGE/ORDER I FOR ATIO ORDER PART ORDER PART TOP VIEW V 1 8 SS NUMBER NUMBER TOP VIEW C FB 2 7 COMP 9 V 1 8 SS C SHDN 3 6 V IN LT1946EMS8E FB 2 7 COMP LT1946EMS8 5 SW GND 4 SHDN 3 6 V IN 5 SW MS8E PACKAGE GND 4 8-LEAD PLASTIC MSOP MS8 PACKAGE MS8 PART MARKING EXPOSED PAD (PIN 9) IS GROUND MS8 PART MARKING 8-LEAD PLASTIC MSOP (MUST BE SOLDERED TO PCB) T = 125C, = 125C/W LTBNW JMAX JA LTUG T = 125C, = 40C/W, JMAX JA (4-LAYER BOARD) = 10C/W JC Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: