LT1946 Datasheet | Linear Technology

LT1946 1.2MHz Boost DC/DC Converter with 1.5A Switch and Soft-Start Features s s s s s s s DESCRIPTIO 1.5A, 36V Internal Switch 1.2MHz Switching Frequency Integrated Soft-Start Function Output Voltage Up to 34V Low VCESAT Switch: 300m V at 1.5A (Typ) 8V at 430m A from a 3.3V Input Small 8-Lead MSOP Package U APPLICATIO S s s s s TFT-LCD Bias Supplies GPS Receivers DSL Modems Local Power Supplies The LT®1946 is a fixed frequency step-up DC/DC converter containing an internal 1.5A, 36V switch. Capable of generating 8V at 430m A from a 3.3V input, the LT1946 is ideal for large TFT-LCD panel power supplies. The LT1946 switches at 1.2MHz, allowing the use of tiny, low profile inductors and low value ceramic capacitors. Loop pensation can be either internal or external, giving the user flexibility in setting loop pensation and allowing optimized transient response with low ESR ceramic output capacitors. Soft-start is controlled with an external capacitor, which determines the input current ramp rate during start-up. The 8-lead MSOP package and high switching frequency ensure a low profile overall solution less than 1.2mm high. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO VIN 3.3V 3 1 L1 4.7µH 6 VIN SHDN LT1946 VC SS CSS 100n F 8 7 FB P GND 4 OFF ON C1 2.2µF RC 49.9k CC 470p F 5 SW D1 VOUT 8V 430m A 85 80 EFFICIENCY (%) R1 28.7k 2 R2 5.23k C2 20µF 75 70 65 60 55 C1: 2.2µF, X5R OR X7R, 6.3V C2: 2 × 10µF, X5R OR X7R, 10V D1: MICROSEMI UPS120 OR EQUIVALENT L1: TDK RLF5018T-4R7M1R4 1946 F01 Figure 1. 3.3V to 8V, 430m A Step-Up DC/DC Converter Efficiency 200 400 300 LOAD CURRENT (m A) 500 1946 F01b U sn1946 1946fs ABSOLUTE (Note 1) AXI U RATI GS U U W PACKAGE/ORDER I FOR ATIO TOP VIEW VC FB SHDN GND 1 2 3 4 8 7 6 5 SS P VIN SW VIN Voltage ............................................................. 16V SW Voltage ..................................................