LT1949 Datasheet | Linear Technology

LT1949 600k Hz, 1A Switch PWM DC/DC Converter Features s s s s s s s DESCRIPTIO 1A, 0.5Ω, 30V Internal Switch Operates with VIN as Low as 1.5V 600k Hz Fixed Frequency Operation Low-Battery Detector Stays Active in Shutdown Low VCESAT Switch: 410m V at 800m A Pin-for-Pin patible with the LT1317B Small 8-Lead MSOP and SO Packages U APPLICATIO S s s s s s LCD Bias Supplies GPS Receivers Battery Backup Portable Electronic Equipment Diagnostic Medical Instrumentation The LT ®1949 is a fixed frequency step-up DC/DC converter with a 1A, 0.5Ω internal switch. Capable of generating 10V at 175m A from a 3.3V input, the LT1949 is ideal for generating bias voltages for large screen LCD panels. Constant frequency 600k Hz operation results in a low noise output that is easy to filter and the 30V switch rating allows output voltage up to 28V using a single inductor. An external pensation pin gives the user flexibility in optimizing loop pensation, allowing small low ESR ceramic capacitors to be used at the output. The 8-lead MSOP and SO packages ensure a low profile overall solution. The LT1949 includes a low-battery detector that stays alive when the device goes into shutdown. Quiescent current in shutdown is 25µA, while operating current is 4.5m A. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO VIN 3.3V L1 10µH 90 D1 80 SW 70 3.6VIN 4.2VIN 3VIN VOUT = 10V + C1 22µF VIN LT1949 SHUTDOWN SHDN VC 68k 330p F FB GND R2 140k VOUT 10V 175m A C2 10µF CERAMIC EFFICIENCY (%) R1 1M 60 50 40 30 C1: AVX TAJA226M006R C2: TAIYO YUDEN LMK325BJ106MN D1: MBRM120LT3 L1: SUMIDA CDRH62B-100 1949 F01 20 5 10 50 100 LOAD CURRENT (m A) 300 1949 F02 Figure 1. 3.3V to 10V/175m A DC/DC Converter Figure 2. 3.3V to 10V Converter Efficiency ABSOLUTE AXI U RATI GS VIN, LBO Voltage ..................................................... 12V SW Voltage ............................................... - 0.4V to 30V FB Voltage...