RT8271GFP Richtek

RT8271 2A, 24V, 1.2MHz Step-Down Converter General Description Features zz z zz Wide Operating Input Range : 4.75V to 24V The RT8271 is a high voltage buck converter that can zz z zz Adjustable Output Voltage Range : 0.92V to 16V support the input voltage range from 4.75V to 24V and the zz z zz Output Current up to 2A output current can be up to 2A. Current Mode operation zz z zz 22A Low Shutdown Current provides fast transient response and eases loop zz z zz Power MOSFET : 0.18 stabilization. The RT8271 also provides adjustable soft- zz z zz High Efficiency up to 92% start to be a flexible solution for customers. zz z zz 1.2MHz Fixed Switching Frequency The chip provides protection functions such as cycle-by- zz z zz Stable with Low ESR Output Ceramic Capacitors cycle current limiting and thermal shutdown protection. zz z zz Programmable Soft-Start In shutdown mode, the regulator draws 22A of supply zz z zz Thermal Shutdown Protection current. The RT8271 is available in the SOP-8 and zz z zz Cycle-By-Cycle Over Current Protection MSOP-10 (Exposed Pad) surface mount package. zz z zz RoHS Compliant and Halogen Free Ordering Information Applications RT8271 Package Type z Distributive Power Systems S : SOP-8 z Battery Charger FP : MSOP-10 (Exposed Pad) z DSL Modems Lead Plating System z Pre-regulator for Linear Regulators G : Green (Halogen Free and Pb Free) Note : Pin Configurations Richtek products are : (TOP VIEW) RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. NC 10 SS BOOT 2 9 EN Suitable for use in SnPb or Pb-free soldering processes. 3 NC 8 COMP GND VIN 4 7 FB 11 5 SW 6 GND Marking Information MSOP-10 (Exposed Pad) For marking information, contact our sales representative directly or through a Richtek distributor located in your 8 BOOT SS area, otherwise visit our website for detail. 2 7 VIN EN 3 6 SW COMP 4 GND 5 FB SOP-8 DS8271-02 March 2011 www.richtek.com 1RT8271 Typical Application Circuit V IN VIN BOOT 4.75V to 24V C IN C BOOT L1 RT8271 10F/25V 4.7H 10nF V OUT SW 2.5V Chip Enable D1 EN R1 B230A 16.9k C OUT SS FB 22F/6.3V C C SS C R C R2 1.5nF 10nF 15k 10k COMP GND C P NC Table 1. Recommended Component Selection V (V) R1 (k) R2 (k ) R (k ) C (nF) L (H) C ( F) OUT C C OUT 15 154 10 68 0.56 22 22 10 100 10 49.9 0.82 15 22 8 76.8 10 49.9 1 10 22 5 44.2 10 33 1.2 6.8 22 3.3 25.5 10 22 1.5 4.7 22 2.5 16.9 10 15 1.5 4.7 22 1.8 9.53 10 12 1.5 2.2 22 1.2 3 10 12 1.5 2.2 22 Function Block Diagram VIN Current Sense V CC Slope Comp Internal Amplifier Oscillator Regulator 1.2MHz/440kHz + VA 1A - VA V CC Foldback 10k BOOT - Control EN + 1V 0.5V + Shutdown SW 3V Logic - Comparator + UV V - CC Comparator GND Current 10A Comparator 0.92V + SS +EA - Gm = 920A/V FB COMP www.richtek.com DS8271-02 March 2011 2