RT8228BGQW

RT8228B Single Synchronous Buck PWM Controller General Description Features z Built in 1% 0.5V Reference Voltage The RT8228B PWM controller provides high efficiency, z Adjustable 0.5V to 3.3V Output Range excellent transient response, and high DC output accuracy z Support Pure MLCC Output Capacitor needed for stepping down high voltage batteries to z Quick Load Step Response within 100ns generate low voltage CPU core, I/O, and chipset RAM z 4700ppm/C Programmable Current Limit by Low supplies in notebook computers. Side R Sensing DS(ON) The constant on-time PWM control scheme handles wide z 4.5V to 26V Battery Input Range input/output voltage ratios with ease and provides 100ns z Resistor Programmable Frequency instant-on response to load transients while maintaining z Internal Ramp Current Limit Soft-Start Control a relatively constant switching frequency. z Drives Large Synchronous Rectifier FETs The RT8228B achieves high efficiency at a reduced cost z Integrated Boost Switch by eliminating the current sense resistor found in z Over/Under Voltage Protection traditional current mode PWMs. Efficiency is further z Thermal Shutdown enhanced by its ability to drive very large synchronous z Power Good Indicator rectifier MOSFETs and enter diode emulation mode at z RoHS Compliant and Halogen Free light load condition. The buck conversion allows this device to directly step down high voltage batteries at the highest Applications possible efficiency. The RT8228B is intended for CPU core, z Notebook Computers chipset, DRAM, or other low voltage supplies as low as z CPU Core Supply 0.5V. The RT8228B is available in a WQFN-12L 2x2 z Chipset/RAM Supply as Low as 0.5V package. z Generic DC/DC Power Regulator Ordering Information Pin Configurations RT8228B Package Type (TOP VIEW) QW : WQFN-12L 2x2 (W-Type) Lead Plating System 12 11 10 G : Green (Halogen Free and Pb Free) Z : ECO (Ecological Element with 1 9 LGATE PGOOD Halogen Free and Pb free) GND 2 PHASE 8 EN 13 3 7 UGATE MODE Note : 4 5 6 Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. WQFN-12L 2x2 Suitable for use in SnPb or Pb-free soldering processes. RT8228B-05 October 2011 www.richtek.com 1 BOOT GND VCC TON FB CSV IN 4.5V to 26V R TON 360k 10F R4 RT8228B 0 11 4 TON BOOT C3 5 R5 VCC 0.1F 0 3 L1 UGATE Q1 1H * : Optional 4.7F 2 PHASE 100k 1 Q2 R7* LGATE C5* C6* 22F 22F 22F 22F R8 10k 9 C7* 10 CS 6 FB 7 R9 E MODE To 5V : D M 10k To GND : FCCM 8 12, 13 (Exposed Pad) RT8228B Marking Information RT8228BGQW RT8228BZQW 44 : Product Code 44 : Product Code W : Date Code W : Date Code 44W 44W Typical Application Circuit V OUT VDDP 1V C1 C8 C9 C10 PGOOD PGOOD Chip Enable EN www.richtek.com RT8228B-05 October 2011 2 C4 C2 R2 R6 GND