RT8241EZQW

® RT8241E High Efficiency Single Synchronous Buck PWM Controller General Description Features The RT8241E PWM controller provides high efficiency, excellent transient response, and high DC output accuracy needed for stepping down high voltage batteries to generate low voltage CPU core, I/O, and chipset RAM supplies in notebook computers. z Meet Intel VCCSA Voltage Slew Rate z Built-in 1% Reference Voltage 2-Bit Programmable Output Voltage with Integrated Transition Support Quick Load-Step Response within 100ns 4700 ppm/°°C Programmable Current Limit by Low Side RDS(ON) Sensing 4.5V to 26V Battery Input Range Internal Ramp Current Limit Soft-Start Control Drives Large Synchronous Rectifier FETs Integrated Boost Switch Over/Under Voltage Protection Thermal Shutdown Power Good Indicator RoHS Compliant and Halogen Free z z z z z z z z z Applications z z z z Notebook Computers CPU/GPU Core Supply Chipset/RAM Supply Generic DC/DC Power Regulator Pin Configurations The RT8241E is available in a WQFN-12L 2x2 package. RT8241E Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Note : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` GND 13 3 4 5 6 9 PGOOD 8 G1 G0 7 33 : Product Code 33W DS8241E-03 January 2014 2 10 Marking Information Suitable for use in SnPb or Pb-free soldering processes. Copyright © 2014 Richtek Technology Corporation. All rights reserved. 1 11 WQFN-12L 2x2 Richtek products are : ` LGATE PHASE UGATE 12 EN Package Type QW : WQFN-12L 2x2 (W-Type) FB Ordering Information CS (TOP VIEW) GND The RT8241E achieves high efficiency at a reduced cost by eliminating the current-sense resistor found in traditional current-mode PWMs. Efficiency is further enhanced by its ability to drive very large synchronous rectifier MOSFETs and enter diode emulation mode at light load condition. The buck conversion allows this device to directly step down high voltage batteries at the highest possible efficiency. The RT8241E is intended for CPU core, chipset, DRAM, or other low voltage supplies as low as 0.675V. z VCC The constant-on-time PWM control scheme handles wide input/output voltage ratios with ease and provides 100ns “instant-on” response to load transients while maintaining a relatively constant switching frequency. BOOT The RT8241E supports on chip voltage programming function between 0.675V and 0.9V by controlling GX digital inputs. z W : Date Code is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8241E Typical Application Circuit For Fixed Voltage Regulator : RT8241E 5 VCC BOOT 4 R1 VCC CBYPASS R2 UGATE 3 C1 CIN R4 Q2 VOUT C2* G0 7 G1 8 GND COUT R5* LGATE 1 11 CS 12, 13 (Exposed Pad) LOUT PHASE 2 6 EN VIN Q1 9 PGOOD Chip Enable RCS R3 FB 10 * : Optional For Adjustable Voltage Regulator : VCC RT8241E 5 VCC BOOT 4 R1 CBYPASS R2 Chip Enable UGATE 3 R4 C1 CIN 11 CS 12, 13 (Exposed Pad) VIN Q1 9 PGOOD 6 EN RCS R3 LOUT PHASE 2 LGATE 1 R5* Q2 G0 7 G1 8 GND C2* RFB1 C3* VOUT COUT RFB2 FB 10 * : Optional G0 0 0 1 1 Table 1. VID Table G1 0 1 0 1 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 VFB 0.9V 0.85V 0.725V 0.675V is a registered trademark of Richtek Technology Corporation. DS8241E-03 January 2014 RT8241E Functional Pin Description Pin No. Pin Name Pin Function 1 LGATE Gate Drive Output for Low Side External MOSFET. 2 PHASE External Inductor Connection Pin for PWM Converter. It behaves as the current sense comparator input for low side MOSFET RDS(ON) sensing and reference voltage for on time generation. 3 UGATE 4 BOOT 5 VCC 6 EN Chip Enable (Active High). 7 G0 2-Bit Input Pin. 8 G1 2-Bit Input Pin. 9 PGOOD Open Drain Power Good Indicator. High impedance indicates power is good. 10 FB 11 CS Output Voltage Feedback Input. Current Limit Threshold Setting Input. Connect a setting resistor to GND and the current limit threshold is equal to 1/8 of the voltage seen at this pin. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Gate Drive Output for the High Side External MOSFET. Supply Input for High Side Driver. Connect a capacitor to the floating node (PHASE) pin. Control Voltage Input. Provides the power for the buck controller, the low side driver and the bootstrap circuit for high side driver. Bypass to GND with a 4.7μF ceramic capacitor. 12, 13 (Exposed Pad) GND Function Block Diagram TRIG On-time compute One shot PHASE FB SS (Internal) tON R - COMP GM + VREF + 0.45V + Voltage Programmer 85% VREF VCC G1 ZCD + - Thermal Shutdown SS EN Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8241E-03 January 2014 LGATE LG RDS(ON) + UGATE PHASE Diode Emuation GND PGOOD leakage - G0 UG RDS(ON) DRV UV Latch S1 Q - BST switch resistance DRV Min toff Q TRIG One shot OV Latch S1 Q - 1.1V BOOT S Q + 10µA + - 1/8 CS OC threshold is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8241E Absolute Maximum Ratings (Note 1) VCC, FB, PGOOD, EN, CS, G0, G1 to GND ----------------------------------------------------------------------PHASE to GND DC ----------------------------------------------------------------------------------------------------------------------------