RT8241AZQW

® RT8241 High Efficiency Single Synchronous Buck PWM Controller General Description Features The RT8241 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 4700ppm/°°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 The RT8241 supports on chip voltage programming function between 0.675V and 0.9V by controlling GX digital inputs. z z z z 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. The RT8241 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 RT8241 is intended for CPU core, chipset, DRAM, or other low voltage supplies as low as 0.675V. The RT8241 is available in a WQFN-12L 2x2 package. 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 2 FB 10 GND 13 3 4 5 6 EN Switching Frequency Operation A : 300kHz B : 400kHz C : 500kHz 1 11 VCC Lead Plating System G : Green (Halogen Free and Pb Free) Z : ECO (Ecological Element with Halogen Free and Pb free) LGATE PHASE UGATE 12 BOOT Package Type QW : WQFN-12L 2x2 (W-Type) CS RT8241 GND (TOP VIEW) Ordering Information 9 PGOOD 8 G1 G0 7 WQFN-12L 2x2 Note : Richtek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8241-03 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8241 Marking Information RT8241BGQW RT8241AGQW 30 : Product Code 30W W : Date Code 41W RT8241AZQW 30 : Product Code 30W RT8241CGQW 41 : Product Code 40 : Product Code W : Date Code 40W RT8241BZQW 41 : Product Code W : Date Code 41W W : Date Code RT8241CZQW 40 : Product Code W : Date Code 40W W : Date Code Typical Application Circuit For Fixed Voltage Regulator : VCC RT8241 5 VCC BOOT 4 R1 CBYPASS UGATE 3 R2 R3 C1 CIN R4 Q1 9 PGOOD Chip Enable VOUT COUT R5* LGATE 1 11 CS 12, 13 (Exposed Pad) LOUT PHASE 2 6 EN RCS VIN Q2 G0 7 G1 8 GND C2* FB 10 * : Optional For Adjustable Voltage Regulator : VCC RT8241 5 VCC BOOT 4 R1 CBYPASS UGATE 3 R2 R3 C1 CIN R4 Q1 9 PGOOD Chip Enable R5* LGATE 1 11 CS 12, 13 (Exposed Pad) LOUT PHASE 2 6 EN RCS VIN Q2 G0 7 G1 8 GND RFB1 C3* VOUT COUT C2* RFB2 FB 10 * : Optional Table 1. VID Table G0 0 0 1 1 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 G1 0 1 0 1 VFB 0.9V 0.8V 0.725V 0.675V is a registered trademark of Richtek Technology Corporation. DS8241-03 January 2014 RT8241 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 Output Voltage Feedback Input. 11 CS 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. 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. 12, 13 (Exposed Pad) GND Function Block Diagram PHASE FB TRIG On-time compute One shot R - COMP GM + SS (Internal) TON S Q + VREF - 1.1V - 0.45V DRV VCC Voltage Programmer ZCD + - + 85% VREF G1 Thermal Shutdown SS EN Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8241-03 January 2014 LGATE LG RDS(ON) Diode Emuation GND PGOOD leakage - G0 UGATE PHASE DRV UV Latch S1 Q + BST switch resistance Min toff Q TRIG One shot OV Latch S1 Q + BOOT UG RDS(ON) 10µA + - 1/8 CS OC threshold is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8241 Absolute Maximum Ratings (Note 1) VCC, FB, PGOOD, EN, CS, G0, G1 to GND ----------------------------------------------------------------------PHASE to GND DC ----------------------------------------------------------------------------------------------------------------------------