RT8240BZQW

® RT8240A/B/C High Efficiency Single Synchronous Buck PWM Controller General Description Features The RT8240A/B/C 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 Built-in 0.5% Reference Voltage z 1 Bit Programmable Output Voltage Between 1V and 1.05V with Integrated Transition Support Output Voltage Range from 1V to 3.6V Quick Load-Step Response within 100ns Support Pure MLCC Output Capacitor 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 RT8240A/B/C supports on chip voltage programming function between 1V and 1.05V by controlling G0 digital inputs. z 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 RT8240A/B/C 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 RT8240A/B/C is intended for CPU core, chipset, DRAM, or other low voltage supplies as low as 1V. The RT8240A/B/C 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 Note : PHASE UGATE 2 CS 10 GND 13 3 4 5 6 VOUT 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 12 BOOT Package Type QW : WQFN-12L 2x2 (W-Type) G0 RT8240A/B/C GND (TOP VIEW) Ordering Information 9 PGOOD 8 EN RGND 7 WQFN-12L 2x2 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. DS8240A/B/C-04 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8240A/B/C Marking Information RT8240AGQW RT8240CGQW 45: Product Code 45W 43 : Product Code YMDNN : Date Code 43W RT8240AZQW RT8240CZQW 45: Product Code 45W YMDNN : Date Code 43 : Product Code YMDNN : Date Code 43W YMDNN : Date Code RT8240BGQW 29 : Product Code 29W YMDNN : Date Code RT8240BZQW 29 : Product Code 29W YMDNN : Date Code Typical Application Circuit (1) Remote Sense RT8240A/B/C VCC 5 VCC 9 PGOOD Chip Enable VIN UGATE 3 PHASE 2 8 EN 11 12, 13 (Exposed Pad) 10 VOUT LGATE 1 G0 6 GND VOUT CS RGND 7 Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 BOOT 4 Remote (+) Remote (-) is a registered trademark of Richtek Technology Corporation. DS8240A/B/C-04 January 2014 RT8240A/B/C (2) Local Sense RT8240A/B/C VCC 5 VCC 9 PGOOD Chip Enable BOOT 4 VIN UGATE 3 PHASE 2 8 EN 11 12, 13 (Exposed Pad) 10 VOUT LGATE 1 G0 GND CS VOUT 6 RGND 7 VID Table G0 VOUT 0 1V 1 1.05V Copyright © 2014 Richtek Technology Corporation. All rights reserved. DS8240A/B/C-04 January 2014 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8240A/B/C 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 Gate Drive Output for the High Side External MOSFET. 4 BOOT 5 VCC 6 VOUT Output Voltage Feedback Input. Connect VOUT to converter output node. 7 RGND Remote Voltage Sense Ground Pin. 8 EN PWM Enable Pin. Pull low to GND to disable the PWM. 9 PGOOD Open Drain Power Good Indicator. High impedance indicates power is good. CS Current Limit Threshold Setting Input. Connect a setting resistor to GND and the current limit threshold is equal to 1/8 of the voltage at this pin. 10 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. 11 G0 12, GND 13 (Exposed Pad) Input Pin for Programming the Output Voltage Between 1V and 1.05V. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Function Block Diagram TRIG On-time compute One shot PHASE S Q + 1V Q + 120% VREF - 70% VREF + BOOT R - COMP GM + VREF TON OV Latch S1 Q UV Latch S1 Q BST switch resistance Voltage Programmer VOUT RGND EN 90% VREF UGATE PHASE VCC LGATE DRV LG RDS(ON) ZCD + - GND PGOOD leakage + SS Timer Thermal Shutdown Copyright © 2014 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 UG RDS(ON) Min toff TRIG One shot - G0 DRV FCCM/DEM + - OC threshold 1/8 10µA CS is a registered trademark of Richtek Technology Corporation. DS8240A/B/C-04 January 2014 RT8240A/B/C Absolute Maximum Ratings (Note 1) VCC, VOUT, PGOOD, EN, CS, G0 to GND ------------------------------------------------------------------------RGND to GND -------------------------------------------------------------------------------------------------------------z PHASE to GND DC ----------------------------------------------------------------------------------------------------------------------------