RT8207GQW

RT8207 Complete DDRII/DDRIII Memory Power Supply Controller General Description Features The RT8207 provides a complete power supply for both DDRII/DDRIII memory systems. It integrates a synchronous PWM buck controller with a 3A sink/source tracking linear regulator and a buffered low noise reference. z ` Resistor Programmable Current Limit by Low-Side The PWM controller provides the high efficiency, excellent transient response, and high DC output accuracy needed for stepping down high-voltage batteries to generate low voltage chipset RAM supplies in notebook computers. 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 RT8207 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. The buck conversion allows this device to directly step down high-voltage batteries for the highest possible efficiency. PWM Controller z RDS(ON) Sense ` Quick Load-Step Response within 100ns ` 1% VOUT Accuracy Over Line and Load ` Fixed 1.8V (DDRII), 1.5V (DDRIII) or Adjustable 0.75V to 3.3V Output Range ` Battery Input Range 2.5V to 26V ` Resistor Programmable Frequency ` Over/Under Voltage Protection ` 4 Steps Current Limit During Soft-Start ` Drives Large Synchronous-Rectifier FETs ` Power-Good Indicator 3A LDO (VTT), Buffered Reference (VTTREF) ` Capable to Sink and Source Up to 3A ` LDO Input Available to Optimize Power Losses ` Requires Only 20μ μF Ceramic Output Capacitor ` Buffered Low Noise 10mA VTTREF Output ` Accuracy ±20mV for Both VTTREF and VTT ` Supports High-Z in S3 and Soft-Off in S4/S5 RoHS Compliant and Halogen Free The 3A sink/source LDO maintains fast transient response only requiring 20μF of ceramic output capacitance. In addition, the LDO supply input is available externally to significantly reduce the total power losses. The RT8207 supports all of the sleep state controls placing VTT at High-Z in S3 and discharging VDDQ, VTT and VTTREF (soft-off) in S4/S5. z The RT8207 has all of the protection features including thermal shutdown and is available in the WQFN-24L 4x4 package. Pin Configurations Applications z (TOP VIEW) VTT VLDOIN BOOT UGATE PHASE LGATE z DDRII/DDRIII Memory Power Supplies Notebook Computers SSTL18, SSTL15 and HSTL Bus Termination Ordering Information RT8207 Package Type QW : WQFN-24L 4x4 (W-Type) Note : Lead Plating System G : Green (Halogen Free and Pb Free) Richtek products are : ` RoHS compliant and compatible with the current require- 24 23 22 21 20 19 VTTGND VTTSNS GND MODE VTTREF DEM 1 18 2 17 3 16 GND 4 15 25 5 14 13 6 7 8 PGND NC CS VDDP VDD PGOOD 9 10 11 12 NC VDDQ FB S3 S5 TON z WQFN-24L 4x4 ments of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. DS8207-07 March 2011 www.richtek.com 1 RT8207 Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. Typical Application Circuit VIN 2.5V to 26V R4 620k 12 VDDP 5V 15 R1 5.1 C1 1µF C2 1µF R2 100k PGOOD R5 0 RT8207 BOOT 22 TON VDDP PHASE R3 5.6k 16 CS 13 PGOOD C4 0.1µF Q1 BSC09 4N035 R6 0 UGATE 21 14 VDD C9 10µF x 3 20 LGATE 19 VVDDQ 1.2V L1 1µH C7 220µF R7 Q2 BSC032N035 R8 6k C5 FB 9 C6 R9 10k 10 S3 11 VLDOIN 23 S5 VDDQ Control 4 VDDQ 8 Discharge Mode MODE 6 DEM CCM/DEM 24 VTT 3 , Exposed Pad (25) 2 GND VTTSNS 18 PGND 1 VTTGND VTTREF 5 VTT/VTTREF Control C9 0.1µF C8 10µF x 2 C3 33nF Figure A. Adjustable Voltage Regulator VIN 2.5V to 26V R4 620k 12 VDDP 5V 15 C1 1µF R2 100k PGOOD VTT/VTTREF Control VDDQ Control Discharge Mode R1 5.1 C2 1µF RT8207 BOOT 22 TON VDDP 14 VDD R3 5.6k 16 CS 13 PGOOD 10 S3 11 S5 4 MODE 6 DEM CCM/DEM 3 , Exposed Pad (25) GND 18 PGND 1 VTTGND UGATE 21 PHASE R5 0 C8 10µF x 2 C4 0.1µF 20 LGATE 19 VVDDQ 1.8V/1.5V Q1 BSC09 4N035 R6 0 Q2 BSC032N035 L1 1µH R7 C6 220µF C5 VDDQ 8 VLDOIN 23 VTT 24 VTTSNS 2 VTTREF 5 C7 10µF x 2 C3 33nF FB 9 VDDP for DDRII GND for DDRIII Figure B. Fixed Voltage Regulator www.richtek.com 2 DS8207-07 March 2011 RT8207 Function Block Diagram TRIG On-time Compute 1-SHOT VDDQ TON - + GM + - + S FB 70% VREF + - OV Latch S1 Q - UV Latch S1 Q + UGATE DRV PHASE VDDP 1-SHOT PGND Diode Emulation + + Thermal Shutdown SS Timer S5 LGATE DRV 90% VREF VDD PWM Q Min. TOFF Q TRIG VREF 0.75V 115% VREF BOOT R Comp - GM + CS VDD PWM 10µA DEM PGOOD S3 MODE Discharge Mode Select VTTREF VLDOIN + + + - VTT + - VTTSNS 110% VVTTREF GND 90% VVTTREF + + VTTGND DS8207-07 March 2011 www.richtek.com 3 RT8207 Functional Pin Description Pin No. Pin Name 1 VTTGND 2 VTTSNS 3, 25 (Exposed Pad) GND Pin Function Power Ground for the VTT_LDO. Voltage Sense Input for the VTT_LDO. Connect to the terminal of the VTT_LDO output capacitor Analog Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. 4 MODE Output Discharge Mode Setting Pin. Connect to VDDQ for tracking discharge. Connect to GND for non-tracking discharge. Connect to VDD for no discharge. 5 VTTREF VTTREF Buffered Reference Output. 6 DEM 7, 17 NC Diode-Emulation Mode Enable Pin. Connect to VDD will enable diode-emulation mode. Connect to GND will always operate in forced CCM mode. No Internal Connection. VDDQ Reference Input for VTT and VTTREF. Discharge current sinking terminal 8 VDDQ for VDDQ non-tracking discharge. Output voltage feedback input for VDDQ output if FB pin is connected to VDD or GND VDDQ Output Setting Pin. Connect to GND for DDRIII (VDDQ = 1.5V) power supply. The pin should be connect to VDD for DDRII (VDDQ = 1.8V) power supply 9 FB 10 S3 S3 Signal Input. 11 S5 S5 Signal Input 12 TON 13 PGOOD Power-Good Open-Drain Output. This pin will be in HIGH state when VDDQ output voltage is within the target range. 14 VDD Supply Input for the Analog Supply. 15 VDDP Supply Input for the Low Gate Driver. 16 CS 18 PGND Power Ground for Low-Side MOSFET. 19 LGATE Low-Side Gate Driver Output for VDDQ. 20 PHASE External Inductor Connection for VDDQ and it behaves as the current sense comparator input for Low-Side MOSFET RDS(ON) sensing. 21 UGATE High-Side Gate Driver Output for VDDQ. 22 BOOT Boost Flying Capacitor Connection for VDDQ. 23 VLDOIN Power Supply for the VTT_LDO. 24 VTT Power Output for the VTT_LDO www.richtek.com 4 or be connected to a resistive voltage divider from VDDQ to GND to adjust the output of PWM from 0.75V to 3.3V. The pin is used to set the UGATE on time through a pull-up resistor connecting to V IN. Current Limit Threshold Setting Input. Connect this pin to VDD through the voltage setting resistor. DS8207-07 March 2011 RT8207 Absolute Maximum Ratings z z z z z z z z z z z z z z z (Note 1) Input Voltage, TON to GND ---------------------------------------------------------------------------------------------BOOT to GND -------------------------------------------------------------------------------------------------------------PHASE to GND DC ----------------------------------------------------------------------------------------------------------------------------