RT2701GQW

® RT2701 Dual-Phase PWM Controller for GPU Core Power Supply General Description Features The RT2701 is a dual-phase synchronous Buck PWM controller with integrated drivers which are optimized for high performance graphic microprocessor and computer applications. The IC integrates a PWM controller, two 12V MOSFET drivers with internal bootstrap diodes, as well as output current monitoring and protection functions into the WQFN-24L 4x4 package. The RT2701 adopts DCR and RDS(ON) current sensing. Over current protection is z Dual-Phase PWM Controller z Two Embedded MOSFET Drivers and Embedded Switching Boot Diode Dynamic Auto Phase Control with Adjustable Threshold Cross-talk Jitter Suspend (CJSTM) Remote GND Detection for High Accuracy Automatic Diode Emulation Mode/Or Ultrasonic Mode at Light Load Lossless RDS(ON) Current Sensing for Current Balance Lossless DCR Current Sensing for AVP & OCP Reference Voltage Output with 1% Accuracy External Reference Input with Soft-Start (RISS) Embedded One-Bit VID Control Adjustable OCP Threshold Adjustable Switching Frequency Reference Tracking UVP/OVP Protection Shoot Through Protection and Short Pulse Free Technology RoHS Compliant and Halogen Free accomplished through continuous inductor DCR current sensing, while RDS(ON) current sensing is used for accurate channel current balance. Using both methods of current sampling utilizes the best advantages of each technique. The RT2701 also features an one-bit VID control operation in which the feedback voltage is regulated and tracks external input reference voltage. Other features include adjustable operating frequency, external compensation and enable/shutdown functions. z z z z z z z z z z z z z Ordering Information RT2701 z Package Type QW : WQFN-24L 4x4 (W-Type) (Exposed Pad-Option 1) Applications z Lead Plating System G : Green (Halogen Free and Pb Free) z Note : z Richtek products are : z ` Middle to High End GPU Core Power High End Desktop PC Memory Core Power Low Voltage, High Current DC/DC Converter Voltage Regulator Modules RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit RT2701 VIN GPIO VCC VID PHASE1 PHASE2 MOSFET L1 VVDD L2 MOSFET OCP PS PGND RMPSET Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS2701-00 May 2013 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT2701 Pin Configurations Marking Information 03= : Product Code RSET VID BOOT2 UGATE2 PHASE2 LGATE2 (TOP VIEW) 03=YM DNN YMDNN : Date Code 24 23 22 21 20 19 VSET VREF EN/MSEL RMPSET COMP FB 1 18 2 17 3 16 PGND 4 15 25 5 14 13 6 8 9 10 11 12 VRTN TON OCP CSN CSP PS 7 VCC VDD LGATE1 PHASE1 UGATE1 BOOT1 WQFN-24L 4x4 Functional Pin Description Pin No. Pin Name Pin Function 1 VSET Output Voltage Setting. Connect a voltage divider from VREF to VSET to set the output voltage. 2 VREF Reference Voltage Output (2V). The RT2701 generates a 2V reference voltage from VREF to VRTN. Enable Control Input and Mode Selection. This pin is a tri-state input. Pull up this pin to be higher than 4.2V, the controller operates in DEM mode. Pull up this pin to between 1.2V to 3V, the controller operates in ASM mode. Pull down this pin to GND, the controller will shutdown. Internal Ramp Slew Rate Setting. Connect a resistor (RRMP) from RMPSET to GND to the ramp slew rate. The value of RRMP must be set equal to RTON. 3 EN/MSEL 4 RMPSET 5 COMP Compensation Node. This pin is the output node of the error amplifier. 6 FB 7 VRTN 8 TON 9 OCP Feedback Voltage Input. This pin is the negative input node of the error amplifier. Remote Differential Feedback, Invert Input. This pin is the negative node of the differential remote voltage sensing. Switching Frequency Setting. Connect a resistor (RTON ) from TON to VIN to set the switching frequency. The value of R TON must be set equal to RRMP . OCP Level Setting. Connect a resistor from OCP to GND to set the current limit threshold. 10 CSN Negative Input of Current Sensing. 11 CSP Positive Input of Current Sensing. 12 PS Dynamic Phase Control Input. Connect a resistor from PS to GND to set the auto down phase threshold. 13 BOOT1 Bootstrap Supply for High Side MOSFET Driver of Phase1. 14 UGATE1 High Side Gate Driver of Phase1. Connect this pin to the Gate of high side MOSFET. 15 PHASE1 Return node of Phase1 High Side Driver. Connect this pin to the Source of high side MOSFET together with the drain of low side MOSFET and the inductor. 16 LGATE1 Low Side Gate Driver of Phase1. Connect this pin to the Gate of low side MOSFET. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS2701-00 May 2013 RT2701 Pin No. Pin Name Pin Function 17 VDD Regulator Power for Internal Circuit. The regulated voltage provides power supply for all low voltage circuits. 18 VCC Supply Voltage Input. Connect this pin to GND by a ceramic cap larger than 1μF. 19 LGATE2 Low Side Gate Driver of Phase2. Connect this pin to the Gate of low side MOSFET. 20 PHASE2 21 UGATE2 22 BOOT2 23 VID 24 RSET Return node of Phase2 High Side Driver. Connect this pin to the Source of high side MOSFET together with the Drain low side of MOSFET and the inductor. High Side Gate Driver of Phase2. Connect this pin to the Gate of high side MOSFET. Bootstrap Supply for High Side MOSFET Driver of Phase2. Programming Output Voltage Control. When VID pin is logic high, internal N-MOSFET that connected to RSET pin is turn on. Output Voltage Setting. Connect a resistor from RSET pin to VSET pin, the output voltage can be switched two levels by driving VID pin. Power Ground. The exposed pad must be soldered to a large PCB and connected to PGND for maximum power dissipation. 25 PGND (Exposed Pad) Function Block Diagram VID RSET VREF VCC Reference Output Gen. Internal Regulator&BG VDD Power On Reset & Central Logic VSET UV Trip Point + - OV Trip Point Control & Protection Logic + - Boot-Phase Detection 1 Ramp Gen RMPSET Boot-Phase Detection 2 VSETA VRTN Soft-Start + FB ERROR AMP COMP EN/MSEL EN/Mode Select + + + + + LPF BOOT1 UGATE1 PHASE1 TON Gen 1 PWM CMP PWM1 + + To Power on Reset To driver Logic ZCD To Power on Reset PHASE1 To driver Logic LGATE1 Driver Logic TON Gen 2 LGATE2 PGND VIN Detection TON S/H GM + S/H GM + Current Balance PS APS CSP CSN OCP + - Copyright © 2013 Richtek Technology Corporation. All rights reserved. DS2701-00 May 2013 BOOT2 UGATE2 PHASE2 PWM2 AOC Isum Phase shedding OCP + 1/2 ++ To Protection Logic is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT2701 Operation The RT2701 integrates a PWM controller, two 12V MOSFET drivers with internal bootstrap diodes, as well as output current monitoring and protection functions. Power On Reset The Power On Reset (POR) circuit monitors the supply voltage of the controller (VCC). When VCC exceeds the POR rising threshold, the controller will be enabled. If VCC falls below the POR falling threshold during normal operation, all MOSFETs stop switching. There is a hysteresis between the POR rising threshold and falling threshold to prevent noise mis-trigger. Soft-Start Current Balance The RT2701 implements internal current balance mechanism in the current loop. The RT2701 senses each phase current signal and compares it with the average current. If the sensed current of any particular phase is higher than average current, the on-time of this phase will be adjusted to be shorter. OCP Once the sensed total current exceeds the current limit threshold, the driver will be forced to turn off the gate drivers for high side power MOSFETs. Until the OCP situation is removed. An internal soft-start function is used to prevent large inrush current while converter is powered-up. The FB voltage will track the internal soft-start voltage during softstart interval. During the soft-start period, the controller will operate in dual-phase mode to ensure enough charge for output loads. Over Voltage Protection EN/Mode Select Under Voltage Protection The RT2701 supports DEM (Diode Emulation Mode) and ASM (Audio Skipping Mode) operation which can be enabled by EN/MSEL pin. When the EN/MSEL pin is pulled up above 4.2V, the controller will operate in DEM and reduce the switching frequency at light load conditions for saving power loss. If the EN/MSEL voltage is between 1.2V and 3V, the controller will operate in ASM. In ASM operation, the minimum switching frequency is limited to 30kHz to avoid acoustic noises. If the pin is pulled to GND, the RT2701 will be shut down. The voltage on CSN pin is also monitored for Under Voltage Protection (UVP). If the output voltage is lower than the UVP threshold, the controller will turn off both high side and low side MOSFETs. When the UVP is triggered, the RT2701 will enter hiccup mode and continuously try to restart until the UVP situation is removed. Copyright © 2013 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 The RT2701 monitors the output voltage via the CSN pin for Over Voltage Protection (OVP). Once the output voltage exceeds the OVP threshold, the controller will turn off high side MOSFETs and turn on low side MOSFETs to protect the load until the OVP situation is removed. is a registered trademark of Richtek Technology Corporation. DS2701-00 May 2013 RT2701 Absolute Maximum Ratings z z z z z z z z z z z z z (Note 1) VDD, VSEN, COMP, VSET, VREF, EN/MSEL, PS, OCP, CSN, CSP, RSET, VID, RMPSET to PGND ------------------------------------------------------------ −0.3V to 6V VCC, TON to PGND --------------------------------------------------------------------------------- −0.3V to 15V VRTN to PGND ---------------------------------------------------------------------------------------- −0.3V to 0.3V BOOTx to PHASEx ---------------------------------------------------------------------------------- −0.3V to 15V PHASEx to PGND DC -------------------------------------------------------------------------------------------------------- −3V to 15V