V IN RT8115A BO T O V OUT UGATE PHASE LGATE COMP/EN EN FB RT8115A 12V Green Voltage Mode High Efficiency Synchronous Buck PWM Controller General Description Features TM zz z zz Green Voltage Mode (GVM ) Control The RT8115A is a high efficiency single phase zz z zz High Light Load Efficiency synchronous Buck DC/DC controller with 5V/12V supply TM zz z zz Single 5V to 12V Driver Voltage voltage. The IC features Green Voltage Mode (GVM ) zz z zz Integrated High Driving Capability N-MOSFET Gate control, which is specifically designed to improve converter Drivers efficiency at light load condition. At light load condition, zz z zz 300kHz Fixed Frequency Internal Oscillator the IC automatically operates in the diode emulation mode zz z zz 85% Maximum PWM Duty Cycle with constant on-time PFM to reduce switching frequency zz z zz Power Good Indicator so as to improve conversion efficiency. As the load current zz z zz Enable/Disable Control increases, the RT8115A leaves the Diode Emulation Mode zz z zz Adaptive Zero-Current Detection (DEM) and operates in the continuous conduction mode zz z zz Internal Soft-Start with fixed frequency PWM. zz z zz Lossless Low-Side MOSFET R Current Sensing DS(ON) The RT8115A has embedded MOSFET gate driver with for Over-Current Fault Monitoring high driving capability, supporting driving voltage up to 12V zz z zz LGATE Over-Current Setting (LGOCS) for high output current application. This device uses zz z zz Dedicated Output Voltage Monitor lossless low-side MOSFET R current sense DS(ON) zz z zz OCP, UVP, OVP, OTP, UVLO technique for over-current protection with adjustable zz z zz RoHs Compliant and Halogen Free threshold set by the LGATE pin (LGOCS). Other features include power good indication, enable/disable control and Applications internal soft-start. The RT8115A also provides fault z Motherboard, Memory/Chip-set Power protection functions to protect the power stage output. z Graphic Card, GPU/Memory Core Power With above functions, the IC provides customers a cost- z Low Voltage, High Current DC/DC Regulator effective solution for high efficiency power conversion. The RT8115A is available in the WDFN-10L 3x3 package. Simplified Application Circuit Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8115A-02 August 2013 www.richtek.com 1 V VCC CC V PGOOD PGOOD GNDRT8115A Ordering Information Pin Configurations RT8115A (TOP VIEW) Package Type 10 BOOT 1 PGOOD QW : WDFN-10L 3x3 (W-Type) 2 9 PHASE NC 3 8 UGATE FB Lead Plating System 4 7 LGATE COMP/EN Z : ECO (Ecological Element with 11 5 6 GND VCC Halogen Free and Pb free) WDFN-10L 3x3 Note : Richtek products are : Marking Information RoHS compliant and compatible with the current require- JH : Product Code ments of IPC/JEDEC J-STD-020. YMDNN : Date Code JH YM Suitable for use in SnPb or Pb-free soldering processes. DNN Functional Pin Description Pin No. Pin Name Pin Function Bootstrap Supply for High-Side Gate Driver. Connect this pin to a power source V through a bootstrap diode, and connect a 0.1 F or greater ceramic CC 1 BOOT capacitor from this pin to the PHASE pin to supply the power for high-side gate driver. Switch Node. Connect this pin to the switching node of Buck converter. This pin is also the floating drive return of the high-side MOSFET gate driver. The 2 PHASE PHASE voltage is sensed for zero current detection and over-current protection when low-side MOSFET is on. High-Side MOSFET Gate Driver Output. Connect this pin to the Gate of 3 UGATE high-side MOSFET for floating drive. Low-Side MOSFET Gate Driver Output. Connect this pin to the Gate of low-side MOSFET. This pin is also used for over-current protection (OCP) threshold 4 LGATE setting. Connect a resistor (R ) from this pin to the GND pin to set the OCP OCSET threshold. 5, Ground. The exposed pad must be soldered to a large PCB and connected to GND 11 (Exposed Pad) GND for maximum power dissipation. Supply Voltage Input. It is recommended to connect a 1F or greater ceramic 6 VCC capacitor from this pin to the GND pin. VCC also powers the low-side gate driver. Compensation Node. Connect R-C network between this pin and the FB pin for PWM control loop compensation. This pin is also used for enable/disable 7 COMP/EN control. Connect a small signal MOSFET to this pin to implement enable/disable control. Feedback Voltage Input. This pin is used for output voltage feedback input and it is also monitored for power good indication, over-voltage and under-voltage 8 FB protections. Connect this pin to the converter output through voltage divider resistors for output voltage regulation. 9 NC No Internal Connection. Power Good Indicator Output. This pin provides an open-drain output. Connect this pin to a voltage source through a pull-up resistor. The PGOOD voltage goes 10 PGOOD high to indicate the output voltage is in regulation. This pin can be left open if the power good indication function is not used. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8115A-02 August 2013 www.richtek.com 2 GND