your power partner. RT8279GSP Evaluation Board RT8279 Step-Down Converter Evaluation Board Purpose The RT8279 is a Current mode operation step-down regulator with an internal power MOSFET. This document explains the function and use of the RT8279 evaluation board (EVB) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements. Table of Contents Purpose ............................................................................................................................................................... 1 Introduction.......................................................................................................................................................... 2 General Product Description ................................................................................................................................ 2 Product Features ................................................................................................................................................. 2 Application ........................................................................................................................................................... 2 Evaluation Board ................................................................................................................................................. 3 Specification ........................................................................................................................................................ 4 Schematic............................................................................................................................................................ 4 BOM .................................................................................................................................................................... 4 PCB Layout ......................................................................................................................................................... 5 Step-Down Converter Efficiency Test ................................................................................................................... 7 More Information.................................................................................................................................................. 8 Important Notice for Richtek Evaluation Board ..................................................................................................... 8 EVB_RT8279GSP-00 June 2015 http://www.richtek.com your power partner. RT8279GSP Evaluation Board Introduction General Product Description The RT8279 is a step-down regulator with an internal power MOSFET. It achieves 5A of continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. For protection, the RT8279 provides cycle-by-cycle current limiting and thermal shutdown protection. An adjustable soft-start reduces the stress on the input source at start up. In shutdown mode, the regulator draws only 25μA of supply current. The RT8279 requires a minimum number of readily available external components, providing a compact solution. The RT8279 is available in the SOP-8 (Exposed Pad) package. Product Features 5A Output Current Internal Soft-Start 110mΩ Internal Power MOSFET Switch Internal Compensation Minimizes External Parts Count High Efficiency up to 90% 25μA Shutdown Mode Fixed 500kHz Frequency Thermal Shutdown Cycle-by-Cycle Over Current Protection Wide 5.5V to 36V Operating Input Range Adjustable Output Voltage from 1.222V to 26V Available In an SOP-8 (Exposed Pad) Package RoHS Compliant and Halogen Free Application Distributive Power Systems Battery Charger DSL Modems Pre-regulator for Linear Regulators EVB_RT8279GSP-00 June 2015 http://www.richtek.com RT8279GSP Evaluation Board your power partner. Evaluation Board Please carefully inspect the EVB IC and external components, comparing them to the following Bill of Materials, to ensure that all components are installed and undamaged. If any components are missing or damaged during transportation, please contact the distributor or send e-mail to [email protected] Test Points The EVB is provided with the test points and pin names listed in the table below. Test point/Pin name Signal Comment (expected waveforms or voltage levels on test points) VIN Input voltage Input voltage range = 5.5V to 36V VOUT Output voltage Output voltage = 2.4V SW Switch Node The EN pin is externally pulled to High by adding a 100kΩ resistor (R4) from the VIN pin in this EVB setting. For another enable EN Chip Enable Operation operation, pull the EN pin low (<0.4V) will shutdown the device, drive the EN pin to high (>1.4V, <5.5V) will turn on the device again. GND Ground Ground Power-up & Measurement Procedure 1. Connect input power (5.5V< VIN < 36V) and input ground to Vin and GND pins respectively. 2. Connect positive end and negative end of load to VOUT and GND of output pins respectively. 3. The output voltage of (VOUT) can be set by R1 and R2. VOUT = VREF * (1+R1/R2) where VREF = 1.222V (typ.) EVB_RT8279GSP-00 June 2015 http://www.richtek.com RT8279GSP Evaluation Board your power partner. Specification Parameter Symbol Min VIN 5.5 Input Voltage Range Output Voltage VOUT Oscillator Frequency fOSC Output Current IOUT Current Limit ILIM Typ. Max Units 36 V 2.4 425 V 500 6 575 kHz 5 A 9 A 7.5 Schematic GP1 SW 1 1 GP3 EN D2 NC 1 2 U1 C11 Vin/5.5 to 36V PH-8 GND GND SIP-2P-PW C5 22uF C6 0.1uF C4 22uF D1 B550C 100k R5 NC NC ENA-5 VSENSE-4 PowerPad(Exposed Pad) Connect to Pin6 100k GND-6 R1 NC-3 C8 Vout/5A J2 VOUT 7uH 100nF NC-2 R4 0.1uF L1 BS-1 C3 C1 C2 4.7uF GND SIP-2P-PW 4.7uF 100k VIN-7 C12 82pF J1 1 R2 GP4 GND BOM Reference Q'ty U1 1 RT8279GSP Step-down converter SOP-8 RICHTEK C1, C2 2 GRM32ER71H475K 4.7μF/50V/X7R C-1210 MURATA C3, C6, C11 3 C1608X7R1H104K080AA 0.1μF/±10%/50V/X7R C-0603 TDK C4, C5 2 GRM32ER61C226KE20 22μF/±10%/16V/X5R C-1210 MURATA C12 1 82pF C-0603 L1 1 74437368068 6.8μH, 6A, ±20%, DCR = 23.3mΩ 10 x 10 x 3.8mm WE-LHMI D1 1 B550C 50V/5A DIODES R1, R2, R4 3 100k C8, R5 2 NC EVB_RT8279GSP-00 P/N June 2015 Description Package Manufacture R-0402 http://www.richtek.com RT8279GSP Evaluation Board your power partner. PCB Layout st PCS Layout (1 layer) nd PCS Layout (2 EVB_RT8279GSP-00 June 2015 layer) http://www.richtek.com RT8279GSP Evaluation Board your power partner. rd PCS Layout (3 layer) th PCS Layout (4 layer) EVB_RT8279GSP-00 June 2015 http://www.richtek.com your power partner. RT8279GSP Evaluation Board Step-Down Converter Efficiency Test EVB_RT8279GSP-00 June 2015 http://www.richtek.com your power partner. RT8279GSP Evaluation Board More Information For more information, please find the related datasheet or application notes from Richtek website http://www.richtek.com. Important Notice for Richtek Evaluation Board THIS DOCUMENT IS FOR REFERENCE ONLY, NOTHING CONTAINED IN THIS DOCUMENT SHALL BE CONSTRUED AS RICHTEK’S WARRANTY, EXPRESS OR IMPLIED, UNDER CONTRACT, TORT OR STATUTORY, WITH RESPECT TO THE PRESENTATION HEREIN. IN NO EVENT SHALL RICHTEK BE LIABLE T O BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES. EVB_RT8279GSP-00 June 2015 http://www.richtek.com