EVB_RT2805AGSP

your power partner. RT2805AGSP Evaluation Board RT2805A Step-Down Converter Evaluation Board Purpose The RT2805A is a current mode asynchronous step-down converter that achieves excellent load and line regulation. This document explains the function and use of the RT2805A 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 Application ........................................................................................................................................................... 2 Bench Test Setup Conditions ............................................................................................................................... 3 Step-Down Converter Efficiency Test ................................................................................................................... 7 More Information.................................................................................................................................................. 8 Important Notice for Richtek Evaluation Board ..................................................................................................... 8 EVB_RT2805AGSP-00 June 2015 http://www.richtek.com your power partner. RT2805AGSP Evaluation Board Introduction General Product Description The RT2805A is a current mode asynchronous step-down converter that achieves excellent load and line regulation. Over a wide input voltage range from 5.5V to 36V and supports output current up to 5A. The Current mode operation provides fast transient response and eases loop stabilization. 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 RT2805A requires a minimum number of readily available external components, providing a compact solution. The RT2805A provides protection functions inducing input under voltage lockout, cycle-by-cycle current limit, short circuit protection and thermal shutdown protection. The RT2805A is available in the SOP-8 (Exposed Pad) package. Product Features              5A Output Current Wide Operating Input Range 5.5V to 36V Adjustable Output Voltage from 1.222V to 26V High Efficiency up to 90% Internal Compensation Minimizes External Parts Count Internal Soft-Start 110mΩ Internal Power MOSFET Switch 25μA Shutdown Mode Fixed 500kHz Frequency Thermal Shutdown Cycle-by-Cycle Current Limit 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_RT2805AGSP-00 June 2015 http://www.richtek.com RT2805AGSP Evaluation Board your power partner. Bench Test Setup Conditions Headers Description and Placement 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 evb_service@richtek.com Test Points The EVB is provided with the test points and pin names listed in the table below. Test point/ Pin name VIN Signal Input voltage VOUT SW Output voltage Comment (expected waveforms or voltage levels on test points) Input voltage range = 5.5V to 36V Output voltage = 2.4V Switch Node EN Chip Enable Operation GND Ground 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 operation, the converter is turned on when the EN pin is higher than 1.4V and turned off when the EN pin is lower than 0.4V. 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_RT2805AGSP-00 June 2015 http://www.richtek.com RT2805AGSP 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 2.4 400 V 500 6 600 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 SIP-2P-PW C2 4.7uF GND 4.7uF 100k VIN-7 C12 82pF J1 1 R2 GP4 GND BOM Reference Q'ty P/N Description Package Manufacture U1 1 RT2805AGSP 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 D1 1 B550C 50V/5A R1, R2, R4 3 100k C8, R5 2 NC EVB_RT2805AGSP-00 June 2015 WE-LHMI DIODES R-0402 http://www.richtek.com RT2805AGSP Evaluation Board your power partner. PCB Layout PCB Layout (1st layer) PCB Layout (2nd layer) EVB_RT2805AGSP-00 June 2015 http://www.richtek.com RT2805AGSP Evaluation Board your power partner. PCB Layout (3rd layer) PCB Layout (4th layer) EVB_RT2805AGSP-00 June 2015 http://www.richtek.com your power partner. RT2805AGSP Evaluation Board Step-Down Converter Efficiency Test EVB_RT2805AGSP-00 June 2015 http://www.richtek.com your power partner. RT2805AGSP 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_RT2805AGSP-00 June 2015 http://www.richtek.com