your power partner. RT2872GSP Evaluation Board RT2872 Step-Down Converter Evaluation Board Purpose The RT2872 is a high-efficiency current mode synchronous step-down regulator that can deliver up to 3A output current from a wide input voltage range of 4.5V to 36V. This document explains the function and use of the RT2872 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 .................................................................................................................................................................... 5 PCB Layout ......................................................................................................................................................... 6 Step-Down Converter Efficiency Test ................................................................................................................. 10 More Information................................................................................................................................................ 11 Important Notice for Richtek Evaluation Board ................................................................................................... 11 EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP Evaluation Board Introduction General Product Description The RT2872 is a high efficiency, current mode synchronous step-down DC/DC converter that can deliver up to 3A output current over a wide input voltage range from 4.5V to 36V. The device integrates a 105mΩ high side and an 80mΩ low side MOSFET to achieve high conversion efficiency up to 95%. The current mode control architecture supports fast transient response and uses a simple compensation circuit. A cycle-by-cycle current limit function provides protection against a shorted output and an internal soft-start eliminates input surge current during start-up. The RT2872 provides complete protection functions such as input under voltage lockout, output under voltage protection, over current protection and thermal shutdown. The RT2872 is available in the thermal enhanced SOP-8 (Exposed Pad) package. Product Features 4.5V to 36V Input Voltage Range 3A Output Current Internal N-MOSFETs Current Mode Control Frequency Operation : 300kHz to 1MHz Adjustable Output Voltage from 0.8V to 30V High Efficiency Up to 95% Stable with Low ESR Ceramic Output Capacitors Cycle-by-Cycle Current Limit AEC-Q100 Grade 3 Certification Application Point of Load Regulator in Distributed Power Systems Digital Set Top Boxes Broadband Communications Vehicle Electronics Automotive Audio, Navigation, and Information Systems Enterprise Datacom Platforms Point of Load (POL) Industrial Grade General Purpose Point of Load EVB_RT2872GSP-01 May 2016 http://www.richtek.com RT2872GSP 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 VIN Signal Input voltage Comment (expected waveforms or voltage levels on test points) Input voltage range = 4.5V to 36V Default output voltage = 3.3V VOUT Output voltage Output voltage range = 0.8V to 30V (see ‘’ Output Voltage Setting’’ section for changing output voltage level) SW Switch Node SW waveform EN Chip Enable Operation BOOT Boot strap supply test point Floating supply voltage for the high-side N-MOSFET switch MODE RT test point Switch frequency setting point GND Ground Ground Enable signal. EN is automatically pulled high (by R4) to enable operation. Connect EN low to disable operation. Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4.5V < VIN < 36V) to the VIN and GND terminals. 2. The EN voltage is pulled to logic high by R4 (100kΩ to VIN) to enable operation. Drive EN high (>2.0V) to enable operation or low (<0.4V) to disable operation. 3. Verify the output voltage (approximately 3.3V) between VOUT and GND. 4. Connect an external load up to 3A to the VOUT and GND terminals and verify the output voltage and current. EVB_RT2872GSP-01 May 2016 http://www.richtek.com RT2872GSP Evaluation Board your power partner. Output Voltage Setting Set the output voltage with the resistive divider (R1, R2) between VOUT and GND with the midpoint connected to FB through RCAMP. The output is set by the following formula: VOUT = 0.8 x (1 + R1 ) R2 The installed VOUT capacitors (C4, C5) are 22μF, 16V X5R ceramic types. Do not exceed their operating voltage range and consider their voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is sufficient to maintain stability and provide sufficient transient response for your application. This can be verified by checking the output transient response as described in the RT2872 IC datasheet. Specification Parameter Input Voltage Range Symbol Min VIN 4.5 Output Voltage VOUT Oscillator Frequency fOSC Output Current IOUT High-Side Switch Current Limit Range UOC Typ. Max Units 36 V 3.3 300k 4.25 5 V 1M Hz 3 A 5.75 A Schematic EVB_RT2872GSP-01 May 2016 http://www.richtek.com RT2872GSP Evaluation Board your power partner. BOM Reference Q'ty P/N Description Package Manufacture U1 1 RT2872GSP DC/DC Converter PSOP-8 Richtek C1, C2 2 C3216X5R1H106K160AB 10μF/±10%/50V/X5R Ceramic Capacitor 1206 TDK C4, C5 2 GRM32ER61C226KE20# 22μF/±10%/16V/X5R Ceramic Capacitor 1210 Murata C7 1 0603B272K500 2.7nF/±10%/50V/X7R Ceramic Capacitor 0603 WALSIN C3, C6, C11 3 C1608X7R1H104K080AA 0.1μF/±10%/50V/X7R Ceramic Capacitor 0603 TDK C8, C9, C12, C13 0 Not Installed 0603 L1 1 4.7μH/4.1A 8 x 8 x 4.2mm R1 1 75kΩ/±1%, Resistor 0603 R2 1 24kΩ/±1%, Resistor 0603 R3 1 13kΩ/±1%, Resistor 0603 R4 1 100kΩ/±1%, Resistor 0603 R5, D1, D2 0 Not Installed R6, RCAMP 2 0Ω, Resistor 0603 RT 1 113kΩ/±1%, Resistor 0603 TP 4 Test Pin GP 4 Golden Pin EVB_RT2872GSP-01 May 2016 NR8040T4R7N TAIYO YUDEN http://www.richtek.com RT2872GSP Evaluation Board your power partner. PCB Layout Top View (1st layer) Bottom View (4th Layer) EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP Evaluation Board Component Placement Guide—Component Side (1st layer) PCB Layout—Component Side (1st Layer) EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP Evaluation Board PCB Layout—Inner Side (2nd Layer) PCB Layout—Inner Side (3rd Layer) EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP Evaluation Board Component Placement Guide—Bottom Side (4th Layer) PCB Layout—Bottom Side (4th layer) EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP Evaluation Board Step-Down Converter Efficiency Test EVB_RT2872GSP-01 May 2016 http://www.richtek.com your power partner. RT2872GSP 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_RT2872GSP-01 May 2016 http://www.richtek.com