RT5795AGQW Evaluation Board your power partner. 2A, 5.5V, Low IQ ACOT Synchronous Step-Down Converter Purpose The RT5795A is an Advanced Constant-On-Time (ACOT) synchronous step-down converter with the input voltage range from 2.5V to 5.5V and provides 2A output current. This document explains the function and use of the RT5795A evaluation board (EVB), and provides information to enable operation, modification of the evaluation board and circuit to suit individual requirements. Table of Contents Purpose ................................................................................................................................................................. 1 Introduction............................................................................................................................................................ 2 Key Performance Summary Table .......................................................................................................................... 2 Bench Test Setup Conditions ................................................................................................................................. 3 Schematic, Bill of Materials & Board Layout ........................................................................................................... 5 More Information.................................................................................................................................................... 7 Important Notice for Richtek Evaluation Board ....................................................................................................... 7 EVB_RT5795AGQW-00 Aug 2015 1 http://www.richtek.com RT5795AGQW Evaluation Board your power partner. Introduction General Product Information The RT5795A is a full featured 5.5V, 2A, Advanced Constant-On-Time (ACOT) synchronous step-down converter with two integrated MOSFETs. The advanced COT operation allows transient responses to be optimized over a wide range of loads, and output capacitors to efficiently reduce external component count. The RT5795A provides up to 2.7MHz switching frequency to minimize the size of output inductor and capacitors. Product Feature 2.5V to 5.5V Input Voltage Range Advanced COT Control loop design Fast Transient Response Internal 100m and 80m Synchronous Rectifier Highly Accurate VOUT Regulation Over Load/Line Range Robust Loop Stability with Low-ESR COUT Key Performance Summary Table Key Features Evaluation Board Number : PCB035_V1 Default Input Voltage 3.3V Max Output Current 2A Default Output Voltage 1.2V Default Marking & Package Type RT5795AGQW, WDFN-8SL 2x2 Operation Frequency Fixed 2.7MHz EVB_RT5795AGQW-00 Aug 2015 2 http://www.richtek.com RT5795AGQW 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 [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 Power input supply voltage, 2.5V to 5.5V. EN Enable test point Enable control input. Pull high to enable. PGOOD Power Ground The exposed pad must be soldered to a large PCB and connected to GND for maximum thermal dissipation. AGND Analog Ground Should be electrically connected to GND close to the device. PGND Power Ground The exposed pad must be soldered to a large PCB and connected to PGND for maximum power dissipation. VOS No internal connection Output voltage sense pin for the Internal Control Loop. Must be connected to output. FB Feedback test point Feedback voltage input. LX Switch node test point Switch node. The source of the internal high-side power MOSFET, and drain of the internal low-side (synchronous) rectifier MOSFET. EVB_RT5795AGQW-00 Aug 2015 3 http://www.richtek.com RT5795AGQW Evaluation Board your power partner. Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (2.5V < VIN < 5.5V) to the VIN and GND terminals. 2. Set the jumper at JP1 to connect terminals 2 and 3, connecting EN to enable operation. 3. Verify the output voltage (approximately 1.2V) between VOUT and GND. 4. Connect an external load up to 2A to the VOUT and GND terminals and verify the output voltage and current. Output Voltage Setting Set the output voltage with the resistive divider (R24, R29) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula : VOUT = 0.45 x (1 + EVB_RT5795AGQW-00 R24 ) R29 Aug 2015 4 http://www.richtek.com RT5795AGQW Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram PGOOD VIN 8 VIN 6 PGOOD R31 J3 C13 C15 C14 EN LX 1 EN LX VOS L1 7 Thermal Pad VIN J2 C11 MODE C10 3 VIN C12 AGND VOS 5 R24 C31 SIP-2P-PW R30 GND 2 JP1 3 2 1 PGND FB 4 3 2 1 R29 TP4 CP1 EN 1 VOS 2 TP6 PGOOD VOS short PGOOD TP1 TP5 LX EN LX EN Bill of Materials Reference Qty Part Number Description Package Manufacture U4 1 RT5795AGQW DC/DC Converter WDFN-8SL 2x2 RICHTEK C12, C13, C31 3 C10, C14 2 C1608X7R1H104K080AA 0.1μF/±10%/50V/X7R C-0603 TDK C15 1 GRM31CR71E106KA12L 10μF/25V/X7R C-1206 MURATA C11 1 GRM31CR61A226KE19L 22μF/10V/X5R C-1206 MURATA L1 1 PIFE25201T-R47MS 0.47μH 2.5 x 2.0 mm CYNTEC R24 1 65.3k R-0603 R29 1 39.2k R-0603 R30 1 100k R-0603 R31 1 180k R-0603 L 1 3.3μH/2.15A 4.5 x 4 mm EVB_RT5795AGQW-00 NC SR04033R3MSB Aug 2015 5 ABC ELECTRONICS http://www.richtek.com RT5795AGQW Evaluation Board your power partner. PCB Layout Top View Bottom View EVB_RT5795AGQW-00 Aug 2015 6 http://www.richtek.com RT5795AGQW Evaluation Board your power partner. 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 TO BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES. EVB_RT5795AGQW-00 Aug 2015 7 http://www.richtek.com