RT7285CGJ6 Evaluation Board your power partner. RT7285CGJ6 Evaluation Board Purpose The RT7285C is a synchronous step-down converter with Advanced Constant On-Time (ACOT™) mode control. It can deliver up to 1.5A output current from a wide input voltage range of 4.3V to 18V. This document explains the function and use of the RT7285C 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 KEY PERFORMANCE SUMMARY TABLE ................................................................................................................................... 2 BENCH TEST SETUP CONDITIONS............................................................................................................................................ 3 SCHEMATIC, BILL OF MATERIALS AND BOARD LAYOUT........................................................................................................... 5 MORE INFORMATION........................................................................................................................................................... 10 IMPORTANT NOTICE FOR RICHTEK REFERENCE DESIGNS ...................................................................................................... 10 UG7285CGJ6-00 January 2015 1 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. Introduction General Product Information The RT7285C is a synchronous step-down converter with Advanced Constant On-Time (ACOT™) mode control. The ACOT™ provides a very fast transient response with few external components. The low impedance internal MOSFET supports high efficiency operation with wide input voltage range from 4.3V to 18V. The proprietary circuit of the RT7285C enables to support all ceramic capacitors. The output voltage can be adjusted between 0.6V and 8V. The RT7285C also provides output under voltage protection and thermal shutdown protection. The low current (<4μA) shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7285C is available in TSOT-23-6 package. Product Feature ±1.5% High Accuracy Feedback Voltage 4.3V to 18V Input Voltage Range 1.5A Output Current Integrated N-MOSFET Switches ACOTTM mode control Fixed Frequency Operation : 500kHz Output Adjustable from 0.6V to 8V Up to 95% Efficiency Fast Transient Response Stable with Low-ESR Ceramic Output Capacitors Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection Thermal Shutdown Protection RoHS Compliant and Halogen Free Key Performance Summary Table Key Features Evaluation Board Number: PCB007_V1 Default Input Voltage 12V Max Output Current 1.5A Default Output Voltage 1.2V Default Marking & Package Type RT7285CGJ6, TSOT-23-6 Operation Frequency Steady 500kHz at all loads Other Key Features ACOTTM for Fast Transient Response Protection Output Under-Voltage Protection (hiccup mode): Cycle-by-cycle Current Limit Thermal Shutdown UG7285CGJ6-00 January 2015 2 http://www.richtek.com RT7285CGJ6 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/ Signal Comment (expected waveforms or voltage levels on test points) VIN Input voltage Input voltage range= 4.3V to 18V VOUT Output voltage Default output voltage = 1.2V Pin name Output voltage range= 0.6V to 8V (see ‘’ Output Voltage Setting’’ section for changing output voltage level) SW Switching node test point SW waveform EN Enable test point Enable signal. Drive EN or install a shorting block on Jumper JP2 to enable operation or disable operation. JP2 Chip enable control Install jumper or drive EN directly to enable or disable operation BOOT Boot strap supply test point Floating supply voltage for the high-side N-MOSFET switch GND Ground Ground Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4.3V < VIN < 18V) to the VIN and GND terminals. 2. The EN voltage is pulled to logic high by R5 (100kΩ to VIN) to enable operation. Drive EN high (>1.5V) to enable operation or low (<0.4V) to disable operation. 3. Verify the output voltage (approximately 1.2V) between VOUT and GND. 4. Connect an external load up to 1.5A to the VOUT and GND terminals and verify the output voltage and current. UG7285CGJ6-00 January 2015 3 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. Output Voltage Setting Set the output voltage with the resistive divider (R2, R3) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula: The installed VOUT capacitors (C9, C10) 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 RT7285C IC datasheet. UG7285CGJ6-00 January 2015 4 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram C3, C4: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K C9, C10: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K L1: 2μH TAIYO YUDEN NR8040T2R0N, DCR=9mΩ UG7285CGJ6-00 January 2015 5 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. Bill of Materials Reference Qty Part number Description Package Manufacture U1 1 RT7285CGJ6 DC-DC Converter TSOT-23-6 (FC) RICHTEK C3, C4 2 C3216X5R1H106K160AB 1206 TDK 1210 Murata 0603 TDK 10μF/±10%/50V/X5R Ceramic Capacitor 22μF/±10%/16V/X5R C9, C10 2 GRM32ER61C226KE20# Ceramic Capacitor 0.1μF/±10%/50V/X7R C6, C8, C12 3 C1608X7R1H104K080AA Ceramic Capacitor C1, C11, D2 0 L1 1 Not Installed 0603 2.0μH/7.4A/±30%, NR8040T2R0N 8mmx8mmx4mm TAIYO YUDEN DCR=9mΩ, Inductor R2 1 10kΩ/±1%, Resistor 0603 R3 1 10kΩ/±1%, Resistor 0603 R5 1 100kΩ/±1%, Resistor 0603 CP1 1 Short JP2, J5 2 3-Pin Header GP 4 EN, B( E), BOOT, SW Golden Pin TP 3 Vout, GND, VIN Test Pin J3, J6, J7, J8 4 VIN, VOUT, GND, GND Test Pin UG7285CGJ6-00 January 2015 6 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. EVB Layout st Top View (1 layer) Bottom View (4th Layer) UG7285CGJ6-00 January 2015 7 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. st Component Placement Guide—Component Side (1 layer) st PCB Layout—Component Side (1 Layer) UG7285CGJ6-00 January 2015 8 http://www.richtek.com RT7285CGJ6 Evaluation Board your power partner. PCB Layout—Bottom Side (4th layer) UG7285CGJ6-00 January 2015 9 http://www.richtek.com RT7285CGJ6 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 Reference Designs 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 R ICHTEK BE LIABLE TO BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES. Connect Richtek Through WeChat 微信扫一扫，服务马上到！ UG7285CGJ6-00 January 2015 10 http://www.richtek.com