RT7250BZSP Evaluation Board your power partner. RT7250BZSP Evaluation Board Purpose The RT7250B is a high-efficiency current mode synchronous step-down regulator that can deliver up to 2A output current from a wide input voltage range of 4V to 17V. This document explains the function and use of the RT7250B 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 & BOARD LAYOUT ............................................................................................................... 5 MORE INFORMATION........................................................................................................................................................... 10 IMPORTANT NOTICE FOR RICHTEK REFERENCE DESIGNS ...................................................................................................... 10 UG7250BZSP-00 January 2015 1 http://www.richtek.com RT7250BZSP Evaluation Board your power partner. Introduction General Product Information The RT7250B is a high efficiency, monolithic synchronous step-down DC/DC converter that operates at 800kHz and delivers up to 2A output current from a 4V to 17V input supply. The RT7250B’s current mode architecture allows the transient response to be optimized. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over voltage protection, and thermal shutdown. The low current (<5μA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems. The RT7250B is available in a SOP-8 (Exposed Pad) package. Product Feature 4V to 17V Input Voltage Range 2A Output Current Internal N-MOSFETs Current Mode Control Fixed Frequency Operation : 800kHz Output Adjustable from 0.8V to 12V Up to 95% Efficiency Internal Compensation Stable with Low ESR Ceramic Output Capacitors Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection Output Over Voltage Protection Power Good Indicator Thermal Shutdown Protection RoHS Compliant and Halogen Free Key Performance Summary Table Key Features Evaluation Board Number: PCB009_V1 Default Input Voltage 12V Max Output Current 2A Default Output Voltage 3.3V Default Marking & Package Type RT7250BZSP (SOP-8 (Exposed Pad)) Operation Frequency Steady 800kHz at all load currents Other Key Features 4V to 17V Input Voltage Range Power Good Indicator Protection Over Current Protection Hiccup Mode Output Under-Voltage & Over-Voltage Protection Thermal Shutdown UG7250BZSP-00 January 2015 2 http://www.richtek.com RT7250BZSP 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= 4V to 17V VOUT Output voltage Default output voltage = 3.3V Pin name Output voltage range= 0.8V to 12V (see ‘’ Output Voltage Setting’’ section for changing output voltage level) SW Switching node test point SW waveform EN Enable test point Enable signal. EN is automatically pulled high (by R4) to enable operation. Connect EN low to disable operation. BS Boot strap supply test point Floating supply voltage for the high-side N-MOSFET switch PG Power Good test point Power Good Indicator V1 External Voltage for PG External voltage terminal for PG pull-up voltage. GND Ground Ground Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4V < VIN < 17V) 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 (>2.5V) 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 2A to the VOUT and GND terminals and verify the output voltage and current. UG7250BZSP-00 January 2015 3 http://www.richtek.com RT7250BZSP 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. 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 RT7250 IC datasheet. UG7250BZSP-00 January 2015 4 http://www.richtek.com RT7250BZSP Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K L1: 6.8μH TAIYO YUDEN NR8040T6R8N, DCR=25mΩ UG7250BZSP-00 January 2015 5 http://www.richtek.com RT7250BZSP Evaluation Board your power partner. Bill of Materials Reference Qty Part number Description U1 1 RT7250BZSP DC-DC Converter Package Manufacture SOP-8 Richtek (Exposed Pad) C1, C2 2 C3216X5R1H106K160AB 10μF/±10%/50V/X5R 1206 TDK 1210 Murata 0603 Murata 0603 TDK Ceramic Capacitor C4, C5 2 GRM32ER61C226KE20# 22μF/±10%/16V/X5R Ceramic Capacitor 10nF/±10%/50V/X7R C7 1 GRM32MR71H103KA01# Ceramic Capacitor C3, C6 2 C1608X7R1H104K080AA 0.1μF/±10%/50V/X7R Ceramic Capacitor C8, C9, 0 Not Installed 0603 C10 1 R1 1 47kΩ/±1%, Resistor 0603 R2 1 15kΩ/±1%, Resistor 0603 R3, R4 1 100kΩ/±1%, Resistor 0603 CP1 1 Short D3, R6 0 Not Installed TP 4 Test Pin GP 6 Golden Pin UG7250BZSP-00 NR8040T6R8N 6.8μH/3.7A/±30%, L1 January 2015 DCR=25mΩ, Inductor 6 8mmx8mmx4mm TAIYO YUDEN http://www.richtek.com RT7250BZSP Evaluation Board your power partner. EVB Layout st Top View (1 layer) Bottom View (4th Layer) UG7250BZSP-00 January 2015 7 http://www.richtek.com RT7250BZSP Evaluation Board your power partner. st Component Placement Guide—Component Side (1 layer) st PCB Layout—Component Side (1 Layer) UG7250BZSP-00 January 2015 8 http://www.richtek.com RT7250BZSP Evaluation Board your power partner. th PCB Layout—Bottom Side (4 Layer) UG7250BZSP-00 January 2015 9 http://www.richtek.com RT7250BZSP 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 RICHTEK 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！ UG7250BZSP-00 January 2015 10 http://www.richtek.com