EVB_RT7272AGSP

RT7272AGSP Evaluation Board Purpose The RT7272A 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 RT7272A 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 Information ...................................................................................................................... 2 Key Performance Summary Table ............................................................................................................. 2 Bench Test Setup Conditions ......................................................................................................................... 3 Headers Description and Placement .......................................................................................................... 3 Test Points .................................................................................................................................................. 3 Power-up & Measurement Procedure ........................................................................................................ 4 Output Voltage Setting ............................................................................................................................... 4 Schematic, Bill of Materials and Board Layout ............................................................................................... 5 EVB Schematic Diagram ............................................................................................................................ 5 Bill of Materials ........................................................................................................................................... 6 EVB Layout................................................................................................................................................. 7 More Information .......................................................................................................................................... 11 Important Notice for Richtek Evaluation Board ............................................................................................ 11 UG7272AGSP-00 March 2014 www.richtek.com RT7272AGSP Evaluation Board Introduction General Product Information General Description The RT7272A 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 150mΩ 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 RT7272A provides complete protection functions such as input under voltage lockout, output under voltage protection, over current protection and thermal shutdown. The RT7272A is available in the thermal enhanced SOP-8 (Exposed Pad) package. Features  4.5V to 36V Input Voltage Range  3A Output Current  Internal N-MOSFETs  Current Mode Control  Fixed Frequency Operation : 500kHz  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  Adjustable Current Limit Key Performance Summary Table Key features Default Input Voltage Max Output Current Default Output Voltage Default Marking & Package Type Operation Frequency Other Key Features Protection UG7272AGSP-00 March 2014 Evaluation board number: PCB001_V1 12V 3A (OCP level set to 5.5A typical by RLIM = 137kΩ) 3.3V RT7272AGSP, SOP-8 (Exposed Pad) Steady 500kHz at all load currents 4.5V to 36V Wide Input Voltage Range Adjustable Current Limit 2A to 6A Over Current Protection & Output Under-Voltage-Protection (hiccup mode) Input Under-voltage Lock-out Thermal Shutdown www.richtek.com 2 RT7272AGSP Evaluation Board 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 Comment (expected waveforms or voltage levels on test points) Input voltage 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 Switching node test point EN Enable test point BOOT Boot strap supply test point Floating supply voltage for the high-side N-MOSFET switch MODE RLIM test point Current limit setting point GND Ground Ground UG7272AGSP-00 March 2014 SW waveform Enable signal. EN is automatically pulled high (by R4) to enable operation. Connect EN low to disable operation. www.richtek.com 3 RT7272AGSP Evaluation Board 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 (