RT7296AGJ8F Evaluation Board your power partner. RT7296AGJ8F Step-Down Converter Evaluation Board Purpose The RT7296A is a current mode step-down converter with the input voltage range from 4.5V to 17V and provides 3A output current. This document explains the function and use of the RT7296A 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.................................................................................................................................................... 8 Important Notice for Richtek Evaluation Board ....................................................................................................... 8 EVB_RT7296AGJ8F-01 November 2015 1 http://www.richtek.com RT7296AGJ8F Evaluation Board your power partner. Introduction General Product Information The RT7296A is a high-efficiency, 3A current mode synchronous step-down DC/DC converter with a wide input voltage range from 4.5V to 17V. The device integrates 80mΩ high-side and 30mΩ low-side MOSFETs to achieve high efficiency conversion. The current mode control architecture supports fast transient response and internal compensation. A cycle-by-cycle current limit function provides protection against shorted output. The RT7296A provides complete protection functions such as input under-voltage lockout, output under-voltage protection, over-current protection, and thermal shutdown. The PWM frequency is adjustable by the EN/SYNC pin. The RT7296A is available in the TSOT-23-8 (FC) package. Product Feature 4.5V to 17V Input Voltage Range 3A Output Current Internal N-Channel MOSFETs Current Mode Control Fixed Switching Frequency : 500kHz Synchronous to External Clock : 200kHz to 2MHz Cycle-by-Cycle Current Limit TTH Power-Save Mode Internal Soft-Start Function Input Under-Voltage Lockout Output Under-Voltage Protection Thermal Shutdown Key Performance Summary Table Key Features Evaluation Board Number : PCB040_V1 Default Input Voltage 12V Max Output Current 3A Default Output Voltage 3.3V Default Marking & Package Type RT7296AGJ8F, TSOT-23-8 (FC) Operation Frequency Steady 500kHz at all loads EVB_RT7296AGJ8F-01 November 2015 2 http://www.richtek.com RT7296AGJ8F 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. Support 4.5V to17V Input Voltage. Must bypass with a suitable large ceramic capacitor at this pin. EN/SYNC Enable test point High = Enable. Apply an external clock to adjust the switching frequency. GND Ground Ground. TTH Transition threshold Connect a resistor divider to let the RT7296A into power saving mode under light loads. Connect to PVCC to force RT7296A into forced PWM mode. PVCC Internal regulator output 5V bias supply output. Connect a 0.1µF capacitor to ground. BOOT Bootstrap supply test point Bootstrap supply for high-side gate driver. Connect a 0.1µF ceramic capacitor between the BOOT and SW pins. SW Switch node test point Connect this pin to an external L-C filter. EVB_RT7296AGJ8F-01 November 2015 3 http://www.richtek.com RT7296AGJ8F Evaluation Board your power partner. Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4.5V < VIN < 17V) to the VIN and GND terminals. 2. Set the jumper at JP1 to connect terminals 2 and 3, connecting EN to VIN through resistor R30, to enable 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. Output Voltage Setting Set the output voltage with the resistive divider (R23, R28) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula : VOUT = 0.8 x (1 + EVB_RT7296AGJ8F-01 R23 ) R28 November 2015 4 http://www.richtek.com RT7296AGJ8F Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram Bill of Materials Reference Qty Part Number Description Package Manufacture U4 1 RT7296AGJ8F DC/DC Converter TSOT-23-8 (FC) RICHTEK C7, C9 2 GRM31CR71E106KA12L 10µF/25V/X7R C-1206 MURATA C8, C10, C27, C29 4 C1608X7R1H104K080AA 0.1μF/±10%/50V/X7R C-0603 TDK C11, C12 2 C3225X5R1E226MT 22µF/25V/X7R C-1210 TDK C30 1 0603N220J500 22pF/50V/NPO C-0603 WALSIN C31 1 C32 1 C1608X5R1E105KT000E 1μF/±10%/25V/X5R C-0603 TDK L1 1 NR8040T4R7N 4.7µH/4.1A 8 x 8 x 4.2 mm TAIYO YUDEN R23 1 40.2k R-0603 R24 1 10 R-0603 R25 1 33k R-0603 R28 1 13k R-0603 R29 1 10k R-0603 R30 1 100k R-0603 R31 1 91k R-0603 EVB_RT7296AGJ8F-01 NC November 2015 5 http://www.richtek.com RT7296AGJ8F Evaluation Board your power partner. PCB Layout st Top View (1 layer) nd PCB Layout—Inner Side (2 EVB_RT7296AGJ8F-01 November 2015 6 Layer) http://www.richtek.com RT7296AGJ8F Evaluation Board your power partner. rd PCB Layout—Inner Side (3 Layer) th Bottom View (4 Layer) EVB_RT7296AGJ8F-01 November 2015 7 http://www.richtek.com RT7296AGJ8F 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 T O BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES. EVB_RT7296AGJ8F-01 November 2015 8 http://www.richtek.com