RT8296AHZSP Evaluation Board Purpose The RT8296A 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 23V. This document explains the function and use of the RT8296A 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 ............................................................................................. 3 Bench Test Setup Conditions ......................................................................................................... 4 Headers Description and Placement .......................................................................................... 4 Test Points.................................................................................................................................. 4 Power-up & Measurement Procedure ........................................................................................ 5 Output Voltage Setting ............................................................................................................... 5 Schematic, Bill of Materials and Board Layout ............................................................................... 6 EVB Schematic Diagram ............................................................................................................ 6 Bill of Materials ........................................................................................................................... 7 EVB Layout................................................................................................................................. 8 Other Technical Information ......................................................................................................... 10 UG8296AHZSP-00 July 2014 www.richtek.com RT8296AHZSP Evaluation Board Introduction General Product Information General Description The RT8296A is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 3A output current from a 4.5V to 23V input supply. The RT8296A's current mode architecture and external compensation allow the transient response to be optimized over a wide range of loads and output capacitors. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The RT8296A also provides output under voltage protection and thermal shutdown protection. The low current (<3μA) shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT8296A is available in an SOP-8 (Exposed Pad) package. Features ±1.5% High Accuracy Feedback Voltage 4.5V to 23V Input Voltage Range 3A Output Current Integrated N-MOSFET Switches Current Mode Control PWM Frequency Operation : 340kHz Output Adjustable from 0.8V to 20V Up to 95% Efficiency Programmable Soft-Start Stable with Low-ESR Ceramic Output Capacitors Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection Thermal Shutdown Protection UG8296AHZSP-00 July 2014 www.richtek.com 2 RT8296AHZSP Evaluation Board Key Performance Summary Table Key features Evaluation board number: PCB004_V1 Default Input Voltage 12V Max Output Current 3A Default Output Voltage 3.3V Default Marking & Package Type RT8296AHZSP, PSOP-8 (Exposed Pad) Operation Frequency Steady 340kHz at PWM Other Key Features 4.5V to 23V Input Voltage Range Programmable Soft-Start PSM/ PWM Auto Switched Protection Output Under-Voltage Protection (hiccup mode): Cycle-by-cycle Current Limit Thermal Shutdown UG8296AHZSP-00 July 2014 www.richtek.com 3 RT8296AHZSP 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 [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 Input voltage range= 4.5V to 23V VOUT Output voltage Default output voltage = 3.3V Output voltage range= 0.8V to 20V (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 SS Soft-start control test point Soft start waveform GND Ground Ground UG8296AHZSP-00 July 2014 www.richtek.com 4 RT8296AHZSP Evaluation Board Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4.5V < VIN < 23V) 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 (>2.7V) 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 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 (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 RT8296 IC datasheet. UG8296AHZSP-00 July 2014 www.richtek.com 5 RT8296AHZSP Evaluation Board Schematic, Bill of Materials and Board Layout EVB Schematic Diagram TP4 BS D2 VOUT NF GND TP2 SS FB NF 75k 5 22uF 22uF 0.1uF C6 GP3 10uH C5 L1 0.1uF C4 EN GP4 GND NF C10 0.1uF SS COMP 6 NF C8 C7 3.3nF 13k R3 24k R2 8 GND R5 C13 3 C11 D1 7 NF 1 R1 SW TP1 EN GND NF BS 4,9 R4 0.1uF 100k C3 10uF C2 C1 10uF VIN C12 2 C9 GP1 GP2 TP3 SW NF U1 SOP-8(Exposed Pad) VIN C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K L1: 10μH TAIYO YUDEN NR8040T100M, DCR=34mΩ UG8296AHZSP-00 July 2014 www.richtek.com 6 RT8296AHZSP Evaluation Board Bill of Materials Reference Qty Part number Description Package Manufacture U1 1 RT8296AHZSP DC-DC Converter PSOP-8 Richtek C1, C2 2 C3216X5R1H106K160AB 1206 TDK C4, C5 2 GRM32ER61C226KE20# 1210 Murata C7 1 0603B332K500 0603 WALSIN C3, C6, C10,C11 4 C1608X7R1H104K080AA 0603 TDK C8,C9,C12,C13 0 L1 1 R1 1 75kΩ/±1%, Resistor 0603 R2 1 24kΩ/±1%, Resistor 0603 R3 1 13kΩ/±1%, Resistor 0603 R4 1 100kΩ/±1%, Resistor 0603 R5 0 Not Installed 0603 D1, D2 0 Not Installed TP 4 Test Pin GP 4 Golden Pin UG8296AHZSP-00 July 2014 10uF/±10%/50V/X5R Ceramic Capacitor 22uF/±10%/16V/X5R Ceramic Capacitor 3.3nF/±10%/50V/X7R Ceramic Capacitor 0.1uF/±10%/50V/X7R Ceramic Capacitor Not Installed NR8040T100M 10uH/3.1A/±20%, DCR=34mΩ, Inductor 0603 8mmx8mmx4mm TAIYO YUDEN www.richtek.com 7 RT8296AHZSP Evaluation Board EVB Layout st Top View (1 layer) Bottom View (2nd Layer) UG8296AHZSP-00 July 2014 www.richtek.com 8 RT8296AHZSP Evaluation Board Component Placement Guide—Component Side (1st layer) PCB Layout—Component Side (1st Layer) UG8296AHZSP-00 July 2014 www.richtek.com 9 RT8296AHZSP Evaluation Board Component Placement Guide—Bottom Side (2 nd PCB Layout—Bottom Side (2 nd layer) layer) Other Technical Information For more information, please find the related datasheet or application notes from the Richtek website http://www.richtek.com UG8296AHZSP-00 July 2014 www.richtek.com 10