EVB_RT7298BHGQW

RT7298BHGQW Evaluation Board your power partner. RT7298BHGQW Evaluation Board Purpose The RT7298BH is a synchronous step-down converter with current mode control, which can deliver up to 6A output current from a wide input voltage range of 4.5V to 18V. This document explains the function and use of the RT7298BH 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 UG7298BHGQW-00 January 2015 1 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. Introduction General Product Information The RT7298BH is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 6A output current from a 4.5V to 18V input supply. The RT7298BH current-mode architecture with external compensation allows 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 startup. Fault condition protections include output under-voltage protection, output over-voltage protection, and over temperature protection. The low current shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7298BH is available in WQFN-14AL 3.5x3.5 package. Product Feature             Low RDS(ON) Power MOSFET Switches 26mΩ/19mΩ Input Voltage Range : 4.5V to 18V Adjustable Switching Frequency : 200kHz to 1.6MHz Current-Mode Control Synchronous to External Clock : 200kHz to 1.6MHz Accurate Voltage Reference : 0.6V ± 1.25% Monotonic Start-Up into Pre-biased Outputs Adjustable Soft-Start Power Good Indicator Under-Voltage and Over-Voltage Protection Input Under-Voltage Lockout RoHS Compliant and Halogen Free Key Performance Summary Table Key Features Evaluation Board Number: PCB006_V1 Default Input Voltage 12V Max Output Current 6A Default Output Voltage 1.0V Default Marking & Package Type RT7298BHGQW, WQFN-14AL 3.5x3.5 Operation Frequency Steady 500kHz at all loads Other Key Features 4.5V to 18V Input Voltage Range Programmable Soft-Start, Adjustable Switching Frequency Synchronous to External Clock Power Good Indicator Protection Output Under-Voltage Protection (hiccup mode) Output Over-Voltage Protection Cycle-by-cycle Current Limit Thermal Shutdown UG7298BHGQW-00 January 2015 2 http://www.richtek.com RT7298BHGQW 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 evb_service@richtek.com 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, VIN_EXT Input voltage Input voltage range= 4.5V to 18V VOUT Output voltage Default output voltage = 1.0V Pin name Output voltage range= 0.6V to 8V (see „‟ Output Voltage Setting‟‟ section for changing output voltage level) LX Switching node test point LX waveform EN Enable test point Enable signal. Floating this EN pin or connecting this pin to pull high enable operation; connecting this pin to GND can disable the device. SYNC Ext Frequency Sync Input External Frequency Synchronization Input. Connecting external clock to this pin changes the switching frequency. BS Boot strap supply test point Floating supply voltage for the high-side N-MOSFET switch GND Ground Ground SS Soft-start control test point Soft start waveform VCC_EXT External Voltage for PG External voltage terminal for PG pull-up voltage. PG Power good output test point Connected to VCC_EXT through RPG1, Power Good Indicator JP2 VIN & PVIN control Install jumper to combine or separate VIN and PVIN. JP1 PG control VIN voltage terminal for PG pull-up voltage. J9 Chip enable control Install jumper or drive EN directly to enable or disable operation UG7298BHGQW-00 January 2015 3 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. Power-up & Measurement Procedure 1. Connect input power (4.5V < VIN < 18V) and input ground to VIN and GND test pins respectively. 2. Connect positive end and negative terminals of load to VOUT and GND test pins respectively. 3. There is a 3-pin header “EN” for enable control. To use a jumper at “H” option to tie EN test pin to input power VIN for enabling the device. Inversely, to use a jumper at “L” option to tie EN test pin and ground GND for disabling the device. 4. The PVIN and VIN pins can be connected together using a jumper across “Combine” by the 3-pin header JP2. Inversely, these two input rails can be separated by using a jumper across “Separate” if desired. 5. The 2-pin header JP1 “VIN-PG” is for PGOOD pin supply, when using a jumper across this header, the PG signal can be supplied by VIN pin Voltage. 6. Verify the output voltage (approximately 1.0V) between VOUT and GND. 7. Connect an external load up to 6A 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 = 0.6 × (1 + 𝑅1 ) 𝑅2 The installed VOUT capacitors (C5, C6) 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 RT7298B IC datasheet. UG7298BHGQW-00 January 2015 4 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram C4: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K C2, C5, C6: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K L1: 1.4μH TAIYO YUDEN NR8040T1R4N, DCR=7mΩ UG7298BHGQW-00 January 2015 5 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. Bill of Materials Reference Qty Part number Description U1 1 RT7298BHGQW DC-DC Converter Package Manufacture WQFN-14AL RICHTEK 3.5x3.5 10μF/±10%/50V/X5R C4 1 C3216X5R1H106K160AB 1206 TDK 1210 Murata 0603 Murata 0603 Murata 0603 WALSIN 0603 TDK Ceramic Capacitor 22μF/±10%/16V/X5R C2, C5, C6 3 GRM32ER61C226KE20# Ceramic Capacitor 10nF/±10%/50V/X7R CSS 1 GRM32MR71H103KA01# Ceramic Capacitor 8.2nF/±10%/50V/X7R CCOMP1 1 CCOMP2 1 C3, C7, CBOOT 3 GRM31CR71A822KA01 Ceramic Capacitor 180pF/±10%/50V/X7R 0603B181K500CT Ceramic Capacitor 0.1μF/±10%/50V/X7R C1608X7R1H104K080AA Ceramic Capacitor C1, CFF, C2F, CEN, REN2, RTR1, 0 Not Installed 0603 RTR2, RPG2, D1 1.4μH/9.0A/±30%, L1 1 NR8040T1R4N 8mmx8mmx4mm TAIYO YUDEN DCR=7mΩ, Inductor R1 1 16kΩ/±1%, Resistor 0603 R2 1 24kΩ/±1%, Resistor 0603 RCOMP 1 0.68kΩ/±1%, 0603 RT, REN1, RPG1 3 100kΩ/±1%, 0603 JP1 1 2-Pin Header JP2, J9 2 3-Pin Header VIN_EXT, BS, SS, TRACK, GP 11 EN, LX, SYNC, PG, Golden Pin VCC_EXT, VIN, GND J3, J4 UG7298BHGQW-00 2 January 2015 VOUT, GND Test Pin 6 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. EVB Layout st Top View (1 layer) Bottom View (4th Layer) UG7298BHGQW-00 January 2015 7 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. st Component Placement Guide—Component Side (1 layer) st PCB Layout—Component Side (1 Layer) UG7298BHGQW-00 January 2015 8 http://www.richtek.com RT7298BHGQW Evaluation Board your power partner. PCB Layout—Bottom Side (4th layer) UG7298BHGQW-00 January 2015 9 http://www.richtek.com RT7298BHGQW 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 TO BUYER OR USER FOR ANY AND ALL DAMAGES INCLUDING WITHOUT LIMITATION TO DIRECT, INDIRECT, SPECIAL, PUNITIVE OR CONSEQUENTIAL DAMAGES. UG7298BHGQW-00 January 2015 10 http://www.richtek.com