RT2853BHGQW Evaluation Board your power partner. 3A, 18V, 650kHz, ACOT™ Synchronous Step-Down Converter Purpose The RT2853BH are high-performance 650kHz 3A step-down regulators with internal power switches and synchronous rectifiers. This document explains the function and use of the RT2853BH 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_RT2853BHGQW-00 April 2016 1 http://www.richtek.com RT2853BHGQW Evaluation Board your power partner. Introduction General Product Information The RT2853BH are high-performance 650kHz 3A step-down regulators with internal power switches and synchronous rectifiers. The feature quick transient response using Advanced Constant On-Time (ACOT™) control architecture that provides stable operation with small ceramic output capacitors and without complicated external compensation, among other benefits. The input voltage range is from 4.5V to 18V and the output is adjustable from 0.765V to 7V. The proprietary ACOT™ control improves upon other fast response constant on-time architectures, achieving nearly constant switching frequency over line, load, and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT2853BH are stable with and optimized for ceramic output capacitors. With internal 110mΩ switches and 30mΩ synchronous rectifiers, the RT2853BH display excellent efficiency and good behavior across a range of applications, especially for low output voltages and low duty cycles. Cycle-bycycle current limit, input under-voltage lock-out, externallyadjustable soft-start, output under- and over-voltage protection, and thermal shutdown provide safe and smooth operation in all operating conditions. The RT2853BH is available in WQFN-16L 3x3 package, with exposed thermal pads. Product Feature Fast Transient Response Steady 650kHz Switching Frequency Advanced Constant On-Time (ACOTTM) Control Optimized for Ceramic Output Capacitors 4.5V to 18V Input Voltage Range Internal 110mΩ Switch and 30mΩ Synchronous Rectifier 0.765V to 7V Adjustable Output Voltage Externally-adjustable, Pre-biased Compatible Soft-Start Cycle-by-Cycle Current Limit Optional Output Discharge Function With Hiccup Mode Output Over- and Under-voltage Shut-down protection Key Performance Summary Table Key Features Evaluation Board Number : PCB033_V1 Input Voltage Range 4.5V to 18V Max Output Current 3A Default Output Voltage 1.05V Default Marking & Package Type RT2853BHGQW, WQFN-16L 3x3 Operation Frequency Fixed 650kHz EVB_RT2853BHGQW-00 April 2016 2 http://www.richtek.com RT2853BHGQW 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. EN Enable test point Externally pulled high to enable and pulled low to disable this chip. It is internally pulled up to high when the pin is floating. GND Ground The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. VREG5 Internal Regulator Output Internal Regulator Output. Connect a 1μF capacitor to GND to stabilize output voltage. SS Soft-Start Control Connect an external capacitor between this pin and GND to set the soft-start time. PG Power good test point Output of power good indicator. BOOT Bootstrap supply test point Bootstrap supply for high-side gate driver. Connect a capacitor between the BOOT and SW pins. SW Switch node test point Connect this pin to an external L-C filter. EVB_RT2853BHGQW-00 April 2016 3 http://www.richtek.com RT2853BHGQW Evaluation Board your power partner. Power-up & Measurement Procedure 1. Apply a 12V nominal input power supply (4.5< VIN < 18V) to the VIN and GND terminals. 2. Set the jumper at JP2 to connect terminals 2 and 3, connecting EN to enable operation. 3. Set the jumper at JP1 to connect terminals 1 and 2, power VCC pin by VIN voltage source. 4. Verify the output voltage (approximately 1.05V) between VOUT and GND. 5. 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 (R2, R3) between VOUT and GND with the midpoint connected to FB. The output is set by the following formula : VOUT = 0.765 × (1 + R2 ) R3 EVB_RT2853BHGQW-00 April 2016 4 http://www.richtek.com RT2853BHGQW Evaluation Board your power partner. Schematic, Bill of Materials & Board Layout EVB Schematic Diagram Bill of Materials Reference Qty Part Number Description Package Manufacture U1 1 RT2853BHGQW DC/DC Converter WQFN-16L 3x3 RICHTEK C2, C6, C8, C12 4 C1608X7R1H104KT000N 0.1μF/50V/X7R C-0603 TDK C3, C4 2 GRM31CR71E106KA12L 10μF/25V/X7R C-1210 MURATA C5 1 C2012X7R1H105KT 1μF/50V/X7R C-0805 TDK C7 1 0603B332K500 3.3nF/50V/X7R C-0603 WALSIN C9, C10 2 C3225X5R1E226MT 22μF/25V/X7R C-1210 TDK C1, C11, C13, C14, R6, R7 6 L1 1 NR8040T1R4N 1.4µH/7A 8 x 8 x 4 mm R1 1 0603 JUMP 0Ω R-0603 TAIYO YUDEN WALSIN R2 1 0603 8K25 1% 8.25k R-0603 WALSIN R3 1 0603 22K1 1% 22.1k R-0603 WALSIN R4, R5 2 0603 100K 1% 100k R-0603 WALSIN EVB_RT2853BHGQW-00 April NA 2016 5 http://www.richtek.com RT2853BHGQW Evaluation Board your power partner. PCB Layout Top View (1st layer) PCB Layout—Inner Side (2nd Layer) EVB_RT2853BHGQW-00 April 2016 6 http://www.richtek.com RT2853BHGQW Evaluation Board your power partner. PCB Layout—Inner Side (3rd Layer) Bottom View (4th Layer) EVB_RT2853BHGQW-00 April 2016 7 http://www.richtek.com RT2853BHGQW 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. EVB_RT2853BHGQW-00 April 2016 8 http://www.richtek.com