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RT8297BZQW Evaluation Board

EVB_RT8297BZQW

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The RT8297B is a high efficiency, monolithic synchronous step-down DC/DC converter that operates at 800kHz and delivers up to 1.5A output current from a 4V to 17V input supply. The RT8297B’s current mode architecture allows the transient response to be optimized. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over voltage protection, and thermal shutdown. The low current (<5μA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems. The RT8297B is available in a WDFN-8L 2x2 package.

Purpose

The RT8297B is a high-efficiency current mode synchronous step-down regulator that can deliver up to 1.5A output current from a wide input voltage range of 4V to 17V. This document explains the function and use of the RT8297B evaluation board (EVB) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements.

Introduction

General Product Information

The RT8297B is a high efficiency, monolithic synchronous step-down DC/DC converter that operates at 800kHz and delivers up to 1.5A output current from a 4V to 17V input supply. The RT8297B’s current mode architecture allows the transient response to be optimized. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over voltage protection, and thermal shutdown. The low current (<5μA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems. The RT8297B is available in a WDFN-8L 2x2 package.

Product Feature

  • 4V to 17V Input Voltage Range
  • 1.5A Output Current
  • Internal N-MOSFETs
  • Current Mode Control
  • Fixed Frequency Operation : 800kHz
  • Output Adjustable from 0.8V to 12V
  • Up to 95% Efficiency
  • Internal Compensation
  • Stable with Low ESR Ceramic Output Capacitors
  • Cycle-by-Cycle Over Current Protection
  • Input Under Voltage Lockout
  • Output Under Voltage Protection
  • Output Over Voltage Protection
  • Power Good Indicator
  • Thermal Shutdown Protection

Key Performance Summary Table

Key features

Evaluation board number: PCB005_V1

Default Input Voltage

12V

Max Output Current

1.5A

Default Output Voltage

3.3V

Default Marking & Package Type

RT8297BZQW (WDFN-8L 2x2)

Operation Frequency

Steady 800kHz at all load currents

Other Key Features

4V to 17V Input Voltage Range

Power Good Indicator

Tiny WDFN-8L 2x2 package

Protection

Over Current Protection

Hiccup Mode Output Under-Voltage & Over-Voltage Protection

Thermal Shutdown

Bench Test Setup Conditions

Headers Description and Placement

Technical Document Image Preview

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

Signal

Comment (expected waveforms or voltage levels on test points)

VIN

Input voltage

Input voltage range= 4V to 17V

VOUT

Output voltage

Default output voltage = 3.3V

Output voltage range= 0.8V to 12V

(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

PG

Power Good test point

Power Good Indicator

V1

External Voltage for PG

External voltage terminal for PG pull-up voltage.

GND

Ground

Ground

Power-up & Measurement Procedure

1.Apply a 12V nominal input power supply (4V < VIN < 17V) 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 (>2.5V) 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 1.5A 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:

Technical Document Image Preview

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 RT8297 IC datasheet.

Schematic, Bill of Materials and Board Layout

EVB Schematic Diagram

Technical Document Image Preview

C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K

C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K

L1: 6.8μH TAIYO YUDEN NR8040T6R8N, DCR=25mΩ

Bill of Materials

Reference

Qty

Part number

Description

Package

Manufacture

U1

1

RT8297BZQW

DC-DC Converter

WDFN-8L 2x2

Richtek

C1, C2

2

C3216X5R1H106K160AB

10μF/±10%/50V/X5R

Ceramic Capacitor

1206

TDK

C4, C5

2

GRM32ER61C226KE20#

22μF/±10%/16V/X5R

Ceramic Capacitor

1210

Murata

C7

1

GRM32MR71H103KA01#

10nF/±10%/50V/X7R

Ceramic Capacitor

0603

Murata

C3, C6

2

C1608X7R1H104K080AA

0.1μF/±10%/50V/X7R

Ceramic Capacitor

0603

TDK

C8, C9, C10

0

Not Installed

0603

L1

1

NR8040T6R8N

6.8uH/3.7A/±30%,

DCR=25mΩ, Inductor

8mmx8mmx4mm

TAIYO YUDEN

R1

1

47kΩ/±1%, Resistor

0603

R2

1

15kΩ/±1%, Resistor

0603

R3, R4

1

100kΩ/±1%, Resistor

0603

CP1

1

Short

D3, R6

0

Not Installed

TP

6

Test Pin

GP

4

Golden Pin

EVB Layout

Technical Document Image Preview

Top View (1stlayer)

Technical Document Image Preview

Bottom View (4th Layer)

Technical Document Image Preview

Component Placement Guide—Component Side (1stlayer)

Technical Document Image Preview

PCB Layout—Component Side (1stLayer)

Technical Document Image Preview

PCB Layout—Inner Side (2ndlayer)

Technical Document Image Preview

PCB Layout—Inner Side (3rd layer)

Technical Document Image Preview

Component Placement Guide—Bottom Side (4th Layer)

Technical Document Image Preview

PCB Layout—Bottom Side (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2015/09/24
Bill of Materials 2015/06/05
Gerber File 2015/09/24
Schematic 2015/09/30
RT8297A/RT8297B

1.5A, 17V, 340/800kHz 同步 Buck 轉換器

RT8297A/RT8297B

RT8297A/B系列為高效率的同步Buck轉換器,工作頻率為340kHz/800kHz,在4V至17V的輸入電源範圍可提供最高為1.5A的輸出電流。RT8297A/B採用電流模式架構,可優化瞬態回應的特性。逐週期電流限制保護元件免受輸出短路影響;軟啟動功能可在啟動過程中消除輸入端電流衝擊。故障保護包括輸出欠壓保護、輸出過壓保護、過熱保護。低電流消耗(<5μA)之電源關機模式會將輸出關閉,有助於電池供電系統的電源管理。RT8297A/B支持WDFN-8L 2x2的封裝規格。

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