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3MHz 4A High Efficiency Step-Down Converter with I2C Interface

EVB_RT8092URWSC

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The RT8092 is a Peak-Current Mode Pulse-Width-Modulated (PWM) step-down DC/DC converter with I2C control interface. Capable of delivering 4A continuing output current over a wide input voltage range from 2.5V to 5.5V, the RT8092 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals.
Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky barrier diode is required in practical application. The RT8092 enters low-dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. The RT8092 enters shutdown mode and consumes less than 5μA when the EN pin is pulled low. The switching ripple is easily smoothedout by small package filtering elements due to a fixed operation frequency of 3MHz. Along with its small WL-CSP-15B 1.2x2 (BSC) package, it is suitable for applications requiring small PCB area. To increase battery life time, the RT8092 provides low power mode with IQ < 15µA in standby and light-load applications. The RT8092 also includes Dynamic Voltage Scaling (DVS) for system low power applications.
The I2C interface let the RT8092 controllable flexibly to select VOUT voltage level, peak current limit level, PWM control mode, and so on. Other features include soft-start, auto discharge, lower internal reference voltage, overtemperature, and over-current protection.

Purpose

The RT8092 is a Peak-Current Mode Pulse-Width-Modulated (PWM) step-down DC/DC converter with I2C control interface. The input voltage range from 2.5V to 5.5V and provides 4A output current. This document explains the function and use of the RT8092 evaluation board (EVB), and provides information to enable operation, modification of the evaluation board and circuit to suit individual requirements.


Introduction

General Product Information

The RT8092 is a Peak-Current Mode Pulse-Width-Modulated (PWM) step-down DC/DC converter with I2C control interface. Capable of delivering 4A continuing output current over a wide input voltage range from 2.5V to 5.5V, the RT8092 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals.

Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky barrier diode is required in practical application. The RT8092 enters low-dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. The RT8092 enters shutdown mode and consumes less than 5μA when the EN pin is pulled low. The switching ripple is easily smoothedout by small package filtering elements due to a fixed operation frequency of 3MHz. Along with its small WL-CSP-15B 1.2x2 (BSC) package, it is suitable for applications requiring small PCB area. To increase battery life time, the RT8092 provides low power mode with IQ < 15µA in standby and light-load applications. The RT8092 also includes Dynamic Voltage Scaling (DVS) for system low power applications.

The I2C interface let the RT8092 controllable flexibly to select VOUT voltage level, peak current limit level, PWM control mode, and so on. Other features include soft-start, auto discharge, lower internal reference voltage, overtemperature, and over-current protection.


Product Feature

  • 2.5V to 5.5V Input Range
  • Low Operation Quiescent Current
  • ► Normal Mode IQ < 60µA
    ► Low Power Mode IQ < 15μA
  • Output range From 0.3V to 5.5V
  • ► Bank 0 : 0.3V to 0.7V
    ► Bank 1 : 0.6V to 1.4V
    ► Bank 2 : 1.2V to 2.8V
    ► Bank 3 : 2.4V to 5.5V
    ► The Default Value is 2.8V (VSEL = High) and 1V (VSEL = Low)
  • 4A Continuing Output Current
  • Support DVS in the Same Bank
  • ► VOUT Adjusting Range (max, min) is Settable
  • High Efficiency
  • ► 90% at 5V→2.8V with 1.5A Load
  • 3MHz Fixed-Frequency PWM Operation
  • ► Auto-PSM/PWM or Force-PWM Selectable
  • Support Remote Ground Sensing for Accurate Output Voltage


Key Performance Summary Table

Key Features

Evaluation Board Number : PCB016_V1

Default Input Voltage

3.3V

Max Output Current

4A

Default Output Voltage

1.0V with VSEL = L

Default Marking & Package Type

RT8092URWSC, WL-CSP-15B 1.2x2 (BSC)

Operation Frequency

Steady 3MHz at all loads



Bench Test Setup Conditions

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)

BAT

Input voltage

Power input. Support 2.5V to 5.5V Input Voltage. Must bypass with a suitable large ceramic capacitor at this pin.

EN

Enable test point

High = Enable.

GND

Ground

Ground.

VSEL

Nominal VOUT setting select input pin

VSEL = Low selects {0x11.ENSEL0, 0x11.VoutSEL0[6:0], 0x14.PWM0}.

VSEL = High selects {0x10.ENSEL1, 0x10.VoutSEL1[6:0], 0x14.PWM1}.

VOUT

Output voltage

Power output. Must bypass with a suitable large ceramic capacitor at this pin.

VOUTR

Output Voltage Sense Input

Output feedback pin.

GNDR

Remote Ground Sense Input

Connect to GND as short as possible.

LX

Switch node test point

Connect this pin to an external L-C filter.



Power-up & Measurement Procedure

1. Connect input power (2.5V < VIN < 5.5V) 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 2-pin switch “EN” for enable control. To switch up position to tie EN test pin to input power VBAT for enabling the device. Inversely, to switch down position to tie EN test pin and ground GND for disabling the device.

4. Verify the output voltage (1.0V with VSEL = L or 2.8V with VSEL = H) between VOUT and GND.

5. Connect an external load up to 4A to the VOUT and GND terminals and verify the output voltage and current.


Output Voltage Setting

Set the output voltage by VSEL pin between BAT and GND. There is a 3-pin header “VSEL” for VOUT selection. To use a jumper at “H” option to tie VSEL test pin to input power BAT for VOUT = 2.8V (dafult setting). Inversely, to use a jumper at “L” option to tie VSEL test pin to ground GND for VOUT = 1.0V (default setting).



Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

Technical Document Image Preview



Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacture

U1

1

RT8092URWSC

Buck Converter

WL-CSP-15B 1.2x2 (BSC)

RICHTEK

C1

1

0603X106M6R3

10µF/6.3V/X5R

C-0603

WALSIN

C4

1

C2012X5R0J226K

22µF/6.3V/X5R

C-0805

TDK

C8

1

C1608X5R0J1A104K

1µF/6.3V/X5R

C-0603

TDK

R5

1

RM06FTN1005

100k/1%/0603

R-0603

WALSIN

R14

1

RM06FTN2202

220/1%/0603

R-0603

TA-I

R9, R10

2

RM06FTN1003

1k/1%/0603

R-0603

WALSIN

L1

1

XFL4015-331MEC

0.33µH/R33C

L-4015

Coilcraft



PCB Layout

Technical Document Image Preview

Top View (1st layer)

Technical Document Image Preview

PCB Layout—Inner Side (2nd Layer)

Technical Document Image Preview

PCB Layout—Inner Side (3rd Layer)

Technical Document Image Preview

Bottom View (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2016/05/06
Bill of Materials 2016/05/06
Gerber File 2016/05/06
Schematic 2016/05/06
RT8092
RT8092

RT8092是一款有I2C控制介面的峰電流模式脈波寬度調變(PWM)同步降壓型 DC/DC 轉換器。輸入範圍2.5V 至5.5V時,輸出電流可達4A。RT8092適用於由單一鋰電池供電的可攜式電子裝置,例如行動電話、PDA與掌上型裝置。
具有低RDS(ON)的內部同步整流器大幅降低了PWM模式下的傳導損耗,且不需外加蕭特基二極體於實際設計中。當PWM不能藉由連續打開上側P-MOSFET來提供調節的輸出電壓時,RT8092會進入low-dropout mode。當EN腳位變成低電位時,RT8092進入shutdown mode,消耗電流小於5μA。由於操作在固定頻率3MHz,切換漣波可由較小封裝的元件進行濾波設計。RT8092採用WL-CSP-15B 1.2x2 (BSC)和WQFN-14L 3.5x3.5封裝。
為了延長電池的壽命,RT8092提供了IQ < 15μA的low power mode,適用於待機和輕載的應用。RT8092還提供了Dynamic Voltage Scaling (DVS)給低系統功耗的應用。
I2C介面讓VOUT電壓準位、峰電流限制準位元、PWM控制模式等選擇更靈活可控。其他功能包含軟啟動、自動放電、低內部參考電壓、過溫保護和過電流保護。

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