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Switch-Mode Single Cell Li-Ion Battery Charger with USB-OTG

EVB_RT9458WSC

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The RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG).

Purpose

The RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG). This document explains the function and use of the RT9458 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 RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG).


Product Feature

  • Support Quick Start for Charger
  • High Accuracy Voltage/Current Regulation
  • Input Current Regulation : 100mA/500mA/700mA/1A
  • Minimum Input Voltage Regulation : 4.1V to 4.7V Per 0.1V Step
  • Charge Voltage Regulation Accuracy : ±1% (0 to 85°C)
  • Charge Current Regulation Accuracy : ±5%
  • Built-In Input Current Sensing and Limiting
  • Integrated Power MOSFETS for Up to 1.55A Charge Rate
  • Integrated Sensing Resistors for Charging Current Sensing
  • Synchronous 1.5MHz Fixed Frequency PWM Controller with Up to 95% Duty Cycle
  • Reverse Leakage Protection to Prevent Battery Drainage
  • Thermal Regulation and Protection
  • Over-Temperature Protection
  • Input Over-Voltage Protection
  • IRQ Output for Communication with I2C
  • Automatic Charging
  • RoHS Compliant and Halogen Free

Key Performance Summary Table

Key Features

Evaluation Board Number : PCB099_V1

Input Voltage

4.3V to 6V

Output Voltage

3.5V to 4.44V

Max Output Current

1.55A

Package Type

RT9458WSC, WL-CSP-20B 2.1x1.87 (BSC)



Bench Test Setup Conditions

Headers Description and Placement

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Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at 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

Power input.

STAT

Interrupt

IRQ output node. Open-drain output. Connect a 10kΩ pull up resistor.

MID

VMID

Connection point between reverse blocking MOSFET and high-side MOSFET.

OTG

OTG

Boost mode control input or current regulation setting for average input current.

ISNSIN

ISNSIN

Charge current sense input.

LX

LX

Switch node.

SCL

SCL

Clock input for I2C. Open-drain output. Connect a 10kΩ pull-up resistor.

BOOT

BOOT

Bootstrap supply for high-side MOSFET. Connect a capacitor between BOOT and LX.

SDA

SDA

Data input for I2C. Open-drain output. Connect a 10kΩ pull-up resistor.

VPULL

Pull high voltage

Pull high voltage source for SDA, SCL and IRQ.

VBAT

VBAT

Feedback voltage input for battery.

BATS

BATS

Test pin for measure battery voltage.

GND

GND

Ground.



Power-up & Measurement Procedure

1. Connect power supply termination to VIN Pin and GND Pin respectively.

2. Set PSU Voltage 4.3 to 6V and then power on PSU.

3. Check VBAT = 4.2V ±1% on EVB.

4. Switch charger work normally.



Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

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Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacturer

U1

1

RT9458WSC

Switching Charger

WL-CSP-20B

2.1x1.87 (BSC)

RICHTEK

C2

1

GRM155R61E474KE01

0.47µF/25V/X5R

0402

muRata

C3

1

GRM155R71E473KA88D

47nF/25V/X7R

0402

muRata

C4

1

GRM188R61C106KAAL

10µF/16V/X5R

0603

muRata

C6

1

C1005X7R1C104K050BC

100nF/16V/X7R

0402

TDK

C10

1

GRM185R60J106ME15

10µF/6.3V/X5R

0603

muRata

L1

1

DFE252012F-1R0M

1µH

2.5x2mm

muRata

R1

1

RL10FTNR056

56mΩ

0805

TA-I

R2, R3, R4, R5

4

WR04X1002FTL

10kΩ

0402

WALSIN



PCB Layout

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Top View (1st layer)

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PCB Layout—Inner Side (2nd Layer)

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PCB Layout—Inner Side (3rd Layer)

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Bottom View (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2018/04/16
Bill of Materials 2018/04/16
Gerber File 2018/04/16
Schematic 2018/04/16
RT9458

Switch-Mode Single Cell Li-Ion Battery Charger with USB-OTG

RT9458

The RT9458 is a switch-mode single cell Li-Ion/Li-Polymer battery charger for portable applications. It integrates a synchronous PWM controller, power MOSFETs, input current sensing, high accuracy voltage regulation and charge termination circuits. The RT9458 also features USB On-The-Go (OTG).

The RT9458 optimizes the charging task by using a control algorithm to vary the charge rate via different modes, including pre-charge mode, fast charge mode, and constant voltage mode. The key charge parameters can be programmed via the I2C interface. The RT9458 resumes the charge cycle whenever the battery voltage falls below an internal threshold and automatically enters sleep mode when the input power supply is removed.

Other features include under-voltage protection, over-voltage protection, thermal regulation and reverse leakage protection.

The RT9458 is available in the small WL-CSP-20B 2.1x1.87 (BSC) package.

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