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5A Single Cell Li-Ion Switching Battery Charger With Direct Charge, Power Path Management and USB OTG Boost Mode

EVB_RT9468GQW

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The RT9468 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 and regulation, high-accuracy voltage regulation, and charge termination. The charge current is regulated through integrated sensing resistors. The RT9468 also features USB On-The-Go (OTG) support. The RT9468 integrates an easy-to-use direct charge function, simply driving an external MOSFET to enable a direct charge path, as well as over-voltage protection, over-current protection, and watchdog functions.

Purpose

The RT9468 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 and regulation, high-accuracy voltage regulation, and charge termination. The charge current is regulated through integrated sensing resistors. The RT9468 also features USB On-The-Go (OTG) support. The RT9468 integrates an easy-to-use direct charge function, simply driving an external MOSFET to enable a direct charge path, as well as over-voltage protection, over-current protection, and watchdog functions. This document explains the function and use of the RT9468 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 RT9468 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 and regulation, high-accuracy voltage regulation, and charge termination. The charge current is regulated through integrated sensing resistors. The RT9468 also features USB On-The-Go (OTG) support. The RT9468 integrates an easy-to-use direct charge function, simply driving an external MOSFET to enable a direct charge path, as well as over-voltage protection, over-current protection, and watchdog functions.


Product Feature

  • Direct Charge with Over-Voltage Protection, Over-Current Protection and Watchdog
  • High Efficiency 5A, 1.5MHz Switching Charger with Output Inductor DFE252012F, TOKO
  • ►Charging Efficiency 90.25% at ICHG = 2A
    ►Charging Efficiency 88.86% at ICHG = 3A
    ►Charging Efficiency 84.2% at ICHG = 5A
  • Synchronous 1.5MHz/0.75MHz Fixed-Frequency PWM Controller with Up to 95% Duty Cycle
  • Power Path Management by BATFET Control
  • Support High Voltage Input (9V/12V)
  • Support High Voltage Input Adapter (Pump Express 1.0/2.0/3.0)
  • Support IR Compensation Function from Charger Output to Cell Terminal
  • Optimize Input Sourcing Capability to Prevent Overload
  • ►AICR Current Limit Setting via I2C
    ►ILIM Pin for Current Limit Setting
    ►Average Input Current Limit Measurement
  • Shipping Mode for Battery Leakage Reduction
  • ►Wake Up System, Exit Shipping Mode, and Reset System byTechnical Document Image PreviewPin
  • Automatic Charging
  • Average Input Current Regulation (AICR) : 0.1A to 3.25A in 50mA Steps
  • Charge Current Regulation Accuracy : ±7%
  • Charge Voltage Regulation Accuracy : ±1% (0 to 85°C)
  • Protection for Overall System Considerations
  • ►Thermal Regulation for Current Reduction and Over-Temperature Protection
    ►Input Over-Voltage Protection
    ►Input Bad Adapter Protection
    ►Battery Over-Voltage Protection
  • Support ADC Conversion for
  • ►VBUS, VBAT, VSYS, REGN, TS_BAT, IBUS, IBAT,TEMP_JC, TS_BUS, VBATS, IBATS
  • INT Output for Communication with Host Through I2C (Watch Dog / Polling Function)

Key Performance Summary Table

Key Features

Evaluation Board Number : PCB097_V1

Input Voltage

3.9V to 14V

Output Voltage

3.8V to 5.06V

Maximum Output Current

0A to 5A

Package Type

RT9468GQW, WQFN-32L 4x4



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)

VBUS

Input

Power input.

D+

USB D+ Port

Connected to USB receptacle.

D-

USB D- Port

Connected to USB receptacle.

TS_BUS

BUS Temperature-Sense Input

Connected to a resistor divider for temperature programming. If there is no need for the battery temperature-sense function, a 50kΩ resistor is connected to REGN and another 50kΩ resistor to ground.

SCL

I2C Interface Serial Clock Input

Open-drain. An external pull-up resistor is required.

SDA

I2C Interface Serial Data Input/Output

Open-drain. An external pull-up resistor is required.

INT

Interrupt output

Active-low open-drain. Indicator of the charger/boost event for system processor.

OTG

OTG Boost Mode Enable Control

Active-high. Act with OTG_PIN_EN (0x01[1]).

CEB

Charger Enable Input

Active-low.

ILIM

Input Current Limit Setting Pin

A resistor is connected from ILIM pin to ground to set the maximum input current limit. The actual input current limit is the lower value set through the ILIM pin and IAICR register bits.

TS_BAT

Battery Temperature-Sense Input

connected to a resistor divider for temperature programming. If there is no need for the battery temperature-sense function, a 50kΩ resistor is connected to REGN and another 50kΩ resistor to ground.

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Internal BATFET Enable Control Input

In shipping mode,Technical Document Image Previewis pulled Low for the duration of tSHIPMODE (typical 0.9s) to exit shipping mode.

IBAT_SN

Negative Battery Current Sense

Negative battery current sense. Connect a 10mΩ between IBAT_SP.

IBAT_SP

Positive Battery Current Sense

Positive battery current sense. Connect a 10mΩ between IBAT_SN.

BAT_SN

Negative Battery Current Sense

Connect to battery connect.

BAT_SP

Positive Battery Current Sense

Connect to battery connect.

BAT

Battery Connection Node

Charging current output node. Internal BATFET is connected between SYS and BAT.

SYS

System Connection Node

The internal BATFET is connected between SYS and BAT. Connect a 20µF ceramic capacitor between SYS and ground.

SW

Switch Node

Switch node for output inductor connection.

BTST

Bootstrap Capacitor Connection for High-Side Gate Driver

Connect a capacitor from BTST to SW to power the internal gate driver.

REGN

Regulated Output Voltage

Connect a 4.7µF ceramic capacitor from REGN to GND.

VG

Gate Driver Output

Gate driver output for external N-MOSFET.

PMID

PMID

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

PGND

Power Ground

Power ground connection. The exposed pad must be connected to GND and well soldered to a large PCB copper area for maximum power dissipation.



Power-Up & Measurement Procedure

1. Connect input power (5 < VBUS < 14V) and input ground to VIN and GND test pins respectively.

2. Connect positive end and negative terminals of VBAT to BAT and BAT_SN test pins respectively.

3. Connect JP11, JP14, JP5 and JP9 let TS_BUS and TS_BAT at normal condition.



Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

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Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacturer

C9, C11

2

GRM188R61E475KE11

4.7µF/25V/X5R

0603

muRata

C12

1

GRM155R60J475ME47

4.7µF/6.3V/X5R

0402

muRata

C13

1

GRM033R61C473KE84

47nF/16V/X5R

0201

muRata

C14, C16, C28

3

GRM185R60J106ME15

10µF/6.3V/X5R

0603

muRata

C24

1

GRM155R61E225KE11

2.2µF/25V/X5R

0402

muRata

L1

1

DFE252012F-1R0M

1µH

2.5x2.0mm

muRata

Q1

1

DMT2004UFDF

NMOS

2x2x0.6mm

DIODES

U2

1

RT9468GQW

Switching Charger

WQFN-32L 4x4

Richtek

R1

1

WR06X5231FTL

5.23k/0603

1206

WELLCOMP TECHNOLOGY

R2, R13

2

WR06X1002FTL

10k/0603

0603

WALSIN

R3, R6, R12, R16, R18, R19, R20, R29, R36

9

WR06X1300FTL

130/0603

0603

WALSIN

R7

1

WR06X4701FTL

4.7k/0603

0603

WALSIN

R8

1

WR06X3012FTL

30.1k/0603

0603

WALSIN

R11, R17

2

WR06X7680FTL

768/0603

0603

WALSIN

R14

1

WR06X5231FTL

5.23k/0603

0603

WALSIN

R35, R37

2

WR06X5101FTL

5.1k/0603

0603

WALSIN

R38, R39

2

WR06X000 PTL

0/0603

0603

WALSIN

USB1

1

SIP-5P

USB-MICRO-TCU-S60M

USB3

1

121U-3CST-09CR

USB TYPE-C 3.1

9.87x9.75mm

JEM (建舜電子)



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 2018/08/21
Bill of Materials 2018/08/21
Gerber File 2018/08/21
Schematic 2018/08/21
RT9468

5A Single Cell Li-Ion Switching Battery Charger with Direct Charge, Power Path Management and USB OTG Boost Mode

RT9468

The RT9468 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 and regulation, high-accuracy voltage regulation, and charge termination. The charge current is regulated through integrated sensing resistors. The RT9468 also features USB On-The-Go (OTG) support. The RT9468 integrates an easy-to-use direct charge function, simply driving an external MOSFET to enable a direct charge path, as well as over-voltage protection, over-current protection, and watchdog functions.

The RT9468 optimizes for charging task by using a control algorithm to vary the charge rate for different modes, including pre-charge mode, fast charge mode (constant voltage and constant current). The key charge parameters are programmable through an I2C interface. The RT9468 will resume the charge cycle whenever the battery voltage falls below an internal recharge threshold, and can automatically enter sleep mode if the input power supply is removed.

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

The RT9468 is available in a WQFN-32L 4x4 package.

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