RT9458WSC datasheet(11/27 Pages) RICHTEK

11 / 27 page

DS9458-02

February 2017

www.richtek.com

RT9458

is a registered trademark of Richtek Technology Corporation.

Applications Information

The RT9458 is an integrated solution of single-cell Li-ion

and Li-polymer battery charger for portable applications.

The part integrates a synchronous PWM controller with

power MOSFETs to provide input voltage MIVR (Minimum

Input Voltage Regulation), input current sensing, high

accuracy current and voltage regulation, and charge

termination in a small package for space limited devices.

The part also features USB OTG (On-The-Go).

The RT9458 has three operation modes : charge mode,

boost mode (USB OTG), and high impedance mode. In

charge mode, the RT9458 supports a precision charging

system for single cell. In boost mode, the RT9458 works

as the Boost converter and boosts the voltage from battery

to VIN pin for sourcing the OTG devices. In high impedance

mode, the RT9458 stops charging or boosting and

operates in a mode with low current from VIN or battery to

reduce the power consumption when the portable device

is in standby mode.

S = Start Condition

W = Write (SDA =

“0”)

R = Read (SDA =

“1”)

Notice that the RT9458 does not integrate input power

source (AC adapter or USB input) detection. Thus, the

RT9458 does not set the charge current automatically.

The charge current needs to be set via I2C interface by

the host. The RT9458 application mechanism and I2C

compatible interface are introduced in later sections. The

slave address for this device is

“1101010”.

I2C Interface Timing Diagram

The RT9458 acts as an I

2C -bus slave. The I2C -bus master

configures the settings for charge mode and boost mode

by sending command bytes to the RT9458 via the 2-wire

2C -bus. After the START condition, the I2C master sends

a chip address. This address is seven bits long followed

by an eighth bit which is a data direction bit (R/W). The

second byte selects the register to which the data will be

written. The third byte contains data to the selected

Charge Mode Operation

Support Quick Start Feature of Charger

When the battery voltage is lower than 2.4V by over-

discharge condition, the RT9458 charges the battery with

60mA to wake up the battery. Once the voltage level is

higher than 2.4V, the RT9458 charges the battery to higher

level with large current and makes sure that the system

could work normally in short period with OTG pin pulled

low.

ACK = Acknowledge

P = Stop Condition

Minimum Input Voltage Regulation (MIVR)

The RT9458 features input voltage MIVR function to prevent

input voltage drop due to insufficient current provided by

the adaptor or USB input. If MIVR function is enabled, the

input voltage decreases when the over current of the input

power source occurs and is regulated at a predetermined

voltage level which can be set as 4.1V to 4.7V per 0.1V

step by I2C interface to MIVR[2:0] in the register of address

0x11 the MIVR bit is set to high. At this time, the current

drawn by the RT9458 equals to the maximum current value

that the input power can provide at the predetermined

voltage level, instead of the set value.

12345

678

B2 B1 B0

789

456789

C5 C4 C3 C2 C1 C0

W ACK

ACK

0B4

ACK

SCL

SDA

C7 C6

Start

1 1 0 1 0 1 0 R/W

B7B6B5B4B3B2B1B0

C7C6C5C4C3C2C1C0

Stop

The 2nd Byte

(Data Address, Data)

The 3rd Byte (Data)

The 1st Byte

(Slave Address, R/W)

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