RT9460WSC datasheet(13/33 Pages) RICHTEK

13 / 33 page

DS9460-04 August 2017

www.richtek.com

RT9460

is a registered trademark of Richtek Technology Corporation.

Fast-Charge Mode and Settings

As the BAT pin rises above VPREC, the charger enters

fast-charge mode and starts charging. Notice that the

MUIC integrates input power source (AC adapter or USB

input) detection. Thus, the switching charger can set the

charge current by option automatically. Unlike the linear

charger (LDO), the switching charger (Buck converter) is

a current amplifier. The current drawn by the switching

charger is different from the current into the battery.

The user can set the Average Input Current Regulation

(AICR) and output charge current (ICHRG) respectively.

Cycle-by-Cycle Current Limit

The charger of the RT9460 has an embedded cycle-by-

cycle current limit for inductor. Once the inductor current

touches the threshold (4.5A typ.), the charger stops

charging immediately to prevent over current from

damaging the device. Notice that, the mechanism can not

be disabled by any way.

Average Input Current Regulation (AICR)

The AICR setting is controlled by I2C. The AICR100 mode

limits the input current to 100mA. The AICR500 mode

limits the input current to 500mA. If the application does

not need input current limit, it can be disabled also. The

AICR levels programmed by I2C and suitable for USB port

and several TA types.

Charge Current (ICHG)

The charge current into the battery is determined by the

power path sensing RON and ICC setting by I2C. The

voltage between the SYS and BAT pins is regulated to

the voltage control by ICC setting. (ICC x RON, RON: power

path RON)

At RT9460, the RON is 35m

Ω and the Fast-Charge currents

is set by the I2C interface from 1.25A to 3.125A per

125mA.

Constant Voltage Mode and Settings

The RT9460 enters constant voltage mode when the BATS

voltage is close to the output-charge voltage (VOREG). In

this mode, the charge current begins to decrease. For

default settings (charge current termination is disabled),

the RT9460 does not turn off and always regulates the

battery voltage at VOREG. However, once the charge

current termination is enabled, the charger terminates if

the charge current is below termination current (IEOC) in

constant-voltage mode. The charge current termination

function is controlled by the I2C interface.

After termination, a new charge cycle restarts when one

of the following conditions is detected :



The BATS pin voltage falls below the VOREG - VRECH

threshold.



VIN Power On Reset (POR).



CHG_EN bit toggle or RST bit is set (via I2C interface).

Output Charge Voltage (VOREG)

The output-charge voltage is set by the I2C interface from

3.5V to 4.62V per 25mV. The default value is 4V (011001).

Termination Current (IEOC)

If the charger current termination is enabled (TE bit = “1”

of REG0x01[3]), the end-of-charge current is determined

by both termination current sense voltage (VEOC) and power

path sense resistor (RON). General RON is 35m

Ω, IEOC is

set by the I2C interface from 100mA to 450mA per 50mA.

Input Voltage Protection in Charge Mode

During charge mode, there are two protection mechanisms

against if input power source capability is less than the

charging current setting. One is AICR and the other is

minimum input voltage regulation. A suitable level of AICR

can prevent VBUS drop by the insufficient capability. As

the AICR setting is not suitable, MIVR will regulate the

VBUS in the setting level and sink the maximum current

of power source.

Sleep Mode (VIN - VBATS < VSLP)

The RT9460 enters sleep mode if the voltage drop between

the VIN and BATS pins falls below VSLP. In sleep mode,

the reverse blocking switch and PWM are all turned off.

This function prevents battery drain during poor or no input

power source.

RT9460WSC Datasheet(PDF) 13 Page - Richtek Technology Corporation

RT9460WSC Datasheet(HTML) 13 Page - Richtek Technology Corporation

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