RT9481 datasheet(15/41 Pages) RICHTEK

15 / 41 page

RT9481

is a registered trademark of Richtek Technology Corporation.

DS9481-00 June 2015

www.richtek.com

Output Charge Voltage (VBATREG)

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

Its range is from 3.65V to 4.6V per 25mV.

Termination Current (IEOC)

If the charger current termination is enabled (TE bit =

“1”), the end-of-charge current is determined by both

the termination current sense voltage (VEOC) and

sense resistor (RSENSE). As RSENSE is 10m, IEOC is

set by the I2C interface from 150mA to 600mA.

Table 5. EOC Register Setting Table

EOC[2:0]

VEOC

IEOC RSENSE is 10m

000

Disable

001

1.5mV

150mA

010

2mV

200mA (default)

011

2.5mV

250mA

100

3mV

300mA

101

4mV

400mA

110

5mV

500mA

111

6mV

600mA

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 (VVBUS VVBAT < VSLP)

The switching charger enters sleep mode if the voltage

drop between the VBUS and ISENSN 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.

Input Over Voltage Protection

When VBUS rises above the input over voltage

threshold, the switching charger stops charging and

then sets fault status bits. The condition is released

when VBUS falls below OVP threshold. The switching

charger then resumes charging operation.

Reverse Boost Mode Operation Trigger and

Operation

The switching charger features Boost support. When

BOOST function is enabled, the synchronous boost

control loop takes over the power MOSFETs. In boost

mode, the VMID pin is regulated to 5V (typ.) to support

other BOOST devices connected to the USB connector.

Output Over-Voltage Protection

In boost mode, the output over voltage protection is

triggered when the VMID voltage is above the output

OVP threshold. When OVP occurs, the boost converter

stops switching and turns off immediately.

Battery Protection

Battery Over-Voltage Protection in Charge Mode

The switching charger monitors the VBAT voltage for

output over voltage protection. In charge mode, if the

VBAT voltage rises above VOVP_BAT x VBATREG, such

as when the battery is suddenly removed, the

switching charger stops charging and then sets fault

status bits and sends out fault pulse at the INT pin.

The condition is released when the VBAT voltage falls

below (VOVP_BAT  VOVP_BAT) x VOVP_BAT. The

switching charger then resumes charging process with

default settings and the fault is cleared.

Low Battery Voltage Protection (LBP)

When the Battery voltage is lower than a specified

value, the converter will stop switching. Until the

battery voltage rises above the low battery voltage

protection threshold plus hysteresis voltage value, the

converter resumes switching. The low battery voltage

protection can be programmed with 8 different levels

(2.5V to 3.2V).

RT9481 Datasheet(PDF) 15 Page - Richtek Technology Corporation

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