RT9468 datasheet(49/57 Pages) RICHTEK

49 / 57 page

DS9468-00 May 2017

www.richtek.com

RT9468

is a registered trademark of Richtek Technology Corporation.

Battery Voltage Level VBAT

Battery Charge Current IBAT

Trickle mode

VBAT < 2V

100mA

Pre-charge mode

VBAT < VPREC (0x08, bit[7:4])

IPREC (0x08, bit[3:0])

Fast-charge mode

VBAT < VOREG (0x04, bit[7:1]) Charge current is determined by several control loops

End-of-charge mode

VBAT = VOREG (0x04, bit[7:1]) Charge current decreases naturally

2. VBUS is above 3.8V (i.e. VBAD_ADP) when sinking 50mA

(i.e. IBAD_ADP_SINK) during 30ms of detection period,

tBADADP_DET. And this detection function can be disabled

by ADP_DIS (0x0B, bit7) register bit.

The charge modes as below, and the charge mode which

the charger operates in will be determined according to

the VBAT level :

In fast-charge mode, the input current limit can be selected

by IINLMTSEL (0x02, bit[3:2]). This flexible setting is

suitable for wide applications of adapters. In addition, the

RT9468 also provides charger warning statuses, such as

MIVR, AICR and TREG (0x50, bit[6:4]), to host.

There are 2 register bits, related to the LX switching of

the RT9468 :

1. SEL_SWFREQ (0x01, bit7) :



If SEL_SWFREQ is disabled (set to 0), the switching

frequency is 1.5MHz (default).



If SEL_SWFREQ is enabled (set to 1), the switching

frequency is 0.75MHz.

2. FIXFREQ (0x01, bit6) :



If FIXFREQ is disable (set to 0), the charge switching

frequency would be varied when VBUS is closed to VBAT.



If FIXFREQ is enable (set to 1), the charger switching

frequency is fixed.

There are 3 enable bits, related to the charger.

1. CFO_EN (0x02, bit1) : This bit is used to enable or

disable the charger and boost.

2. CHG_EN (0x02, bit0) : When CHG_EN bit is disabled,

power path MOS will be turned off so that the zero

charging current is derived. At this time, input power

source continuously delivers power to the system

without charging the battery. However, if the system

load is larger than the input source current limit, the

power path MOS will be turned back on immediately to

supply power to system. The CHG_EN bit function is

same as CEB pin.

3. HZ (0x01, bit2) : When HZ bit is enabled, the most of

the charger internal circuits will be turned off in order

to reduce quiescent current.

In end-of-charge mode, if EOC_EN (0x09, bit3) is enabled,

once the charge current is lower than IEOC (0x09, bit[7:4])

level and within CHG_TEDG_EOC (0x09, bit[2:0]), the

RT9468 will send out INT and CHG_IEOCI = 1 (0x54, bit7).

Then, the RT9468 will start to check statuses of the

following three bits.

1. TE (0x02, bit4) : If this bit is enabled, the power path

will be turned off, and the buck of the charger will keep

providing power to the system.

2. EOC_TIMER (0x07, bit[1:0]) : With CHG_IEOC1 = 1,

the power path will not be turned off. The RT9468 can

keep charging the battery for 30 to 60 minutes to extend

battery charging capacity.

3. BATD_EN (0x0B, bit6) : After charge is done, the

RT9468 will start to sink a sink current of IBAT_SINK

375

μA for about 256ms from the battery. If VBAT drops

to trigger the recharge function, it is to say the battery

is not connected to the charger. The RT9468 will

continue on battery detection for every two seconds.

OTG Mode

The RT9468 also supports OTG mode. It not only provides

several output current limit protection levels, but also has

low battery protection for overall system considerations.

The RT9468 can select switching frequency via

SEL_SWFREQ (0x01, bit7), whether the RT9468 already

operates in OTG mode or not.

There are two ways to enable OTG mode :

1. By way of software : through I2C to set OPA_MODE

(0x01, bit0).

RT9468 Datasheet(PDF) 49 Page - Richtek Technology Corporation

RT9468 Datasheet(HTML) 49 Page - Richtek Technology Corporation

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