RT9758 datasheet(35/61 Pages) RICHTEK

35 / 61 page

RT9758

is a registered trademark of Richtek Technology Corporation.

DS9758-03

May 2023

www.richtek.com

Charge System Introduction

The RT9758 is slave charger that integrated cap divider

and direct charge topology for high voltage application.

The RT9758 can generates high output current with

both topologies. Before enabling the RT9758, the host

set up all of protection and disable main charger in

power solution. The host must monitor the input/output

voltage and current by external sensing circuit during

high current charging period and communicate with the

smart wall adapter to control the charging current flow.

The Figure 2 and Figure 3 are the simplified high

voltage charge system in 1-cell and 2-cell battery

application. These devices can communicate with each

other through I2C serial interface. These system blocks

support dual input power source for high charge current

application. In these charge system, the switching

charger is used to detect USB BC1.2 of adapter and the

PD controller is used to communicate with adapter by

PD protocol. The RT9758 and cap divider charger are

used to implement high current charging period.

In 1-cell battery application, once the smart wall adapter

is detected, the AP will control the switching charger,

cap divider charger and communicate with adapter to

achieve high current charging profile. And If wireless

power transmitter is detected, the AP will control three

charger devices and communicate with wireless

transmitter to achieve high current charging profile.

In 2-cell battery application, once the smart wall adapter

is detected, the AP will control the switching charger,

RT9758 and communicate with adapter to achieve high

current

charging

profile.

And

wireless

power

transmitter is detected, the AP will also control two

charger devices and communicate with wireless

transmitter to achieve high current charging profile.

For monitor the

RT9758’s input and output voltage and

current information, both wireless power receiver and

cap divider charger that establish ADC function are

essential. If not, the system must built-in external

voltage and current detector for safety charge control.

The charge profile of 1-cell and 2-cell battery application

are shown in Figure 4 and Figure 5. The switching

charger is required to dominate pre-charge, fast charge

when battery voltage is lower than system startup

voltage, constant voltage and termination periods.

In 1-cell battery application, when wireless power

source is detected and before system wake up, the

RT9758 will operate in bypass mode to deliver power to

next power stage. After system is waked up, the

RT9758 will operate in DIV2 mode and in series with

cap divider charger to achieve fast charge period.

In 2-cell battery application, when system is waked up,

the RT9758 can operate in DIV2 mode or bypass mode

to achieve fast charge period according to different input

power source voltage level.

To shorten the constant voltage period, the wireless

power receiver or adapter are controlled to reduce the

support current by ramp step when battery voltage

triggers CV level. After the charging current is step

down to desired value, the switching charger will start to

dominate CV period.

RT9758 数据表(PDF) 35 Page - Richtek Technology Corporation

RT9758 数据表(HTML) 35 Page - Richtek Technology Corporation

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