RT4813 datasheet(3/16 Pages) RICHTEK

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RT4813

is a registered trademark of Richtek Technology Corporation.

DS4813-00

April

2016

www.richtek.com

Operation

RT4813 combined built-in power transistors, synchronous

rectification, and low supply current, it provides a compact

solution for system using advanced Li-Ion battery

chemistries.

In boost mode, output voltage regulation is guaranteed to

a maximum load current of 3.1.A. Quiescent current in

Shutdown mode is less than 1

A, which maximizes

battery life.

Mode

Depiction

Condition

LIN

LIN 1

Linear startup 1

VIN > VOUT

LIN 2

Linear startup 2

VIN > VOUT

Soft-Start

Boost soft-start

VOUT < VOUT(MIN)

Boost

Boost mode

VOUT = VOUT(MIN)

LIN State

When VIN is rising, it enters the LIN State. There are

two parts for the LIN state. It provides maximum current

for 1A to charge the COUT in LIN1, and the other one is

for 2A in LIN2. By the way, the EN is pulled high and

VIN > UVLO.

As the figure shown, if the timeout is over the

specification, it will enter the Fault mode.

EN = 1,

Vin > UVLO

LIN 1

Soft-Start

LIN 2

Fault

State

Boost

mode

Timeout < 512

μs

Timeout > 512

μs

Timeout > 1024

μs

Timeout

< 1024

μs

Figure 1. RT4813 State Chart

Startup and Shutdown State

When VIN is rising and through the LIN state, it will

enter the Startup state. If EN is pulled low, any function

is turned-off in shutdown mode.

Soft-Start State

It starts to switch in Soft-start state. After the LIN state,

output voltage is rising with the internal reference

voltage.

Fault State

As the Figure 1 shown, it will enter to the Fault state as

below,



The timeout of LIN2 is over the 1024

s.

It will be the high impedance between the input and

output when the fault is triggered. A restart will be start

after 20ms.

OCP

The converter senses the current signal when the

high-side P-MOSFET turns on. As a result, the OCP is

cycle by-cycle current limitation. If the OCP occurs, the

converter holds off the next on pulse until inductor

current drops below the OCP limit.

OTP

The converter has an over-temperature protection.

When the junction temperature is higher than the

thermal shutdown rising threshold, the system will be

latched and the output voltage will no longer be

regulated until the junction temperature drops under

the falling threshold.

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