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High Efficiency Boost Converter

EVB_RT4813GQUF

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The RT4813 is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery or two alkaline battery series, even when the battery voltage is below system minimum. Quiescent current in shutdown mode is less than 1µA, which maximizes battery life. In boost mode, output voltage regulator is guaranteed to supply 3.1A for maxium loading.

General Description

The RT4813 is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery or two alkaline battery series, even when the battery voltage is below system minimum. Quiescent current in shutdown mode is less than 1µA, which maximizes battery life. In boost mode, output voltage regulator is guaranteed to supply 3.1A for maxium loading.



Performance Specification Summary

The boost conveter has an input voltage range from 1.8V to 5.5V, and the output voltage range is from 1.8V to 5.5V. It can operate in PFM mode and PWM mode in boost operation. And the power-on inrush current and current limit are implemented serval setting for difference application. The RT4813 is available in a UQFN-9L 2x2 (FC) package.


Table 1. RT4813 Evaluation Board Performance Specification Summary

Specification

Test Conditions

Min

Typ

Max

Unit

Input Voltage Range

1.8

--

5.5

V

Output Current

2.5

--

3.25

A

Default Output Voltage

Setting by FB pin

1.8

5

5.5

V

Operation Frequency

--

500

--

kHz

Output Ripple Voltage

VIN = 2.5V, VOUT = 5V, IOUT = 1A

--

60

--

mVp-p

Line Regulation

CCM, VIN = 2.7V to 4.5V, VOUT = 5V, IOUT = 0.5A

--

0.5

--

%

Load Regulation

CCM, VIN = 3.6V, VOUT = 5V, IOUT < 3.1A

--

0.5

--

%

Load Transient Response

VIN = 3.7V, VOUT = 5V, IOUT = 1.5A to 3A

-10

--

10

%

Maximum Efficiency

VIN = 1.8V to 4.2V, VOUT = 5V, IOUT = 0A to 3A

--

96

--

%



Power-up Procedure

Suggestion Required Equipments

  • Connect input voltage (1.8V < VIN < 5.5V) to VIN pin.
  • Setting output voltage by FB pin.(formula shown in below section)
  • Setting BOOST pre-charge current and BOOST_LIMIT for power on inrush current. (setting 0x01 and 0x03 by I2C)
  • To enable Boost converter by external EN pin.
  • To connect an external load to output and verify the output voltage versus applied current.

Output Voltage Setting

The output voltage set by external feedback resistors expressed in the following equation.

Technical Document Image Preview

Where the reference voltage VFB is 0.5V (typ.)

The placement of the resistive divider should be as close as possible to the FB pin. For better output voltage accuracy, the divider resistors with ±1% tolerance or better should be used.



Detailed Description of Hardware

Headers Description and Placement

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Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at evb_service@richtek.com.


Test Points

The EVB is provided with the test points and pin names listed in the table below.

Test Point/

Pin Name

Function

VIN

Input voltage.

VOUT

Output voltage.

GND

Ground.

EN

Enable test point.

LX

Switch node test point.

SCL

I2C interface clock input.

SDA

I2C interface clock input.

FB

Voltage feedback.

PGND

Power ground.



Bill of Materials

VIN = 12V, VOUT = 5.0V, IOUT = 0.5A, fSW = 500kHz

Reference

Count

Part Number

Value

Description

Package

Manufacturer

U1

1

RT4813GQUF

RT4813GQUF

Step-Up

Converter

UQFN-9L 2x2 (FC)

RICHTEK

C1, C2,

C3, C4

4

JMK107BBJ226MA-T

22µF

22µF/6.3V/X5R

0603

TAIYO YUDEN

C6

1

0402X105K100CT

1µF

1µF/10V/X5R

0402

WALSIN

L1

1

SPM6530T-1R5M100

1.5µH

1.5µH/11A

6.5x7.1x3mm

TDK

R7

1

WR06X9093FTL

909k

909k

0603

WALSIN

R8

1

WR06X1003FTL

100k

100k

0603

WALSIN



Typical Applications

EVB Schematic Diagram

Technical Document Image Preview

1. The capacitance values of the input and output capacitors will influence the input and output voltage ripple.

2. MLCC capacitors have degrading capacitance at DC bias voltage, and especially smaller size MLCC capacitors will have much lower capacitance.


Measure Result

Output Ripple Measurement

Output Ripple Measurement

Technical Document Image Preview

Technical Document Image Preview

Load Transient

Load Transient

Technical Document Image Preview

Technical Document Image Preview

Efficiency vs. Output Current

Technical Document Image Preview

Note: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip directly across the output capacitor.



Evaluation Board Layout

Figure 1 to Figure 4 are RT4813GQUF Evaluation Board layout. This board size is 70mm x 50mm and is constructed on four-layer PCB, outer layers with 2 oz. Cu and inner layers with 1 oz. Cu.

Technical Document Image Preview

Figure 1. Top View (1st layer)

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Figure 2. PCB Layout—Inner Side (2nd Layer)


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Figure 3. PCB Layout—Inner Side (3rd Layer)


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Figure 4. Bottom View (4th Layer)

RT4813
RT4813

The RT4813 allows systems to take advantage of new battery chemistries that can supply significant energy when the battery voltage is lower than the required voltage for system power ICs. By combining built-in power transistors, synchronous rectification, and low supply current; this IC provides a compact solution for systems using advanced Li-Ion battery chemistries.

The RT4813 is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery, even when the battery voltage is below system minimum. In boost mode, output voltage regulation is guaranteed to a maximum load current of 3.1A. Quiescent current in Shutdown Mode is less than 2μA, which maximizes battery life.

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