Richtek RT8008-12PB, RT8008-12PJ5, RT8008-15PB, RT8008-15PJ5, RT8008-18PB, RT8008-18PJ5, RT8008-25GB, RT8008-25GJ5, RT8008-25PB, RT8008-25PJ5, RT8008-33PB, RT8008-33PJ5, RT8008GB, RT8008GJ5, RT8008PB, RT8008PJ5 Schematic [ru]

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RT8008

1.5MHz, 600mA, High Efficiency PWM Step-Down DC/DC Converter

General Description

The RT8008 is a high-efficiency pulse-width-modulated (PWM) step-down DC/DC converter. Capable of delivering 600mA output current over a wide input voltage range from 2.5V to 5.5V, the RT8008 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals.

Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. No external Schottky diode is required in practical application. The RT8008 automatically turns off the synchronous rectifier while the inductor current is low and enters discontinuous PWM mode. This can increase efficiency at light load condition.

The RT8008 enters Low-Dropout mode when normal PWM cannot provide regulated output voltage by continuously turning on the upper P-MOSFET. RT8008 enter shutdown mode and consumes less than 0.1μAwhen ENpin is pulled low.

The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.5MHz. This along with small SOT-23-5 and TSOT-23-5 package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection.

Pin Configurations

(TOP VIEW)

FB/VOUT VIN

5 4

2 3

EN GND LX

SOT-23-5/TSOT-23-5

Marking Information

For marking information, contact our sales representative directly or through a Richtek distributor located in your area.

Features

z2.5V to 5.5V Input Range

zAdjustable Output From 0.6V to VIN

z1.0V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/ Adjustable Output Voltage

z600mA Output Current, 1A Peak Current

z95% Efficiency

zNo Schottky Diode Required

z1.5MHz Fixed Frequency PWM Operation

zSmall SOT-23-5 and TSOT-23-5 Package

zRoHS Compliant and 100% Lead (Pb)-Free

Applications

zCellular Telephones

zPersonal Information Appliances

zWireless and DSL Modems

zMP3 Players

zPortable Instruments

Ordering Information

RT8008(-)

Package Type

B : SOT-23-5

J5 : TSOT-23-5

Lead Plating System P : Pb Free

G : Green (Halogen Free and Pb Free)

Output Voltage Default : Adjustable 10 : 1.0V

12 : 1.2V

15 : 1.5V

18 : 1.8V

25 : 2.5V

33 : 3.3V

Note :

Richtek products are :

`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

`Suitable for use in SnPb or Pb-free soldering processes.

DS8008-07 March 2011

www.richtek.com

 

1

RT8008

Typical Application Circuit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L

 

 

 

 

VIN

 

 

 

 

4

VIN

 

 

 

 

 

 

 

 

LX

3

2.2µH

 

 

 

VOUT

2.2V to 5.5V

 

 

 

 

 

 

CIN

 

RT8008

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.7µF

1

5

 

 

 

 

 

 

 

COUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EN

 

 

 

 

 

 

VOUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10µF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1. Fixed Voltage Regulator

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VIN

 

 

 

 

4 VIN

 

 

 

 

 

LX

32.2µH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOUT

 

 

 

2.2V to 5.5V

 

 

 

CIN

 

 

 

 

 

 

 

 

C1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4.7µF

 

RT8008

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

5

 

 

 

 

 

 

 

 

 

R1

 

 

 

COUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

EN

 

 

 

 

 

FB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10µF

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R1

 

 

 

 

 

 

GND

IR2

 

 

 

 

 

 

 

R2

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOUT = VREF x 1

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

with R2 = 300kΩ to 60kΩ so the IR2 = 2μA to 10μA,

and (R1 x C1) should be in the range between 3x10-6 and 6x10-6 for component selection.

Figure 2. Adjustable Voltage Regulator

Layout Guide

VIN

 

 

GND

 

 

 

 

 

VOUT

 

 

VIN

 

 

 

 

 

 

 

GND

 

VOUT

C

IN

C

 

 

 

 

 

 

 

 

 

C

IN

 

 

 

C

OUT

 

 

 

 

 

 

OUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

L

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VIN

 

4

 

 

3

 

 

LX

 

 

 

 

 

 

 

 

VIN

 

 

4

 

 

 

3

 

LX

 

 

 

 

 

 

 

2

 

 

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

GND

 

 

 

 

 

 

 

 

 

 

 

C1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOUT

 

5

 

1

 

 

 

EN

 

 

 

 

 

 

 

 

 

FB

 

 

5

 

 

 

1

 

 

EN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R1

 

 

R2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VOUT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

Figure 3

Layout note:

1.The distance that CIN connects to VIN is as close as possible (Under 2mm).

2.COUT should be placed near RT8008.

www.richtek.com

DS8008-07 March 2011

2

 

 

 

RT8008

Functional Pin Description

Pin Number

Pin Name

Pin Function

 

 

 

1

EN

Chip Enable (Active High, do not leave EN pin floating, and VEN < VIN + 0.6V).

2

GND

Ground.

3

LX

Pin for Switching.

4

VIN

Power Input.

5

FB/VOUT

Feedback Input Pin.

Function Block Diagram

 

 

EN

 

 

VIN

 

 

OSC &

 

 

RS1

 

 

Current

 

 

 

 

Shutdown

 

 

 

 

Limit

 

 

 

 

Control

 

 

 

Slope

Detector

 

 

 

 

 

 

 

 

 

 

 

 

Compensation

Current

 

 

 

 

 

 

 

 

 

 

Sense

 

 

 

 

 

 

Control

Driver

LX

 

 

PWM

Logic

 

 

 

 

 

 

 

FB/VOUT

Error

Comparator

 

 

 

 

Amplifier

 

 

 

 

 

RC

 

 

 

 

 

 

UVLO &

Zero

 

RS2

 

COMP

Detector

 

 

Power Good

 

 

 

 

 

 

 

 

 

Detector

VREF

 

 

 

 

 

 

 

 

 

 

 

GND

 

DS8008-07 March 2011

www.richtek.com

3

RT8008

Absolute Maximum Ratings (Note 1)

Supply Input Voltage ------------------------------------------------------------------------------------------------------

6.5V

Enable, FB Voltage -------------------------------------------------------------------------------------------------------

VIN + 0.6V

Power Dissipation, PD @ TA = 25°C

 

SOT-23-5, TSOT-23-5 -----------------------------------------------------------------------------------------------------

0.4W

Package Thermal Resistance (Note 2)

 

SOT-23-5, TSOT-23-5, θJA -----------------------------------------------------------------------------------------------

250°C/W

SOT-23-5, TSOT-23-5, θJC -----------------------------------------------------------------------------------------------

130°C/W

Junction Temperature Range --------------------------------------------------------------------------------------------

150°C

Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------

260°C

Storage Temperature Range --------------------------------------------------------------------------------------------

−65°C to 150°C

ESD Susceptibility (Note 3)

 

HBM (Human Body Mode) ----------------------------------------------------------------------------------------------

2kV

MM (Machine Mode) ------------------------------------------------------------------------------------------------------

200V

Recommended Operating Conditions

(Note 4)

Supply Input Voltage ------------------------------------------------------------------------------------------------------

2.5V to 5.5V

Junction Temperature Range --------------------------------------------------------------------------------------------

−40°C to 125°C

Ambient Temperature Range --------------------------------------------------------------------------------------------

−40°C to 85°C

Electrical Characteristics

(VIN = 3.6V, VOUT = 2.5V, VREF = 0.6V, L = 2.2μH, CIN = 4.7μF, COUT = 10μF, TA = 25°C, IMAX = 600mA unless otherwise specified)

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

 

 

 

 

 

 

 

 

 

 

Input Voltage Range

VIN

 

2.5

--

5.5

V

 

Quiescent Current

IQ

IOUT = 0mA, VFB = VREF + 5%

--

50

100

μA

 

Shutdown Current

ISHDN

EN = GND

--

0.1

1

μ

 

 

 

 

 

 

 

A

 

Reference Voltage

VREF

For adjustable output voltage

0.588

0.6

0.612

V

 

Adjustable Output Range

VOUT

 

VREF

--

VIN − 0.2

V

 

 

 

VOUT

VIN = 2.2 to 5.5V, VOUT = 1.0V

−3

--

3

%

 

 

 

0A < IOUT < 600mA

 

 

 

 

 

 

 

 

 

 

 

VOUT

VIN = 2.2 to 5.5V, VOUT = 1.2V

−3

--

3

%

 

 

 

0A < IOUT < 600mA

 

 

 

 

 

 

 

 

 

 

 

VOUT

VIN = 2.2 to 5.5V, VOUT = 1.5V

−3

--

3

%

 

 

 

0A < IOUT < 600mA

 

 

Fix

 

 

 

 

 

 

 

VOUT

VIN = 2.2 to 5.5V, VOUT = 1.8V

−3

--

3

%

 

 

 

 

Output Voltage

 

0A < IOUT < 600mA

 

 

 

VIN = 2.8 to 5.5V, VOUT = 2.5V

 

 

 

 

 

Accuracy

 

VOUT

−3

--

3

%

 

 

 

0A < IOUT < 600mA

 

 

 

 

 

 

 

 

 

 

 

VOUT

VIN = 3.5 to 5.5V, VOUT = 3.3V

−3

--

3

%

 

 

 

0A < IOUT < 600mA

 

 

 

 

 

 

 

 

 

 

 

 

VIN = VOUT + 0.2V to 5.5V, VIN 3.5V

−3

--

3

%

 

 

Adjustable

VOUT

0A < IOUT < 600mA

 

 

 

 

 

 

VIN = VOUT + 0.4V to 5.5V, VIN 2.2V

−3

--

3

%

 

 

 

 

0A < IOUT < 600mA

 

 

 

 

 

 

 

 

 

 

 

To be continued

 

 

 

 

 

 

 

 

 

www.richtek.com

 

 

 

DS8008-07 March 2011

4

 

 

 

 

 

 

 

 

RT8008

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

 

 

 

 

 

 

 

 

FB Input Current

IFB

VFB = VIN

−50

--

50

nA

PMOSFET RON

PRDS(ON)

IOUT = 200mA

VIN = 3.6V

--

0.3

--

Ω

VIN = 2.5V

--

0.4

--

 

 

 

 

NMOSFET RON

NRDS(ON)

IOUT = 200mA

VIN = 3.6V

--

0.25

--

Ω

VIN = 2.5V

--

0.35

--

 

 

 

 

P-Channel Current Limit

IP(LM)

VIN = 2.5V to 5.5 V

1

--

1.8

A

EN High-Level Input Voltage

VENH

VIN = 2.5V to 5.5V

1.5

--

--

V

 

 

 

 

 

 

 

EN Low-Level Input Voltage

VENL

VIN = 2.5V to 5.5V

--

--

0.4

V

Under Voltage Lockout Threshold

 

 

 

--

1.8

--

V

 

 

 

 

 

 

 

 

Hysteresis

 

 

 

--

0.1

--

V

 

 

 

 

 

 

 

Oscillator Frequency

fOSC

VIN = 3.6V, IOUT = 100mA

1.2

1.5

1.8

MHz

Thermal Shutdown Temperature

TSD

 

 

--

160

--

°C

Min. On Time

 

 

 

--

50

--

ns

 

 

 

 

 

 

 

 

Max. Duty Cycle

 

 

 

100

--

--

%

 

 

 

 

 

 

 

LX Leakage Current

 

VIN = 3.6V, VLX = 0V or VLX = 3.6V

−1

--

1

μA

Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability.

Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Pin 2 of SOT-23-5/TSOT-23-5 packages is the case position for θJC measurement.

Note 3. Devices are ESD sensitive. Handling precaution recommended.

Note 4. The device is not guaranteed to function outside its operating conditions.

DS8008-07 March 2011

www.richtek.com

 

5

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