Richtek RT8008-12PB, RT8008-12PJ5, RT8008-15PB, RT8008-15PJ5, RT8008-18PB Schematic [ru]

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 . Ca pable of delivering
600mA output current over a wide input voltage ra nge 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
a s cellular phones, PDAs and ha ndy-terminals.

Internal synchronous rectifier with low R

DS(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 tha n 0.1μA when EN pin 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 a nd
TSOT-23-5 pa ckage provides small PCB area a pplication.
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

5

EN

SOT-23-5/TSOT-23-5

VIN

4

23

GND LX

Marking Information

Features

zz

2.5V to 5.5V Input Range

z

zz

zz

z Adjustable Output From 0.6V to V

zz

zz

z 1.0V, 1.2V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/

zz

IN

Adjustable Output Voltage

zz

z 600mA Output Current, 1A Peak Current

zz

zz

z 95% Efficiency

zz

zz

z No Schottky Diode Required

zz

zz

z 1.5MHz Fixed Frequency PWM Operation

zz

zz

z Small SOT-23-5 and TSOT-23-5 Package

zz

zz

z RoHS Compliant and 100% Lead (Pb)-Free

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Applications

z Cellular T elephones
z Personal Information Appliances
z Wireless and DSL Modems
z MP3 Players
z Portable 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 require-

ments of IPC/JEDEC J-STD-020.

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

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

DS8008-07 March 2011 www.richtek.com

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RT8008

Typical Application Circuit

V

IN

2.2V to 5.5V

V

IN

2.2V to 5.5V

R1

⎛

REFOUT

⎜
⎝

⎞

+=

1 x VV

⎟

R2

⎠

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

C

IN

4.7µF

Figure 1. Fixed Voltage Regulator

C

IN

4.7µF

4

1

4

1

VIN

EN

VIN

RT8008

EN

RT8008

VOUT

GND

2

GND

2

LX

FB

LX

3

5

2.2µH

3

5

2.2µH

L

I

L

R2

C1

R1

R2

V

C

OUT

10µF

OUT

V

C

OUT

10µF

OUT

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

V

IN

VOUT

VIN

4

5

C

IN

GND

GND

3

2

1

C

OUT

LX

GND

EN

V

OUT

L

V

OUT

R1

V

C1

IN

VIN

FB

R2

C

IN

4

5

Figure 3

Layout note:

1. The distance that C

2. C

should be placed near RT8008.

OUT

connects to VIN is as close as possible (Under 2mm).

IN

GND

3

2

1

C

GND

OUT

LX

GND

EN

V

OUT

L

DS8008-07 March 2011www.richtek.com

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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

RT8008

FB/VOUT

Slope

Compensation

Error

Amplifier

RC

COMP

EN

OSC &

Shutdown

Control

Current

Sense

PWM

Comparator

UVLO &

Power Good

Detector

V

REF

Current

Limit

Detector

Control

Logic

Zero

Detector

Driver

GND

VIN

RS1

LX

RS2

DS8008-07 March 2011 www.richtek.com

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RT8008

Absolute Maximum Ratings (Note 1)

 Supply Input Voltage ------------------------------------------------------------------------------------------------------ 6.5V

 Enable, FB Voltage ------------------------------------------------------------------------------------------------------- V

 Power Dissipation, P

@ TA = 25°C

D

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

+ 0.6V

IN

Electrical Characteristics

(V

= 3.6V, V

IN

Input Voltage Range

Quiescent Current

Shutdown Current

Refere nce Voltage

Adjustable Output Range

Output V olt age

Accuracy

4

OUT

= 2.5V, V

= 0.6V, L = 2.2μH, C

REF

Parameter Symbol Test Conditions Min Typ Max Unit

V

IN

I

I

Q

I

SHD N

V

REF

V

OUT

ΔV

OU T

ΔV

OU T

ΔV

OU T

Fix

ΔV

OU T

ΔV

OU T

ΔV

OU T

Adj ustable

ΔV

OU T

= 4.7μF, C

IN

OUT

= 10μF, T

= 25°C, I

A

= 600mA unless otherwise specified)

MAX

2.5 -- 5.5 V

= 0mA, VFB = V

OUT

REF

+ 5%

EN = GND -- 0.1 1

-- 50 100

μA
μA

For adjustable output voltage 0.588 0.6 0.612 V

V

= 2.2 to 5.5V, V

IN

0A < I
V

IN

0A < I
V

IN

0A < I
V

IN

0A < I

V

IN

0A < I

V

IN

0A < I

VIN = V

0A < I

V

IN

0A < I

< 600mA

OUT

= 2.2 to 5.5V, V

< 600mA

OUT

= 2.2 to 5.5V, V

< 600mA

OUT

= 2.2 to 5.5V, V

< 600mA

OUT

= 2.8 to 5.5V, V

< 600mA

OUT

= 3.5 to 5.5V, V

< 600mA

OUT

OUT

< 600mA

OUT

= V

OUT

< 600mA

OUT

= 1.0V

OU T

= 1.2V

OU T

= 1.5V

OU T

= 1.8V

OU T

= 2.5V

OU T

= 3.3V

OU T

+ 0.2V to 5.5V, VIN ≧ 3.5V

+ 0.4V to 5.5V, VIN ≧ 2.2V

V

REF

−3 -- 3 %

−3

−3

−3

−3

−3

−3 -- 3 %

−3

--

V

− 0.2

IN

-- 3 %

-- 3 %

-- 3 %

-- 3 %

-- 3 %

-- 3 %

V

To be continued

DS8008-07 March 2011www.richtek.com

RT8008

Parameter Symbol Test Conditions Min Typ Max Unit

FB Input Current

PMOSFET RON P

NMOSFET RON N

P-Channel Current Limit

EN High-Level Input Voltage

EN Low-Level Input Voltage

I

V

FB

RDS(ON)

RDS(ON)

I

V

P(LM)

V

VIN = 2.5V to 5.5V

ENH

V

VIN = 2.5V to 5.5V

ENL

= V

FB

I

= 200mA

OUT

I

= 200mA

OUT

= 2.5V to 5.5 V

IN

IN

V

= 3.6V

IN

V

= 2.5V

IN

V

= 3.6V

IN

V

= 2.5V

IN

−50 -- 50 nA

-- 0.3 --

Ω

-- 0.4 --

-- 0.25 --

Ω

-- 0.35 --

1 -- 1.8 A

1.5 -- -- V

-- -- 0.4 V

Under Voltage Lockout Threshold -- 1.8 -- V

Hysteresis -- 0.1 -- V

Oscillator Frequency

Thermal Shutdown Temperature

V

f

OSC

T

SD

= 3.6V, I

IN

OUT

= 100mA

-- 160 -- °C

1.2 1.5 1.8 MHz

Min. On Time -- 50 -- ns

Max. Duty Cycle 100 -- -- %

LX Leakage Current V

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. θ

Note 3. Devices are ESD sensitive. Handling precaution recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.

is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of

JA

JEDEC 51-3 thermal measurement standard. Pin 2 of SOT-23-5/TSOT-23-5 packages is the case position for θ

measurement.

= 3.6V, V

IN

= 0V or V

LX

= 3.6V −1 -- 1 μA

LX

JC

DS8008-07 March 2011 www.richtek.com

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