RICHTEK RT9262ACS, RT9262CS Datasheet

Preliminary

RT9262/A

High Efficiency, Low Supply Current,

Step-up DC/DC Converter

General Description

The RT9262/A is a compact, high efficient, step-up

DC/DC converter with an adaptive current mode

PWM control loop, providing a stable and high

efficient operation over a wide range of load

currents. It operates in both continuous and

discontinuous current modes in stable waveforms

without external compensation.

The low start-up input voltage below 1V makes

RT9262/A suitable for 1 to 4 battery cell applications

providing up to 400mA output current. The 550KHz

high switching rate minimized the size of external

components. Besides, the 17µA low quiescent

current together with high efficiency maintains long

battery lifetime.

The 1.8V to 5V output voltage is set with 2 external

resistors. Both internal 2A switch and driver for

driving external power devices (NMOS or NPN) are

provided.

A 300mA LDO is included in RT9262 to provide a

secondary low noise output as well as an output

current stop in the shutdown mode. Similarly, a 1.8V

to 5V LDO output voltage can be set with 2 external

resistors. For RT9262A, a low battery detector with

0.86V detection voltage is included. RT9262/A are

provided in SOP-8 packages.

Ordering Information

RT9262A



Package type S : SOP-8

Operating temperature range

C: Commercial standard

A : Include low battery detector

Default : Include LDO

Features

z

1.0V Low Start-up Input Voltage

z

High Supply Capability to Deliver 3.3V 100mA

with 1V Input Voltage

z

17µµµµA Quiescent (Switch-off) Supply Current

z

90% Efficiency

z

550KHz Fixed Switching Rate

z

Providing Flexibility for Using Internal and

External Power Switches

z

Built-in 300mA LDO, also for the Zero-Output-

Current Shutdown Mode (RT9262)

z

Boost DC-DC Integrating LDO for Up-Down

Regulation (RT9262)

z

Built-in 0.86V Voltage Detector (RT9262A)

z

8-Pin SOP Package

Applications

PDA

z

Portable Instrument

z

Wireless Equipment

z

DSC

z

LCD Back Bias Circuit

z

RF-Tags

z

Pin Configurations

Part Number Pin Configurations

RT9262CS

(Plastic SOP-8)

LDOO

RT9262ACS

(Plastic SOP-8)

GND

EXT

LFB

GND

EXT

LBO

LBI

TOP VIEW

1

2

3

4

TOP VIEW

1

2

3

4

CE

8

LX

7

VDD

6

FB

5

CE

8

LX

7

VDD

6

FB

5

DS9262/A-03 July 2001 www.richtek-ic.com.tw

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RT9262/A

Marking Information

Part Number Marking

RT9262CS RT9262CS

RT9262ACS RT9262ACS

Typical Application Circuit

V

IN

Preliminary

100µF

100pF

R1

1.6M

R2

980K

C2 1µF

2.5V V

OU T2

C3

10µF

VDD

CE

R4

1.3M

+

R3

680K

LDOO LX

1nF

LFB GND FB

RT9262

EXT

Fig. 1 RT9262 Typical Application for Portable Instruments below 400mA

V

IN

R1

1.6M

R2

L1

4.7µH

C2 1µF

Low Battery Warning Output

(Open Collector)

VDD

CE

LBO LX

R4

LBI GND FB

R3

RT9262A

100pF

EXT

980K

L1

4.7µH

D1

+

100µF

C1 100µF

3.3V V

OU T1

C1 100µF

3.3V V

OU T1

Fig. 2 RT9262A Typical Application for Portable Instruments below 400mA

www.richtek-ic.com.tw DS9262/A-03 July 2001

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Preliminary

V

IN

RT9262/A

100µF

Chip Ena bl e I np ut

3.3V V

OU T

+

C3

10µF

VDD

CE

LDOO LX

LFB GND FB

RT9262

EXT

100pF

980K

R1

1.6M

R2

L1

4.7µH

C2 1µF

Fig. 3 Application Circuit with Zero-Output-Current Shutdown Mode Control

V

IN

2.5V V

OU T2

C3

10µF

R1

VDD

CE LX

R4

1.3M

+

R3

680K

LDOO EXT

1nF

LFB GND FB

RT9262

100pF

980K

1.6M

R2

L1

4.7µH

Q1 NMOS

C2 1µF

D1

+

C1 100µF

100µF

3.3V V

OU T1

C1 100µF

Fig. 4 0.4A ~ 2A Output Current Application

2.5V V

OU T2

5V V

C3

10µF

L1

IN

100µF

CE

R4

1.3M

+

R3

680K

LDOO LX

1nF

LFB GND FB

VDD

RT9262

10µH

EXT

0.05 ~0. 1

Q1 NMOS

0.1µF

Rm

Ω

D1

2.2M

200K

R1

R2

C2 1µF

+

15V V

OU T1

C1 100µF

Fig. 5 High Voltage Application (Rm should be added when IL > 100mA)

DS9262/A-03 July 2001 www.richtek-ic.com.tw

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RT9262/A

Pin Description

Preliminary

Pin No.

Pin Name

RT9262 RT9262A

11GND

22EXT

3--LFB

4--LDOO

-- 3 LBO

-- 4 LBI

55FB

66VDD

77LX

88CE

Pin Function

Ground

Output pin for driving external NMOS or NPN

When driving an NPN, a resistor should be added for limiting base current.

Feedback pin of the built-in LDO (Internal Vref = 0.86V)

Voltage output pin of the built-in LDO

Drain output pin of the NMOS of the built-in low voltage detector

This pin will be internally pulled low when the voltage at LBI pin drops to

below 0.86V.

Input pin of the built-in low voltage detector

Trip point = 0.86V

Feedback input pin

Internal reference voltage for the error amplifier is 1.25V.

Input positive power pin of RT9262/A

Pin for switching

Chip enable

RT9262/A gets into shutdown mode when CE pin set to low.

Absolute Maximum Ratings

z Supply Voltage -0.3V to 6V

z LX Pin Switch Voltage -0.3V to (VDD + 0.8V)

z LDO Output Voltage -0.3V to (VDD + 0.3V)

z Other I/O Pin Voltages -0.3V to (VDD + 0.3V)

z LX Pin Switch Current 2.5A

z EXT Pin Driver Current 30mA

z LBO Current 30mA

z Power Dissipation, P

SOP-8 0.625W

• Package Thermal Resistance

SOP-8, θ

z Operating Junction Temperature 150°C

z Storage Temperature Range -65°C ~ +150°C

JA

@ TA = 25°C

D

160°C/W

www.richtek-ic.com.tw DS9262/A-03 July 2001

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