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1A Driver Transistor Built-In, Step-Up DC/DC Converters

0

20

40

60

80

100

0.1

1

10

100

1000

Output Current : IOUT (mA)

PWM(MODE:H)

PWM/PFM(MODE:L)

VIN=1.8V

3.7V

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GENERAL DESCRIPTION

T

he XC9128/XC9129 series are synchronous step-up DC/DC converters with a 0.2

Ω (TYP.) N-channel driver transistor and a

synchronous 0.2

Ω (TYP.) P-channel switching transistor built-in. A highly efficient and stable current can be supplied up to

1.0A by reducing ON resistance of the built-in transistors. With a high switching frequency of 1.2MHz, a small inductor is

selectable making the series ideally suited for applications requiring low profile or space saving solutions. With the MODE

pin, the series provides mode selection of PWM control or PFM/PWM automatic switching control. In the PWM/PFM

automatic switching mode, the series switches from PWM to PFM to reduce switching loss when load current is small.

When load current is large, the series switches automatically to the PWM mode so that high efficiency is achievable over a

wide range of load conditions. The series also provides small output ripple from light to large loads by using the built-in

circuit which enables the smooth transition between PWM and PFM. With a adaptor enable function of the XC9128 series,

when a voltage higher than the input voltage is applied to the output, the input and the output become isolated making it

possible for the IC to work in parallel with the likes of an AC adaptor.

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APPLICATIONS

●

Digital audio equipment

●

Digital cameras, Video equipment

●

Computer Mice

●

Various multi-function power supplies using alkali cells (1

to 3 cells), nickel hydride batteries, or single lithium cells

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TYPICAL APPLICATION CIRCUIT

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TYPICAL PERFORMANCE

CHARACTERISTICS

●

Efficiency vs. Output Current

ETR0411-006

XC9128B45CDx

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FEATURES

High Efficiency, Large Current Step-Up Converter

Output Current

Input Voltage Range

: 0.8V~6.0V

Output Voltage Setting

Range

: 1.8V~5.3V (Externally set)

Set up freely with a reference voltage

supply of 0.45V (±0.010V) & external

components

Oscillation Frequency

: 1.2MHz (Fixed oscillation frequency

accuracy ±15%)

Input Current

: 1.0A

Maximum Current Limit

: 1.2A (MIN.), 2.0A (MAX.)

Control

: PWM, PWM/PFM control

externally selectable

High Speed

Transient Response

Protection Circuits

: Thermal shutdown

: Integral latch method (Over current

limit)

Soft-Start Time

: 5ms (TYP.) internally set

Ceramic Capacitor Compatible

Adaptor Enable Function (XC9128 series)

Packages

: MSOP-10, USP-10B, SOP-8

Flag Output (XC9128 series)

: Open-drain output

Lx

VOUT

BAT

FB

FO

AEN/

MODE

PGND

EN

AGND

L

1

3

5

2

4

10

8

6

9

7

MODE

EN

(ceramic)

FO