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Synchronous Step-Down DC/DC Converter

with Built-In LDO Regulator in Parallel Plus Voltage Detector

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GENERAL DESCRIPTION

The XC9509 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in parallel with the

DC/DC converter's output. A voltage detector is also built-in. Since the input for the LDO voltage regulator block comes

from the input power supply, it is suited for use with various applications.

The DC/DC converter block incorporates a P-channel driver transistor and a synchronous N-channel switching transistor.

With an external coil, diode and two capacitors, the XC9509 can deliver output currents up to 600mA at efficiencies over 90%.

The XC9509 is designed for use with small ceramic capacitors.

A choice of three switching frequencies are available, 300kHz, 600kHz, and 1.2MHz. Output voltage settings for the DC/DC

and VR are set-up internally in 100mV steps within the range of 0.9V to 4.0V (± 2.0%). For the VD, the range is of 0.9V to

5.0V (± 2.0%). The soft start time of the series is internally set to 5ms. With the built-in U.V.L.O. (Under Voltage Lock Out)

function, the internal P-channel driver transistor is forced OFF when input voltage becomes 1.4 V or lower. The functions of

the MODE pin can be selected via the external control pin to switch the DC/DC control mode and the disable pin to shut down

either the DC/DC block or the regulator block.

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APPLICATIONS

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CD-R / RW, DVD

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HDD

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PDAs, portable communication modem

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Cellular phones

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Palmtop computers

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Cameras, video recorders

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TYPICAL APPLICATION CIRCUIT

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FEATURES

Input Voltage Range

: 2.4V ~ 6.0V

Low ESR Capacitor

: Ceramic capacitor compatible

VD Function

Small Package

: MSOP-10, USP-10

<DC/DC Converter Block>

Output Voltage Range : 0.9V ~ 4.0V (Accuracy±2%)

Output Current

: 600mA (for MSOP-10 package)

400mA (for USP-10 package)

Control Method

: PWM or PWM/PFM Selectable

Oscillation Frequency : 300kHz, 600kHz, 1.2MHz

<Regulator Block>

Reglator Output

: Parallel Input to DC/DC Converter

Output Voltage Range : 0.9V ~ 4.0V (Accuracy±2%)

Current Limit

: 300mA

Dropout Voltage

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TYPICAL PERFORMANCE

CHARACTERISTICS

XC9509Hxxxx

* Please refer to the typical application circuit when

external components are selected.

MSOP-10 (TOP VIEW)

ETR1006_001