XC9508_1 Datasheet, PDF (1/38 Pages) Torex Semiconductor – Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator in Series Plus Voltage Detector

XC9508 Series
Synchronous Step-Down DC/DC Converter
with Built-In LDO Regulator in Series Plus Voltage Detector
ETR1005_001
■GENERAL DESCRIPTION
The XC9508 series consists of a step-down DC/DC converter and a high-speed LDO regulator connected in series with the
DC/DC converter's output. A voltage detector is also built-in. A highly efficient, low noise output is possible since the
regulator is stepped-down further from the DC/DC output.
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 XC9508 can deliver output currents up to 600mA at efficiencies over 90%.
The XC9508 is designed for use with small ceramic capacitors. A choice of three switching frequencies are available, 300
kHz, 600 kHz, and 1.2 MHz. Output voltage settings for the DC/DC is set-up internally in 100mV steps within the range of
1.6V to 4.0V(± 2.0%) and for the VR are set-up internally 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 the regulator block.
■APPLICATIONS
●CD-R / RW, DVD
●HDD
●PDAs, portable communication modem
●Cellular phones
●Palmtop computers
●Cameras, video recorders
■FEATURES
DC/DC Converter with Built-in LDO and VD Function
Input Voltage Range : 2.4V ~ 6.0V
Low ESR Capacitor : Ceramic capacitor compatible
VD Function
: N-channel open drain output
Small Package
: MSOP-10, USP-10
<DC/DC Converter Block>
Output Voltage Range : 1.6V ~ 4.0V (Accuracy ± 2%)
Output Current
: 600mA (for MSOP-10 package)
400mA (for USP-10 package)
Control Mothod
: PWM or PWM/PFM Selectable
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz
<Regulator Block>
Regulator Input
: Serial input from DC/DC output
Output Voltage Range : 0.9V ~ 4.0V (Accuracy ± 2%)
Current Limit
: 300mA
Dropout Voltage
: 80mV @ IOUT=100mA
(VOUT=2.8V)
High Ripple Rejection : 60dB @1kHz (VOUT=2.8V)
■TYPICAL APPLICATION CIRCUIT
■TYPICAL PERFORMANCE
CHARACTERISTICS
XC9508Cxxxx
VIN=3.6V, Topr=25^OC, L=4.7μH (CDRH4D28C)
CIN:4.7μF ‘(ceramic), CL1:10μF (ceramic), CL2: 4.7μF (ceramic)
MSOP-10 (TOP VIEW)
* Please refer to the typical application circuit when
external components are selected.
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