XC9508 Datasheet, PDF (1/36 Pages) Torex Semiconductor – Synchronous Step-Down DC/DC Converter with Built-In LDO Regulator plus Voltage Detector

June 9, 2005 V7
◆Synchronous Step-Down DC/DC Converter with
■APPLICATIONS
Built-In LDO Regulator plus Voltage Detector
◆Step-Down DC/DC Converter's Output Connected in
Series with LDO Regulator
◆High Efficiency, Low Noise Regulated Output
◆Ultra Small Packages: MSOP-10, USP-10
◆Small-Footprint
◆Output Current DC/DC:600mA, VR: 200mA
●CD-R / RW, DVD
●HDD
●PDAs, portable communication modem
●Cellular phones
●Palmtop computers
●Cameras, video recorders
◆Ceramic Capacitor Compatible (Low ESR Capacitors)
■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.
■TYPICAL APPLICATION CIRCUIT
■FEATURES
Input Voltage Range : 2.4V ~ 6.0V
Low ESR Capacitor : Ceramic capacitor compatible
VD Function
: N-channel open drain output
<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)
Controls
: PWM Control
PWM, PWM/PFM Automatic
Switching External
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz
<Regulator Block>
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 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.
Data Sheet
1
ud200541