XC9511 Datasheet, PDF (1/13 Pages) Torex Semiconductor – Synchronous Step-Down DC/DC Converter with built-in LDO Regulator in parallel plus Voltage Detector

XC9511 Series
February 2, 2004 V5
Synchronous Step-Down DC/DC Converter with built-in LDO Regulator in parallel plus Voltage Detector
Preliminary
! Synchronous step-down DC/DC converter
with built-in LDO regulator plus voltage detector
! Step-down DC/DC converter's output connected in parallel
with LDO regulator
! SOP-8 package for high current
! Small-footprint
! Output Current (DC/DC : 800mA, VR : 400mA)
! Ceramic capacitor compatible (Low ESR capacitors)
! APPLICATIONS
" CD-R / RW, DVD
" HDD
" PDAs, portable communication modem
" Cellular phones
" Palmtop computers
" Cameras, video recorders
! GENERAL DESCRIPTION
The XC9511 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 XC9511 can deliver output currents
up to 800mA at efficiencies over 90%. The XC9511 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 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.
! FEATURES
Input Voltage Range : 2.4V ~ 6.0V
Load Capacitors :
Ceramic Capacitor Compatible
(Low ESR Capacitors)
VD Function :
Detects output voltage from the VDOUT pin
while sensing either VDD, DCOUT,
or VROUT internally.
Nch Open Drain Output
<DC/DC Converter>
Output Voltage Range : 0.9V ~ 4.0V (Accuracy ±2%)
Output Current :
800mA
Controls :
PWM Control
PWM, PWM / PFM Automatic
Switching External
Oscillation Frequency : 300kHz, 600kHz, 1.2MHz
<Regulator>
Output Voltage Range : 0.9V ~ 4.0V (Accuracy ±2%)
Current Limit
600mA
Dropout Voltage :
160mV @ IOUT=200mA (VOUT=2.8V)
High Ripple Rejection 60dB @1kHz (VOUT=2.8V)
! TYPICAL APPLICATION CIRCUIT
1
PGND
2 PVDD
LX 8
DCOUT 7
+
CIN1
+
CIN2
3 AVDD
VROUT 6
4 VDOUT
5
AGND
()
SD
SOP-8 (TOP VIEW)
L
DCOUT
+
C L2
VROUT
+
C L1
! TYPICAL PERFORMANCE CHARACTERISTICS
XC9511Axxxx
VIN=5.0V, Topr=25^OC, L:4.7uH(CDRH4D28C)
CIN:4.7uF(ceramic), CL1:10uF(ceramic), CL2:1uF(ceramic)
100
90
80
70
60
50
40
30
DC/DC Efficiency
20
(DCOUT:3.3V, 1.2MHz)
10
0
0.1
1
10
100
1000
DC/DC Output Current IDOUT
Data Sheet
Semiconductor Ltd.
1