FS
fact sheet
MB39C326
6MHz Synchronous Buck Boost DC/DC Converter
Description0
The Fujitsu MB39C326 6MHz Synchronous Buck Boost DC/DC
Converter is designed to power the radio frequency power am-
plifiers (RFPAs) in mobile handsets or other mobile devices that
use a single-cell Li-ion battery. The DC/DC converter switches at
a higher frequency (6MHz) than conventional converters on the
market. The higher switching frequency is more efficient and
permits the use of a smaller inductor, reducing the overall board
space of the power management circuits by as much as half.
The buck-boost functionality of the Fujitsu MB39C326 helps
prolong battery life and efficiency. By switching automatically
between a buck operation (stepping down the voltage) when
the battery is fully charged and a boost operation (stepping up
the voltage) as the battery is discharged, the MB39C326 maxi-
mizes the overall operating voltage from the lithium battery
while providing a stable power supply to the power amplifier.
The result is a more consistent voltage level and a device that
can operate for longer on a single charge.
The Fujitsu MB39C326 provides up to 800mA of output current
over an input voltage range of 2.5V to 4.8V. The device features
a built-in internal field-effect transistor (FET), over-temperature
protection, and an input-under-voltage lockout. The MB39C326
is available in a 20-pin, 0.4mm-ball-pitch, 2.15mm
x
1.94mm
WL-CSP (wafer-level chip size) package.
Application0
•
Radio frequency power amplifiers (RFPAs) powered by a
single-cell Li-ion battery
•
Mobile phones
•
PDAs and handheld mobile devices
•
PC cards and USB dongles with RF transceivers
•
Medical handheld devices
Power supply for PA
5-6V DC
mobile phone
AC adapter
Charger
Li-ion
1 cell
Power
management
for system
Buck/Boost
DC-DC
converter
Cntl_Vout
Vout
MB39C326
Application Diagram
BaseBand
RF
PA
0.5µH
SWOUT
10µF (1608)
L1
SWIN
SW4
VOUT
3G LTE: 2.2uF (1608)
GSM: SuperCapacitor
VDD
Current
Sense
SW1
C
IN
MB39C326
6MH
Z
R2
V
in
C
in
V
out
area
R2
Conventional
2MH
Z
V
IN
V
OU
C
OUT
C
OUT
GND
Cout
C
OUT
D GND
VCC
EN
ILIMSEL
XPS
Device
Control
Over Temp
Protection
Gate CONTROLLER
BGR
UVLO
Err Amp
GND
GND
GND
C
IN
3.1V up to 4.8V
Vbatt
R1
SW2
SW3
A GND
FB
R3
R1
R2
L
L
2.2µH
Size:4x4mm
VSELSW
Oscillator
VSEL
0.5µH
Size:2x2mm
MB39C326 Block Diagram
Advantages of the MB39C3260
6MHz switching frequency allows for a smaller
inductor and reduced board space
Compared to conventional DC/DC converters that have switch-
ing frequencies between 2 to 3MHz or lower, the Fujitsu 6MHz
Synchronous Buck Boost DC/DC Converter allows for a smaller
size inductor, reducing the overall surface area occupied by
the power supply by as much as half. This is critical for mobile
devices where space is at a premium.
High-efficiency power supply
The MB39C326 features a new, high-efficiency controller de-
signed using a low-gate charge-process technology that reduces
switching loss and power consumption. In combination with the
buck-boost function, the controller greatly enhances the overall
efficiency of the DC/DC converter.
Key Features0
•
6MHz PWM operation, allowing for a 0.5µH small form
inductor
•
Automatic transition between buck mode and boost mode
•
Built-in internal field-effect transistor (FET)
•
Input voltage range: 2.5V to 4.8V
•
Adjustable output voltage range: 0.4V to 4.5V
•
Input current limit: 2A
•
Output current of 800mA
•
Over-temperature protection
•
Input under-voltage lock out
•
Package: 20pin 0.4mm-ball-pitch 2.15mm × 1.94mm
WL-CSP (wafer-level chip-size package)
•
Operating temperature range of –400 ~ +850
Automatic buck-boost operations prolong Li-ion
battery life and efficiency
When a Li-ion battery is fully charged, it starts with a high
operating voltage. As the battery is discharged, its operating
voltage declines to the point where the battery can no longer
provide sufficient voltage to power its host device, even if some
charge remains. The Fujitsu MB39C326 6MHz Synchronous Buck
Boost DC/DC Converter can extend the usable life of a battery by
boosting (stepping up) the output voltage level to provide suf-
ficient power to continue operation. This extends battery life by
more efficiently using the remaining charge in the battery.
8
FUJITSU SEMICONDUCTOR AMERICA, INC.
Corporate Headquarters
1250 E. Arques Avenue, M/S 333, Sunnyvale, CA 94085-5401
Tel: (800) 866-8608 Fax: (408) 737-5999
E-mail: FSA_inquiry@us.fujitsu.com | Website: http://us.fujitsu.com/semi
©
2011 Fujitsu Semiconductor America, Inc. or registered
All company and product names are trademarks
trademarks of their respective owners.
Specifications subject to change without notice.
Printed in the U.S.A. PMIC-FS-21396-03/2011
GND
R1
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