Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
kB3440
Micropower Synchronous
Buck-Boost DC/DC Converter
DESCRIPTION
The kB3440 is a high efficiency, fixed frequency, Buck-
Boost DC/DC converter that operates from input voltages
above, below or equal to the output voltage. The topology
incorporated in the IC provides a continuous transfer
function through all operating modes, making the product
ideal for single lithium-ion, multicell alkaline or NiMH
applications where the output voltage is within the battery
voltage range.
The device includes two 0.19 N-channel MOSFET
switches and two 0.22 P-channel switches. Switching
frequencies up to 2MHz are programmed with an external
resistor and the oscillator can be synchronized to an
external clock. Quiescent current is only 40µA in Burst
Mode operation, maximizing battery life in portable appli-
cations. Burst Mode operation is user controlled and can
be enabled by driving the MODE/SYNC pin high. If the
MODE/SYNC pin has either a clock or is driven low, then
fixed frequency switching is enabled.
Other features include a 1µA shutdown, soft-start con-
trol, thermal shutdown and current limit. The kB3440 is
available in the 10-pin thermally enhanced MSOP and
(3mm
×
3mm) DFN packages.
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
Single Inductor
Fixed Frequency Operation with Battery Voltages
Above, Below or Equal to the Output
Synchronous Rectification: Up to 96% Efficiency
40µA Quiescent Current in Burst Mode
®
Operation
Up to 600mA Continuous Output Current
No Schottky Diodes Required (V
OUT
< 4.3V)
V
OUT
Disconnected from V
IN
During Shutdown
2.5V to 5.5V Input and Output Range
Programmable Oscillator Frequency
from 300kHz to 2MHz
Synchronizable Oscillator
Burst Mode Enable Control
5
µA
Shutdown Current
Small Thermally Enhanced 10-Pin MSOP and
(3mm
×
3mm) DFN Packages
APPLICATIONS
■
■
■
■
Palmtop Computers
Handheld Instruments
MP3 Players
Digital Cameras
TYPICAL APPLICATION
Li-Ion to 3.3V at 600mA Buck-Boost Converter
L1
10µH
4
SW1
SW2
kB3440
6
7
V
IN
V
OUT
3
V
IN
= 2.7V TO 4.2V
8
SHDN/SS
MODE/SYNC
R
T
FB
V
C
GND
9
C5 1.5nF
10
5
R3
15k
R2
200k
C2
22µF
Efficiency vs V
IN
100
V
OUT
3.3V
600mA
V
OUT
= 3.3V
98 I
OUT
= 100mA
96 f
OSC
= 1MHz
94
EFFICIENCY (%)
R1
340k
92
90
88
86
84
82
80
2.5
3.0
3.5
4.0
V
IN
(V)
4.5
5.0
5.5
Li-Ion
+
2
C1 *
10µF
1
R
T
60.4k
*1 = Burst Mode OPERATION
0 = FIXED FREQUENCY
C1: TAIYO YUDEN JMK212BJ106MG
C2: TAIYO YUDEN JMK325BJ226MM
L1: SUMIDA CDRH6D38-100
1
KINGBOR [ KINGBOR TECHNOLOGY CO ]
