Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB3511
System-Power
High Efficiency, Low Noise, Fast Transient
Dual 800mA, 2.2MHz Step-Down DC/DC Converter
FEATURES
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DESCRIPTION
The KB3511 is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. The device is available in an adjustable
version and fixed output voltages of 1.8V and 3.3V. Supply
current during operation is only 25µA and drops to 1µA
in shutdown. The 2.5V to 6.5V input voltage range makes
the KB3511 ideally suited for single Li-Ion battery-pow-
ered applications. 100% duty cycle provides low dropout
operation, extending battery life in portable systems.
Automatic Trickle Mode operation increases efficiency at
light loads, further extending battery life.
Switching frequency is internally set at 2.2MHz, allowing
the use of small surface mount inductors and capacitors.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode. Low
output voltages are easily supported with the 0.6V feed-
back reference voltage. The KB3511 is available in a low
profile (0.8mm) DFN33-10 package.
Up to 97% Efficiency
25uA No Load Current Per Channel
800mA Output Current
2.5V to 6.5V Input Voltage Range
2.2MHz Constant Frequency Operation
No Schottky Diode Required
Low Dropout Operation: 100% Duty Cycle
0.6V Reference Allows Low Output Voltages
Shutdown Mode Draws
1µA
Supply Current
Current Mode Operation for Excellent Line and
Load Transient Response
Overtemperature Protected
DFN33-10 Package
APPLICATIONS
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Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
TYPICAL APPLICATION
KB3511 Efficiency Curve
V
IN
= 3.6V
TO 6.0V
C6
100
VIN=3.6V
*
*
Vin>4.5V Used
10µ F
R1
C1
4.7µF
RESET
L2
2.2µH
C5, 22pF
2
RUN1
3
V
IN
9
RUN2
POR
R5
100k
95
RESET
EFFICIENCY (%)
3.3V
1.8V
6
*
1
MODE/SYNC
8
L1
2.2µH
90
85
80
75
70
KB3511A
V
OUT2
= 3.3V
AT 800mA
4
SW1
DFN3x3mm
1
V
FB1
GND
SW2
7
C4, 22pF
V
OUT1
= 1.8V
AT 800mA
V
FB2
10
R2
R1 300k
150k
C2
4.7µF
C3
4.7µF
R4
680k
65
60
1
10
100
LOAD CURRENT (mA)
1000
R3
150k
11 5
C1, C2, C3: 4.7uF 6.3V 0603
L1, L2: EVERCOM SD11-2R2 (3x3x1.2mm)
Figure 1. 3.3V/1.8V at 800mA Step-Down Regulators
1.3mm Height Core Supply
1
KINGBOR [ KINGBOR TECHNOLOGY CO ]
