KB3511 Datasheet, PDF (1/14 Pages) Kingbor Technology Co – High Efficiency, Low Noise, Fast Transient Dual 800mA, 2.2MHz Step-Down DC/DC Converter

Kingbor Technology Co.,Ltd
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KB3511
System-Power
High Efficiency, Low Noise, Fast Transient
Dual 800mA, 2.2MHz Step-Down DC/DC Converter
FEATURES
■ _{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
■ _{Cellular Telephones}
■ _{Personal Information Appliances}
■ _{Wireless and DSL Modems}
■ _{Digital Still Cameras}
■ _{MP3 Players}
■ _{Portable Instruments}
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.
TYPICAL APPLICATION
V_IN = 3.6V
TO 6.0V
C6
*^{10µ F}
* ^{Vin>4.5V Used R1}
*¹
V_OUT2 = 3.3V
AT 800mA
C1
4.7µF
RESET
L2
2.2µH
C5, 22pF
23
RUN1 V_IN
6 _MODE/SYNC
9
RUN2
POR ⁸
KB3511A
4 _SW1
SW2 ⁷
DFN3x3mm
R5
100k
RESET
L1
2.2µH
C4, 22pF
C3
4.7µF
R4
680k R3
150k
1
V_FB1
GND
11 5
V_FB2 ¹⁰
R2
R1 300k
150k
V_OUT1 = 1.8V
AT 800mA
C2
4.7µF
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
KB3511 Efficiency Curve
VIN=3.6V
100
95
3.3V
90
1.8V
85
80
75
70
65
60
1
10
100
1000
LOAD CURRENT (mA)
1