SC4503 Datasheet, PDF (1/22 Pages) Semtech Corporation – 1.3MHz Step-Up Switching Regulator with 1.4A Switch

SC4503
1.3MHz Step-Up Switching
Regulator with 1.4A Switch
POWER MANAGEMENT
Description
Features
The SC4503 is a 1.3MHz current-mode step-up switch-
ing regulator with an integrated 1.4A power transistor.
Its high switching frequency allows the use of tiny sur-
face-mount external passive components. The SC4503
features a combined shutdown and soft-start pin. The
optional soft-start function eliminates high input current
and output overshoot during start-up. The internal com-
pensation network accommodates a wide range of volt-
age conversion ratios. The internal switch is rated at 34V
making the device suitable for high voltage applications
such as Boost and SEPIC.
The SC4503 is available in low-profile 5-lead TSOT-23 and
8-lead 2X2mm MLPD-W packages. The SC4503’s low
shutdown current (< 1μA), high frequency operation and
small size make it suitable for portable applications.
‹ Low Saturation Voltage Switch: 260mV at 1.4A
‹ 1.3MHz Constant Switching Frequency
‹ Peak Current-mode Control
‹ Internal Compensation
‹ Programmable Soft-Start
‹ Input Voltage Range From 2.5V to 20V
‹ Output Voltage up to 27V
‹ Uses Small Inductors and Ceramic Capacitors
‹ Low Shutdown Current (< 1μA)
‹ Low Profile 5-Lead TSOT-23 and 8-Lead 2X2mm
MLPD-W packages
‹ Fully WEEE and RohS compliant
Applications
‹ Local DC-DC Converters
‹ TFT Bias Supplies
‹ XDSL Power Supplies
‹ Medical Equipment
‹ Digital Cameras
‹ Portable Devices
‹ White LED Drivers
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VIN
L1
D1
VOUT
5V
4.7µH
10BQ015
12V, 0.5A
5
1
IN
SW
C4
R1
15pF 432k
C1
SC4503
1µF
OFF ON ⁴ SHDN/SS
FB ³
C2
4.7µF
GND
2
R2
49.9k
C1: Murata GRM188R61A105K
C2: Murata GRM21BR61C475K
L1: Sumida CDC5D23B-4R7
Efficiency vs Load Current
95
1.3MHz
90
85
80
75
70
65
60
55
V_OUT = 12V
50
0.001
0.010
0.100
Load Current (A)
1.000
Figure 1(a). 5V to 12V Boost Converter
May 4, 2007
Figure 1(b). Efficiency of the 5V to 12V Boost Converter
1
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