SC4501
2Amp, 2MHz Step-Up Switching
Regulator with Soft-Start
POWER MANAGEMENT
Description
The SC4501 is a high-frequency current-mode step-up
switching regulator with an integrated 2A power transis-
tor. Its high switching frequency (programmable up to
2MHz) allows the use of tiny surface-mount external pas-
sive components. Programmable soft-start eliminates high
inrush current during start-up. The internal switch is rated
at 32V making the converter suitable for high voltage ap-
plications such as Boost, SEPIC and Flyback.
The operating frequency of the SC4501 can be set with an
external resistor. The ability to set the operating frequency
gives the SC4501 design flexibilities. A dedicated COMP
pin allows optimization of the loop response. The SC4501
is available in thermally enhanced 8-Pin MSOP and 10-pin
MLPD packages.
Features
u
u
u
u
u
u
u
u
u
Low saturation voltage switch: 220mV at 2A
Constant switching frequency current-mode control
Programmable switching frequency up to 2MHz
Soft-Start function
Input voltage range from 1.4V to 16V
Output voltage up to 32V
Low shutdown current
Adjustable undervoltage lockout threshold
Small low-profile thermally enhanced packages
Applications
u
u
u
u
u
u
u
Flat screen LCD bias supplies
TFT bias supplies
XDSL power supplies
Medical equipment
Digital video cameras
Portables devices
White LED power supplies
Typical Application Circuit
VIN
5V
6
OFF ON 3
C1
2.2µF
8
IN
SHDN
SC4501
SS
GND
C3
47nF
4
COMP
ROSC
7
R4
C4
1
R3
C6
R2
20K
5
SW
FB
2
C2
10µF
L1
D1
VOUT
12V, 0.7A
R1
174K
10BQ015
Efficiency
95
10.5µH, 700KHz
90
85
4.7µH, 1.4MHz
Efficiency (%)
80
3.3µH, 2MHz
75
70
65
60
All Capacitors are Ceramic.
MSOP-8 Pinout
f
/ MHz
0.7
1.35
2
R
3
/ KΩ
22.1
30.9
63.4
R
4
/ KΩ
22.1
9.31
4.75
C
4
/ pF
2200
820
470
C
6
/ pF
-
-
22
L
1
/
µH
10.5
(Falco D08019)
4.7
(Falco D08017)
3.3
(Coilcraft DO1813P)
55
50
0.0
0.1
0.2
0.3
0.4
V
IN
= 5V
V
OUT
= 12V
0.5
0.6
0.7
Load Current (A)
Figure 1(a). 5V to 12V Boost Converter.
Figure 1(b). Efficiencies of 5V to 12V Boost Converters at
700KHz, 1.4MHz and 2MHz.
1
www.semtech.com
Revision: October 25, 2005
SEMTECH [ SEMTECH CORPORATION ]
