SC2440 Datasheet, PDF (1/26 Pages) Semtech Corporation – 2.5 MHz Dual Switching Regulator with Integrated 2A Switches

POWER MANAGEMENT
Description
The SC2440 is an adjustable frequency dual current-
mode switching regulator with 2A integrated switches.
Its high frequency operation allows the use of small
inductors and capacitors, resulting in very compact power
supplies. The SC2440 is suitable for next generation XDSL
modems requiring operating frequencies in excess of 1.5
MHz. The two channels operate at 180° out of phase
for reduced input voltage ripples. Separate soft start/
shutdown pins allow independent control and output
sequencing for latch-up prevention. The SC2440 can also
be externally synchronized up to 2.5 MHz per channel.
Current-mode PWM control allows fast transient
response with simple loop compensation. Cycle-by-cycle
current limiting and hiccup overload protection reduce
power dissipation during overload.
SC2440
2.5 MHz Dual Switching Regulator
with Integrated 2A Switches
Features
u Up to 2.5 MHz/Channel Programmable Switching
Frequency
u Fixed Frequency Current-mode Control
u Wide Input Voltage Range 2.8V to 20V
u Out of Phase Switching Reduces Ripple
u Cycle-by-cycle Current-limiting
u Independent Shutdown/soft-start Pins
u Independent Hiccup Overload Protection
u Independent Power-Good Indicators
u Two 2A Integrated Switches
u External Synchronization
u Thermal Shutdown
u Thermally Enhanced 16-pin TSSOP Package
Applications
u XDSL and Cable Modems
u Set-up Boxes
u Point of Load Applications
u CPE Equipment
u DSP Power Supplies
u Disk Drives
Typical Application Circuit
R6
100K
R5
C5
FB1
PGOOD1 BOOST1
15.4K _{C6 470pF}
C7 10pF
22nF
R9
C10
15K
22nF C9
R7 ^{10pF C8}
24.3K _220pF
COMP1
SW1
SS1 _SC2440
SYNC
IN
ROSC
VIN
12V
C15
10µF
SS2
COMP2
SW2
FB2
BOOST2
GND PGOOD2
C4
0.1µF
R8
100K
D3
C2 1N4148
0.1µF
L1
3.3µH
D1
UPS120
C1
10µF
R1
23. 3K
R2
10K
D2
UPS120
L2
4.4µH
D4
1N4148
C3
10µF
R3
40. 2K
R4
10K
OUT1
3.3V /2A
OUT2
5V/2 A
L1: Sumida CR43
L2: F alco D04012
Figure 1. 1.3MHz 12V to 3.3V and 5V Step-down Converter
Revision: March 5, 2007
1
Efficiency vs Load Current
95
V_IN = 12V
90
V_OUT2 = 5V
85
80
V_OUT1 = 3.3V
75
70
65
60
55
50
0
0.5
1
1.5
2
Load Current (A)
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