SC2440A Datasheet, PDF (1/28 Pages) Semtech Corporation – Dual 30V Step-Down Switching Regulator with 2A Switches

SC2440A
POWER MANAGEMENT
Dual 30V Step-Down Switching
Regulator with 2A Switches
Features
 Wide Input Voltage Range: 2.8V to 30V
 Two Integrated 2A Switches
 Up to 2.5MHz per Channel Programmable Constant
Switching Frequency
 Out of Phase Switching Reduces Input Ripple
 Both Switching Regulators share a single Input Filter-
ing Capacitor, Reducing Cost
 External Synchronization
 Cycle-by-Cycle Current-limiting
 Independent Soft-Start/Enable Pins
 Independent Hiccup Overload Protection
 Power Good Indicators Ease Output Sequencing
 Low Shutdown Current
 Thermally Enhanced 16-pin TSSOP Lead Free Pack-
age
 Fully WEEE and RoHS Compliant
Applications
 XDSL and Cable Modems
 Point of Load Applications
 Security Cameras
Description
The SC2440A is a constant frequency dual current-mode
step-down regulator with integrated 30V switches. It pro-
duces two independent outputs from a common input
power supply. Channel switching frequency can be pro-
grammed up to 2.5MHz. The two regulators switch in
opposite phase, reducing input ripple current. As a result,
a smaller input filtering capacitor can be used.
Current-mode PWM control simplifies loop compensa-
tion. Cycle-by-cycle current limiting and hiccup overload
protection reduce power dissipation during overload. The
SC2440A is output short-circuit robust.
Separate soft-start/enable pins allow independent con-
trol of each channel. Output power good indicators ease
output sequencing. The SC2440A can be synchronized to
an external clock. This eases noise filtering by eliminating
beat frequencies and confining switching noise to a nar-
row band.
Typical Application Circuit
R5
9.31k
C7
C5
680pF
22nF
C10
22nF
R7
14.0k
R9
13.3k
C8
470pF
FB1 PGOOD1
COMP1
BST1
SS1
SW 1
SYNC
ROSC
IN
SC2440A
SS2
COMP2
SW 2
GND
BST2
FB2 PGOOD2
R6
100k
D3
V IN
12V ± 10%
C15
C2 1N4148
0.1µF _L1
3 . 3 µH
D1
UPS120
4 . 7 µF
D2
UPS120
L2
4 . 4 µH
C4
0.1µF _{D 4}
R8
100k
1N4148
C1
1 0 µF
R1
23.3k
R2
10k
OUT1
3.3V/1.8A
OUT2
C3
1 0 µF
5V/1.8A
R3
40.2k
R4
10k
L1: Sumida CR43
L2: Falco D04012
C1, C3: Murata GRM21BR60J106K
C15: Murata GRM21BR61E475K
Figure 1. 1.3MHz 12V to 5V and 3.3V Step-down
Converter
C6
C9
Revision 2.4
10pF
10pF _{© 2014 Semtech Corporation}

C16
0 . 1 µF
Free-running frequency = 957kHz (Rev1 trim m ed part, R9 = 18.7k)