SC2441A
1.8V to 20V Input 2-Phase Synchronous
Step-down Controllers with Step-up Converter
POWER MANAGEMENT
Features
Description
The SC2441A is a programmable frequency dual
independent or dual/multiple phase single output peak
current-mode step-down switching regulator controller. It
is capable of operating from 1.8V to 20V input. A 0.6A
step-up converter in the SC2441A generates an auxiliary
gate drive supply when VIN is below 4.5V. This makes the
SC2441A well suited for applications where a low-voltage
input (<3.3V) is to be stepped down for lower voltage logic,
yet the input is too low to drive power MOSFETs
efficiently.
2-Phase Synchronous Step-down Controllers
ꢀ 2-Phase Synchronous Continuous Conduction Mode
ꢀ Out of Phase Operation for Low Input Current Ripple
ꢀ Operates up to 1MHz Per Channel
ꢀ Excellent Current Sharing Between Phases
ꢀ Duty Cycle Up to 90%
ꢀ 0.5V Feedback voltages for Low-Voltage Outputs
ꢀ Starts into Pre-biased Outputs
ꢀ Adaptive Shoot-through Protection
ꢀ Lossless Inductor DCR Current Sensing
ꢀ 23mV Current-limit Threshold
ꢀ Individual Soft-start, Overload Hiccup and Enable
Step-up Regulator
ꢀ 0.27V VCESAT Switch at 0.6A
ꢀ Fixed frequency Current-mode Control
Common Features
The SC2441A employs a phase-locked synchronizing
circuit that allows the step-up converter to operate at
twice the switching frequency of the step-down
controllers for miniaturization. The clock output signal
enables two or more SC2441As to be daisy chained with
programmable phase shift.
ꢀ Wide input Voltage Range: 1.8V to 20V
ꢀ Synchronizing Frequency Equal to that of the Step-
down Converters
ꢀ 28-lead TSSOP-EDP Lead-free package, fully WEEE
and RoHS compliant
Tying the FB2 pin to VIN makes the second step-down
channel a slave of the first. Operating in this mode, the
SC2441A regulates a single output with shared current in
each channel. Each step-down controller has its own soft-
start and overload shutdown timer for hiccup overload
protection. In the single-output mode, the channel 1 timer
controls the soft-start and overload hiccup of both
controllers.
Applications
ꢀ Low voltage distributed DC-DC converters
ꢀ Telecommunication power supplies
ꢀ Servers and base stations
Typical Application Circuit
Vin
VCC
C1
VCC
R1
R2
C2
D1
C3
R3
R4
C4
D2
L1
R5
C5
U1
D3
1
7
8
IN
FB3
R6
COMP3
27
21
25
23
SW3
VCC
R7
28
18
19
CKOUT
BST2
C6
C7
Q1
BST1
GDH1
Q2
R9
GDH2
L2
VOUT1
VOUT2
R8
L3
C8
D4
Q3
R10
C11
C12
C13
R13
R11
D5
Q4
22
24
26
4
20
R12
GDL1
PGND1
PGND2
CS1+
GDL2
C9
R15
R16
R18
RCS+1
RCS+2
2
PLLF
CS2+
CS2-
16
15
14
13
5
CS1-
11
12
FB1
FB2
C20
C19
COMP1
COMP2
R19
R20
C21
C22
R21
10
9
6
Vin
ROSC SYNC/SHDN
SS1/EN1
C23
R23
R26
3
R24
R25
VCC
17
GND
SS2/EN2
R27
C26
C25
Power
Ground
Signal
Ground
C24
SC2441A
Figure 1
Revision: February 04, 2009
1
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