SC2441 Datasheet, PDF (1/35 Pages) Semtech Corporation – Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter

SC2441
Very Low Input Voltage 2-Phase Synchronous
Step-down Controllers with Step-up Converter
POWER MANAGEMENT
Description
The SC2441 is a high-frequency triple output switching
regulator controller. It consists of a dual out-of-phase
synchronous step-down PWM controller with high-current
output gate drives and a 1.7A integrated step-up switch-
ing regulator.
The dual-phase step-down controller of the SC2441 can
be configured to provide two individually controlled and
regulated outputs or a single output with shared current
in each phase. The buck controller can operate from an
input voltage of at least 4.72V or they can run off a supply
generated locally with the integrated boost regulator. This
makes the SC2441 ideally suited for applications where a
low-voltage input (3.3V, 2.5V, or 1.8V) is to be stepped
down for lower voltage logic yet the input is too low to
drive power MOSFET’s efficiently. The boost regulator can
be used to provide a third auxiliary output while generat-
ing the bias for the buck controllers.
Both the step-down controllers and the step-up regulator
employ fixed frequency peak current-mode control for fast
transient response. The master oscillator frequency can
be programmed by the user.
Individual soft-start and overload shutdown timer are em-
ployed in each step-down controller for hiccup overload
protection. In single-output configuration, the channel 1
timer controls the soft-start and overload shutdown func-
tions of both controllers.
Typical Application Circuit
Features
2-Phase Synchronous step-down controllers
‹ 2-Phase Synchronous Continuous Conduction Mode
For High Efficiency Step-down Converters
‹ Out of Phase Operation For Low Input Current Ripples
‹ Operates Up To 1MHz Per Channel
‹ Configurable Dual Outputs Or 2-Phase Single Output
Operation with Peak Current Mode Control
‹ Excellent Current Sharing Between Phases
‹ Wide Input Voltage Range: 1.8V to 15V
‹ Duty Cycle Up to 90%
‹ 0.5V Feedback Voltages For Low-Voltage Outputs
‹ Precision 50mV Current-Limit Threshold
‹ Patented Combi-sense Technique for High SNR of Cur-
rent-Sensing
‹ Individual Soft-Start, Overload Shutdown and Enable
Step-up Regulator
‹ Wide Input Voltage Range: 1.8V to 15V
‹ Operates At Twice The Individual Channel Frequency
Of The Buck Controllers
‹
‹
0.23V V_CESAT Switch at 1A
Fixed Frequency with Current-Mode Control
Common Features
‹ External Synchronization
‹ Industrial Temperature Range
Applications
‹ Low Voltage Distributed DC-DC Converters
‹ Telecommunication Power Supplies
‹ Servers and base stations
VIN VINGND
R12
+ _C38
D1
D2
R14
VO1
VO1GND
C18
C8
C25
+
R9
L1
C20
R5
RCS+1
RCS-1
R17
Figure 1
Revision: January 10, 2005
VIN
+ ^C1
C2
C19
R10
Q1
D7
Q6
C27
R18
C30
C36
R28
7 _FB3
8 _COMP3
VIN
28 _PVIN
R3
18 _BST2
19 _GDH2
IN ¹
PH3 ²⁷
BST1 ²⁵
GDH1 ²³
SC2441
R7
20 _GDL2
GDL1 ²²
PGND ²⁴
2 _VPN2
VPN1 ²⁶
16 _CS2+
CS1+ ⁴
15 _CS2-
CS1- ⁵
14 _FB2
FB1 ¹¹
13 _COMP2
COMP1 ¹²
GND ⁹
6 _{SY NC}
Rosc ¹⁰
3 _SS1/EN1
VCC ²¹
17 _SS2/EN2
C32
C33
U1
L3
R4
R8
R20
1
D3
Q2
Q7
VIN
C3 _{+ C4}
C17
D10
C23
R13
L2
R6
C21
RCS+2
C28
C31
R19
RCS-2
R11
R16
VO2
C24
C15
+
VO2GND
US patent 6,441,597 ^{www.semtech.com}