SC1102_06 Datasheet, PDF (1/12 Pages) Semtech Corporation – Synchronous Voltage Mode Controller for Distributed Power Supply Applications

SC1102/SC1102A
Synchronous Voltage Mode Controller
for Distributed Power Supply Applications
POWER MANAGEMENT
Description
The SC1102 and SC1102A are low-cost, full featured,
synchronous voltage-mode controllers designed for use
in single ended power supply applications where efficiency
is of primary concern. Synchronous operation allows for
the elimination of heat sinks in many applications. The
SC1102s are ideal for implementing DC/DC converters
needed to power advanced microprocessors in low cost
systems, or in distributed power applications where effi-
ciency is important. Internal level-shift, high-side drive
circuitry, and preset shoot-thru control, allows the use of
inexpensive N-channel power switches.
SC1102s features include temperature compensated
voltage reference, triangle wave oscillator and current
sense comparator circuitry. Power good signaling, shut-
down, and over voltage protection are also provided.
The SC1102 operates at a fixed frequency of 200kHz
and the SC1102A at 500kHz, providing a choice for op-
timum compromise between efficiency, external compo-
nent size, and cost.
Features
‹ 1.265V reference available
‹ Synchronous operation for high efficiency (95%)
‹ R current sensing
DS(ON)
‹ On-chip power good and OVP functions
‹ Small size with minimum external components
‹ Soft Start
‹ Enable function
‹ 14 Pin SOIC lead free package available. Fully
WEEE and RoHS compliant
Applications
‹ Microprocessor core supply
‹ Low cost synchronous applications
‹ Voltage Regulator Modules (VRM)
‹ DDR termination supplies
‹ Networking power supplies
‹ Sequenced power supplies
Two SC1102s can be used together to sequence power
up of telecom systems. The power good of the first
SC1102 connected to the enable of the second SC1102
makes this possible.
Typical Application Circuit
Typical Distributed Power Supply
+5V
R1
R2
1k
PWRGD
0.1
OVP
C1
opt.
C2
0.1
R4
10
U1
SC1102
1 _VCC
GND ¹⁴
2 _PWRGD
SS/SHDN ¹³
R3
1k
3 _OVP
VREF ¹²
4 _OCSET
SENSE ¹¹
5 _PHASE
D1
MBR0520
6
DRVH
BSTH ¹⁰
BSTL ⁹
7 _PGND
DRVL ⁸
C3
0.1
SHDN
VREF
+12V
C4
1.0
R5
3.9
R6
2.2
+
C5
C6
C7
C8
Vin 5V
10.0
680/6.3V 680/6.3V 680/6.3V
_
Q1
STP40NE
L2u1H
Q2
STP40NE
R1284*
R7
127
C9
180/4V
C10
180/4V
C11
180/4V
C12
180/4V
+
C13
180/4V
Vout=2.5V*
_
Figure 1.
NOTE:
*) Vout = 1.265 x (1+R8/R7)
Revision: January 5, 2006
1
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