SC1104A Datasheet, PDF (1/14 Pages) Semtech Corporation – Simple, Synchronous Voltage Mode PWM Controller

SC1104A/B
Simple, Synchronous
Voltage Mode PWM Controller
POWER MANAGEMENT
Description
Features
The SC1104A/B is a versatile voltage-mode PWM con-
troller designed for use in single ended DC/DC power
supply applications. A simple, fixed frequency high effi-
ciency buck regulator can be implemented using the
SC1104A/B with a minimum of external components.
Internal level shift and drive circuitry eliminates the need
for an expensive P-channel, high-side switch. The small
device footprint allows for compact circuit design.
SC1104A/B features include temperature compensated
voltage reference, triangle wave oscillator, current limit
comparator and an externally compensated error ampli-
fier. Current limit is implemented by sensing the voltage
drop across the top FET’s R_DS(ON).
The SC1104 operates at fixed frequencies of
300kHz(A) or 600kHz(B) providing an optimum com-
promise between efficiency, external component size,
and cost. 600kHz switching frequency is reserved for
the SC1104B, +5V_CC operation only.
‹ Up to +14V input, 300kHz operation (SC1104A)
‹ Up to +7V input, 600kHz operation (SC1104B)
‹ High efficiency (>90%)
‹ 1% Reference voltage accuracy
‹ Hiccup mode over current protection
‹ Robust output drive
‹ R_DS(ON) Current sensing
‹ Industrial temperature range
‹ 8-Lead SOIC package. Pb-free package available,
fully WEEE and RoHS compliant
Applications
‹ Termination supplies
‹ Low cost microprocessor supplies
‹ Peripheral card supplies
‹ Industrial power supplies
‹ High density DC/DC conversion
SC1104A/B has a thermal protection circuit, which is
activated if the junction temperature exceeds 150°C.
Typical Application Circuit
Typical Distributed Power Supply
C3
C1
1
510-1500pF
U1
R1
C2
200-2k 0.01
SC1104A/B
1
COMP/SS
SENSE
8
2
GND
VCC
7
D1
MBRA130L
R3
1.00k
3
DL
PHASE
6
4
DH
BST
5
Q1
R6
1-5.1
Si4884DY
R7
Q2
1-5.1 Si4874DY
C9
0.1
D2
(opt)
R4
2.32k
+
C4
C5
C6
C7
Vin 5 to 12V
10.0
47/16V
47/16V
47/16V
_
R5
200-1k ^C8
0.1-0.33
R8
opt
L1
1.5-6.8uH
C10
220/4V
C11
220/4V
C12
220/4V
C13
220/4V
+
C14-17 _3.3V
1.0
_
Revision: November 22, 2006
Figure 1
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