SC1104 Datasheet, PDF (1/7 Pages) Semtech Corporation – Simple, Synchronous Voltage Mode PWM Controller

POWER MANAGEMENT
Description
SC1104A/B
Simple, Synchronous
Voltage Mode PWM Controller
PRELIMINARY
.eatures
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
amplifier. Current limit is implemented by sensing the
voltage drop across the top .ET’s R_DS(ON)..
The SC1104A/B operates at a fixed frequency of 300/
600 kHz, providing an optimum compromise between
efficiency, external component size, and cost. 600kHz
switching frequency is typically reserved for the 5V
operation only.
K +5V or +12V operation
K High efficiency (>90%)
K 1% Reference voltage accuracy
K Hiccup mode over current protection
K Robust output drive
K R_DS(ON) Current sensing
K Industrial temperature range
K SO-8 package
Applications
K Termination supplies
K Low cost microprocessor supplies
K Peripheral card supplies
K Industrial power supplies
K 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
0.1
220-680pF
U1
R1
C2
2k
0.01
SC1104A/B
1 _COMP/SS
SENSE ⁸
2 _GND
VCC ⁷
R2
10
D1
MBRA130L
R3
1.00k
3 _DL
PHASE ⁶
4 _DH
BST ⁵
Q1
Si4884DY
R6
1-5.1
Q2
R7 Si4874DY
1-5.1
C9
0.1
D2
(opt)
C4
10.0
R4
2.32k
R5
200-1k
C8
0.1-0.22
R8
10
L1
1.5-3uH
C10
220/4V
C5
47/16V
C11
220/4V
C6
47/16V
C12
220/4V
+
C7
47/16V
Vin 5 to 12V
_
C13
220/4V
+
C14-17
1.0
3.3V
_
Revision 3, October 2001
.igure 1
1
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