Low Input, High Efficiency
Synchronous, Step Down Controller
POWER MANAGEMENT
Description
The SC4605 is a voltage mode step down (buck) regula-
tor controller that provides accurate high efficiency power
conversion from a input supply range of 2.8V to 5.5V. A
high level of integration reduces external component
count, and makes it suitable for low voltage applications
where cost, size and efficiency are critical.
The SC4605 drives external N-channel MOSFETs with 1A
peak current. A non-overlap protection is provided for
the gate drive signals to prevent shoot through of the
MOSFET pair. The voltage drop across the high side
MOSFET during its conduction is sensed for lossless short
circuit current limiting.
The quiescent supply current in sleep mode is typically
lower than 10
µ
A. A 1.8ms soft start is internally provided
to prevent output voltage overshoot during start-up.
The SC4605 is an ideal choice for 3.3V, 5V or other low
input supply systems. It’s available in 10 pin MSOP pack-
age.
SC4605
Features
BICMOS voltage mode PWM controller
2.8V to 5.5V Input voltage range
Output voltages as low as 0.8V
+/-1% Reference accuracy
Sleep mode (Icc = 10µA typ)
Lossless adjustable short circuit current limiting
Combination pulse by pulse & hiccup mode
current limit
High efficiency synchronous switching
0% to 97% Duty cycle range
1A Peak current driver
10-Pin MSOP package
Applications
Distributed power architecture
Servers/workstations
Local microprocessor core power supplies
DSP and I/O power supplies
Battery powered applications
Telecommunications equipment
Data processing applications
Typical Application Circuit
Vin = 2.8V - 5.5V
D2
C14
0.1u
C3
4.7u
R13
1
1
2
3
4
C1
180p
R1
14.3k
C2 2.2n
C20
470pF
5
1u
C71
M1
U1
BST
VCC
ISET
COMP
DRVH
PHASE
DRVL
GND
VSENSE
10
9
8
7
6
M2
1.8u
C6
330u
C5
22u
C4
22u
L1
C10
220u
C11
22u
C12
22u
R3
Vout = 1.5V (as low as 0.8V * ) / 12A
FS/SYNC
FSET
C9
4.7n
R8
200
R7
10k
SC4605
R9
11.5k
*
External components can be modified to provide a Vout as low as 0.8V.
Revision: October 14, 2004
1
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