SC4609 Datasheet, PDF (1/18 Pages) Semtech Corporation – Low Input, MHz Operation, High Efficiency Synchronous Buck

POWER MANAGEMENT
Description
The SC4609 is a voltage mode step down (buck) regula-
tor controller that provides accurate high efficiency power
conversion from an input supply range of 2.7V 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 SC4609
is capable of producing an output voltage as low as 0.5V.
The SC4609 drives external, N-channel MOSFETs with a
peak gate current of 1A. A non-overlap protection is pro-
vided for the gate drive signals to prevent shoot through
of the MOSFET pair. The SC4609 features lossless cur-
rent sensing of the voltage drop across the drain to
source resistance of the high side MOSFET during its
conduction period. Its switching frequency can be pro-
grammed up to 1MHz.
SC4609
Low Input, MHz Operation,
High Efficiency Synchronous Buck
Features
‹ Asynchronous start up
‹ Programmable switching frequency up to 1MHz
‹ BiCMOS voltage mode PWM controller
‹ 2.7V to 5.5V input voltage range
‹ Output voltage as low as 0.5V
‹ +/-1% reference accuracy
‹ Sleep mode (Icc = 10µA typ)
‹ Adjustable lossless short circuit current limiting
‹ Combination pulse by pulse & hiccup mode
current limit
‹ High efficiency synchronous switching
‹ 1A peak current driver
‹ External soft start
‹ 12-pin MLP Lead-free package, fully WEEE and RoHS
compliant
The quiescent supply current in sleep mode is typically
lower than 10µA. A external soft start is provided to pre-
vent output voltage overshoot during start-up.
The SC4609 is an ideal choice for converting 3.3V, 5V or
other low input supply voltages. It’s available in 12 pin
MLP package.
Typical Application Circuit
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
D2
1u
C17
M11
R13
R3
1
U1
12 _BST
DRVH ¹¹
R6
C3
4.7u
1 _VCC
2 _ISET
PHASE ¹⁰
1
DRVL ⁹
R5
C16
3 _COMP
PGND ⁸
1
M2
C2 2.2n
4 _FSET
AGND ⁷
C1
560pF 5 _VSENSE
SS ⁶
180p
R1
14.3k
SC4609
Css
22u
C10
220u
Vin=2.7V - 5.5V
C13
C14
22u
22u
L1
1.8u
C6
330u
Vout=1.5V (as low as 0.5V*) / 12A
C9
C5
C4
4.7n
22u
22u
R7
10k
R8
200
*External components can be modified to provide a Vout as low as 0.5V
R9
4.99k
Revision: February 8, 2006
1
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