Low Input, High Efficiency
Synchronous, Step Down Controller
POWER MANAGEMENT
Description
The SC4601 is a voltage mode step down (buck) regula-
tor controller that provides accurate high efficiency power
conversion from input supply range 2.75V 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 SC4601 drives external complementary power
MOSFETs; P-channel on the high side and N-channel on
the low side. The use of high side P-channel MOSFETs
eliminates the need for an external charge pump and
simplifies the high side gate driver. Non-overlap protec-
tion is provided for the gate drive signals to prevent shoot
through of the MOSFET pair. The voltage drop across the
P-channel MOSFET during its conduction is sensed for
lossless short circuit current limiting.
A low power sleep mode can be achieved by forcing the
SYNC/SLEEP pin below 0.8V. A synchronous mode of op-
eration is activated as the SYNC/SLEEP pin is driven by
an external clock. The quiescent supply current in sleep
mode is typically lower than 10
µ
A. A 2.4ms soft start is
internally provided to prevent output voltage overshoot
during start-up. A 100% maximum duty cycle allows the
SC4601 to operate as a low dropout regulator in the
event of a low battery condition. Its switching frequency
can be programmed up to 600KHz.
The SC4601 is an ideal choice for 3.3V, 5V or other low
input supply systems. It’s available in 10 pin MSOP
package.
SC4601
Features
Programmable switching frequency up to 600KHz
BICMOS voltage mode PWM controller
2.75V to 5.5V Input voltage range
Output voltage as low as 0.8V
+/-1% Reference accuracy
Sleep mode (Icc = 10µA typ)
Lossless adjustable overcurrent protection
Combination pulse by pulse & hiccup mode
current limit
High efficiency synchronous switching
Up to 100% Duty cycle range
Synchronization to external clock
10-Pin MSOP surface mount package. Available in
Lead-free package, fully WEEE and RoHS compliant
Applications
Distributed power architecture
Servers/workstations
Local microprocessor core power supplies
DSP and I/O power supplies
Battery powered applications
Telecommunication equipment
Data processing applications
Typical Application Circuit
R15
1
RT
30.1K
5
C3
4.7u
1
2
3
C1
R1
5.11K
470p
C2
4
U1
FS
VCC
SYNC
COMP
VSENSE
ISET
PDRV
PHASE
NDRV
GND
6
10
7
9
8
R5
M2
R6
1.0
L1
1.6u
C7
150u
C4
22u
R8
147
C9
3.9n
R7
4.53k
R3
C14
33n
M1
C10
22u
C11
22u
Vin = 2.75V ~ 5.5V
C12
22u
C13
22u
Vout = 1.5V (as low as 0.5V * ) /6A
SC4601
6.8n
1.0
* External components can be modified to provide a V
OUT
as low as 0.8V.
Revision: February 22, 2006
1
R9
5.11k
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SEMTECH [ SEMTECH CORPORATION ]
