SC4603 Datasheet, PDF (1/16 Pages) Semtech Corporation – Very Low Input, MHz Operation, High Efficiency Synchronous Buck

POWER MANAGEMENT
Description
The SC4603 is a voltage mode step down (buck) regula-
tor controller that provides accurate high efficiency power
conversion from input supply range 2.25V 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 SC4603 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 10µA. A 1.7ms soft start is
internally provided to prevent output voltage overshoot
during start-up. A 100% maximum duty cycle allows the
SC4603 to operate as a low dropout regulator in the
event of a low battery condition.
SC4603
Very Low Input, MHz Operation,
High Efficiency Synchronous Buck
Features
‹ BICMOS voltage mode PWM controller
‹ 2.25V to 5.5V Input voltage range
‹ Output voltages as low as 0.5V
‹ Sleep mode (Icc = 10µA typ)
‹ Lossless adjustable overcurrent protection
‹ Combination pulse by pulse & hiccup mode current
limit
‹ High efficiency synchronous switching
‹ 0% to 100% Duty cycle range
‹ Synchronization to external clock
‹ Asynchronous start-up
‹ 1MHz frequency of operation
‹ 10-Pin MSOP surface mount package
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
The SC4603 is an ideal choice for 3.3V, 5V or other low
input supply systems. It’s available in 10 pin MSOP
package.
Typical Application Circuit
RT
34.8k
C3 ^4.7u
C1 _150p
R1
C2
20k
1n
R 15
1
U1
5 _FS
1 _VCC
2 _SYNC
3 _COMP
4 _VSENSE
R3
ISET ⁶
PDRV ¹⁰
PHASE ⁷
NDRV ⁹
GND ⁸
SC4603
C 14
M1
33n
R6
1. 0
M2
R5
1.0
Vin = 2.25V ~ 5.5V
C10
C11
C12 C13
22u
22u
22u 22u
L1
Vout = 1.5V (as low as 0.5V * ) /6A
2. 3u
C7
C4
150u
22u
C9
1. 2n
R7
14k
R8
806
R9
* External components can be modified to provide a Vout as low as 0.5V.
6.98k
Revision: May 5, 2004
1
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