High Efficiency Synchronous,
Step Down Controller
POWER MANAGEMENT
Description
The SC4602A/B is a voltage mode step down (buck) regu-
lator controller that provides accurate high efficiency
power conversion from an input supply range of 2.75V
to 5.5V. A high level of integration reduces external com-
ponent count and makes it suitable for low voltage appli-
cations where cost, size and efficiency are critical.
The SC4602A/B 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 MOSFET
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. 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 soft start (2.4ms for
the SC4602A and 1.2ms for the SC4602B) is internally
provided to prevent output voltage overshoot during start-
up. A 100% maximum duty cycle allows the SC4602A/B
to operate as a low dropout regulator in the event of a
low battery condition. The SC4602A/B has fixed switch-
ing frequency (300KHz for the SC4602A and 550KHz
for the SC4602B).
The SC4602A/B is an ideal choice for 3.3V, 5V or other
low input supply sytems. It’s available in a 8 pin MSOP
package.
SC4602A/B
Features
BICMOS Voltage mode PWM controller
2.75V to 5.5V Input voltage range
Output voltages as low as 0.8V
+/-1% Reference accuracy
Sleep Mode (Icc = 10µA typ)
Lossless short circuit current limiting
Combination pulse by pulse & hiccup mode current
limit
High efficiency synchronous switching
Up to 100% Duty cycle range
Synchronization to external clock
8-Pin MSOP surface mount package. Lead-free pack-
age available, fully WEEE and RoHS compliant
Applications
Distributed power system
RF power supply
Local microprocessor core power supplies
DSP and I/O power supplies
Battery powered applications
Servers and workstations
Typical Application Circuit
R15
1
M1
C10
22u
Vin = 2.75V ~ 5.5V
C11
22u
C12
22u
C13
22u
U1
1
C3
4.7u
2
3
4
C1
470p
C2
6.8n
R1
5.11k
VCC
PDRV
8
7
6
5
R6
1.0
L1
1.6u
M2
R5
1.0
C7
150u
C4
22u
C9
3.3n
R8
169
R7
4.64k
SY NC/SLEEP NDRV
COMP
VSENSE
GND
PHASE
Vo = 1.5V (as low as 0.8V )/6A
SC4602B
* External components can be modified to provide a V
OUT
as low as 0.8V.
Revision: January 20, 2006
1
R9
5.36k
www.semtech.com
SEMTECH [ SEMTECH CORPORATION ]
