SC4602A Datasheet, PDF (1/18 Pages) Semtech Corporation – 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 10µA. 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).
SC4602A/B
High Efficiency Synchronous,
Step Down Controller
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
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.
Typical Application Circuit
R15
1
M1
C3
4.7u
C1
470p
C2
6.8n
R1
5.11k
U1
1 _VCC
PDRV ⁸
2 _{SY NC/SLEEP NDRV} 7
3 _COMP
GND ⁶
4 _VSENSE
PHASE ⁵
SC4602B
R6
1.0
M2
R5
1.0
Vin = 2.75V ~ 5.5V
C10
C11
C12
C13
22u
22u
22u
22u
L1
Vo = 1.5V (as low as 0.8V )/6A
1.6u
C7
C4
150u
22u
C9
3.3n
R8
169
R7
4.64k
* External components can be modified to provide a V_OUT as low as 0.8V.
R9
5.36k
Revision: January 20, 2006
1
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