SC4530 Datasheet, PDF (1/23 Pages) Semtech Corporation – 30V, 300mA Output Micropower Step-Down Switching Regulator

SC4530
POWER MANAGEMENT
Features
 Input Voltage Range: 3V to 30V
 Low Quiescent Current: Drawing 19mA from V_IN when
Stepping Down from 12V to 3.3V at No Load
 High Efficiency from 12V Input to 5V Output
> 80% at 650mA
> 85% at 10mA - 300mA
 Up to 300mA Continuous DC Output Current
 Integrated Power Switch and Schottky Diodes
 Low Output Ripple
 <1mA Shutdown Current
 Hysteretic Current-Mode Control
 Cycle-by-Cycle Current Limiting
 Alternating Between Micropower Idling and Switch-
ing States at Light Loads to Conserve Power
 Output Short-Circuit Protection
 Solution Footprint as Small as 50mm²
 Low-Profile 3mm x 2mm MLPD 8-Lead Package
Applications
 Portable Equipment
 Notebook Computers
 Distributed Supplies
 Backup Power Supplies
30V, 300mA Output Micropower
Step-Down Switching Regulator
Description
The SC4530 is a micropower hysteretic current-mode
step-down switching regulator capable of providing up
to 300mA of output current from 3V to 30V input voltage
range. It is designed to provide very high standby efficiency
while simplifying design.
At light loads, the SC4530 switches only as needed to main-
tain regulation, while idling most of the time, to improve
efficiency. Typical quiescent currents from V_IN and BIAS
are 7mA and 26mA respectively. The control scheme pro-
duces less than 10mV of FB voltage ripple at light loads. The
SC4530 automatically switches to continuous-conduction
mode at heavy loads.
The SC4530 has integrated power devices and on-chip
control circuitry, simplifying design and enabling a solu-
tion footprint as small as 50mm². Only an inductor and a
few passive components are needed to complete a DC-DC
regulator. The inductor current hysteretic control of SC4530
makes it inherently short-circuit robust. The wide input
voltage range enables the device to operate from a variety
of input sources, including single- or multi-cell batteries,
system rails and wall transformers.
Typical Application Circuit
OFF ON
BIAS
EN
BST
VIN
IN
SW
SC4530
C2
4.7µF
FB
GND
C3
0.22µF _L1
33µH
C4
10pF
R1
619k
R2
200k
OUT
5V/0.3A
C1
22µF
L1: Coilcraft LPS4018
C1: Murata GRM31CR60J226K
C2: Murata GRM32ER71H475K
Figure 1. 5V Output Step-Down Converter
Efficiency vs Load Current
90
V_IN = 12V
80
V_IN = 24V
70
60
50
40
0.1
V_OUT = 5V
1.0
10.0
100.0
Load Current (mA)
1000.0
September 24, 2012

C4=10pF C5=33pF Verified 1/12/2012