SC461 Datasheet, PDF (1/31 Pages) Semtech Corporation – EcoSpeed® DC-DC Buck Controller with Integrated LDO

SC461
POWER MANAGEMENT
EcoSpeed^® DC-DC Buck Controller
with Integrated LDO
Features
Description
 Power system
• Input voltage — 3V to 28V
• Integrated bootstrap switch
• Fixed 5V LDO output — 200mA
• 1% reference tolerance -40 to +85 °C
• Selectable internal/external bias power supply
• EcoSpeed^® architecture with pseudo-fixed fre-
quency adaptive on-time control
 Logic input and output control
• Independent enable controls for LDO and
switcher
• Programmable soft-start time
• Programmable V_IN UVLO threshold
• Power Good output
• Selectable power-save mode
 Protections
• Automatic restart on fault shutdown
• Over-voltage and under-voltage
• TC compensated R_DS(ON) sensed current limit
• Thermal shutdown
• Smart power-save
• Pre-bias start-up
 Capacitor types: SP, POSCAP, OSCON, and ceramic
 Package — 3 x 3(mm), 20-pin MLPQ
 Lead-free and halogen-free
 RoHS and WEEE compliant
Applications
 Office automation and computing
 Networking and telecommunication equipment
 Point-of-load power supplies and module replacement
The SC461 is a synchronous EcoSpeed^® buck regulator
which incorporates Semtech’s advanced, patented adap-
tive on-time control architecture to provide excellent
light-load efficiency and fast transient response. It fea-
tures an integrated bootstrap switch and a fixed 5V LDO in
a 3 x 3(mm) package. The device is highly efficient and
uses minimal PCB area.
The SC461 supports using standard capacitor types such as
electrolytic or special polymer, in addition to ceramic, at switch-
ing frequencies up to 1MHz. The programmable frequency,
synchronous operation, and programmable power-save
provide high efficiency operation over a wide load range.
Additional features include cycle-by-cycle current limit,
programmable soft-start, under and over-voltage protec-
tion, programmable over-current protection, start-up into
pre-biased output, automatic fault recovery (hiccup restart),
soft-shutdown, and a selectable power-save mode. The
device also provides separate enable inputs for the PWM
controller and LDO as well as a Power Good output for the
PWM controller. Output voltage range is 0.6 to 5V, with
output voltages greater than 5V supported using additional
components.
The input voltage can range from 3V to 28V. The wide
input voltage range, programmable frequency, and inte-
grated 5V LDO make the device extremely flexible and
easy to use in a broad range of applications. Support is
provided for multi-cell battery systems in addition to tra-
ditional DC power supply applications.
Typical Application Circuit
PGOOD
ENABLE
ENABLE LDO
VEXT or VLDO
RTON
VEXT or VLDO
VLDO
PSV
0.1µF
1µF
1µF
10nF
PGOOD
EN
ENL
TON
VDDA
VDDP
VLDO
SS
PSV
SC461
AGND
VIN
DH
LX
BST
ILIM
RLIM
DL
VOUT
PGND ^FB
CIN
L1
VIN
+ _COUT
VOUT
Revision 2.0
© 2012 Semtech Corporation