?2010 Semtech Corporation
1
SC403
6A EcoSpeed
TM
Integrated FET
Regulator with Programmable LDO
Features
Power System:
Input voltage 3V to 28V
Internal or external bias voltage 3V to 5V
Integrated bootstrap switch
Programmable LDO output 200mA
1% reference tolerance -40 to +85 癈
EcoSpeed
TM
architecture with pseudo-fixed
frequency adaptive on-time control
Logic Input/Output Control:
Independent control EN for LDO and switcher
Programmable V
IN
UVLO threshold
Power good output
Selectable ultrasonic power save mode
Programmable soft start time
Protections:
Over-voltage and under-voltage
TC compensated R
DS(ON)
sensed current limit
Thermal shutdown
Any ESR SP, POSCAP, OSCON, and ceramic capacitors
Package:
Lead-free package 5x5mm, 32-pin MLPQ
Fully RoHS/WEEE compliant and halogen free
Applications
Office automation and computing
Networking and telecommunication equipment
Point of load power supplies and module replacement
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Description
The SC403 is a stand-alone synchronous EcoSpeed
TM
buck
power supply which incorporates Semtechs advanced
patent-pending adaptive on-time control architecture to
provide excellent light-load efficiency and fast transient
response. It features integrated power MOSFETs, a boot-
strap switch, and a programmable LDO in a 5x5mm
package. The device is highly efficient and uses minimal
PCB area.
The SC403 supports using standard capacitor types such
as electrolytic or special polymer, in addition to ceramic, at
switching frequencies up to 1MHz. The programmable
frequency, synchronous operation, and selectable power-
save provide high efficiency operation over a wide load
range.
Additional features include a programmable soft-start,
programmable cycle-by-cycle over-current limit protec-
tion, under and over-voltage protections, soft shutdown,
and selectable power-save. The device also provides sep-
arate enable inputs for the PWM controller and LDO as
well as a power good output for the PWM controller.
The wide input and bias voltage ranges, programmable
frequency, and programmable LDO make the device
extremely flexible and easy to use in a broad range of
applications. The SC403 can be used in server computers
and single cell or multi-cell battery systems in addition to
traditional DC power supply applications.
August 26, 2010
POWER MANAGEMENT
RTON
SC403
FB
VOUT
VDD
VIN
SS
BST
LX
PGOOD
LXS
ENL
RILIM
CBST
ENABLE/PSAVE
ENABLE LDO
VEXT/LDO
+
RFB1
RFB2
VOUT
COUT
L1
CIN
VIN
PGOOD
TON
1礔
CSOFT
10&
Typical Application Circuit