SC190 Datasheet, PDF (1/18 Pages) Semtech Corporation – Synchronous Buck Converter with Programmable Output

POWER MANAGEMENT
Description
SC190
Synchronous Buck Converter
with Programmable Output
FFeeaattuurreess
The SC190 is a synchronous step-down converter with
integrated power devices and an integrated front-end
LDO to minimize input supply ripple. Output voltage is
programmable using two control bits, eliminating the need
for feedback resistors tied to the output. The device is
offered in four distinct variants with each variant providing
four fixed output voltage options to choose from.
The front-end LDO can be bypassed externally to maximize
efficiency. A second LDO is switched in place of the
switching regulator for low current operation to further
improve efficiency and reduce noise.
The SC190’s flexible clocking scheme allows it to be
synchronized to an external oscillator or controlled by the
internal oscillator. The 1MHz switching frequency allows
the use of small inductors and capacitors.
 Less than 1mV Supply Ripple
 Output Voltage Regulated by Either the Switching
Regulator or Linear Regulator
 Dynamic Handover Between Linear and Switching
Regulator for Maximum Efficiency
 2.7V to 5.5V Input Range
 300mA Guaranteed Output Current
 Fixed Frequency 1MHz Operation or 750kHz to
1.5MHz Clocked Operation
 No Schottky Diode Required
 Up to 95% Efficiency (VIN=BP)
 Over-current Protection
 Over-voltage Protection
 Over-temperature Protection
 Soft Start
 MLP-10, 3 x 3mm Lead-frame, Lead-free Package
 Low Output Noise < 100µVrms
The internal MOSFET switches provide peak current
greater than 500mA to achieve a DC output of at least
300mA. Shutdown current is typically 0.1µA.
The SC190 has four different variants with four voltage
settings each. It is designed for single-cell Li-ion battery
applications, but also performs well in fixed 3.3V and 5V
applications.
Applications
 Cell Phones
 Cordless Phones
 Notebook and Subnotebook Computers
 PDAs and Mobile Communicators
 WLAN Peripherals
 1 Li-Ion or 3 NiMH/NiCd Powered Devices
Typical Application Circuit
VIN
CIN
4.7µF
VIN _{SC190 LX}
EN
VOUT
SYNC/PWM
VID0
VID1
MODE
BP
GND
4.7µH
LOUT
VOUT
CBP
4.7µF
COUT
4.7µF
June 30, 2005
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