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POWER MANAGEMENT
Description
Synchronous Buck Converter
with Programmable Output
SC190
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.
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.
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
Cell Phones
Cordless Phones
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
WLAN Peripherals
1 Li-Ion or 3 NiMH/NiCd Powered Devices
SC190
4.7μF
4.7μF
4.7μH
VIN
VOUT
VIN
EN
SYNC/PWM
VID0
VID1
MODE
LX
VOUT
BP
GND
CIN
CBP
COUT
LOUT
4.7μF
June 30, 2005
Applications
Features
Typical Application Circuit