Si9177 Datasheet, PDF (1/9 Pages) Vishay Siliconix – 200-mA PSM Step Down Converter with Bypass Capability

New Product
Si9177
Vishay Siliconix
200-mA PSM Step Down Converter with Bypass Capability
FEATURES
D 2.7-V to 6-V Input Voltage Range
D 1.2-V to 5-V Output
D Efficiency of 95% for V_OUT of 3.3 V @ 200-mA Load
D Selectable Pulse Skipping Modulation (PSM) or
Bypass Mode (BP) Operation
D 150-mW Bypass Switch for 800-mA Loads
D Integrated MOSFET with Low External Part Count
D Shutdown Current <1 mA
D Integrated UVLO and Power on Reset
D Integrated Soft-Start
D Over Temperature Protection
D MLP33-10 or MSOP-10 Packages
APPLICATIONS
D Cellular Phones, Cordless Phones
D Computer Point of Use, Notebook
D PDAs
D Battery Powered Devices
D MP3 Players
DESCRIPTION
The Si9177 is a dual-mode power adjustable output converter.
When it is set to PSM mode, the Si9177 operates as a
pulse-skipping-modulation controlled step-down (buck)
converter with an output voltage range of 1.2 V to 5 V. It has an
integrated MOSFET, capable of supplying 200-mA load
current with a 1.5-mH inductor. The output voltage is adjusted
by a resistive divider on the F_B pin. The typical conversion
efficiency is above 90%. A logic HIGH at the BP/PSM pin puts
Si9177 in bypass mode. The main PMOS buck switch is forced
to turn on at 100% duty cycle, overriding the F_B signal. The
voltage differential between input and output is the resistive
voltage drop on the internal 150-mW PMOS and the inductor.
The Si9177 delivers 800-mA load in bypass mode.
The Si9177 is available in the space saving MLP33-10 and
MSOP-10 packages. In order to satisfy the stringent ambient
temperature requirements, the Si9177 is rated to handle the
industrial temperature range of -25_C to 85_C.
TYPICAL APPLICATION CIRCUIT
V_IN
C_IN
ON/OFF
BP/PSM
1
V_IN
2 _VIN
10
L_X
9
L_X
SI9177
8
GND
3
ENABLE
4 _BP/PSM
5 _NC
F_B ⁷
6
REF
1.5 mH
C_OUT
C_REF
V_OUT
R₁
R₂
Document Number: 70312
S-03663—Rev. B, 07-Apr-03
www.vishay.com
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