SC121 Datasheet, PDF (1/23 Pages) Silan Microelectronics Joint-stock – LI+ BATTERY PROTECTION CIRCUIT

SC121
POWER MANAGEMENT
Features
„ Input voltage — 0.7V to 4.5V
„ Minimum start-up voltage — 0.85V
„ Output voltage — fixed at 3.3V; adjustable from 1.8V
to 5.0V
„ Peak input current limit — 1.2A
„ Output current at 3.3 V — 80mA with V = 1.0V,
OUT
IN
190mA with V = 1.5V
IN
„ Forced PWM operation at all loads
„ Efficiency up to 94%
„ Internal synchronous rectifier
„ No forward conduction path during shutdown
„ Switching frequency — 1.2MHz
„ Soft-start startup current limiting
„ Shutdown current — 0.1μA (typ)
„ Ultra-thin 1.5 × 2.0 × 0.6 (mm) MLPD-UT-6 package
„ Lead-free and halogen-free
„ WEEE and RoHS compliant
Applications
„ MP3 players
„ Smart phones and cellular phones
„ Palmtop computers and handheld instruments
„ PCMCIA cards and memory cards
„ Digital cordless phones
„ Personal medical products
„ Wireless VoIP phones
„ Small motors
Low Voltage Synchronous
Boost Regulator
Description
The SC121 is a high efficiency, low noise, synchronous
step-up DC-DC converter that provides boosted voltage
levels in low-voltage handheld applications. The wide
input voltage range allows use in systems with single
NiMH or alkaline battery cells as well as in systems with
higher voltage battery supplies. It features an internal
1.2A switch and synchronous rectifier to achieve up to
94% efficiency and to eliminate the need for an external
Schottky diode. The output voltage can be set to 3.3V
with internal feedback, or to any voltage within the speci-
fied range using a standard resistor divider.
The SC121 operates exclusively in Pulse Width Modulation
(PWM) mode for low ripple and fixed-frequency switching.
Output disconnect capability is included to reduce leakage
current, improve efficiency, and eliminate external com-
ponents sometimes needed to disconnect the load from
the supply during shutdown.
Low quiescent current is maintained with a high 1.2MHz
operating frequency. Small external components and the
space saving MLPD-UT-6, 1.5×2.0×0.6 (mm) package
make this device an excellent choice for small handheld
applications that require the longest possible battery life.
Typical Application Circuit
L1
Single
Cell
(1.2V)
C_IN
IN
EN
GND
LX
OUT
FB
SC121
3.3V
C_OUT
April 13, 2010
© 2010 Semtech Corporation
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