SC631 Datasheet, PDF (1/14 Pages) Semtech Corporation – Fixed 4.4V Output Charge Pump Regulator

POWER MANAGEMENT
Features
„ Input voltage range — 2.9V to 5.5V
„ V tolerance — 4.4V ±3%
OUT
„ Continuous output current — 250mA
„ Peak output current — 500mA
„ Three charge pump modes: 1x, 1.5x and 2x
„ Output ripple ≤ 30mV for I ≤ 400mA
PP
OUT
„ Short circuit, over-voltage, and over-temperature
protection
„ Soft-start functionality
„ Shutdown current — 0.1μA, typical
„ Ultra thin package — 2 x 2 x 0.6 (mm)
„ Fully WEEE and RoHS compliant
Applications
„ Mobile phones
„ Multi-LED backlit LCDs
„ PMPs
„ Digital video cameras
„ Digital still cameras
„ PDAs
„ LED camera flash
„ Audio amplifier power
SC631
Fixed 4.4V Output
Charge Pump Regulator
Description
The SC631 is a high-current voltage regulator using
Semtech’s proprietary low-noise charge pump technol-
ogy. Performance is optimized for use in single Li-Ion
battery cell applications. The regulator provides the per-
formance of a linear, low drop-out (LDO) voltage regulator
when the input is greater than 4.4V. Unlike an LDO, drop-
out is avoided when the input is less than 4.4V. Instead, a
charge pump is activated to provide voltage boost and
the head-room needed for voltage regulation.
Only two 2.2μF bucket capacitors are required to deliver
the full output current. The charge pump provides a low
EMI solution compared to inductive boost regulators.
The SC631’s charge pump has three modes of operation:
2x, 1.5x, and 1x modes. The 2x and 1.5x modes deliver
current to the load in each of two phases. The 1x mode
turns off the charge pump, delivering current through an
LDO. When active, the charge pump provides low-ripple
operation at 200kHz, which is typically less than 30mVpp
at the output. The SC631 is capable of delivering 250mA
continuous current, with peak current to 500mA. A 22μF
output capacitor is used for decoupling the load and for
smoothing mode transitions. Hysteresis is provided to
prevent chatter between charge pump modes.
The micro lead-frame package is both small and thermally
efficient, measuring 2 x 2 x 0.6 (mm).
Typical Application Circuit
V_BAT
IN
C_IN
22μF
OUT
V_OUT = 4.4V @ 250mA
C_OUT
22μF
SC631
Chip
enable
EN
C1+
C1-
C2+
GND
C2-
C₁
2.2μF
C₂
2.2μF
July 24, 2008
© 2008 Semtech Corporation
Patents Pending
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