LM2757 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – Switched Capacitor Boost Regulator with High Impedance Output in Shutdown

October 2007
LM2757
Switched Capacitor Boost Regulator with High Impedance
Output in Shutdown
General Description
The LM2757 is a constant frequency pre-regulated switched-
capacitor charge pump that operates at 1.25 MHz to produce
a low-noise regulated output voltage. The device can be con-
figured to provide up to 100 mA at 4.1V, 110 mA at 4.5V, or
180 mA at 5V. Excellent efficiency is achieved without the use
of an inductor by operating the charge pump in a gain of either
3/2 or 2 according to the input voltage and output voltage op-
tion selection.
The LM2757 presents a high impedance at the V_OUT pin when
shut down. This allows for use in applications that require the
regulated output bus to be driven by another supply while the
LM2757 is shut down.
A perfect fit for space-constrained, battery-operated applica-
tions, the LM2757 requires only 4 small, inexpensive ceramic
capacitors. LM2757 is a tiny 1.2 mm X 1.6 mm 12–bump micro
SMD device. Built in soft-start, over-current protection, and
thermal shutdown features are also included in this device.
Features
■ ^{Inductorless solution uses only 4 small ceramic}
capacitors.
■ ^{True input-output and output-input disconnect.}
■ ^{Up to 180 mA output current capability (5V).}
■ ^{Selectable 4.1V, 4.5V or 5.0V output.}
■ ^{Pre-regulation minimizes input current ripple.}
■ ^{1.24 MHz switching frequency for a low-noise, low-ripple}
output voltage.
■ ^{Efficient dual gain converter (2X, 3/2X).}
■ ^{Integrated Over Current Protection.}
■ ^{Integrated Thermal Shutdown Protection.}
■ ^{Tiny 1.2 mm X 1.6 mm X 0.4 mm pitch, 12–bump micro}
SMD package.
Applications
■ ^{Keypad LED Drive}
■ ^{USB/USB-OTG Power}
■ ^{Cellular Phone SIM cards}
■ ^{Audio amplifier power supplies}
■ ^{Low-current Camera Flash}
■ ^{General Purpose Li-Ion-to-5V Conversion}
■ ^{Supercapacitor Charger}
Typical Application Circuit
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