LM2770 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – High Efficiency Switched Capacitor Step-Down DC/DC Regulator with Sleep Mode

December 2004
LM2770
High Efficiency Switched Capacitor Step-Down DC/DC
Regulator with Sleep Mode
General Description
The LM2770 is a switched capacitor step-down regulator
that is ideal for powering low-voltage applications in portable
systems. The LM2770 can supply load currents up to 250mA
and operates over an input voltage range of 2.7V to 5.5V.
This makes the LM2770 a great choice for systems powered
by 1-cell Li-Ion batteries and chargers. The output voltage of
the LM2770 can be dynamically switched between two out-
put levels with a logic input pin. Output voltage pairs cur-
rently available include 1.2V/1.5V and 1.2V/1.575V. Other
pairs of voltage options can be developed upon request.
LM2770 efficiency is superior to both fixed-gain switched
capacitor buck regulators and low-dropout linear regulators
(LDO’s). Multiple fractional gains maximize power efficiency
over the entire input voltage and output current ranges. The
LM2770 can also be switched into a low-power sleep mode
when load currents are light (≤ 20mA). In sleep mode, the
charge pump is off, and the output is driven with a low-noise,
low-power linear regulator.
Soft-start, short-circuit protection, current-limit protection,
and thermal-shutdown protection are also included. The
LM2770 is available in National’s small 10-pin Leadless
Leadframe Package (LLP-10).
Features
n High Efficiency Multi-Gain Architecture: Peak Power
Efficiency >85%
n Output Voltage Pairs: 1.2V/1.5V and 1.2V/1.575V
n Dynamic Output Voltage Selection
n ±3% Output Voltage Accuracy
n Output Currents up to 250mA
n 2.7V to 5.5V Input Range
n Low-Supply-Current Sleep Mode
n 55µA Quiescent Supply Current in Full-Power Mode
n Soft-Start
n Short-Circuit Protection in Full-Power Mode
n Current-Limit Protection in Sleep Mode
n LLP-10 Package (3mm x 3mm x 0.8mm)
Applications
n DSP Power Supplies
n Baseband Power Supplies
n Mobile Phones and Pagers
n Portable Electronic Equipment
Typical Application Circuit
LM2770 Efficiency vs.
Low-Dropout Linear Regulator (LDO) Efficiency
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© 2004 National Semiconductor Corporation DS201260
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