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Features
Output voltage options:
2.0V ± 5%, 1.8V ± 5%, and 1.5V ± 6%
120mA output current capability
Multi-Gain and Gain Hopping for Highest Possible Efficiency - up to 90% Efficient
2.6V to 5.5V input range
Input and Output Voltage Monitoring (BATOK and POK)
Low operating supply current: 35µA
Shutdown supply current: 0.1µA
Thermal and short circuit protection
LM2798 turn-on time: 400µs
LM2797 turn-on time: 100µs
Available in an 10-Pin MSOP Package
Description The LM2797/98 switched capacitor step-down DC/DC converters efficiently produce a 120mA regulated low-voltage rail from a
2.6V to 5.5V input. Fixed output voltage options of 1.5V, 1.8V, and 2.0V are available. The LM2797/98 uses multiple fractional
gain configurations to maximize conversion efficiency over the entire input voltage and output current ranges. Also contributing
to high overall efficiency is the extremely low supply current of the LM2797/98: 35µA operating unloaded and 0.1µA in shutdown.
Features of the LM2797/98 include input voltage and output voltage monitoring. Pin BATOK provides battery monitoring by indicating
when the input voltage is above 2.85V (typ.). Pin POK verifies that the output voltage is not more than 5% (typ.) below the
nominal output voltage of the part.
The optimal external component requirements of the LM2797/98 solution minimize size and cost, making the part ideal for Li-Ion
and other battery powered designs. Two 1µF flying capacitors and two 10µF bypass capacitors are all that is required, and
no inductors are needed.
The LM2797/98 also features short-circuit protection over-temperature protection, and soft-start circuitry to prevent excessive
inrush currents. The LM2798 has a 400µs turn-on time. The turn-on time of the LM2797 is 100µs.
Applications
Cellular Phones
Pagers
H/PC and P/PC Devices
Portable Electronic Equipment
Handheld Instrumentation
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