LM3668_15 Datasheet, PDF (18/30 Pages) Texas Instruments – 1-A, High-Efficiency Dual-Mode Single-Inductor Buck-Boost DC-DC Converter

LM3668
SNVS449O – JUNE 2007 – REVISED APRIL 2015
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Device Functional Modes (continued)
In the buck PFM operation, P2 is always turned on and N2 is always turned off , P1 and N1 power switches are
switching. P1 and N1 are turned off to enter " sleep mode" when the output voltage reaches the "high"
comparator threshold. In boost PFM operation, P2 and N2 are switching. P1 is turned on and N1 is turned off
when the output voltage is below the "high" threshold. Unlike in buck mode, all four power switches are turned off
to enter "sleep" mode when the output voltage reaches the "high" threshold in boost mode. In addition, the
internal current sensing of the I_PFM is used to determine the precise condition to switch over to buck or boost
mode via the PFM generator.
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