Journal of Applied Sciences

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DC-DC Converter with PWM/PFM Automatic Switching

CHANG Chang-yuan, YAO Jin-nan, TAN Chun-ling, ZOU Yi-zhao, SHI Long-xin   

  1. College of Integrated Circuit, Southeast University, Nanjing 210096, China
  • Received:2006-12-01 Revised:2007-04-03 Online:2007-07-30 Published:2007-07-30

Abstract: We present an efficient CMOS DC-DC converter with automatic PWM/PFM switching, which can automatically switch between pulse width modulation (PWM) and pulse frequency modulation (PFM) modes according to the load variation. An expression of the load current at the threshold of automatic switching is derived. A simulated system works properly, achieving automatic PWM/PFM switching and high efficiency over a wide ranged of varied load.

Key words: pulse width modulation (PWM)/pulse frequency modulation (PFM) automatic switching,switching threshold current, DC-DC converter