POWER FACTOR CORRECTION AUTODETECT

摘要

A power supply system includes an Offline Total Power Management Integrated Circuit (OTPMIC). The OTPMIC controls a Power Factor Correction (PFC) converter, a main AC/DC converter, and a standby AC/DC converter. A PFC Autodetect circuit in the OTPMIC monitors current flow in the PFC converter. If a high power condition is detected, then the PFC Autodetect circuit enables the PFC converter. The high power condition may be a voltage drop across a current sense resistor of a predetermined voltage for a predetermined time, within one half period of the incoming AC supply voltage. If a low power condition is detected, then the PFC Autodetect circuit disables the PFC converter. The PFC Autodetect circuit stores an IMON value that determines the predetermined voltage, and a TMON value that determines the predetermined time. The IMON and TMON values are loaded into the Autodetect circuit across an optocoupler link of the standby converter.

主权项

1. An integrated circuit adapted for coupling to an external AC/DC circuit that includes an external Power Factor Correction (PFC) circuit, wherein the external AC/DC circuit is adapted to receive an AC sinusoidal input signal, wherein the external PFC circuit is adapted to output a DC supply voltage, wherein the AC sinusoidal input signal has a plurality of periods, wherein each period includes two half periods, the integrated circuit comprising:
a first terminal; a second terminal; a third terminal; a PFC control circuit comprising:
a Pulse Width Modulator (PWM) adapted to output a pulse width modulated signal onto the third terminal; anda PFC Autodetect circuit that monitors a voltage between the first terminal and the second terminal, wherein (a) if a digital enable/disable signal is latched to a first digital logic value then the PFC Autodetect circuit enables the PWM if the voltage exceeds a first predetermined voltage for more than a predetermined amount of time, and (b) if the digital enable/disable signal is latched to the second digital logic value then the PFC Autodetect circuit disables the PWM if a low power condition is detected.