Ambient light sensing module with signal generation function

摘要

The present invention provides an ambient light sensing module, which comprises a sawtooth signal generating circuit, an optical sensing unit, and a comparing unit. The sawtooth signal generating circuit produces a sawtooth signal. The optical sensing unit senses a light source and produces a light-sensing signal. The comparing unit produces a pulse-width modulation (PWM) signal related to the intensity of the light source according to the light-sensing signal and the sawtooth signal so that the PWM signal can be used as the control signal of the electronic device. The ambient light sensing module further comprises at least a fuse for determining a processing parameter. A signal processing unit processes the light-sensing signal according to the processing parameter for outputting a converting signal. The comparing unit compares the converting signal with the sawtooth signal for producing the PWM signal. An adjusting unit produces an adjusting signal according to the PWM signal and the light intensity or according to the converting signal and the light intensity for controlling a trimming unit to trim the fuse and thus modifying the processing parameter.

主权项

1. An ambient light sensing module with a signal generation function, comprising:
a sawtooth signal generating circuit, producing a sawtooth signal; an optical sensing unit, sensing a light source, and producing a light-sensing signal; and a comparing unit, producing a pulse-width modulation signal related to the intensity of said light source according to said light-sensing signal and said sawtooth signal; wherein said sawtooth signal generating circuit comprises a generator for producing said sawtooth signal, said generator comprises:
a storage capacitor, used for producing a driving voltage;a charging current source, producing a first charging current for charging said storage capacitor and producing said driving voltage;a discharging current source, producing a discharging current for discharging said storage capacitor;a first switch, coupled to said storage capacitor, controlled by said driving voltage, and producing a reference current;a current mirror, producing a second charging current according to said reference current;an output capacitor, coupled to said current mirror, producing said sawtooth signal, and said second charging current charging said output capacitor for producing said sawtooth signal;a second switch, coupled between said output capacitor and the ground for discharging said output capacitor;a delay unit, delaying an input signal for producing a delay signal; anda logic unit, producing a control signal according to said input signal and said delay signal for controlling said second switch;where a phase/frequency detector controls said charging current source and said discharging current source according to a phase of said input signal and a phase of a pulse signal.