System and method for LCD loop control

摘要

An LCD controller includes a charge pump for generating a charge voltage responsive to an external voltage and a clock signal. The controller further includes an oscillator for generating the clock signal responsive to an oscillator control signal. An LCD driver voltage circuit generates a plurality of LCD driver voltages for driving segments of an associated LCD display. A loop control circuit within the LCD controller monitors an LCD driver voltage from the LCD driver voltage circuit and generates the oscillator control signal responsive thereto to enable and disable the oscillator.

主权项

1. An LCD controller, comprising:
a charge pump circuit for generating a charge voltage responsive to an external voltage and a clock signal; an oscillator for generating the clock signal responsive to an oscillator control signal; an LCD driver voltage circuit for generating a plurality of LCD driver voltages for driving segments of an LCD display; and loop control circuit for monitoring an LCD driver voltage from the LCD driver voltage circuit and generating the oscillator control signal responsive thereto to enable and disable the oscillator by using a latch, the loop control circuit further comprising: a comparator for comparing the LCD driver voltage with a reference voltage and generating an output at a first logical level when the LCD driver voltage exceeds the reference voltage by a first predetermined level and generating the output at a second logical level when the LCD driver voltage falls below the reference voltage by a second predetermined level; wherein the latch latches the output at either the first logical level or the second logical level; and control logic for generating the oscillator control signal to enable the oscillator responsive to the output at the second logical level and for generating the oscillator control signal to disable the oscillator responsive to the output at the first logical level.