DIGITAL PULSE WIDTH MODULATION GENERATOR WITH CLOCK DIVIDER AND CLOCK SYNTHESIZER

摘要

A digital PWM(Pulse Width Modulation) generator using a clock divider and a clock synthesizer is provided to reduce a size of a circuit and increase compatibility with an external digital system by changing an analog PWM process of a saw tooth wave or latch structure into a digital PWM circuit which divides and synthesizes a reference clock. A digital PWM generator using a clock divider and a clock synthesizer includes a clock generator(1), a clock divider(2), a clock selection unit(3), a clock control unit(5), a clock synthesizer(4), and a pulse width adjusting unit(6). The clock generator(1) generates an internal reference clock of a system. The clock divider(2) divides the generated reference clock into N clocks. The clock selection unit(3) selectively transmits some clocks to the clock synthesizer(4) according to a control signal which is transmitted from the clock control unit(5) of a plurality of clocks divided by the clock divider(2). The clock control unit(5) analyzes a control signal or a command selected by an external system using an SMPS(Switching Mode Power Supply). The clock control unit(5) controls the clock selection unit(3) in a normal mode by transmitting the control signal to the clock selection unit(3) or checking a load change of the SMPS. The clock synthesizer(4) synthesizes and converts signals selected from the clock selection unit(3) into PWM signals. The pulse width adjusting unit(6) analyzes and transmits a load change signal of the SMPS to the clock control unit(5).