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PWM circuit and PWM integrated circuit for use in PWM circuit

a technology of integrated circuits and circuits, applied in pulse duration/width modulation, pulse manipulation, pulse techniques, etc., can solve problems such as the inability to program internal circuits inside the pwm integrated circui

Active Publication Date: 2007-12-20
RICHTEK TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above-mentioned conventional PWM circuits have a drawback that an additional pin P7 is required for over current protection, which is not desired.
Another drawback of the conventional PWM circuit is that, it is not possible to program the internal circuit inside the PWM integrated circuit unless an additional pin is provided.

Method used

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  • PWM circuit and PWM integrated circuit for use in PWM circuit
  • PWM circuit and PWM integrated circuit for use in PWM circuit
  • PWM circuit and PWM integrated circuit for use in PWM circuit

Examples

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Embodiment Construction

[0026]Referring to FIG. 3 which schematically shows a preferred embodiment according to the present invention, a PWM integrated circuit 200 comprises a programming unit 70 electrically connected between the lower output of the comparator 10 and the pin P4 for controlling the synchronous switch SYN_SW. (In this paragraph, we first explain the function of the programming unit 70, while the detailed circuit structure of the programming unit 70 will be described later with respect to FIG. 5.) The programming unit 70 has two modes: a programming mode and an normal operation mode. In the programming mode, the programming unit 70 serves to set / program a parameter, such as an over current threshold or other programmable parameters, in the integrated circuit 200. After the setting / programming is done, the programming unit 70 may be switched to the normal operation mode wherein the programming unit 70 becomes a normal driver gate transmitting the output of the comparator 10 to the synchronous...

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Abstract

The present invention discloses a PWM integrated circuit which may receive a programming signal without any extra pin. The PWM integrated circuit comprises: a comparator having two outputs; two pins respectively electrically connected with the two outputs; and a programming unit electrically connected with at least one of the two pins for setting a parameter inside the PWM integrated circuit. The two pins of the PWM integrated circuit may be used to respectively control a control switch and a synchronous switch, constituting a PWM circuit for generating PWM signals.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a PWM (Pulse Width Modulation) circuit, and in particular to a PWM integrated circuit capable of receiving an external programming signal without any extra pin, and a PWM integrated circuit for use in such a PWM circuit.[0003]2. Description of the Related Art[0004]As shown in FIG. 1, a conventional PWM circuit comprises a comparator 10. An output voltage at the output terminal Vo is sampled by a voltage sampler circuit 20, and compensated by a compensation circuit 30; the output of the compensation circuit 30 is sent to an input terminal of the comparator 10, to be compared with a reference sawtooth wave and generate comparison output signals thereby, for controlling the operations of a control switch CTL_SW and a synchronous switch SYN_SW. The output voltage at the terminal Vo, after sampled by the voltage sampler circuit 20, is also fed back and compared with a reference voltage Vr, to...

Claims

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Application Information

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IPC IPC(8): H03K3/017
CPCH03K7/08
Inventor CHEN, ISAAC Y.
Owner RICHTEK TECH