LED constant current drive circuit used for portable device

Abstract

The invention relates to an LED constant current drive circuit used for a portable device. The LED constant current drive circuit comprises a power supply cell and an LED that is driven; besides, the LED constant current drive circuit also includes: a control chip, which is used for emitting a PWM control signal according to a feedback signal; a switch circuit, which is used for enabling the LED constant current drive circuit to be connected or disconnected according to the PWM control signal; a filter circuit, which is used for converting a pulse current that is output by the switch circuit into a constant current; an output circuit, which is used for outputting the constant current to drive the LED; and a feedback circuit, which is used for emitting the feedback signal according to the constant current. According to the LED constant current drive circuit used for a portable device in the invention, a circuit that is formed by combination of simple electronic components like a one-chip microcomputer is utilized to drive an LED; therefore, the LED can be driven by constant currents and extended functions including power source voltage detection and prompting and the like can be realized; defects of high cost and low expansibility of an original LED constant current drive circuit for a portable device can be overcome.

Description

technical field [0001] The invention relates to the field of constant current driving, more specifically, relates to an LED constant current driving circuit for portable devices. Background technique [0002] With the development of society, various portable devices are more and more used by the majority of people. In order to be portable, the power supply of these devices generally uses DC output batteries as the power supply, but some batteries have unstable output current due to aging or power. . At present, the LED constant current drive of portable devices mainly relies on dedicated integrated chips. Although it is easy to use, the price is higher than that of other non-LED dedicated constant current drive circuits. smaller. Contents of the invention [0003] The technical problem to be solved by the present invention is to provide a circuit composed of simple electronic components such as a single-chip microcomputer, aiming at the defects of high cost and low scala...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a circuit composed of simple electronic components such as a single-chip microcomputer, aiming at the defects of high cost and low scalability of the above-mentioned LED constant current drive circuit for portable devices in the prior art For LED driving, it can not only drive LED with constant current, but also realize extended functions such as power supply voltage detection and warning, etc. LED constant current driving circuit for portable devices

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