External power supply identification circuit for large current touch equipment and electronic signature screen

Abstract

The invention is suitable for the field of electronics and provides an external power supply identification circuit for large current touch equipment and an electronic signature screen. The circuit comprises a USB (universal serial bus) detection unit, a DC (direct current) detection unit, an identification control unit and a filtering unit, wherein the USB detection unit is used for generating a USB detection signal during external USB power supply; the DC detection unit is used for generating a DC detection signal and DC power supply voltage / current during external DC power supply; the identification control unit is used for outputting USB power supply voltage / current when the USB detection signal is only received and stopping outputting USB power supply voltage / current when the DC detection signal is received; the filtering unit is used for filtering USB power supply voltage / current or DC power supply voltage / current. The circuit has the beneficial effects that low current USB power supply is used without external power adapters; under the condition of insufficiency of USB power supply, power is supplied by the external power adapters, and meanwhile, a USB power supply circuit is blocked to prevent the current of the power adapters from flowing back to the USB, thus solving the problem of insufficiency of USB power supply.

Description

technical field [0001] The invention belongs to the field of electronics, and in particular relates to an external power supply identification circuit and an electronic signature screen for high-current touch devices. Background technique [0002] With the development of electronic technology, electronic signature screens have been widely used in finance, mobile business, and paperless office systems. At present, most of the electronic signature screens on the market use USB for power supply. With the increasing requirements for the response speed and display effect of electronic signature screens, the size of liquid crystal displays (Liquid Crystal Display, LCD) is getting larger and larger. The operating current required by the signature screen is also increasing, and the current that the traditional USB power supply method can provide is limited, which can no longer meet the new power supply demand. Contents of the invention [0003] The purpose of the embodiments of t...

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Problems solved by technology

[0003] The purpose of the embodiments of the present invention is to provide an external power supply identification circuit for high-current touch devices, aiming to solve the problem that the existing USB power supply is insufficient and cannot meet the power supply requirements of high-current electronic signature screens

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