LED optimization low-voltage current source circuit module of USB keyboard controller

Abstract

The utility model discloses an LED optimization low-voltage current source circuit module of a USB keyboard controller. Two N-type field effect transistors NMOS are installed on a low-voltage currentsource circuit (5). A substrate and a source end of the NMOS1 are connected and are both connected to a zero potential; the source end of the NMOS2 and the substrate are also connected to the zero potential together; the NMOS1 and the NMOS2 share the same gate and are connected to the output end of an OP; the drain end of the NMOS1 is connected with the forward input end of the OP and the reference current source input current IIN; the drain end of the NMOS2 is respectively connected with the negative input end of the OP and the negative end of the LED lamp; the LED lamp and the reference current source are jointly connected to a power supply VCC; and a compensation capacitor CC is bridged between the gate end and the drain end of the NMOS1. The module has good current matching performance, large dynamic range, small layout area and low design cost, and is very suitable for specific LED driving chips and USB keyboard controllers.

Description

technical field [0001] The invention relates to a low-voltage current source technology for a USB keyboard controller, in particular to an LED optimized low-voltage current source circuit module of the USB keyboard controller. Background technique [0002] As a representative and rapidly developing keyboard controller, a game controller is a device used to control video games. Traditional game controllers such as: joysticks, mice, or gamepads. When the game is on the computer, the keyboard and mouse replace the controller, and there are fixed keys on the keyboard. The newly developed USB keyboard controller even involves the integrated application of technologies such as fingerprint identification, dynamic definition of key values, and safe self-destruction, which also drives the rapid progress of controller technology and provides new controllers for a wider range of applications. the material basis. [0003] The USB keyboard is a basic input control device commonly used...

AI Technical Summary

Problems solved by technology

[0007] A. In the case of low power supply voltage drop, M2 will enter the linear region, which will make the negative feedback network useless, so that the output impedance of the current source becomes smaller, which deteriorates the accuracy of the current mirror

[0008] B. Since the drain-source voltage of M1 is approximately equal to the drain-source voltage of M8, but not equal to the gate-source voltage of NMOS at the mirrored source terminal, there is a certain absolute current error in this structure due to the channel modulation effect

[0009] C. In order to work at a lower power supply voltage, M1 must have a very low overdrive voltage (Vdsat). In applications where the output LED current is relatively large, too low Vdsat will result in a large aspect ratio, so The current source circuit consumes a large layout area and wastes cost

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