Current driver

Abstract

A current driving device,comprising a first comparator, a second comparator, a low frequency saw tooth wave generator and a high frequency saw tooth wave generator, a amplifier of which amplifying ratio can be adjusted, a field effect transistor, a time sequence control voltage source, a amplitude control voltage source, the low frequency saw tooth wave generator produces the low frequency saw tooth wave signal that is inputted to the input end of first comparator with time sequence control signal produced by time sequence control voltage source, the output signal of the first comparator is inputted to the input end of the amplifying ratio tunable amplifier, the amplitude control signal produced by amplitude control voltage source is inputted to the another end of the amplifying ratio tunable amplifier, the output signal of the amplifying ratio tunable amplifier and the high frequency saw tooth wave signal produced by high frequency saw tooth wave generator are inputted to the input end of the second comparator, the output end of the second comparator connects to the grid of the field effect transistor, the assistant power connects to the source of the field effect transistor, the drain electrode of the field effect transistor outputs the driving current.

Description

【Technical field】 [0001] The invention relates to a current drive device, in particular to a pulse width modulation current drive device. 【Background technique】 [0002] see figure 1 , is a driving device in the prior art, and its load is a light-emitting diode, wherein the voltage source 10 applies a voltage to the light-emitting diode array 30 through the current limiting resistor 20, and the light-emitting diode array 30 includes m rows and n columns of light-emitting diodes 31 , the resistance of the current limiting resistor 20 is R, the voltage of the voltage source 10 is U, the main circuit current is I, and the equivalent resistance of a single light emitting diode 31 is Rs. [0003] Its volt-ampere characteristics are expressed by the following formula: [0004] U-m*Von=I(R+Rs(m / n)) [0005] This formula simplifies to: [0006] U-Vx=I(R+Rx) where, Vx=m*Von, Rx=Rs(m / n) [0007] Due to the existence of the start-up voltage Von of the light emitting diode 31, the ...

AI Technical Summary

Problems solved by technology

[0010] In order to overcome the defects in the prior art that it is difficult to accurately control the driving current and that adding a timing control circuit will make the entire circuit complex, the present invention provides a current driving device that can precisely control the driving current and can simply perform timing control

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