Current-steering dac circuit and led circuit using the same

Patent metadata

Field	Value
Publication number	US-2016128146-A1
Application number	US-201514635740-A
Country	US
Kind code	A1
Filing date	Mar 2, 2015
Priority date	Nov 5, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

A current-steering DAC circuit for switching a light emitting diode, the current-steering DAC circuit including a current-steering DAC and a resistor. The current-steering DAC outputs a stable current and includes a plurality of current-steering units with a first output end and a second output end. The first output end is electrically connected to the light emitting diode, and the second output end is electrically connected to the resistor. Each of the current-steering units includes a current source and a switching circuit. A first end of the switching circuit is electrically connected to the current source. A second end and a third end of the switching circuit are electrically connected to the first output end and the second output end of the current-steering DAC, respectively. The switching circuit is controlled by a switching signal so as to selectively connect one of the second end and the third end to the first end.

First claim

What is claimed is:

1 . A current-steering digital-to-analog converter (DAC) circuit for switching a diode, said current-steering DAC circuit comprising:
a current-steering DAC for outputting a stable current, said current-steering DAC being provided with a first output end and a second output end, wherein said first output end is electrically connected to said diode; and a resistor being electrically connected to said second output end of said current-steering DAC; wherein said current-steering DAC comprises:
a plurality of current-steering units, each of the said current-steering units comprising a current source and a switching circuit, wherein a first end of said switching circuit is electrically connected to said current source, a second end and a third end of said switching circuit are electrically connected to said first output end and said second output end, respectively, and said switching circuit is controlled by a switching signal to selectively connect one of said second end and said third end to said first end.

2 . The current-steering DAC circuit of claim 1 , wherein said diode is a light emitting diode.

3 . The current-steering DAC circuit of claim 1 , wherein a voltage at said first output end when said first end is connected to said second end of said switching circuit of each of said current-steering units is equal to a voltage at said second output end when said first end is connected to said third end of said switching circuit of each of said current-steering units.

4 . The current-steering DAC circuit of claim 1 , wherein said current-steering DAC outputs said stable current to said diode when said second end of said switching circuit of each of said current-steering units is connected to said first end of said switching circuit of each of said current-steering units.

5 . The current-steering DAC circuit of claim 1 , wherein said current-steering DAC outputs said stable current to said resistor when said third end of said switching circuit of each of said current-steering units is connected to said first end of said switching circuit of each of said current-steering units.

6 . The current-steering DAC circuit of claim 1 , wherein one end of said resistor and one end of said diode are electrically connected to a system voltage, and the other end of said diode and the other end of said resistor are electrically connected to said first output end and said second output end, respectively.

7 . The current-steering DAC circuit of claim 1 , wherein said switching signal comprises a first control signal and a second control signal, said second control signal is a reverse signal of said first control signal, said switching circuit comprises a first transistor and a second transistor, a drain of said first transistor and a drain of said second transistor are electrically connected to said second end and said third end, respectively, a source of said first transistor and a source of said second transistor are electrically connected to said first end, and a gate of said first transistor and a gate of said second transistor receive said first control signal and said second control signal, respectively.

8 . A light emitting diode (LED) circuit, comprising:
a light emitting diode; and a current-steering DAC circuit for switching said light emitting diode, said current-steering DAC circuit comprising: a current-steering DAC for outputting a stable current, said current-steering DAC being provided with a first output end and a second output end, wherein said first output end is electrically connected to said light emitting diode; and a resistor being electrically connected to said second output end of said current-steering DAC; wherein said current-steering DAC comprises:
a plurality of current-steering units, each of the said current-steering units comprising a current source and a switching circuit, wherein a first end of said switching circuit is electrically connected to said current source, a second end and a third end of said switching circuit are electrically connected to said first output end and said second output end, respectively, and said switching circuit is controlled by a switching signal to selectively connect one of said second end and said third end to said first end.

9 . The LED circuit of claim 8 , wherein one end of said resistor and one end of said light emitting diode are electrically connected to a system voltage, and the other end of said light emitting diode and the other end of said resistor are electrically connected to said first output end and said second output end, respectively.

10 . The LED circuit of claim 9 , wherein said switching signal comprises a first control signal and a second control signal, said second control signal is a reverse signal of said first control signal, said switching circuit comprises a first transistor and a second transistor, a drain of said first transistor and a drain of said second transistor are electrically connected to said second end and said third end, respectively, a source of said first transistor and a source of said second transistor are electrically connected to said first end, and a gate of said first transistor and a gate of said second transistor receive said first control signal and said second control signal, respectively.

Assignees

• Pixart Imaging Inc

Inventors

• Wu Chia-Hsun
• Chen Peng-Sheng
• Hwang Hsiang-Wei
• Chiu Jui-Te

Classifications

• H05B45/46 Primary

  having LEDs disposed in parallel lines · CPC title

• H03M1/742

  using current sources as quantisation value generators · CPC title

• H05B33/0845

  Electricity · mapped topic

• H03M1/66

  Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• H05B33/0815 Primary

  Electricity · mapped topic