DC-DC converter with temperature compensation circuit

• US 7,859,511 B2
• Filed: 07/09/2007
• Issued: 12/28/2010
• Est. Priority Date: 06/12/2007
• Status: Expired due to Fees

• Current Assignee: VastView Technology Inc.
• Original Assignee: VastView Technology Inc.
• Inventors: Shen, Yuhren, Wang, Ming-Chia, Chu, Hung-Chi
• Primary Examiner(s): Nguyen; Chanh
• Assistant Examiner(s): Yang; Kwang-Su
• Application Number:
  US11/822,574
• Publication Number:
  US 20080309608A1
• Time in Patent Office: 1,268 Days
• Field of Search: 345/101, 345/214, 348/602, 323/285
• US Class Current: 345/101
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A DC-DC converter includes a temperature compensation circuit arranged between a feedback differential amplification circuit and an output voltage detection circuit to compensate the variation of the voltage level of the DC output voltage of the converter caused by ambient temperature changes. The temperature compensation circuit includes a temperature detection circuit that detects the ambient temperature and, in response thereto, generates a temperature signal; and a current source circuit that is connected between a feedback signal input terminal of the feedback differential amplification circuit and the output voltage detection circuit. The current source circuit, based on the temperature signal, generates an electrical current and a compensation voltage proportional to the electrical current. The compensation voltage is applied to the DC output voltage to thereby regulate the voltage level of the DC output voltage. The temperature signal is a temperature signal of positive temperature characteristics and/or a temperature signal of negative temperature characteristics.

Claims

1. A DC-DC converter for converting a DC input voltage and supplying a DC output voltage at a voltage output terminal through a voltage supply circuit loop, the DC-DC converter comprising:

a transistor based switching unit, having a source, a drain, and a gate, the drain being connected to the voltage supply circuit loop, the source being connected to a ground potential;

a comparator, having a saw-tooth wave signal input terminal, a differential signal input terminal, and an output terminal, the saw-tooth wave signal input terminal receiving a saw-tooth wave signal, the output terminal being connected through a gate driver circuit to the gate of the transistor based switching unit;

an output voltage detection circuit, being electrically connected to the voltage supply circuit loop to detect a voltage level of the DC output voltage and generating a feedback signal at a feedback node;

a feedback differential amplification circuit, having a reference voltage input terminal, a feedback signal input terminal, and a differential signal output terminal, the reference voltage input terminal receiving a reference voltage, the feedback signal input terminal receiving the feedback signal from the output voltage detection circuit, the differential signal output terminal being connected to the differential signal input terminal of the comparator; and

a temperature compensation circuit connected between the feedback differential amplification circuit and the output voltage detection circuit and comprising;

a temperature detection circuit that detects an ambient temperature and, in response thereto, generates a temperature signal, and

a current source circuit connected between the feedback signal input terminal of the feedback differential amplification circuit and the output voltage detection circuit, wherein the current source circuit, based on the temperature signal from the temperature detection circuit, generates an electrical current and generates a compensation voltage proportional to the electrical current, the compensation voltage being applied to the DC output voltage to thereby regulate the voltage level of the DC output voltage.

2. The DC-DC converter as claimed in claim 1, wherein the current source circuit of the temperature compensation circuit is connected between a power supply and the feedback node of the output voltage detection circuit.

3. The DC-DC converter as claimed in claim 1, wherein the current source circuit of the temperature compensation circuit is connected between the feedback node of the output voltage detection circuit and a grounding point.

4. The DC-DC converter as claimed in claim 1, wherein the current source circuit of the temperature compensation circuit comprises:

a first current source;

a first switch connected in series to the first current source, the series connection of the first switch and the first current source being further connected between a power supply and the feedback node of the output voltage detection circuit, the first switch having on/off state controlled by a first switching signal;

a second current source; and

a second switch connected in series to the second current source, the series connection of the second switch and the second current source being further connected between the feedback node of the output voltage detection circuit and a grounding point, the second switch having on/off state controlled by a second switching signal.

5. The DC-DC converter as claimed in claim 1, wherein the temperature signal generated by the temperature detection circuit comprises a temperature signal of positive temperature characteristics.

6. The DC-DC converter as claimed in claim 1, wherein the temperature signal generated by the temperature detection circuit comprises a temperature signal of negative temperature characteristics.

7. The DC-DC converter as claimed in claim 1, wherein the temperature signal generated by the temperature detection circuit comprises a first temperature signal of positive temperature characteristics and a second temperature signal of negative temperature characteristics.

8. The DC-DC converter as claimed in claim 1, wherein the DC output voltage generated by the DC-DC converter is adapted to be fed to a liquid crystal display to serve as a working voltage of the liquid crystal display.

9. The DC-DC converter as claimed in claim 8, wherein the DC output voltage generated by the DC-DC converter is fed to the liquid crystal display to serve as a data driving voltage of a data driver circuit of the liquid crystal display.

10. The DC-DC converter as claimed in claim 8, wherein the DC output voltage generated by the DC-DC converter is fed to the liquid crystal display to serve as a gate switching-on voltage of a gate driver circuit of the liquid crystal display.

11. The DC-DC converter as claimed in claim 1, wherein the voltage supply circuit loop comprises an inductor and a forward-connected diode, the DC input voltage being fed through the inductor and the diode to provide the DC output voltage by the diode, the drain of the transistor based switching unit being connected to a node between the inductor and the diode.