Switching power supply circuit using a silicon based LED for feedback

• US 6,885,016 B2
• Filed: 09/03/2002
• Issued: 04/26/2005
• Est. Priority Date: 09/04/2001
• Status: Expired due to Fees

• Current Assignee: Charles Ye Ying Jie Chu, Eugene Robert Worley
• Original Assignee: Charles Ye Ying Jie Chu, Eugene Robert Worley
• Inventors: Chu, Charles Ye Ying Jie, Worley, Eugene Robert
• Primary Examiner(s): Luu, Thanh X.
• Assistant Examiner(s): Sohn, Seung C.
• Application Number:
  US10/233,982
• Publication Number:
  US 20030042437A1
• Time in Patent Office: 966 Days
• Field of Search: 250/551, 250/239, 250/227.24, 438/25, 438/26, 257 80- 84, 323/282, 323/284, 323/287
• US Class Current: 250/551
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01055 Cesium [Cs]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

Flyback power supplies require three chip integrated circuits to control the switching cycles on the primary of a transformer including a chip that detects when a voltage threshold and optionally when a current threshold has been crossed on the secondary side of the transformer, an opto-coupler to isolate the secondary to primary feedback from the first chip, and a switch control circuit that receives the feedback information from the opto-coupler and uses the information to modulate the primary pulses in order to regulate the secondary voltage and to optionally set a current compliance limit on the secondary current. This invention shows how these three integrated circuits can be combined into one package using silicon based LEDs. Furthermore, circuit techniques are presented that allow the detection of low level light produced by silicon based LEDs. These techniques include disconnecting the power supply from sensing circuits and using a charge capacitor for power and performing the sensing operation during a period of time when clocked digital circuits are inactive.

Claims

1. An opto-coupler package, comprising:

a first integrated circuit comprising

a silicon based LED; and

a threshold detector circuit electrically coupled to the LED;

a second integrated circuit comprising

a light detector configured to detect light from the LED; and

a switch control circuit electrically coupled to the light detector;

a first pin electrically coupled to the first integrated circuit;

a second pin electrically coupled to the second integrated circuit;

a transparent insulator disposed between the first integrated circuit and the second integrated circuit; and

an encapsulant encasing the first integrated circuit, the second integrated circuit and the transparent insulator.

2. The package of claim 1, wherein the LED is a silicon PN junction LED.

3. The package of claim 2, wherein the light detector is a Schottky barrier diode.

4. The package of claim 1, wherein the threshold detector circuit is configured to turn on the LED when a voltage signal exceeds a voltage threshold value.

5. The package of claim 4, wherein the threshold detector circuit is configured to turn on the LED when a current signal exceeds a current threshold value.