Optocoupler with Multiple Photodetectors and Improved Feedback Control of LED

• US 20130168531A1
• Filed: 01/03/2012
• Published: 07/04/2013
• Est. Priority Date: 01/03/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Wong, Chee Mang, Lau, Kok Chien, Sia, Chin Hian
• Granted Patent: US 9,012,826 B2
• Time in Patent Office: Days
• US Class Current: 250/201.1
• CPC Class Codes: G01J 1/42 using electric radiation detectors optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• 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 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H04B 10/802 for isolation, e.g. using optocouplers

Abstract

Various embodiments of methods and devices are provided for an optocoupler comprising a layer of dielectric optically semi-reflective and transmissive material disposed between an LED and a first photodetector located above an upper surface of the layer, and a second photodetector located beneath the lower surface of the layer. The layer reflects a first portion of light generated by the LED towards the first photodetector to generate LED feedback control signals, and transmits a second portion of light generated by the LED through the layer for detection by the second photodetector to generate isolated output signals.

Claims

20. A method of operating an optocoupler package, comprising:

providing input signals across first and second input signal terminals of an LED included in the optocoupler package;

generating and emitting, on the basis of the input signals, infrared or near-infrared light signals with the LED;

reflecting a first portion of light generated by the LED and incident upon an upper surface of a layer of dielectric semi-reflective material towards a first photodetector thereby to generate and provide LED feedback control signals therefrom, the LED and the first photodetector being located above the upper surface;

transmitting a second portion of light generated by the LED through the upper surface and an opposing lower surface of the layer of dielectric semi-reflective material towards a second photodetector thereby to generate and provide isolated output signals therefrom, the second photodetector being located beneath the lower surface.

1. An optocoupler package, comprising:

first and second input signal terminals;

first and second output terminals;

third and fourth output terminals;

a layer of dielectric optically semi-reflective and transmissive material having an upper surface and a lower surface;

a light emitting diode (LED) operably connected to the first and second input signal terminals and configured to emit infrared or near-infrared light in proportion to at least one predetermined characteristic of the input signals;

a first photodetector operably connected to the first and second output terminals and configured to provide LED feedback control signals thereacross, and

a second photodetector operably connected to the third and fourth output terminals and configured to provide isolated output signals thereacross;

wherein the LED and the first photodetector are both located above the upper surface of the layer of dielectric semi-reflective material, the second photodetector is located beneath the lower surface of the layer of dielectric semi-reflective material, and the layer of dielectric semi-reflective material is configured to reflect a first portion of light generated by the LED and incident upon the upper surface thereof towards the first photodetector thereby to provide the feedback control signals therefrom and to transmit a second portion of light generated by the LED through the upper and lower surfaces thereof for detection by the second photodetector thereby to provide the isolated output signals therefrom.

2. The optocoupler of claim 1, wherein the LED and the first photodetector are operably connected to a first lead frame.

3. The optocoupler of claim 2, wherein the first lead frame comprises the first and second input signal terminals and the first and second output terminals.

4. The optocoupler of claim 1, wherein the second photodetector is operably connected to a second lead frame.

5. The optocoupler of claim 4, wherein the second lead frame comprises the third and fourth output terminals.

6. The optocoupler of claim 1, wherein at least one of the first and second photodetectors is a photo diode, a bipolar detector transistor, and a Darlington detector transistor.

7. The optocoupler of claim 1, wherein the LED is one of an AlGaAs LED, an ACE AlGaAs LED, a DPUP AlGaAs LED, and a GaAsP LED.

8. The optocoupler of claim 1, wherein the optocoupler further comprises a molding compound that at least partially surrounds or encases a plurality of the terminals and portions of the layer of dielectric optically semi-reflective and transmissive material.

9. The optocoupler of claim 8, wherein the molding compound comprises plastic.

10. The optocoupler of claim 1, wherein the optocoupler is an 8-pin DIP package.

11. The optocoupler of claim 1, wherein the layer of dielectric optically semi-reflective and transmissive material is at least partially polymeric.

12. The optocoupler of claim 1, wherein the layer of dielectric optically semi-reflective and transmissive material is a film.

13. The optocoupler of claim 12, wherein the film is at least partially polymeric.

14. The optocoupler of claim 13, wherein the at least partially polymeric film is a multi-layer optical film.

15. The optocoupler of claim 14, wherein the multi-layer optical film is a selective wavelength mirror multi-layer optical film.

16. The optocoupler of claim 12, wherein the film comprises between about 100 layers and about 1,000 layers.

17. The optocoupler of claim 16, wherein each of the layers ranges between about 10 nanometers and about 200 nanometers in thickness.

18. The optocoupler of claim 1, wherein the LED feedback control signals are employed to regulate and control the output of the LED.

19. The optocoupler of claim 1, wherein the at least one predetermined characteristic includes at least one of input signal amplitude, phase and frequency.

21. The method of claim 20, wherein at least one of the first and second photodetectors is a photo diode, a bipolar detector transistor, and a Darlington detector transistor.

22. The method of claim 20, wherein the LED is one of an AlGaAs LED, an ACE AlGaAs LED, a DPUP AlGaAs LED, and a GaAsP LED.

23. The method of claim 20, wherein the layer of dielectric optically semi-reflective and transmissive material is at least partially polymeric.

24. The method of claim 20, wherein the layer of dielectric optically semi-reflective and transmissive material is a film.

25. The method of claim 24, wherein the film is at least partially polymeric.

26. The method of claim 25, wherein the at least partially polymeric film is a multi-layer optical film.

27. The method of claim 26, wherein the multi-layer optical film is a selective wavelength mirror multi-layer optical film.

28. The method of claim 24, wherein the film comprises between about 100 layers and about 1,000 layers.

29. The method of claim 28, wherein each of the layers ranges between about 10 nanometers and about 200 nanometers in thickness.

30. The method of claim 20, further comprising regulating and controlling the output of the LED using the LED feedback control signals.

22-1. The method of claim 20, wherein the optocoupler is an 8-pin DIP package.