I remember seeing a DC/DC up-converter that was based on LED's, but I can't seem to Google it down. It was in a SOIC, I think, and it had one LED that shined on a few to produce a higher voltage (a low current device). Does anyone know who makes this?...or was this just some crazy dream?
Thomas
You can buy p-v optocouplers that generate something like 9v at something like 10 uA... handy sometimes. They're an led and an integrated silicon pv stack, I think. Google "photovoltaic optocoupler."
John
Sounds like a photovoltaic optocoupler. It also provides isolation.
For example:
Best regards, Spehro Pefhany
Hello Thomas,
John and Spehro have already pointed out where to find them.
However, these devices usually do not provide much power. If you just need a very highly isolated power transfer think along the lines of contactless chargers and the like. It is possible to transfer power over several millimeters, through PVC barriers, glass and so on.
Regards, Joerg
And I've heard of using things called "transformers."
John
You can also do small amounts of power by sending RF through a few pF and using small Schottky diodes to rectify it. If the logic signal comes from a CPLD or FPGA, the logic in the device can be changed to AND the signal with the system clock. Don't expect to get a lot of power this way but it is cheap.
There are app circuits that use an LED to sense ambient light level and adjust the drive to other LEDs to compensate- brighter when high light level and dimmer when less light level.
Right now, I'm designing a family of VME modules, each with 16 isolated signal conditioning channels. So I need 16 low-noise, low-cost, zero-footprint floating power supplies. I'm thinking about using tiny ISDN or similar telecom transformers with sinewave drive.
or maybe
John
Hello Ken,
Alternatively you could follow with a diode-capacitor cascade to multiply. Power isn't going to be that great since many FPGA output stage FETs won't go much below 30-40 ohms. Other times the allowed continued load must not be exceeded.
Regards, Joerg
Hello John,
They can be awfully small if the frequency is high. But whenever I used some like that and the time for the design review came people often stared at those curly thingies on the schematic in disbelief. An analog part in a digital module? Yeccchh.
Regards, Joerg
Hello John,
They also make real quad versions like the LAN transformer TTW6176.
Check Asian mfgs. I don't know what Murata carries in transformers right now but I have used their CM chokes a lot. Good prices.
Regards, Joerg
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