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Maxim Integrated - Integration Nation
Dennis Feucht

An Instrument on a Chip? The Minimum-Subsystem Instrument

Dennis Feucht
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Vishal Prajapati
Vishal Prajapati
6/25/2013 7:28:09 AM
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How about AC/DC converter in a single IC?
Your blog has inspired me to think about power supply. The most critical part to design is power supply. How would it be easy, if we just need to insert an IC and it will convert the AC supply in to DC right away. Even without need of transformer. The power supply will also be on board then.

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Brad Albing
Brad Albing
6/25/2013 12:48:37 PM
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Re: How about AC/DC converter in a single IC?
@Vishal - that would be nice - but at present, probably impractical. You would need an IC built using a high-voltage process - with the corresponding high cost associated with that. And you would also need lower voltage sections of circuitry - so you either need two separate fab-processes - or do it all with the same high-voltage process. Expensive either way.

Oh - and you'd need galvanic isolation between the input voltage and the output voltage. Also expensive.

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goafrit2
goafrit2
6/25/2013 1:21:34 PM
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Re: How about AC/DC converter in a single IC?
>> How would it be easy, if we just need to insert an IC and it will convert the AC supply in to DC right away. Even without need of transformer

They present paradigm of external power supply is primitive. But I think the challenge has lack of ways to plug directly to mains. When we move to the realm of wireless charging, the IC for AC to DC will be done easily internally inside systems.

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goafrit2
goafrit2
6/25/2013 1:30:12 PM
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Re: How about AC/DC converter in a single IC?
>> , probably impractical. You would need an IC built using a high-voltage process - with the corresponding high cost associated with that. And you would also need lower voltage sections of circuitry

Technically, this can be done easily. With the design technique used in Charge Pump, one can do this. Floating gates can also be used. Sure, there are some needs to modify processes. But the generation of HV can be done.

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Vishal Prajapati
Vishal Prajapati
6/26/2013 2:12:16 AM
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Re: How about AC/DC converter in a single IC?
Sir, I can understand that providing galvanic isolation is harder to implement in ICs specially when delivering higher power. Still few isolators are available from Analog Devices which uses transofmer kind of thing inside the IC to provide galvanic isolation.

Sir, I want to know why high voltage ICs are not much? What is the constraint behind making high voltage ICs?

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Vishal Prajapati
Vishal Prajapati
6/26/2013 2:24:21 AM
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Re: How about AC/DC converter in a single IC?
There exists AC LEDs which can directly work on AC mains, why can't other ICs work on mains?

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CarlWH
CarlWH
6/26/2013 6:23:55 AM
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Re: How about AC/DC converter in a single IC?
@Vishal – there seems to be several questions here.

I hope these pointers help

1) You are correct there are AC LED's, I suggest though you take a look and see how these devices are implemented and how the power is dissipated. You should be able to find some indications of the difficulties.

2) Galvanic Isolation – to me this means spark reduction in hazardous areas and is used in ATEX type devices. Isolation is required, as it would be on any device, (e.g PCB) where you are mixing voltages and signals.

3) Available processes- there are high voltage processes available which will allow high voltage devices and logic. These are not expensive, but think about what you are doing when rectifying AC, then think about what this will mean for device sizes on chip. Given that your bridge would dominate the chip, would you really want to do this? Also another thing you may want to consider is capacitance and how easy that is to do on chip.

When considering AC/DC conversion you really have to put some limits on what you are thinking of. What load you are driving, how much power, what peak voltages and currents, regulation etc?. It would be nice if all our AC supplies were ideal.

4) A charge pump for me is a DC to DC converter and I am not sure what this comment was aiming at, sorry if I have missed the point.

In summary, you can put it onto a chip, but you have to ask yourself does this make sense to do so?

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Vishal Prajapati
Vishal Prajapati
6/26/2013 7:08:20 AM
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Re: How about AC/DC converter in a single IC?
Thanks Carl, for elaborated response. I think it has cleared all my doubts. And for isolation, it is not just to reduce the spark reduction. For consumer products, device needs to have isolation to avoid electrical shock.

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JAYARAMAN KIRUTHI VASAN
JAYARAMAN KIRUTHI VASAN
6/26/2013 10:59:40 AM
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Re: How about AC/DC converter in a single IC?
@Carl,

Spot on.

Expecting everything on a chip is similar to using those ready-made coffee-cream-sugar mixtures. Customising taste and flavour is a no-no.

 

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Brad Albing
Brad Albing
6/26/2013 12:31:11 PM
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Re: How about AC/DC converter in a single IC?
@VP - the short answer is cost. The higher voltage semiconductor process is more expensive. Then there are issues of certification (i.e., UL testing & listing) and liability if something goes wrong.

Those ADI devices are very low-voltage parts for passing low level digital signals. Scaling those up to higher power and higher voltage is not easy.

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Page 1 / 4   >   >>
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