dsPIC - power LED control

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#1
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Hi there,

Yesterday afternoon I had a meeting with some guys from microchip Italy R&D department. For those who are interesteed of power LED products (like emergency luminaires), engineers there made a good design using a dsPIC (28 pins, price <= 1 euro) that controls power LEDs with a PWM at 500KHz. They also told me that a new smaller design will be ready in some days.

As they told me schematics, pcbs and source code is free for everyone. Also they sell their design as a reference.

I tell you this as an information.

Michael.

Michael.

User of:
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Altium Designer

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Why would that application need the (expensive) computing power of a DSP ?

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dsPICs aren't expensive. The power control versions are intended for applications like that.

Leon

Leon Heller G1HSM

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I still don't see the point to have DSP to light an LED.

IIRC, Cypress has some LED uC in the PSoC family, but none of them have DSP features.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Those are high-power LEDs used in luminaires. I think they need quite complex control systems to maximise the light output without burning them out.

Leon

Leon Heller G1HSM

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Look guys,

We have almost finished an emergency luminaire using power LEDs (350mA at 3V6). The point is to get the higher posible eficiency for a voltage range of 2.4V up to 5.9V. This is because manufacturers of emergency luminaires use NiCd or NiMH battery packs with 2, 3, or 4 cells.
The market of this type of products is killed, and you have to use as possible as cheaper (smaller) passive and also high eficiency, because this will be the point of the battery choice.
The guys from Microchip get 90% eficiency (step up converter), with very small inductors. The higher the frequency the lower the inductance.

Michael.

Michael.

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And all this is controlled by DSP calculations or by dedicated HW (SMPS)?

I had made a similar project, less power (50mA rated LED's) and not for emergency lightning, but since this was an alarm that should keep running (at >96dB @ 1m) for 10 hours, efficency was really important to keep the batteries small. No uC inside, though.

So what one saves when switching from bulbs and Pb accumulators to NiMH and LED's is spent in SMP (an LED's also).

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Mike,
Great info!! Although this is not a PIC forum, it is good o know if one ever runs into this situation.

What does development equipment cost? That was my main reason for abandoning Microchip to begin with.

Jim

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Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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The PICkit 2 costs $35. I use an ICD 2 that costs a lot more but handles every chip and is replaced free if it ever fails.

Leon

Leon Heller G1HSM

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Leon,

There is also another tool from Microchip, like ICD2 that gives you the feature to see some values in run time, without stelling time from the processor. Unfortunately I don't know the tool's name.

Michael.

Michael.

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That's the RealICE. It's quite expensive.

Leon

Leon Heller G1HSM