What are the brand of chips and drivers for downlight?

If u have a downlight, you have to get one that has the uplight/downlighting feature. Need to get from a dealer.

place a multimeter across the low voltage wires. Start at high voltage and reduce when you have some idea of the out put. Check for either ac or dc voltage.

why not, cant you figure out how to change a light bulb? Look carefully at the way it is made, look for screws to remove a plastic or glass cover to get access to the downlight ,which i assume is a light that points down.
worst case senario is you have to read the owners manual under how to change the light bulb
or call up customer service and ask them how or at least how to call techinical service.
In all fairness , a down light may not be a light bulb that points down , but some kind of compact flouresent light bulb.
check if vaxcel has a web site. they might have instructions on how to change a down light bulb.

1. Decide where you wish to place your chosen downlights measuring out the ceiling and marking the central point of the light. Now drill a small pilot hole through the ceiling.
2. Now you have marked out the positions of the downlights it is a good idea to check above the ceiling to ensure that there are no joists / wires / pipes in the way. You should be able to see a small pinprick of light coming through the ceiling where you drilled the pilot holes. If you are unable to view the ceiling from above it gets trickier. The best way is to determine which way the joists run and what the spacing of them are. You could then use an old wire coat hanger bent at a 900 angle to the width of the downlight. Insert the wire through the hole until the 900 bend is through. Now twist the wire a full 3600 and hopefully it will not bump into any obstructions.
3. In the instructions or on the box of the downlights it will say what the cut-out for that downlight will be. For the best results I will generally use a hole saw (a type of drill bit) to the correct size of the downlight which can be purchased very cheaply from most DIY stores. Alternatively the use of a plasterboard saw (Pad Saw) can be used which eliminates the need for a drill and hole saw. For this method you will need to draw a circle on the ceiling to the correct size as a guide for when you start to saw.
4. Hopefully now you have produced a clean cut hole in the ceiling, got the plaster out of your eyes and shaken yourself outside to stop you looking like Casper the ghost!
5. Once the wiring has been pulled through the hole the downlight can be wired. To fit the downlight into the hole hold the two springs back against the sides of the downlighter and push up into the hole. The springs then lie flat on the top of the ceiling holding it in place

Connect to live and neutral, cap other wires and see what happens.
If you have 2 live wires, you might have 3-way switch

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You should try measuring the voltage that the lamp is getting without something else running, and then with something running. If you are getting a large fluctuation in voltage, then a regulator might do the trick.

If this is an over the range model you are talking about the cooktop light? If so, it may be either a screw in type bulb or a pin type bulb (pin types are simply pulled strait out... turning them will likely result in breaking the bulb glass, so be careful).
If you still can't get the bulb out, what is your brand and model name/number?

Please be specific about the type of downlight