Thermometers for hot spots on pcb - suggestions?
OakGraphics
Posts: 202
I am designing a propeller controlled DMX LED RGB+W lighting controller, and part of the equation is thermal management.
I am familiar with ds1820 type of things, but what I need is a good, small surface mount thermometer that I can place on the board next to the LEDs thermal Junction so I can tell if I am frying the Luxeon Rebel LEDs. I figure I need at least 4 thermal check points on the LED board (one for each channel) and possibly 2 additional on the controller board for some of the power components. I can't do any vias on the pcb that will not be attached to the thermal layer because the bottom of the pcb will have thermal paste on it and directly bolted to a heat-sink and fan to help with thermal spreading and sinking.
Anybody have any luck with something like the maxim MAX6697 or something similar? The problem I see is the thermal diodes need to be off the controller pcb, and attached by about a foot of cable to the LED board.
I don't need total accuracy - just need to know when I am heading towards the 'danger' zone. (kinda like the 'dangometer' from Cloudy with a chance of Meatballs.
) I want to keep the temps of the LEDS below 100c to keep them out of danger of thermal overrun.
I am familiar with ds1820 type of things, but what I need is a good, small surface mount thermometer that I can place on the board next to the LEDs thermal Junction so I can tell if I am frying the Luxeon Rebel LEDs. I figure I need at least 4 thermal check points on the LED board (one for each channel) and possibly 2 additional on the controller board for some of the power components. I can't do any vias on the pcb that will not be attached to the thermal layer because the bottom of the pcb will have thermal paste on it and directly bolted to a heat-sink and fan to help with thermal spreading and sinking.
Anybody have any luck with something like the maxim MAX6697 or something similar? The problem I see is the thermal diodes need to be off the controller pcb, and attached by about a foot of cable to the LED board.
I don't need total accuracy - just need to know when I am heading towards the 'danger' zone. (kinda like the 'dangometer' from Cloudy with a chance of Meatballs.
) I want to keep the temps of the LEDS below 100c to keep them out of danger of thermal overrun.
Comments
This is as I see it·I hope this helps
You will need to make the LEDs and Temp Sensors Board (or all· on one Board )·a close as you can
·I would use shield cable ( Or a·Ground Plane between the Temp Sensor· and ·MAX6697·especially If you are using a switch regulator
The programing of this chip may take some doing I have not read all of the data sheet
How ever I have played with MAX chip before and it has taken some time to understand how to control there chips
I am very interested· in high power LEDs and thermal management of them and in your project
If Maxim·dose not tell me that·I can not have any more free samples I will order some and give it a try to write a demo for this chip
Please post what you have and how you put it all together
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Sam
Post Edited (sam_sam_sam) : 2/21/2010 3:01:08 AM GMT