thermal resistance<\/a> of the heat sink. θjc refers to the LED COB module’s thermal resistance. And you can get this value from the datasheets.θb refers to the thermal resistance between the heat sink and LED case.<\/p>\n\n\n\nThe Tj in the equation is the maximum junction temperature. The value is usually on the LED datasheet. So, the matter should be below 90%.<\/p>\n\n\n\n
Ta refers to ambient air temperature around the LED heat sink. If you’re working with recessed ceiling light, the value may be close to 50 or 550C. But, if you have an open-air mounted spotlight, you should expect 300<\/sup>C.<\/p>\n\n\n\nPd is the power distributed from the LED module. You can estimate the value as 80%.<\/p>\n\n\n\n
So, after the calculation, you’ll get a discount for θs. Or you’ll get a range. With this value, you can make a good decision about the ideal heat sink.<\/p>\n\n\n