Resistor: RN60E1000BB14 Vishay / Dale | Mouser
Mouser calls it a 1/8th watt resistor in the description, but lists the power rating as 250mW. The datasheet says it is 1/4W at 70*C and 1/8W at 125*C. What would you consider this?
Mouser calls it a 1/8th watt resistor in the description, but lists the power rating as 250mW. The datasheet says it is 1/4W at 70*C and 1/8W at 125*C. What would you consider this?
Yes, I know. I said so in my post. My question is, which value sets the rating? When the spec calls for 1/4W, what temperature is assumed?
Typically 25C, but you want to use your inside chassis temp after thermal stabilization at high ambient.
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You can increase the power rating of any resistor (double or more) by leaving additional lead-in wire (I occasionally loop the leads) raising the resistor off the PCB and/or drilling a hole or removing the PCB substrate from underneath the resistor.
If there is a critical temperature rating for a given component one would expect the circuit designer would specify under what conditions the rating is made and exactly how the component needs to be installed. In many instances the rating of a resistor is to suit the PCB hole spacing (power rating is relative to size), and the power rating itself isn't important because the dissipation is most like way below specified maximum.
If there is a critical temperature rating for a given component one would expect the circuit designer would specify under what conditions the rating is made and exactly how the component needs to be installed. In many instances the rating of a resistor is to suit the PCB hole spacing (power rating is relative to size), and the power rating itself isn't important because the dissipation is most like way below specified maximum.
The datasheet is clear for RN60, 0.25W at 70C ambient, 0.125W at 125C ambient. So its 1/4 watt in normal usage, since commercial temperature range goes to 70C.
This is a comprehensive list: Temperature Ranges | Renesas
The automotive rating going up to 105C accords with my experience that hot-melt glue sticks should never be left in a car during the day. Certainly hot enough to melt them into the upholstery...
The automotive rating going up to 105C accords with my experience that hot-melt glue sticks should never be left in a car during the day. Certainly hot enough to melt them into the upholstery...
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