I am a design engineer and have an application where I need a 3W, 2512 SMT Power resistor 22K, 5% (nominal) that has a working voltage >= 500V. I see many that have a 500V overload but only 250V working.
Please let me know if you can suggest anything.
Welcome to the Tech Forum.
What you are asking for is not possible. A 3 Watt 22K Ohm resistor cannot handle 500V continuously, as it would exceed it’s power rating. According to Ohm’s law, if one applied 500V to a 22K Ohm resistor, a 22.73mA current would flow . . .
500V / 22,000 Ohms = 0.02273A
. . . and this would mean it would be dissipating 11.36 Watts – nearly 4x its rated value.
500V x 0.02273A = 11.36W
The reason for the voltage rating is to satisfy our internal voltage derating requirements. The actual application is for a Half-Wave rectified 240VAC (with high-line considerations) PEAK voltage derated to 80% of working voltage—gives a voltage rating of 466V. That’s the reason.
Ah, I see.
This is a bit larger, but have you taken a look at the SMF322KJT?
The datasheet does not specify a “Max. Overload Voltage” but it does state that its “Max Operating Voltage” is 500V.
Thank you, yes, I have seen that one but was trying to keep my PC artwork in-tact as much as possible.
Because the current is 1/2 wave rectified, it turns out that I can just get away with a 2W and still have a safety factor. The CRGP2512F22K from TE will work, but our company requires a second source if at all possible. Do you have any insight into that?
No, sorry. The best alternative I could find in the 2512 size and rated 2W or more was the CRM2512-JW-223ELF, which is rated for 300V max working voltage and 600V max overload voltage.
Ok, thank you.