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Understand thermal performance specs from top semiconductor suppliers: RJA, RJC, power ratings, and heat dissipation for reliable electronics. Stocked locally at Communica.
RJA, RJC, and max junction temp explained for real-world parts.
Find stocked semiconductors and heatsinking solutions from trusted suppliers.
Practical advice and formulas for choosing and cooling semiconductors.
The thermal performance of a semiconductor device - such as transistors, MOSFETs, voltage regulators, or power ICs - is crucial for reliable operation. Excess heat can lower efficiency, distort signals, shorten component lifetime, and even cause sudden failure. For South African engineers, students, and procurement teams, understanding and comparing supplier-provided thermal specs is essential for robust design, especially given local climate extremes and compact PCB layouts.
South African Context: In summer, PCB and enclosure temperatures can easily reach 40-50 degreesC. Always factor in local conditions for derating!
| Package Type | RJA ( degreesC/W) | Tj(max) ( degreesC) | Example Supplier |
|---|---|---|---|
| TO-220 | 45-62 | 150-175 | STMicroelectronics, ON Semiconductor |
| DPAK (SMD) | 60-110 | 150 | Infineon, Vishay |
| SOT-23 (SMD) | 160-330 | 150-175 | Nexperia, Diodes Inc. |
| TO-247 | 35-55 | 150-175 | Fairchild (ON), Toshiba |
These figures are typical ranges; always check the latest supplier datasheet. At Communica, you'll find brands such as STMicroelectronics, Infineon, Vishay, Nexperia, ON Semiconductor, and Diodes Inc. in popular through-hole and SMD packages, plus heatsinks and thermal interfaces to match.
To ensure long-term reliability, always check that your worst-case junction temperature stays well below Tj(max) for your chosen semiconductor. Here's how:
The fundamental equation is:
Tj = Ta + (Pd x RJA)
Suppose you're using a TO-220 MOSFET (RJA = 55 degreesC/W), with 1W dissipation, in a workshop at 35 degreesC:
Tj = 35 degreesC + (1W x 55 degreesC/W) = 90 degreesC
This is safe (<175 degreesC limit), but if power rises to 2W, Tj = 145 degreesC. For extended life (especially for critical designs), staying under 120 degreesC is good design practice.
Callout: If your calculation exceeds Tj(max), choose a lower-RJA package, add a heatsink (see RJC), or reduce load.
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Online support and communication is next level - great communication, fast response - very helpfull, recomended supplier - online payment was no hasse...
He's polite, good with people and made me feel free to talk.. all in all he's helpful
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Excellent service so far
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Needed to buy a bluetooth GPS receiver. The staff was friendly, knowledgeable and assisted without any issues. This is a toys tore of note for peopl...
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They have mostly any electronic tool and components that you may require - Thanks to Nicole for helping me.
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The service was excellent, Nicole and Rehaan were very helpful and professional in their work.
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Quick quality customer service.
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Verified customerNicolene
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Verified customerGood Array of products and sound advice
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I visit Communica once in a blue moon. Always wish i have more time to look at everything. Good & friendly service. Nothing wrong with a queuing syste...
Currently have only purchased items from their on-line store. Received what I ordered plus quick delivery. No complaints to date.
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I got the most pleasant service from Sydney and Windie
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Verified customerWhatever you need they have
Verified customerLarge number of electronic components
Verified customerCan spend hours in there
Verified customerRather a slow process
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Verified customerPlace if definite interest
Verified customerGet electronic kits
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Verified customerWaiting time can be annoing.
Verified customerCommunica supplies semiconductors and electronic components to industries such as automotive, electrical, automation, mining, and education.
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