{"product_id":"pc817c-optocoupler-dip4-5kv-isolation-50-300-ctr-35v-10pack","title":"PC817C Optocoupler IC — DIP-4, 5kV Isolation, 50–300% CTR, 35V Output (10-Pack)","description":"\u003ch2\u003ePC817C Optocoupler — DIP-4, 5kV Isolation, 100–300% CTR, 35V Output (10-Pack)\u003c\/h2\u003e\u003cp\u003eThe PC817C is a general-purpose phototransistor optocoupler in a DIP-4 through-hole package, providing 5,000V RMS galvanic isolation between input and output circuits. With a current transfer ratio (CTR) of 100–300% (Grade C), it is the most widely used optocoupler for SMPS feedback loops, PLC digital I\/O isolation, and microcontroller-to-high-voltage circuit interfaces.\u003c\/p\u003e\u003ch3\u003eKey Specifications\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePackage\u003c\/td\u003e\n\u003ctd\u003eDIP-4 (through-hole)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eIsolation Voltage\u003c\/td\u003e\n\u003ctd\u003e5,000V RMS\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCTR Grade\u003c\/td\u003e\n\u003ctd\u003eC: 100–300% (at IF=5mA)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOutput Collector Voltage (VCEO)\u003c\/td\u003e\n\u003ctd\u003e35V\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eForward Current (IF)\u003c\/td\u003e\n\u003ctd\u003e50mA max\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCollector Current (IC)\u003c\/td\u003e\n\u003ctd\u003e50mA max\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eResponse Time (tr\/tf)\u003c\/td\u003e\n\u003ctd\u003e4μs \/ 3μs typ.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e-30°C to +100°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eQuantity\u003c\/td\u003e\n\u003ctd\u003e10 pieces\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003ePC817 CTR Grade Guide\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eGrade\u003c\/th\u003e\n\u003cth\u003eCTR Range\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eA\u003c\/td\u003e\n\u003ctd\u003e50–150%\u003c\/td\u003e\n\u003ctd\u003eLow-sensitivity circuits\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eB\u003c\/td\u003e\n\u003ctd\u003e100–200%\u003c\/td\u003e\n\u003ctd\u003eGeneral purpose\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eC\u003c\/td\u003e\n\u003ctd\u003e100–300%\u003c\/td\u003e\n\u003ctd\u003eSMPS feedback (recommended)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eD\u003c\/td\u003e\n\u003ctd\u003e200–400%\u003c\/td\u003e\n\u003ctd\u003eHigh-sensitivity circuits\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003eWhy Choose PC817C?\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGrade C (100–300% CTR)\u003c\/strong\u003e — optimal for SMPS feedback where consistent CTR is critical for stable regulation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e5kV isolation\u003c\/strong\u003e — meets safety requirements for mains-connected and industrial circuits\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDIP-4 through-hole\u003c\/strong\u003e — easy to prototype on breadboard and replace in existing PCBs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIndustry-standard pinout\u003c\/strong\u003e — pin-compatible with EL817, LTV817, 4N35 (check datasheet)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e10-pack value\u003c\/strong\u003e — sufficient for multiple builds and repair stock\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eCompatible With \/ Common Use Cases\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSMPS feedback\u003c\/strong\u003e: Flyback converter output voltage regulation loop (with TL431 shunt reference)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePLC I\/O isolation\u003c\/strong\u003e: 24V industrial signal to 3.3V\/5V MCU input isolation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRelay driver isolation\u003c\/strong\u003e: MCU GPIO to high-voltage relay coil drive\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAC zero-crossing detection\u003c\/strong\u003e: Mains voltage sensing for phase control circuits\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRS-232 \/ RS-485 isolation\u003c\/strong\u003e: Serial communication galvanic isolation\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the difference between PC817A, PC817B, PC817C, and PC817D?\u003c\/strong\u003e\u003cbr\u003eA: All are the same DIP-4 optocoupler with 5kV isolation — only the CTR (current transfer ratio) grade differs. Grade A: 50–150%, B: 100–200%, C: 100–300%, D: 200–400%. For SMPS feedback, Grade C is recommended for its balance of sensitivity and consistency.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Can I replace PC817 with EL817 or LTV817?\u003c\/strong\u003e\u003cbr\u003eA: Yes. EL817 (Everlight) and LTV817 (Lite-On) are direct pin-compatible replacements for PC817 (Sharp) with identical electrical specifications. Verify the CTR grade matches your circuit requirements.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: How do I calculate the input resistor for PC817 in an SMPS feedback circuit?\u003c\/strong\u003e\u003cbr\u003eA: The LED forward voltage is ~1.2V at IF=5mA. For a 5V logic input: R = (5V − 1.2V) \/ 5mA = 760Ω, use 820Ω standard value. For 3.3V logic: R = (3.3V − 1.2V) \/ 5mA = 420Ω, use 470Ω.\u003c\/p\u003e\u003ch3\u003ePackage Contents\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e10× PC817C Optocoupler IC (DIP-4)\u003c\/li\u003e\u003c\/ul\u003e","brand":"Keszoox","offers":[{"title":"Default Title","offer_id":46991456829675,"sku":"\u003cnone\u003e","price":5.36,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/1005\/8731\/files\/pc817c-dip-4-optocoupler-isolation-ic.webp?v=1761796837","url":"https:\/\/keszoox.com\/products\/pc817c-optocoupler-dip4-5kv-isolation-50-300-ctr-35v-10pack","provider":"Keszoox","version":"1.0","type":"link"}