{"product_id":"uc3845an-uc3845bn-uc3843an-uc3842-current-mode-pwm-controller-dip8-5pack","title":"UC3845AN \/ UC3845BN \/ UC3843AN \/ UC3842 Current-Mode PWM Controller — DIP-8 (5-Pack)","description":"\u003ch2\u003eUC3845AN \/ UC3845BN \/ UC3843AN \/ UC3842 Current-Mode PWM Controller — DIP-8 (5-Pack)\u003c\/h2\u003e\u003cp\u003eThe UC384x series are industry-standard current-mode PWM controller ICs in DIP-8 packages, widely used in flyback, forward, and boost switching power supply designs. They integrate an oscillator, error amplifier, current-sense comparator, and gate driver in a single package, providing all the control functions needed for a complete SMPS. The UC3842\/UC3843\/UC3845 variants differ in startup voltage and maximum duty cycle, making them suitable for different SMPS topologies and input voltage ranges.\u003c\/p\u003e\u003ch3\u003eVariant Comparison\u003c\/h3\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003cth\u003eStartup Voltage\u003c\/th\u003e\n\u003cth\u003eMax Duty Cycle\u003c\/th\u003e\n\u003cth\u003eBest For\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUC3842 \/ UC3842A\u003c\/td\u003e\n\u003ctd\u003e16V (UVLO on: 16V, off: 10V)\u003c\/td\u003e\n\u003ctd\u003e100%\u003c\/td\u003e\n\u003ctd\u003eContinuous-mode flyback, forward converter\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUC3843 \/ UC3843AN\u003c\/td\u003e\n\u003ctd\u003e8.5V (UVLO on: 8.5V, off: 7.6V)\u003c\/td\u003e\n\u003ctd\u003e100%\u003c\/td\u003e\n\u003ctd\u003eLow-voltage startup SMPS, battery-powered\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUC3845 \/ UC3845AN \/ UC3845BN\u003c\/td\u003e\n\u003ctd\u003e16V (UVLO on: 16V, off: 10V)\u003c\/td\u003e\n\u003ctd\u003e50%\u003c\/td\u003e\n\u003ctd\u003ePush-pull, half-bridge, two-switch forward\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003eKey Specifications (All Variants)\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-8 (through-hole)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOscillator Frequency\u003c\/td\u003e\n\u003ctd\u003eUp to 500kHz (external R\/C)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eGate Drive Output\u003c\/td\u003e\n\u003ctd\u003e1A peak source\/sink\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eReference Voltage\u003c\/td\u003e\n\u003ctd\u003e5.0V (±1%)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eError Amplifier GBW\u003c\/td\u003e\n\u003ctd\u003e1MHz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCurrent Sense Input\u003c\/td\u003e\n\u003ctd\u003e1V threshold (cycle-by-cycle OCP)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e0°C to +70°C (UC38xx) \/ -40°C to +85°C (UC28xx)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eQuantity\u003c\/td\u003e\n\u003ctd\u003e5 pieces\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003ch3\u003eWhy Choose UC384x Series?\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eCycle-by-cycle current limiting\u003c\/strong\u003e — instantaneous overcurrent protection prevents transformer saturation\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1A gate drive\u003c\/strong\u003e — directly drives power MOSFETs up to ~100nC gate charge without external buffer\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500kHz max frequency\u003c\/strong\u003e — allows compact transformer and filter designs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e5V precision reference\u003c\/strong\u003e — stable reference for feedback network design\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIndustry-standard pinout\u003c\/strong\u003e — compatible with UC2842\/UC2843\/UC2845 (industrial grade) and KA3842\/KA3843 (Samsung equivalents)\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eCompatible With \/ Common Use Cases\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFlyback SMPS repair\u003c\/strong\u003e: Most common repair IC in ATX power supplies, monitor power boards, and industrial SMPS\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eForward converter design\u003c\/strong\u003e: UC3842\/UC3843 for single-switch forward topology\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePush-pull \/ half-bridge\u003c\/strong\u003e: UC3845 (50% max duty cycle) for push-pull and half-bridge topologies\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eATX power supply repair\u003c\/strong\u003e: UC3842 or UC3843 is the primary PWM controller in most ATX PSUs\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReference designs\u003c\/strong\u003e: Texas Instruments SLUA107, ON Semiconductor AND8016 application notes\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the difference between UC3842 and UC3843?\u003c\/strong\u003e\u003cbr\u003eA: Both have 100% max duty cycle and identical pinout. The key difference is UVLO (undervoltage lockout) threshold: UC3842 starts at 16V (suitable for offline SMPS with bootstrap startup), UC3843 starts at 8.5V (suitable for low-voltage and battery-powered SMPS). Use UC3843 when your VCC supply cannot reach 16V during startup.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Why does my SMPS use UC3845 instead of UC3842?\u003c\/strong\u003e\u003cbr\u003eA: UC3845 limits maximum duty cycle to 50%, which is required for push-pull and half-bridge topologies to prevent simultaneous conduction of both switches (shoot-through). UC3842 allows up to 100% duty cycle, suitable for single-switch flyback and forward converters only.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Can I replace UC3842 with KA3842 or SG3842?\u003c\/strong\u003e\u003cbr\u003eA: Yes — KA3842 (Samsung\/Fairchild), SG3842 (Silicon General), and UC3842 (TI\/ON Semi) are functionally identical with the same pinout and specifications. They are direct drop-in replacements for each other.\u003c\/p\u003e\u003ch3\u003ePackage Contents\u003c\/h3\u003e\u003cul\u003e\u003cli\u003e5× UC3845AN \/ UC3845BN \/ UC3843AN \/ UC3842 PWM Controller IC (DIP-8) — variant as selected\u003c\/li\u003e\u003c\/ul\u003e","brand":"Keszoox","offers":[{"title":"UC3842AN","offer_id":46991460729067,"sku":"14:1202#UC3842AN","price":5.88,"currency_code":"USD","in_stock":true},{"title":"UC3845BN","offer_id":46991460761835,"sku":"14:4044226#UC3845BN","price":6.48,"currency_code":"USD","in_stock":true},{"title":"UC3845AN","offer_id":46991460794603,"sku":"14:350852#UC3845AN","price":6.68,"currency_code":"USD","in_stock":true},{"title":"UC3843AN","offer_id":46991460827371,"sku":"14:351074#UC3843AN","price":5.88,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0677\/1005\/8731\/files\/uc3845an-uc3845bn-uc3843an-uc3842-dip-8-pwm-controller-ic-chipset.webp?v=1761794654","url":"https:\/\/keszoox.com\/products\/uc3845an-uc3845bn-uc3843an-uc3842-current-mode-pwm-controller-dip8-5pack","provider":"Keszoox","version":"1.0","type":"link"}