The UCC2804DTR from Texas Instruments is a low-power BiCMOS current-mode PWM controller operating up to 1MHz with 50% maximum duty cycle, 12.5V\/8.3V UVLO thresholds, and 1A totem-pole gate drive output. Pin-compatible with UC3842, it adds internal soft start and leading-edge blanking in an SOIC-8 package.<\/p>\n
Product Overview The UCC2804DTR from Texas Instruments is a low-power BiCMOS current-mode PWM controller operating up to 1MHz with 50% maximum duty cycle, 12.5V\/8.3V UVLO thresholds, and 1A totem-pole gate drive output. Pin-compatible with UC3842, it adds internal soft start and leading-edge blanking in an SOIC-8 package. Key Specifications Topology: Boost, Flyback, Forward Control Mode: […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[31,13],"tags":[],"chip_brand":[138],"class_list":["post-6526","post","type-post","status-publish","format-standard","hentry","category-dc-dc-converters","category-integrated-circuits-ics","chip_brand-ti"],"acf":{"brief_explanation":"Current-mode PWM controller, 1MHz, 50% duty, 1A gate drive, soft start, SOIC-8, UC3842 pinout","date_code":"","package_case":"SOIC-8","in_stock":6500,"datasheet":"https:\/\/www.ti.com\/lit\/ds\/symlink\/ucc2802.pdf","price":"$0.92","product_introduction":"The UCC2804DTR from Texas Instruments is a BiCMOS current-mode PWM controller that serves as a pin-compatible, feature-enhanced replacement for the classic UC3842. The BiCMOS process reduces operating supply current to 500\u00b5A (vs. 11mA for bipolar UC3842), enabling lower standby power. The internal full-cycle soft start gradually increases the COMP voltage clamp on start-up, eliminating the external RC soft-start circuit required by UC3842 designs. The internal leading-edge blanking suppresses the current-sense spike that occurs when the MOSFET turns on, removing the need for the external RC filter typically placed on the CS pin. The 12.5V\/8.3V UVLO thresholds with 4.2V hysteresis are optimized for off-line power supplies with bootstrap start-up from a high-voltage resistor. The DTR suffix indicates SOIC-8 tape and reel packaging.","working_principle":"The UCC2804DTR implements peak current-mode control. An internal oscillator sets the switching frequency (determined by RT and CT) and generates a clock pulse that sets the output latch, turning on the external MOSFET. The MOSFET current is sensed through a shunt resistor on the CS pin. When the sensed voltage exceeds the error amplifier output voltage (on the COMP pin), the PWM comparator resets the latch, turning off the MOSFET. The internal leading-edge blanking disconnects the CS comparator for 100ns after each output rising edge, ignoring the turn-on current spike. The error amplifier compares a fraction of the output voltage (fed back through the FB pin) with the 5V reference, adjusting the COMP voltage to regulate the output. If the CS voltage exceeds the overcurrent threshold (independent of COMP), a soft-start cycle is triggered. The 50% maximum duty cycle is suitable for forward and boost topologies.","pin_description":"
| Pin<\/th> | Name<\/th> | Function<\/th><\/tr> | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1<\/td> | COMP<\/td> | Error amplifier output \/ PWM comparator input<\/td><\/tr> | ||||||||||||
| 2<\/td> | FB<\/td> | Error amplifier inverting input (voltage feedback)<\/td><\/tr> | ||||||||||||
| 3<\/td> | CS<\/td> | Current sense input (with leading-edge blanking)<\/td><\/tr> | ||||||||||||
| 4<\/td> | RT\/CT<\/td> | Oscillator timing resistor and capacitor<\/td><\/tr> | ||||||||||||
| 5<\/td> | GND<\/td> | Ground<\/td><\/tr> | ||||||||||||
| 6<\/td> | OUT<\/td> | Gate drive output (1A totem-pole)<\/td><\/tr> | ||||||||||||
| 7<\/td> | VCC<\/td> | Supply voltage (UVLO ON=12.5V)<\/td><\/tr> | ||||||||||||
| 8<\/td> | REF<\/td> | 5V reference output (1.5% tolerance)<\/td><\/tr><\/table>","application_scenarios":"The UCC2804DTR is used in off-line flyback converters for consumer electronics where the high UVLO hysteresis ensures reliable start-up from a bootstrap resistor. In DC-DC boost converters, the 1MHz maximum frequency allows compact magnetics. For LED driver applications, the current-mode control provides inherent cycle-by-cycle current limiting. The 50% duty cycle limit makes it unsuitable for buck or SEPIC topologies requiring >50% duty cycle; UCC2803 (100% duty) or UCC2800 should be used instead. The pin-compatibility with UC3842 allows upgrading existing designs without PCB changes.","alternative_models":"
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