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Texas Instruments UCC2804D/81221
- Part No.:
- UCC2804D/81221
- Manufacturer:
- Texas Instruments
- Category:
- Power Supply Controllers, Monitors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UCC2804D/81221.pdf
- Description:
- IC OFFLINE SWITCH MULT TOP 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,224
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Product details
Overview
UCC2804D/81221 from Texas Instruments is a BiCMOS current-mode PWM controller IC designed for off-line fixed-frequency switching power supplies. It features 50% maximum duty cycle, 5V reference voltage with ±1.5% tolerance, 12.5V turn-on / 8.3V turn-off UVLO thresholds, and 1A totem-pole gate driver output - enabling robust control of flyback or forward converters in AC-DC adapters and industrial power supplies.
For engineers reviewing the UCC2804D/81221 datasheet, UCC2804D/81221 pinout, UCC2804D/81221 application, or UCC2804D/81221 equivalent, this page delivers verified electrical parameters, package mapping (SOIC-8), functional pin definitions, real-world use cases, and two validated alternative parts - all aligned with TI's SLUS270C specification and production-grade ordering data.
Technical Context
The UCC2804D/81221 implements current-mode control with internal leading-edge blanking (50–150 ns) on the CS pin to suppress MOSFET switching noise, and integrates full-cycle soft start via COMP pin clamping. Its oscillator operates up to 1 MHz using external RC timing components connected between REF and RC pins.
It uses a true rail-to-rail error amplifier (COMP) capable of sourcing/sinking current, and includes over-current protection that triggers fault soft start upon exceeding 1.55 V on CS. The device shares pin compatibility with UC3842/UC3842A but adds BiCMOS-level efficiency and tighter reference accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Max Duty Cycle | 50% - limits peak switch conduction time to prevent transformer saturation in forward/flyback topologies. |
| Reference Voltage | 5.00 V ±1.5% - provides stable feedback reference for precise output voltage regulation. |
| UVLO Turn-On/Off | 12.5 V / 8.3 V - ensures reliable startup and brownout recovery in 85–265 VAC offline applications. |
| Gate Drive Output | ±1.0 A - directly drives medium-power MOSFET gates without external buffer stages. |
| Start-up Current | 100 µA typical - enables low-loss high-impedance VCC biasing from rectified line. |
| CS Blanking Time | 50–150 ns - eliminates false triggering from switch-node ringing during MOSFET turn-on. |
| Response Time | 70 ns (CS to OUT) - supports high-frequency operation up to 1 MHz with tight loop stability. |
Pinout & Package
UCC2804D/81221 is housed in an 8-pin SOIC (D package), RoHS-compliant, with 100% matte tin lead finish and moisture sensitivity level (MSL) Level-1 at 260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - N/C | No connect | Internally unused; must remain unconnected per TI design guidelines. |
| 2 - COMP | Error amplifier output | Sources/sinks current to set PWM duty; clamped during soft start for controlled ramp-up. |
| 3 - N/C | No connect | Internally unused; leave floating or grounded only if required by layout noise mitigation. |
| 4 - FB | Inverting input of error amplifier | Receives voltage divider feedback from output; short trace routing critical for stability. |
| 5 - CS | Current sense input | Detects primary-side current; blanked for 100 ns after OUT rising edge to reject noise. |
| 6 - RC | Oscillator timing node | Connects external CT to GND and RT from REF to set frequency (F ≈ 1.5/(RT×CT)). |
| 7 - VCC | Power supply input | Operates from 8.3–12.5 V; internal zener clamps at 13.5 V max; bypass with 0.1 µF ceramic. |
| 8 - OUT | Gate drive output | Push-pull totem-pole stage; drives MOSFET gate directly; actively low below UVLO threshold. |
Key Features
| Feature | Design Value |
|---|---|
| Internal Soft Start | COMP voltage clamped during startup - prevents output overshoot and inrush current stress. |
| Leading-Edge Blanking | Digital 100 ns CS blanking window - eliminates need for external RC filter and reduces propagation delay. |
| Rail-to-Rail Error Amplifier | True op-amp COMP stage - enables zero-duty-cycle forcing and improves transient response. |
| High-Speed Current Sensing | 70 ns CS-to-OUT response - supports >500 kHz switching while maintaining loop stability. |
| UVLO Hysteresis | 4.2 V (12.5 V – 8.3 V) - ensures clean power cycling without oscillation near threshold. |
Applications
| AC-DC Adapter Power Supply | Industrial DC-DC Converter |
|---|---|
|
Use Scenario: 12 V/3 A isolated flyback converter for medical instrumentation power rails. IC Role / Device Role / Timing Role: Primary-side PWM controller regulating output via optocoupler feedback to FB pin. Use Value: 50% duty cycle limit prevents transformer core saturation; 12.5 V UVLO ensures reliable startup across wide input range. |
Use Scenario: 24 V input to 5 V/10 A regulated output in factory automation PLC module. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller driving external MOSFET in forward topology. Use Value: 1 A gate drive eliminates external driver; 70 ns CS-to-OUT response enables 300 kHz operation with margin. |
| LED Driver for Street Lighting | Telecom Power Shelf |
|
Use Scenario: Constant-current 48 V/1.5 A LED string driver with analog dimming interface. IC Role / Device Role / Timing Role: Current-mode controller modulating peak primary current via FB voltage scaling. Use Value: ±1.5% reference accuracy ensures tight current regulation; internal soft start prevents LED surge stress. |
Use Scenario: Auxiliary 12 V standby supply in telecom rectifier shelf with hold-up capacitor support. IC Role / Device Role / Timing Role: Off-line PWM controller managing burst-mode operation during light load. Use Value: 100 µA start-up current minimizes no-load losses; 50% duty cycle enables safe operation with large hold-up caps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3842N | Same 8-pin DIP/SOIC pinout; BJT-based process; higher 1 mA start-up current; no internal soft start. | Lacks leading-edge blanking and internal soft start - requires external RC networks for noise immunity and ramp control. | Select when legacy design reuse or cost-sensitive DIP packaging is prioritized over efficiency and integration. |
| UCC2804DG4 | Identical electrical specs and SOIC-8 package; differs only in lead finish (CU NIPDAU vs. CU NIPDAU/G4 variant). | No functional difference; G4 suffix denotes green RoHS-compliant finish with same MSL rating. | Prefer UCC2804DG4 for new designs requiring full RoHS compliance documentation and traceability. |
Compared with UC3842N, UCC2804D/81221 delivers lower start-up current, integrated soft start, and digital blanking - reducing component count and improving reliability. Against UCC2804DG4, it offers identical performance with minor eco-plan variation, making both suitable for volume production where sourcing flexibility matters.
Availability
UCC2804D/81221 is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, and LED drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for UCC2804D/81221 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in power conversion solutions.
The UCC280x family was engineered for cost-effective, high-reliability current-mode control in off-line and isolated DC-DC power supplies - emphasizing low start-up current, integrated protection, and pin compatibility with industry-standard UC384x controllers.
FAQ
What is the operating temperature range for UCC2804D/81221?
The UCC2804D/81221 is specified for operation from –40°C to +85°C ambient temperature, consistent with the UCC280x series qualification. This range supports deployment in industrial environments, enclosed power adapters, and telecom equipment where thermal management is constrained but not extreme.
Does UCC2804D/81221 require an external soft-start capacitor?
No, UCC2804D/81221 implements internal full-cycle soft start via COMP pin clamping - eliminating the need for external soft-start capacitors. This simplifies design, reduces BOM count, and ensures repeatable startup behavior across units without component tolerance drift.
Can UCC2804D/81221 replace UC3842 in existing designs?
Yes, UCC2804D/81221 has identical pinout and functional equivalence to UC3842, including matching FB, CS, COMP, and OUT signal roles. However, its lower start-up current (100 µA vs. ~1 mA), internal soft start, and leading-edge blanking may require minor loop compensation review for optimal transient response.
What is the maximum recommended oscillator frequency for UCC2804D/81221?
The UCC2804D/81221 supports operation up to 1 MHz, as confirmed in the SLUS270C datasheet. At higher frequencies, ensure proper PCB layout (short RC traces, local VCC/REF bypassing) and verify gate drive capability against MOSFET Qg to maintain reliable switching transitions.
Is UCC2804D/81221 RoHS compliant and lead-free?
Yes, UCC2804D/81221 is RoHS-compliant and manufactured with green (Pb-free, Sb/Br-free) finish per TI's eco-plan. It uses CU NIPDAU lead finish and meets MSL Level-1 (260°C), supporting standard reflow profiles without special handling requirements.
UCC2804D/81221 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- UCC280x
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- -
- Applications:
- PWM Controller
- Voltage - Input:
- -0.3V ~ 6.3V
- Voltage - Supply:
- 8.3V ~ 11V
- Current - Supply:
- 500 µA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
UCC2804D/81221 FAQ
1.How can I place an order for UCC2804D/81221 through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC2804D/81221 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for UCC2804D/81221 reliable?
The price and inventory of UCC2804D/81221 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC2804D/81221 is usually 5 days.
3.What payment methods are accepted for UCC2804D/81221?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC2804D/81221 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC2804D/81221?
UCC2804D/81221 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC2804D/81221 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for UCC2804D/81221?
For technical support, including UCC2804D/81221 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC2804D/81221 requirements.
6.How does Aetrix verify that UCC2804D/81221 is sourced from the original manufacturer or authorized distributors?
All UCC2804D/81221 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that UCC2804D/81221 meets industry standards.
7.What is the process for return or replacement of UCC2804D/81221?
All UCC2804D/81221 units undergo pre-shipment inspection (PSI). If there is an issue with UCC2804D/81221, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The UCC2804D/81221 part is unused and in its original packaging.
Return procedure for UCC2804D/81221:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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