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Texas Instruments UCC2804DTR/81221
- Part No.:
- UCC2804DTR/81221
- Manufacturer:
- Texas Instruments
- Category:
- Power Supply Controllers, Monitors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
UCC2804DTR/81221.pdf
- Description:
- IC OFFLINE SWITCH MULT TOP 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,408
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Product details
Overview
UCC2804DTR/81221 from Texas Instruments is a BiCMOS current-mode PWM controller IC designed for fixed-frequency off-line and DC-DC 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 operates from –40°C to +85°C in an SOIC-8 package. It delivers 1A totem-pole gate drive output and supports up to 1MHz operation in AC-DC adapter and industrial SMPS designs.
For engineers reviewing the UCC2804DTR/81221 datasheet, UCC2804DTR/81221 pinout, UCC2804DTR/81221 application, or UCC2804DTR/81221 equivalent, key selection criteria include its 50% duty-cycle limit, high-precision 5V reference, internal soft start, leading-edge blanking for current-sense immunity, and compatibility with UC3842/UC3842A layouts.
Technical Context
The UCC2804DTR/81221 implements current-mode control using an internal error amplifier (2MHz GBW), PWM comparator, and digital leading-edge blanking on the CS pin to suppress switching noise. Its oscillator uses external RC timing components (REF→RC resistor, RC→GND capacitor) to set frequency, with output frequency equal to oscillator frequency (not doubled).
It integrates a 1A totem-pole output stage capable of driving MOSFET gates directly, internal 5V reference with 1.5% initial tolerance and <130µV RMS noise, and undervoltage lockout with 4.2V hysteresis (12.5V ON / 8.3V OFF). The COMP pin sources/sinks current and serves as both error amplifier output and PWM comparator input.
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 regulation in isolated power supplies. |
| UVLO Thresholds | 12.5 V turn-on / 8.3 V turn-off - ensures reliable startup and brownout protection in universal-input AC-DC applications. |
| Operating Temp Range | –40°C to +85°C - qualified for industrial and commercial power supply environments. |
| Gate Drive Output | ±1.0 A totem-pole - directly drives medium-power MOSFETs without external buffers in sub-100W designs. |
| Current Sense Blanking | 100 ns - digitally blanks CS input after OUT rising edge, eliminating need for external RC filter in most layouts. |
| Start-up Current | 100 µA typical - enables high-impedance VCC biasing for low-loss auxiliary winding startup. |
Pinout & Package
UCC2804DTR/81221 is housed in an 8-pin SOIC (D package), RoHS-compliant, with standard pinout matching UC3842/UC3842A. Pin 1 is OUT; Pin 2 is VCC; Pin 3 is REF; Pin 4 is GND; Pin 5 is FB; Pin 6 is COMP; Pin 7 is CS; Pin 8 is RC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT (Pin 1) | Power driver output | Drives MOSFET gate with ±1A peak; actively held low during UVLO. |
| VCC (Pin 2) | Supply input | Accepts 10–12V; powers internal circuitry and gate driver; requires local 0.1µF ceramic bypass. |
| REF (Pin 3) | 5V reference output | Stable 5V source for feedback divider and logic; requires 0.1µF ceramic bypass to GND. |
| GND (Pin 4) | Power and signal ground | Common return for all internal functions; must be low-impedance connection to power ground plane. |
| FB (Pin 5) | Inverting error amp input | Connects to voltage divider from output; sets regulated output voltage via REF reference. |
| COMP (Pin 6) | Error amp output / PWM comparator input | Sources/sinks current; clamped during soft start; controls duty cycle based on FB and CS signals. |
| CS (Pin 7) | Current sense input | Monitors primary-side current via sense resistor; blanked for 100ns after each OUT pulse. |
| RC (Pin 8) | Oscillator timing | Connects to timing capacitor (to GND) and resistor (from REF); sets switching frequency per F = 1.5/(R×C). |
Key Features
| Feature | Design Value |
|---|---|
| Internal full-cycle soft start | COMP voltage ramped over 4–10 ms to limit inrush current and prevent overshoot at startup. |
| Leading-edge blanking (LEB) | Digital 100 ns blanking window on CS pin eliminates need for analog RC filtering and reduces propagation delay. |
| 1.5% reference tolerance | Enables tight output voltage regulation (<±2%) without post-regulation trimming in cost-sensitive SMPS. |
| 70 ns CS-to-OUT response | Ensures fast overcurrent shutdown, critical for protecting MOSFETs and transformers under fault conditions. |
| Same pinout as UC3842/UC3842A | Allows drop-in replacement in legacy UC3842-based designs without PCB layout changes. |
Applications
| AC-DC Adapter | Industrial SMPS |
|---|---|
Use Scenario: 12V/5A offline flyback converter powering consumer electronics with universal AC input (85–265VAC). IC Role / Device Role / Timing Role: Primary-side current-mode PWM controller generating gate drive for power MOSFET; regulates output via optocoupler feedback to FB pin. Use Value: 50% duty cycle prevents transformer core saturation; 12.5V UVLO ensures reliable startup across wide input range; 1A drive supports 400V MOSFETs with <20nC gate charge. |
Use Scenario: 24V/3A industrial DC-DC converter operating in harsh ambient (–25°C to +70°C) with high line transient immunity. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller managing synchronous rectification timing and overcurrent protection via CS pin. Use Value: Internal LEB rejects EMI-induced false triggering; 8.3V UVLO hysteresis prevents oscillation during brownouts; SOIC-8 package supports automated assembly and thermal relief. |
| LED Driver | Telecom Power Module |
Use Scenario: Constant-current 48V LED string driver with dimming interface and short-circuit protection. IC Role / Device Role / Timing Role: PWM controller regulating average LED current via secondary-side sense resistor and CS feedback path. Use Value: 100 µA start-up current enables direct auxiliary winding biasing; 5V reference accuracy ensures stable current setpoint across temperature. |
Use Scenario: 5V/10A telecom half-bridge DC-DC module requiring high reliability and fast transient response. IC Role / Device Role / Timing Role: Primary-side controller synchronizing gate drive with isolated current sensing and fault latching. Use Value: 70 ns CS-to-OUT response enables sub-500 ns fault shutdown; 1.5% reference supports <±1% output tolerance required by GR-1089 compliance. |
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; 1A drive; but higher 16V/10V UVLO, no internal soft start, no LEB, 2% reference tolerance. | Lacks integrated soft start and LEB-requires external RC networks for stability and noise immunity. | Choose UC3842N only if legacy design reuse is mandatory and external compensation is acceptable. |
| UCC2804DR81221G4 | Identical electrical specs and SOIC-8 packaging; differs only in tape-and-reel packaging (2500 pcs vs. 2500 pcs) and RoHS marking (G4 suffix). | No functional difference; identical performance, thermal behavior, and layout compatibility. | Select UCC2804DR81221G4 when G4-compliant labeling or specific reel logistics are required. |
Compared with UC3842N, UCC2804DTR/81221 adds internal soft start and leading-edge blanking-reducing BOM count and improving noise immunity-while UCC2804DR81221G4 offers identical functionality with updated RoHS compliance labeling and reel packaging.
Availability
UCC2804DTR/81221 is available at Aetrix Electronics and suitable for AC-DC adapters, industrial SMPS, and telecom power modules requiring stable component supply, long-term manufacturability, and RoHS-compliant sourcing.
Supply support for UCC2804DTR/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 technologies with over 50 years of innovation in power conversion ICs.
The UCC280x series was designed specifically for cost-effective, high-reliability current-mode switching power supplies in industrial and commercial applications, emphasizing low start-up current, integrated protection, and layout compatibility with industry-standard controllers.
FAQ
What is the maximum operating frequency of the UCC2804DTR/81221?
The UCC2804DTR/81221 supports operation up to 1 MHz. Its oscillator frequency is set externally using a resistor from REF to RC and a capacitor from RC to GND, with frequency calculated as F = 1.5/(R × C). At 1 MHz, the device maintains stable current-mode control and full 50% duty-cycle capability, making it suitable for compact, high-density power supplies where size and efficiency are critical.
Does the UCC2804DTR/81221 require an external soft-start circuit?
No, the UCC2804DTR/81221 includes internal full-cycle soft start, which ramps the COMP voltage from 0 V to REF – 1 V over 4–10 ms. This eliminates the need for external soft-start components and ensures controlled output voltage rise, reducing stress on output capacitors and preventing inrush-related failures in the UCC2804DTR/81221-based design.
Can the UCC2804DTR/81221 replace a UC3842 in an existing design?
Yes-the UCC2804DTR/81221 has identical pinout, drive strength, and basic functional architecture as the UC3842 and UC3842A. However, it adds internal soft start and leading-edge blanking, so existing UC3842 designs may require minor tuning of feedback compensation or removal of external soft-start components to fully leverage UCC2804DTR/81221 capabilities.
What is the purpose of the REF pin on the UCC2804DTR/81221?
The REF pin on the UCC2804DTR/81221 provides a precision 5.00 V ±1.5% reference used for the error amplifier's feedback loop and as a logic supply for internal comparators and oscillators. It must be bypassed with at least 0.1 µF ceramic capacitance to GND, placed adjacent to the pin, to ensure stability and low-noise operation of the UCC2804DTR/81221 in high-frequency switching environments.
How does the current-sense blanking function work in the UCC2804DTR/81221?
The UCC2804DTR/81221 implements digital leading-edge blanking: for 100 ns after each rising edge of the OUT signal, the CS pin is disconnected from the current-sense comparator. This prevents false triggering due to MOSFET switching spikes and eliminates the need for external RC filters-reducing component count and propagation delay while maintaining robust overcurrent protection in the UCC2804DTR/81221-based power supply.
UCC2804DTR/81221 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- UCC280x
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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
UCC2804DTR/81221 FAQ
1.How can I place an order for UCC2804DTR/81221 through Aetrix?
Please submit a Request for Quotation (RFQ) for UCC2804DTR/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 UCC2804DTR/81221 reliable?
The price and inventory of UCC2804DTR/81221 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for UCC2804DTR/81221 is usually 5 days.
3.What payment methods are accepted for UCC2804DTR/81221?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for UCC2804DTR/81221 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for UCC2804DTR/81221?
UCC2804DTR/81221 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your UCC2804DTR/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 UCC2804DTR/81221?
For technical support, including UCC2804DTR/81221 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your UCC2804DTR/81221 requirements.
6.How does Aetrix verify that UCC2804DTR/81221 is sourced from the original manufacturer or authorized distributors?
All UCC2804DTR/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 UCC2804DTR/81221 meets industry standards.
7.What is the process for return or replacement of UCC2804DTR/81221?
All UCC2804DTR/81221 units undergo pre-shipment inspection (PSI). If there is an issue with UCC2804DTR/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 UCC2804DTR/81221 part is unused and in its original packaging.
Return procedure for UCC2804DTR/81221:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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