Texas Instruments UCC2804DTRG4

Overview

UCC2804DTRG4 from Texas Instruments is a low-power BiCMOS current-mode PWM controller for off-line and DC-DC fixed-frequency switching power supplies, featuring 50% maximum duty cycle, 12.5 V UVLO turn-on threshold, 8.3 V turn-off threshold, 1.5% reference voltage tolerance, and 70 ns current-sense-to-output response. It serves as the core control IC in isolated AC/DC adapters and industrial off-line PSUs.

For engineers reviewing the UCC2804DTRG4 datasheet, UCC2804DTRG4 pinout, UCC2804DTRG4 application, or UCC2804DTRG4 equivalent, key selection criteria include its 50% duty cycle limit, high-UVLO hysteresis (4.2 V), internal leading-edge blanking, full-cycle soft start, and SOIC-8 package compatibility with UC3842A-based designs.

Technical Context

The UCC2804DTRG4 implements a fixed-frequency current-mode control architecture with dual comparators on the CS pin - one for PWM regulation and another for overcurrent fault detection - enabling automatic soft-start recovery on fault. Its error amplifier delivers 2 MHz gain-bandwidth and true low-impedance sourcing/sinking capability at COMP.

Oscillator frequency is set via external RC network between REF and RC pins, supporting up to 1 MHz operation using Equation f = 1.5/(R × C); timing accuracy is maintained across –40°C to 125°C with ±2.5% oscillator temperature stability and 2.45 V peak-to-peak amplitude.

Key Specifications

Pinout & Package

UCC2804DTRG4 is housed in an 8-pin SOIC (D package), 3.91 mm × 4.90 mm body size, rated for –40°C to 125°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PWM controller applications.

Compared with UCC2802DTRG4, the UCC2804DTRG4 trades duty cycle headroom for tighter fault containment; versus UC3842AD8TRG4, it reduces external component count by integrating soft start, blanking, and enhanced COMP drive - critical for compact, low-noise, and high-reliability off-line supplies.

Availability

UCC2804DTRG4 is available at Aetrix Electronics and suitable for industrial off-line PSUs, automotive infotainment DC-DC converters, and battery charger auxiliary supplies requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.

Supply support for UCC2804DTRG4 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 decades of expertise in high-reliability power conversion ICs.

The UCC280x product line was designed specifically for high-efficiency, low-component-count current-mode switching power supplies targeting off-line and DC-DC applications across industrial, automotive, and computing markets.

FAQ

What is the maximum operating frequency of the UCC2804DTRG4?

The UCC2804DTRG4 supports oscillator frequencies up to 1 MHz, calculated using f = 1.5/(R × C) with recommended timing resistors (10 kΩ–200 kΩ) and capacitors (100 pF–1000 pF). At 1 MHz, the device maintains stable current-mode control and 49% maximum duty cycle, making it suitable for high-density flyback and forward converters where switching loss and magnetics size are critical constraints. The UCC2804DTRG4 achieves this with 2.45 V peak-to-peak oscillator amplitude and ±2.5% temperature stability.

Does the UCC2804DTRG4 require an external soft-start circuit?

No, the UCC2804DTRG4 integrates full-cycle soft start with a fixed 4–10 ms COMP voltage ramp, eliminating the need for external components like a PNP transistor, resistor, and capacitor. This internal implementation ensures controlled duty cycle buildup during power-up, preventing output overshoot and limiting inrush current into bulk capacitors. The UCC2804DTRG4 also features fault soft start, automatically restarting the COMP ramp upon overcurrent detection - a feature absent in UC3842-family controllers.

How does the CS pin functionality differ between UCC2804DTRG4 and UC3842A?

The UCC2804DTRG4 CS pin connects to two independent comparators - one for PWM regulation and another for overcurrent fault detection - whereas the UC3842A CS pin feeds only a single PWM comparator. Additionally, the UCC2804DTRG4 implements 100 ns digital leading-edge blanking, removing the need for external RC filtering in most applications. Its current-sense gain is 1.65 V/V (vs. 3 V/V in UC3842A), requiring recalibration of shunt resistor values when migrating designs.

Is the UCC2804DTRG4 pin-compatible with UC3842A-based PCBs?

Yes, the UCC2804DTRG4 uses the same SOIC-8 pinout as UC3842A and UC3842, enabling direct PCB footprint reuse. However, it is not a plug-in replacement: differences in COMP drive capability (low-Z op-amp vs. open-collector), CS architecture (dual comparators + blanking), and internal soft start require schematic verification and potential feedback loop compensation adjustments. The UCC2804DTRG4's higher UVLO thresholds (12.5 V/8.3 V) also necessitate validation of startup behavior in existing UC3842A designs.

What thermal performance can be expected from the UCC2804DTRG4 in SOIC-8 package?

In its SOIC-8 (D) package, the UCC2804DTRG4 has a junction-to-ambient thermal resistance (RθJA) of 117.9°C/W. At 25°C ambient and 500 µA operating current, typical power dissipation remains below 10 mW, resulting in negligible self-heating. Under full-load conditions with 20 mA average OUT current and 10 V VCC, power dissipation rises to ~200 mW, yielding ~24°C junction rise above ambient - well within the –40°C to 125°C operating range. For high-power designs, thermal relief pads and copper pours are recommended to enhance heat spreading.