Texas Instruments UCC2800D

Overview

UCC2800D from Texas Instruments is a low-power BiCMOS current-mode PWM controller for fixed-frequency off-line and DC-DC switching power supplies. It delivers 100% maximum duty cycle, 5 V reference voltage with ±1.5% tolerance, 70 ns current-sense-to-output response, and operates up to 1 MHz. It serves as the core control IC in isolated flyback and forward converters for industrial and automotive PSU applications.

For engineers reviewing the UCC2800D datasheet, UCC2800D pinout, UCC2800D application, or UCC2800D equivalent, key selection criteria include UVLO thresholds (7.2 V turn-on / 6.9 V turn-off), internal soft start timing (4 ms COMP rise), leading-edge blanking (100 ns), and compatibility with UC3842/UC3842A PCB layouts while reducing external component count.

Technical Context

The UCC2800D implements a current-mode control architecture with dual comparators on the CS pin - one for PWM regulation and one for overcurrent fault detection - both protected by digital leading-edge blanking. Its error amplifier is a true 2-MHz, low-output-impedance op-amp capable of sourcing and sinking current, enabling zero-duty-cycle forcing via COMP grounding.

It features an internal oscillator with REF-referenced timing (RT from REF to RC, CT from RC to GND), supporting frequencies up to 1 MHz using Equation f = 1.5/(R×C). The device integrates full-cycle soft start clamping on COMP and low-bias UVLO hysteresis (0.3 V) optimized for stable startup in high-noise environments.

Key Specifications

Pinout & Package

UCC2800D 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 current-mode PWM controller applications.

Compared with UC3842D, UCC2800D reduces component count by eliminating soft-start and CS filtering parts while improving noise immunity; versus UCC2802D, it lowers UVLO thresholds for better compatibility with low-voltage DC inputs, trading off universal AC input capability for tighter control in battery-powered systems.

Availability

UCC2800D is available at Aetrix Electronics and suitable for industrial AC-DC adapters, automotive DC-DC converters, and telecom power modules requiring stable component supply, long-lifecycle support, and AEC-Q100-aligned reliability.

Supply support for UCC2800D 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 company specializing in analog, embedded processing, and power management technologies with over 50 years of power IC innovation.

The UCC280x family was designed specifically for high-efficiency, low-component-count current-mode switching power supplies targeting industrial, automotive, and telecom applications demanding extended temperature operation and robust noise immunity.

FAQ

What is the maximum operating frequency of the UCC2800D?

The UCC2800D supports oscillator frequencies up to 1 MHz, enabled by its BiCMOS process and REF-referenced timing architecture. This is double the 500 kHz limit of UC3842-family controllers. Frequency is set via RT (from REF to RC) and CT (from RC to GND) using f = 1.5/(R×C), with recommended R = 10–200 kΩ and C = 100–1000 pF. At 1 MHz, the UCC2800D maintains stable 100% duty cycle and 70 ns CS-to-OUT response.

Does the UCC2800D require an external soft-start circuit?

No, the UCC2800D includes internal full-cycle soft start that clamps the COMP voltage and ramps it to 5 V over 4 ms. This eliminates the need for external components such as a soft-start capacitor, resistor, and PNP transistor typically used with UC3842. The integrated solution improves startup repeatability and reduces BOM count by three parts while maintaining controlled output voltage rise in the UCC2800D.

How does the CS pin functionality differ between UCC2800D and UC3842D?

The UCC2800D CS pin connects to two independent comparators - one for PWM regulation and one for overcurrent fault detection - both protected by 100 ns digital leading-edge blanking. In contrast, UC3842D has only a single PWM comparator on CS with no built-in blanking, requiring external RC filtering. This makes the UCC2800D more robust in noisy switch-node environments and simplifies layout, directly benefiting UCC2800D-based designs.

Is the UCC2800D pin-compatible with UC3842 and UC3842A?

Yes, the UCC2800D uses the identical 8-pin SOIC (D) package and pin configuration as UC3842 and UC3842A - including COMP, FB, CS, RC, GND, OUT, VCC, and REF assignments. However, it is not a plug-in replacement due to differences in internal soft start, CS blanking, and oscillator architecture. Layout reuse is possible, but minor schematic updates (e.g., removing external soft-start and CS filter) are required to fully leverage UCC2800D capabilities.

What are the UVLO thresholds and hysteresis of the UCC2800D?

The UCC2800D has a turn-on threshold of 7.2 V (±0.6 V) and a turn-off threshold of 6.9 V (±0.6 V), resulting in 0.3 V nominal hysteresis. This narrow hysteresis ensures stable operation during marginal input conditions, especially in 12 V DC systems subject to ripple or sag. The thresholds track the internal VCC Zener (13.5 V), providing predictable startup behavior - a key differentiator from UC3842 variants with wider hysteresis - and critical for consistent UCC2800D performance in automotive and industrial applications.