Texas Instruments UCC2803D

Overview

UCC2803D from Texas Instruments is a low-power BiCMOS current-mode PWM controller for fixed-frequency DC-DC and off-line SMPS, featuring 4 V reference voltage, 4.1 V UVLO turn-on threshold, 100% maximum duty cycle, 70 ns current-sense-to-output response, and SOIC-8 package. It targets battery-operated power supplies requiring low quiescent current and stable regulation under light loads.

For engineers reviewing the UCC2803D datasheet, UCC2803D pinout, UCC2803D application, or UCC2803D equivalent, key selection criteria include its 100 μA start-up supply current, internal leading-edge blanking, full-cycle soft start, 1.5% reference tolerance, and compatibility with UC3842/UC3842A PCB layouts-enabling drop-in upgrades in space-constrained, low-voltage PSU designs.

Technical Context

The UCC2803D implements a current-mode control architecture with dual comparators on the CS pin (PWM + overcurrent), digital leading-edge blanking (50–150 ns), and a true low-impedance 2-MHz error amplifier capable of sourcing/sinking COMP current. Its oscillator uses REF-derived charging current and RC timing to achieve up to 1 MHz operation with 2.45 V peak-to-peak amplitude.

Unlike UC3842, it integrates full-cycle fault soft start and eliminates external soft-start components via a 4–10 ms COMP ramp. The 4 V reference and low 3.6–4.5 V UVLO hysteresis are optimized for battery-fed systems, while the 1 A totem-pole output drives MOSFET gates directly without external buffers.

Key Specifications

Pinout & Package

UCC2803D 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, UCC2803D reduces component count and improves transient response via integrated features; compared with UCC2803DR, the D package offers easier hand-soldering and higher mechanical robustness in industrial environments.

Availability

UCC2803D is available at Aetrix Electronics and suitable for battery-operated DC-DC converters, low-voltage flyback PSUs, and industrial sensor node power supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for UCC2803D 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 control ICs.

The UCC280x product line was designed specifically for cost-sensitive, low-power fixed-frequency current-mode SMPS in battery-powered and industrial applications-emphasizing integration, efficiency, and layout simplicity over legacy UC3842 compatibility alone.

FAQ

What is the UVLO hysteresis of the UCC2803D?

The UCC2803D has a UVLO hysteresis of 0.2–0.8 V, with a typical turn-on threshold of 4.1 V and turn-off threshold of 3.6 V. This narrow hysteresis enables precise brown-out detection in battery systems where voltage sag must be distinguished from true depletion. The UCC2803D maintains stable operation across its full –40°C to 125°C range without hysteresis drift exceeding ±0.1 V.

Can the UCC2803D replace UC3842 in an existing design without changes?

The UCC2803D shares identical pinout and basic functional mapping with UC3842, but is not a direct drop-in replacement. Key differences include lower UVLO thresholds, 4 V reference (vs 5 V), internal soft start, and leading-edge blanking-requiring verification of feedback divider, startup resistor, and CS filtering. The UCC2803D reduces external part count but may need minor tuning for optimal stability.

What is the maximum recommended oscillator frequency for UCC2803D?

The UCC2803D supports oscillator frequencies up to 1 MHz, though typical operation with standard RC values (e.g., 100 kΩ/330 pF) yields 26–36 kHz. At 1 MHz, propagation delays and gate drive strength remain sufficient for small MOSFETs (Qg < 5 nC), but thermal dissipation in the SOIC-8 package must be validated per RθJA = 117.9°C/W under worst-case load conditions.

How does the COMP pin function differ between UCC2803D and UC3842?

Unlike UC3842's open-collector COMP output, the UCC2803D features a true low-impedance 2-MHz operational amplifier at COMP that both sources and sinks current. This allows direct zero-duty-cycle forcing by pulling COMP to GND and enables faster loop compensation. The UCC2803D also clamps COMP during soft start, eliminating the need for external soft-start circuitry used with UC3842.

Is the UCC2803D qualified for automotive applications?

The UCC2803D is specified for operation from –40°C to 125°C and meets AEC-Q100 HBM (±2500 V) and CDM (±1500 V) ESD ratings, making it suitable for under-hood and infotainment power supplies. However, it is not officially AEC-Q100 grade-1 certified; for ASIL-B or higher automotive safety applications, TI recommends the pin-compatible AEC-Q100 qualified UCC2803QDRQ1 variant instead of UCC2803D.