Texas Instruments UCC2803N

Overview

UCC2803N from Texas Instruments is a low-power, current-mode PWM controller IC designed for fixed-frequency DC-to-DC and battery-operated switch-mode power supplies. It features 4 V internal reference voltage, 4.1 V UVLO turn-on threshold, 100% maximum duty cycle, 1 A totem-pole gate driver output, and operates across –40°C to 125°C. Its primary role is error-amplified current-mode control with integrated soft start and leading-edge blanking in compact SOIC-8 packaging.

For engineers reviewing the UCC2803N datasheet, UCC2803N pinout, UCC2803N application, or UCC2803N equivalent, key selection criteria include its 4 V reference optimized for low-input systems, 100 μA start-up current enabling ultra-low-power wake-up, internal leading-edge blanking eliminating external RC filtering on CS, and pin compatibility with UC3842/UC3842A - all critical for space-constrained, battery-powered PSU designs.

Technical Context

The UCC2803N implements a BiCMOS-based current-mode control architecture with dual comparators on the CS pin (PWM + overcurrent fault), 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, supporting up to 1 MHz operation with frequency calculated via f = 1.0/(R × C).

It integrates full-cycle soft start (COMP rise time ~4–10 ms), internal 4 V reference with ±1.5% tolerance, and UVLO with 4.1 V turn-on / 3.6 V turn-off (0.5 V hysteresis). The 1 A totem-pole output drives MOSFET gates directly, while OUT remains actively low during UVLO - ensuring safe startup sequencing in battery-fed converters.

Key Specifications

Pinout & Package

UCC2803N is supplied in an 8-pin SOIC (D package), body size 3.91 mm × 4.90 mm, 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 UC3842N, UCC2803N reduces external component count by integrating soft start and blanking, while offering 4× lower start-up current and better low-voltage operability; versus UCC2805N, it shares identical electrical behavior but may differ in screening or packaging options - making UCC2803N the baseline choice for general-purpose battery-fed DC-DC control.

Availability

UCC2803N is available at Aetrix Electronics and suitable for battery-operated power supplies, portable medical devices, and industrial sensor nodes requiring stable component supply with extended temperature support and low-power operation.

Supply support for UCC2803N 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 delivering analog, embedded processing, and connectivity solutions with emphasis on power management innovation and industrial reliability.

The UCC280x family was designed specifically for high-efficiency, low-component-count current-mode switching power supplies - targeting battery-powered, automotive, and industrial DC-DC applications where low IQ, thermal robustness, and integrated protection are essential.

FAQ

What is the UVLO hysteresis of the UCC2803N?

The UCC2803N has a UVLO turn-on threshold of 4.1 V (min) and turn-off threshold of 3.6 V (max), resulting in a guaranteed hysteresis of 0.2 V (min) to 0.8 V (max). This narrow hysteresis prevents oscillatory startup near battery depletion and ensures clean entry/exit from regulation in low-voltage systems. The exact value depends on device variation and temperature, but remains tightly controlled within datasheet limits for UCC2803N.

Does the UCC2803N require an external soft-start circuit?

No, the UCC2803N includes internal full-cycle soft start that clamps COMP voltage during power-up, ramping it to REF in 4–10 ms. This eliminates the need for external components like a soft-start capacitor, resistor, or PNP transistor - reducing bill-of-materials cost and PCB area. The feature is active on every power cycle and fault recovery, ensuring repeatable, controlled output voltage ramp in every UCC2803N application.

Can the UCC2803N replace UC3842 in an existing design?

Yes, the UCC2803N has identical pinout and basic functional compatibility with UC3842 and UC3842A, enabling drop-in replacement in many cases. However, due to its 4 V reference (vs. 5 V), lower UVLO thresholds, and integrated features like soft start and leading-edge blanking, minor schematic adjustments - especially to feedback divider and CS filtering - may be needed. Always validate loop stability and startup behavior when substituting UCC2803N for UC3842.

What is the maximum recommended oscillator frequency for UCC2803N?

The UCC2803N supports oscillator frequencies up to 1 MHz per datasheet specifications, though typical operation at 26–36 kHz (with RT = 100 kΩ, CT = 330 pF) is common for battery-fed DC-DC converters. At higher frequencies, ensure VCC bypassing meets minimum 1 µF + 0.1 µF requirements, keep RC traces short and isolated, and verify gate drive strength suffices for MOSFET Qg at target switching speed. Thermal derating may apply above 500 kHz in high-ambient environments.

How does the CS pin of UCC2803N differ from UC3842?

The UCC2803N CS pin connects to two independent comparators (PWM and overcurrent) and incorporates digital leading-edge blanking (50–150 ns), whereas UC3842 connects CS only to the PWM comparator and requires external RC filtering. This makes UCC2803N's CS inherently more noise-immune, eliminates the need for analog filtering, and reduces CS-to-OUT propagation delay - simplifying layout and improving reliability in noisy, high-dV/dt battery converter applications.