Texas Instruments UCC2804PW

Overview

UCC2804PW from Texas Instruments is a low-power, current-mode PWM controller IC for fixed-frequency off-line and DC-DC switching power supplies. It features 50% maximum duty cycle, 12.5 V turn-on/8.3 V turn-off UVLO thresholds, 5 V reference with 1.5% tolerance, 1 A totem-pole gate driver output, and 70 ns current-sense-to-output response - enabling compact, high-efficiency designs in automotive PSUs and industrial AC/DC adapters.

For engineers reviewing the UCC2804PW datasheet, UCC2804PW pinout, UCC2804PW application, or UCC2804PW equivalent, key selection criteria include its TSSOP-8 package, internal leading-edge blanking (100 ns), full-cycle soft start, BiCMOS process for low quiescent current (100 μA start / 500 μA operating), and compatibility with UC3842/UC3842A PCB layouts.

Technical Context

The UCC2804PW implements fixed-frequency current-mode control using an internal oscillator (up to 1 MHz) with RC timing (REF→RC resistor + RC→GND capacitor), dual current-sense comparators (PWM and overcurrent), and digital leading-edge blanking synchronized to OUT rising edge. Its error amplifier delivers 2 MHz bandwidth and true low-impedance COMP output capable of sourcing/sinking current.

UVLO hysteresis (4.2 V) and 50% duty-cycle limit are hardwired for off-line applications requiring robust startup and controlled peak current. The device integrates internal soft-start clamp on COMP, eliminating external components, and uses a 5 V reference shared across error amplifier, logic, and oscillator circuits.

Key Specifications

Pinout & Package

TSSOP-8 (PW) package: 4.40 mm × 3.00 mm body, 0.65 mm pitch, surface-mount, moisture-sensitive level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC2802D and UC3842N, the UCC2804PW delivers higher integration (no external soft-start or CS filter), tighter reference tolerance (1.5% vs 2%), and lower start-up current (100 μA vs 1 mA), making it optimal for modern, compact, and energy-efficient power supplies.

Availability

UCC2804PW is available at Aetrix Electronics and suitable for automotive power supplies, industrial AC/DC adapters, and medical battery chargers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for UCC2804PW 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 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 automotive, industrial, and medical markets.

FAQ

What is the maximum operating frequency of the UCC2804PW?

The UCC2804PW supports oscillator frequencies up to 1 MHz, enabled by its BiCMOS process and optimized internal timing architecture. This allows designers to reduce transformer and filter component sizes while maintaining stable current-mode control. The actual frequency is set externally via resistor (REF to RC) and capacitor (RC to GND), with recommended values between 10 kΩ–200 kΩ and 100 pF–1000 pF respectively. UCC2804PW achieves this without sacrificing UVLO stability or reference accuracy.

Does the UCC2804PW require an external soft-start circuit?

No, the UCC2804PW integrates full-cycle soft start with a fixed 4 ms COMP voltage ramp to 5 V, eliminating the need for external resistors, capacitors, or transistors. This internal implementation ensures consistent startup behavior across temperature and supply variations. Unlike UC3842-based designs, UCC2804PW achieves zero external soft-start components while maintaining precise control over duty-cycle ramp rate - a verified feature confirmed in TI's SLUS270H datasheet Section 7.3.1.1.

How does the current-sense blanking function in the UCC2804PW?

The UCC2804PW implements digital leading-edge blanking (LEB) for 100 ns after each OUT rising edge, disconnecting the CS pin from both PWM and overcurrent comparators during that interval. This removes gate-drive-induced current-sense spikes without requiring external RC filtering. As confirmed in Table 5-1 and Section 7.3.1.3, LEB reduces CS-to-OUT propagation delay versus analog filters and prevents false overcurrent trips - a key advantage over UC3842-family controllers.

Is the UCC2804PW pin-compatible with the UC3842?

Yes, the UCC2804PW shares identical pin configuration, numbering, and signal assignment with UC3842 and UC3842A in both SOIC and TSSOP packages. However, it is not a plug-in replacement due to differences in COMP drive strength, internal soft start, and LEB functionality. Layout reuse is fully supported, but minor schematic updates (e.g., removal of external soft-start network) are required to leverage UCC2804PW's integrated features.

What is the purpose of the REF pin on the UCC2804PW?

The REF pin on the UCC2804PW outputs a precision 5 V reference (±1.5%) used internally for the error amplifier, oscillator, and logic circuits - and can also supply up to 5 mA to external circuitry such as feedback dividers or optocoupler biasing. Per Section 5.1 and Figure 5-2, REF must be bypassed with ≥0.1 µF ceramic capacitor placed adjacent to the pin to ensure stability and low noise; failure to do so risks regulation inaccuracy and oscillation.