Texas Instruments UCC2805PW

Overview

UCC2805PW from Texas Instruments is a low-power BiCMOS current-mode PWM controller in an 8-pin TSSOP package, designed for fixed-frequency DC-to-DC converters and battery-operated power supplies. It features a 4 V reference voltage, 50% maximum duty cycle, 4.1 V turn-on UVLO threshold, 70 ns current-sense-to-output response, and internal leading-edge blanking - enabling compact, low-noise SMPS designs with minimal external components.

For engineers reviewing the UCC2805PW datasheet, UCC2805PW pinout, UCC2805PW application, or UCC2805PW equivalent, key selection criteria include its 4 V reference (optimized for low-input systems), 50% duty cycle limit, TSSOP-8 thermal performance (R_θJA = 117.9°C/W), and compatibility with UC3842-family layouts while delivering lower operating current (500 μA typ) and integrated soft start.

Technical Context

The UCC2805PW implements fixed-frequency current-mode control using a 2-MHz error amplifier, dual current-sense comparators (PWM + overcurrent), and digital leading-edge blanking (50–150 ns). Its oscillator uses REF-derived charging current into RC-timed capacitor, supporting up to 1 MHz operation with equations f ≈ 1.0/(R·C) for this variant.

It integrates full-cycle soft start (COMP rise time: 4–10 ms), internal 4 V reference (±1.5% tolerance), and UVLO with 4.1 V turn-on / 3.6 V turn-off thresholds and 0.5 V hysteresis - all optimized for stable startup and fault recovery in low-voltage battery-fed systems.

Key Specifications

Pinout & Package

UCC2805PW is housed in an 8-pin TSSOP (PW) package measuring 4.40 mm × 3.00 mm, optimized for thermal performance in surface-mount power supply designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC2803PW and UC3842D, the UCC2805PW delivers optimal trade-offs for battery-fed flyback converters: its 50% duty cycle prevents transformer saturation, 4 V reference minimizes dropout loss, and integrated features reduce external part count - without requiring PCB redesign due to identical TSSOP-8 footprint and UC3842-compatible pinout.

Availability

UCC2805PW is available at Aetrix Electronics and suitable for battery-operated power supplies, industrial IoT edge nodes, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for UCC2805PW 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 ICs, with decades of expertise in power conversion solutions.

The UCC280x product line was engineered specifically for high-efficiency, low-quiescent-current current-mode PWM control in battery-powered and thermally constrained DC-DC applications - emphasizing integration, precision reference stability, and robust fault handling.

FAQ

What is the maximum operating frequency of the UCC2805PW?

The UCC2805PW supports oscillator frequencies up to 1 MHz. Its typical base operating range is 26–36 kHz (at RT = 100 kΩ, CT = 330 pF), calculated using f ≈ 1.0/(R·C). The device maintains stable current-mode control and 50% duty cycle limit across this full range, with propagation delays and blanking timing preserved per datasheet specifications.

Does the UCC2805PW require an external soft-start circuit?

No, the UCC2805PW does not require an external soft-start circuit. It integrates full-cycle soft start with a fixed COMP voltage ramp (4–10 ms to REF), which inherently limits maximum duty cycle during startup. This eliminates the need for external components like a PNP transistor, resistor, and capacitor - reducing BOM count and improving reliability in compact power supply designs.

How does the UCC2805PW differ from the UC3842 in current-sense architecture?

The UCC2805PW differs from the UC3842 by incorporating dual current-sense comparators (PWM + overcurrent) and digital leading-edge blanking (50–150 ns), whereas the UC3842 uses a single comparator without blanking. This allows the UCC2805PW to accept raw current-sense signals directly - eliminating the external RC filter required by UC3842 - and provides faster fault detection with dedicated overcurrent protection that triggers a soft-start cycle.

What is the purpose of the REF pin on the UCC2805PW?

The REF pin on the UCC2805PW outputs a precision 4.0 V reference (±1.5% tolerance) used by the error amplifier, oscillator, and internal logic. It serves as the bias source for the RC timing network and must be bypassed with ≥0.1 μF ceramic capacitance placed adjacent to the pin. REF can also function as a logic-level power-good indicator when VCC rises above 1 V but remains below UVLO threshold.

Is the UCC2805PW pin-compatible with the UC3842 family?

Yes, the UCC2805PW has identical pin configuration and numbering to the UC3842 and UC3842A in both SOIC-8 and TSSOP-8 packages. This allows direct PCB footprint reuse. However, it is not a plug-in replacement: differences in reference voltage (4 V vs 5 V), UVLO thresholds, soft-start behavior, and current-sense architecture require validation of loop compensation and startup sequencing in existing UC3842 designs.