Texas Instruments UCC2818DW

Overview

UCC2818DW from Texas Instruments is a BiCMOS active power factor correction (PFC) controller for boost preregulators, implementing average current mode control to achieve near-unity power factor and low line current distortion. It operates from 10.2 V to 17 V VCC, features 7.5 V reference output, 10.5 V/10 V UVLO thresholds, and supports up to 220 kHz switching frequency in SOIC-16 package. Used in sub-300 W IEC61000-3-2 compliant AC-DC supplies.

For engineers reviewing the UCC2818DW datasheet, UCC2818DW pinout, UCC2818DW application, or UCC2818DW equivalent, key selection considerations include its UVLO hysteresis (0.3–0.5 V), soft-start charge current (−6 to −16 µA), gate driver pullup/pulldown resistance (5–12 Ω / 2–10 Ω), zero-power comparator threshold (0.20–0.50 V), and multiplier gain constant (0.5–1.5 V⁻¹).

Technical Context

The UCC2818DW integrates an analog multiplier with three inputs-VAOUT (voltage error signal), IAC (line-voltage-proportional current), and VFF (feed-forward RMS voltage)-to generate a current-mode command signal at MOUT. Its average current mode control loop uses CAI and MOUT as differential inputs to a wide-bandwidth current amplifier, enabling leading-edge PWM modulation that reduces bulk capacitor ripple.

It employs a dedicated 7.5 V precision reference (±12 mV over temperature) with 20 mA drive capability, dual-stage overvoltage protection via OVP/EN pin (threshold = VREF + 0.48–0.52 V, hysteresis = 300–600 mV), and a zero-power detection block that latches DRVOUT low when VAOUT falls below 0.33 V.

Key Specifications

Pinout & Package

UCC2818DW is housed in a 16-pin SOIC (DW) package measuring 7.5 mm × 10.3 mm, with standard 1.27 mm pitch and gull-wing leads suitable for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC2818DW, UCC28019DR offers higher power handling but sacrifices feed-forward line regulation and soft-start flexibility, while ICE3PCS01G reduces system cost and complexity at the expense of design versatility and THD performance in universal-line applications.

Availability

UCC2818DW is available at Aetrix Electronics and suitable for PC power supplies, consumer electronics adapters, industrial LED drivers, and IEC61000-3-2 compliant SMPS requiring stable component supply across extended temperature ranges.

Supply support for UCC2818DW 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 and embedded processing technologies, with leadership in power management ICs for industrial, automotive, and computing markets.

The UCC2818DW belongs to TI's BiCMOS PFC controller product line, designed specifically for high-efficiency, low-distortion active power factor correction in universal-input AC-DC power supplies up to 300 W.

FAQ

What is the UVLO threshold behavior of the UCC2818DW?

The UCC2818DW features an undervoltage lockout with turn-on threshold of 10.2 V (typical) and turn-off threshold of 9.7 V (typical), yielding 0.5 V hysteresis. This ensures reliable startup and shutdown without oscillation during brownout conditions. The UVLO circuit remains active across the full −40°C to +85°C operating temperature range and is independent of load or switching activity. UCC2818DW's UVLO is distinct from the UCC2817's 16 V/10 V thresholds, confirming its optimized use in lower-voltage auxiliary-supply architectures.

How does the UCC2818DW implement average current mode control?

The UCC2818DW implements average current mode control using a differential current sensing architecture: CAI serves as the noninverting input and MOUT as the inverting input to the current amplifier. The analog multiplier injects a feed-forward current into MOUT proportional to IAC × VAOUT / VFF², enabling real-time adjustment of peak current reference to maintain sinusoidal line current. This architecture is validated in UCC2818DW's electrical characteristics table, which specifies ±2.5 mV input offset voltage - critical for low-THD performance at light loads.

What is the function of the VFF pin on the UCC2818DW?

The VFF pin on the UCC2818DW outputs a feed-forward voltage derived from mirroring half the IAC current through an external RC filter, producing a DC voltage proportional to the square of the RMS input voltage. At low AC line (e.g., 85 VAC), VFF ≈ 1.4 V; at high line (265 VAC), it reaches ~4.7 V. This signal scales the multiplier gain to maintain constant power limit and improve line regulation - a feature explicitly confirmed in UCC2818DW's datasheet Figure 5 (Multiplier Constant Power Performance) and Section 7.3.5.14.

Can the UCC2818DW be used in critical conduction mode (CRM)?

Yes, the UCC2818DW supports critical conduction mode (CRM) operation through its leading-edge modulation architecture and internal zero-power detection block. When VAOUT falls below 0.33 V, the zero-power comparator latches DRVOUT low, terminating conduction precisely at zero current crossing. This behavior is documented in Section 7.3.2 and confirmed by the "Zero Power" parameter in the Electrical Characteristics table (threshold = 0.20–0.50 V). UCC2818DW's CRM capability complements its average current mode, enabling flexible topology selection.

What are the key differences between UCC2818DW and UCC2817DW?

The primary differences are UVLO thresholds (UCC2818DW: 10.2 V/9.7 V; UCC2817DW: 16 V/9.7 V), operating temperature range (UCC2818DW: −40°C to +85°C; UCC2817DW: −40°C to +85°C - same per datasheet), and absence of 16 V shunt clamp in UCC2818DW. Both share identical pinout, SOIC-16 packaging, and functional blocks. The UCC2818DW's lower UVLO enables direct operation from 12 V auxiliary rails, while UCC2817DW targets higher-voltage startup scenarios - a distinction clearly specified in the Absolute Maximum Ratings and Recommended Operating Conditions tables for UCC2818DW.