Texas Instruments UCC3818APWR

Overview

UCC3818APWR from Texas Instruments is a BiCMOS average current-mode power factor correction (PFC) controller for boost preregulators, operating from 12 V to 18 V VCC, featuring 10.2 V UVLO turn-on threshold, 7.5 V reference output, and ±1.2 A peak gate drive capability. It enables IEC 61000-3-2-compliant <300 W supplies in PC power, lighting, and industrial AC/DC systems.

For engineers reviewing the UCC3818APWR datasheet, UCC3818APWR pinout, UCC3818APWR application, or UCC3818APWR equivalent, key selection criteria include its fixed-supply UVLO profile (10.2 V/9.7 V), average current mode control architecture, soft-start functionality, and TSSOP-16 package compatibility with space-constrained PFC stages.

Technical Context

The UCC3818APWR implements average current mode control using a high-gain current amplifier (90 dB open-loop gain, ±2 mV offset), multiplier-based feed-forward line regulation (VFF input, K = 1/V gain constant), and leading-edge PWM modulation synchronized to reduce bulk capacitor ripple. Its zero-power comparator triggers at 0.33 V on VAOUT to disable switching during no-load conditions.

It integrates a 7.5 V ±1.5% voltage reference (20 mA sink/source), overvoltage protection with 500 mV hysteresis on OVP/EN, and a programmable oscillator (6–220 kHz via RT/CT) with 80–120 kHz total variation across line and temperature. The gate driver delivers ±1.2 A peak current with 9 Ω pull-up and 4 Ω pull-down resistance.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm body size), thermally enhanced for surface-mount PFC controller placement near boost inductor and MOSFET.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power factor correction controller applications.

Compared with UCC3818APWR, UCC3817APWR supports bootstrap VCC but lacks fixed-supply optimization, while UCC2818APWR offers identical functionality with broader thermal qualification-making UCC3818APWR optimal for cost-sensitive commercial designs within 0°C–70°C ambient.

Availability

UCC3818APWR is available at Aetrix Electronics and suitable for PC power supplies, LED drivers, industrial AC/DC converters, and consumer audio power systems requiring stable component supply and long-term PFC controller availability.

Supply support for UCC3818APWR 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The UCC381xA family was designed specifically for high-efficiency, average current-mode active power factor correction in boost preregulators up to 300 W, targeting IEC 61000-3-2 compliance and reduced system-level component count.

FAQ

What is the UVLO behavior of the UCC3818APWR?

The UCC3818APWR features an undervoltage lockout with 10.2 V turn-on threshold and 9.7 V turn-off threshold, providing 0.5 V hysteresis. This fixed-supply UVLO profile ensures reliable startup and shutdown in designs with regulated VCC rails. Unlike the UCC3817A variant, the UCC3818APWR does not include an internal shunt regulator-its operation assumes a stable external 12–18 V supply. The UVLO function is fully integrated and requires no external components.

How does the UCC3818APWR implement average current mode control?

The UCC3818APWR implements average current mode control using a dedicated current amplifier with 90 dB open-loop gain and ±2 mV input offset, combined with a high-impedance multiplier that accepts IAC (line voltage proportional current), VFF (feed-forward voltage), and VAOUT (voltage error signal). The resulting MOUT current commands the PWM latch to maintain precise average inductor current tracking. This architecture eliminates need for slope compensation and provides inherent stability across line and load variations.

Can the UCC3818APWR be used in critical conduction mode (CRM)?

No-the UCC3818APWR is designed exclusively for continuous conduction mode (CCM) average current-mode PFC control. Its internal architecture-including the current amplifier transfer function, multiplier design, and PWM latch timing-is optimized for CCM operation. For CRM applications, TI recommends the UCC3805x or UCC3819 families. Attempting CRM operation with UCC3818APWR will result in unstable current regulation and failure to meet IEC 61000-3-2 harmonic limits.

What is the purpose of the VFF pin on the UCC3818APWR?

The VFF (voltage feed-forward) pin on the UCC3818APWR accepts a filtered RMS representation of the AC input voltage, typically generated by mirroring half the IAC current into an RC network. At low line (85 VAC), VFF is 1.4 V; at high line (265 VAC), it scales accordingly. This signal dynamically adjusts the multiplier gain to maintain constant power delivery and minimize input current distortion across universal AC input ranges-directly enabling compliance with IEC 61000-3-2 Class D limits.

Does the UCC3818APWR support overvoltage protection?

Yes-the UCC3818APWR includes integrated overvoltage protection via the OVP/EN pin, which functions as a window comparator. When the boost output voltage exceeds the programmed threshold (set by external resistor divider), the IC halts switching immediately. The protection features 500 mV hysteresis to prevent chatter during transients. Additionally, pulling OVP/EN below 1.9 V disables both gate drive and soft-start, providing a robust enable/disable interface for system-level fault management.