Texas Instruments UCC3818APW

Overview

UCC3818APW from Texas Instruments is a BiCMOS average current-mode power factor correction (PFC) controller for boost preregulators, featuring 10.2 V UVLO turn-on threshold, 7.5-V reference output, ±1.2-A peak gate drive, 6–220 kHz programmable oscillator frequency, and OVP/EN pin with 1.9-V enable threshold - used in IEC61000-3-2-compliant sub-300-W PC and industrial power supplies.

For engineers reviewing the UCC3818APW datasheet, UCC3818APW pinout, UCC3818APW application, or UCC3818APW equivalent, key selection criteria include its fixed-supply UVLO profile (10.2 V/9.7 V), TSSOP-16 package thermal resistance (RθJA = 98.9°C/W), average current mode control architecture, and compatibility with leading-edge modulation for bulk capacitor ripple reduction.

Technical Context

The UCC3818APW 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 zero-power comparator with 0.33-V threshold on VAOUT. Its PWM latch uses leading-edge modulation synchronized to oscillator ramp for reduced output capacitor ripple.

It integrates a 7.5-V precision reference (±1.5% initial accuracy, 10 mV load/line regulation), voltage error amplifier (50–90 dB gain, 5.5-V clamped output), and robust gate driver (9 Ω pull-up / 4 Ω pull-down, 25–50 ns rise/fall times). The device operates from 12–18 V VCC and supports world-wide AC line inputs via VFF scaling.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm body size, 1.2 mm max height), surface-mount, RoHS-compliant, with exposed thermal pad (not electrically connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC3817APW and UCC2818APW, the UCC3818APW offers optimal cost/performance for fixed-supply commercial power supplies operating at 0°C–70°C, with no design changes needed beyond VCC sourcing and UVLO configuration.

Availability

UCC3818APW is available at Aetrix Electronics and suitable for PC power supplies, industrial AC-DC adapters, and LED driver front-ends requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for UCC3818APW 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 delivering analog and embedded processing solutions, with leadership in power management ICs and industrial interface technologies.

The UCC3818APW belongs to TI's UCCx81xA BiCMOS PFC controller family, designed specifically for cost-sensitive, high-efficiency boost preregulators in sub-300-W IEC61000-3-2-compliant power supplies.

FAQ

What is the UVLO behavior of the UCC3818APW?

The UCC3818APW features an undervoltage lockout with 10.2 V turn-on threshold and 9.7 V turn-off threshold, providing 0.5 V hysteresis. This ensures clean startup and shutdown without oscillation during brownout conditions. Unlike the UCC3817A variant, the UCC3818APW is intended for fixed VCC supplies - it does not integrate a shunt regulator. The UVLO behavior is fully characterized across temperature and ensures reliable operation in commercial-grade power supplies.

How does the UCC3818APW implement average current mode control?

The UCC3818APW implements average current mode control using a dedicated current amplifier with 90 dB open-loop gain and ±2 mV input offset, fed by CAI (non-inverting) and MOUT (inverting) inputs. The amplifier output (CAOUT) drives a PWM comparator referenced to the oscillator ramp. This architecture maintains stable, low-distortion sinusoidal line current by continuously adjusting duty cycle to match the average sensed current to the multiplier output - critical for meeting IEC61000-3-2 harmonic limits.

What is the function of the VFF pin on the UCC3818APW?

The VFF (voltage feed-forward) pin on the UCC3818APW accepts a scaled RMS representation of the AC input voltage (1.4 V at low line, 4.7 V at high line) to dynamically adjust the multiplier gain. This compensates for line-voltage variations and maintains constant power delivery across universal 85–265 VAC inputs. The VFF signal ensures the PFC stage delivers consistent output power regardless of input voltage, improving efficiency and thermal stability in real-world operating conditions.

Can the UCC3818APW be used with leading-edge modulation?

Yes, the UCC3818APW supports leading-edge modulation via its oscillator architecture and PWM latch design. When synchronized to an external clock or configured with appropriate timing components, the leading-edge PWM reduces ripple current in the bulk output capacitor by up to 40%, lowering RMS stress on electrolytics and extending power supply lifetime. This feature is explicitly documented in TI's SLUS577D datasheet and validated in typical application circuits.

What package type is the UCC3818APW supplied in?

The UCC3818APW is supplied in a TSSOP-16 package (body size 5.00 mm × 4.40 mm, 1.2 mm max height), with gull-wing leads and RoHS-compliant finish. It features an exposed thermal pad (non-electrical) for improved heat dissipation. Thermal resistance is RθJA = 98.9°C/W, making it suitable for compact, convection-cooled PFC designs. The PW suffix explicitly denotes this TSSOP variant per TI's orderable addendum.