Texas Instruments UCC3817DTR

Overview

UCC3817DTR 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 features a 7.5-V reference, 16-V UVLO turn-on threshold, 95% maximum duty cycle, and integrated totem-pole gate driver delivering up to 1.2-A peak sink current - designed for IEC 61000-3-2-compliant <300-W AC/DC supplies.

For engineers reviewing the UCC3817DTR datasheet, UCC3817DTR pinout, UCC3817DTR application, or UCC3817DTR equivalent, key selection considerations include its 0°C to 70°C operating temperature range, SOIC-16 package, leading-edge PWM modulation for reduced bulk capacitor ripple, and compatibility with universal AC input (85–265 VAC) in PC power, lighting, and industrial power supply designs.

Technical Context

The UCC3817DTR employs an analog multiplier with three inputs (VAOUT, IAC, VFF) to generate a current-mode command signal (IMOUT), enabling precise feed-forward line regulation and constant-power limiting. Its voltage error amplifier provides 90-dB open-loop gain and 5.5-V clamped output, while the current amplifier delivers ±2-mV offset and operates down to GND on both inputs for robust sensing.

UVLO thresholds are fixed at 16 V (turn-on) / 9.7 V (turn-off) with 6.3-V hysteresis; OVP/EN functions as a window comparator with 1.9-V enable threshold and programmable overvoltage detection referenced to VREF + 0.50 V. The oscillator uses external RT/CT components to set frequency between 6 kHz and 220 kHz per f ≈ 0.6/(RT × CT).

Key Specifications

Pinout & Package

UCC3817DTR is housed in a 16-pin SOIC (D) package measuring 3.91 mm × 9.9 mm, optimized for thermal dissipation (R_θJA = 73.9°C/W) and PCB layout simplicity in high-density power stages.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC2817DTR and ICE3PCS01G, the UCC3817DTR offers superior thermal margin for mid-power industrial use, greater design flexibility via programmable frequency, and higher gate drive strength - making it optimal for 200–300 W systems requiring robustness and regulatory compliance.

Availability

UCC3817DTR is available at Aetrix Electronics and suitable for PC power supplies, LED driver input stages, industrial AC/DC modules, and consumer audio power supplies requiring stable component supply and long-term production continuity.

Supply support for UCC3817DTR 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 over 50 years of power conversion innovation.

The UCC3817DTR belongs to TI's BiCMOS PFC controller product line, engineered 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 operating temperature range for the UCC3817DTR?

The UCC3817DTR is specified for operation from 0°C to +70°C ambient temperature. This distinguishes it from the UCC2817DTR, which supports –40°C to +85°C. The UCC3817DTR's thermal design targets commercial-grade power supplies where internal board temperatures remain within this range during continuous operation.

Does the UCC3817DTR support discontinuous conduction mode (DCM) operation?

The UCC3817DTR implements average current-mode control optimized for continuous conduction mode (CCM) boost operation. While it can function in transition mode near light loads, it does not include dedicated zero-current detection or DCM-specific compensation - unlike controllers such as the UCC28070. For pure DCM designs, alternate PFC ICs are recommended.

What is the purpose of the VFF pin on the UCC3817DTR?

The VFF pin on the UCC3817DTR provides a feed-forward RMS voltage derived from half the IAC current, filtered externally. At low AC line (e.g., 85 VAC), VFF settles near 1.4 V; at high line (265 VAC), it reaches ~4.7 V. This scales the multiplier's power-limiting behavior dynamically, maintaining consistent output power across universal input without manual adjustment.

Can the UCC3817DTR be used without the SS (soft-start) capacitor?

No - the UCC3817DTR requires an external capacitor on the SS pin to control startup ramp rate. Grounding SS does not force 0% duty cycle and may cause uncontrolled inrush current. A typical 100-nF capacitor yields ~100-ms soft-start time with the internal 10-μA charge current, preventing output overshoot and MOSFET stress during power-up.

How is overvoltage protection implemented on the UCC3817DTR?

OVP on the UCC3817DTR is implemented via the OVP/EN pin, which functions as a window comparator. When voltage at this pin exceeds VREF + 0.50 V (≈8.0 V), the controller halts switching. Hysteresis of 500 mV ensures clean recovery. The threshold is programmable using a resistor divider from the boost output, allowing precise trip points like 410 V or 430 V DC.