Texas Instruments UCC3817ADR

Overview

UCC3817ADR from Texas Instruments is a BiCMOS average current-mode power factor correction (PFC) controller for boost preregulators, delivering near-unity power factor, 16 V UVLO turn-on threshold, ±1.2 A peak gate drive, and 6–220 kHz programmable oscillator frequency. It operates across 0°C to 70°C and supports IEC 61000-3-2 compliance in sub-300 W AC/DC supplies.

For engineers reviewing the UCC3817ADR datasheet, UCC3817ADR pinout, UCC3817ADR application, or UCC3817ADR equivalent, this device is selected for high-efficiency, low-distortion PFC stages requiring accurate feed-forward line regulation, overvoltage protection, and robust soft-start control in PC, lighting, and industrial power supplies.

Technical Context

The UCC3817ADR implements average current-mode control with a high-gain current amplifier (90 dB open-loop gain, ±2 mV offset), a precision 7.5 V reference (±1.5% accuracy), and a three-input analog multiplier (IAC, VFF, VAOUT) enabling leading-edge modulation. Its zero-power comparator triggers at 0.33 V on VAOUT to disable switching during no-load conditions.

Oscillator frequency is set via external RT (10–100 kΩ) and CT (270 pF typical), yielding 80–120 kHz total variation across line and temperature. The gate driver features 9 Ω pull-up and 4 Ω pull-down resistance, supporting fast rise/fall times (25 ns / 10 ns into 1 nF) and 95% maximum duty cycle.

Key Specifications

Pinout & Package

UCC3817ADR is housed in a 16-pin SOIC (D package), 4.90 mm × 3.91 mm body, tape-and-reel format (2500 units/reel). Pin functions are validated per TI SLUS577D Rev D.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC3817ADR, UCC3817AD offers identical performance in tube packaging for flexibility, while UCC2817AD extends thermal range at no functional trade-off-making it suitable for harsh environments where UCC3817ADR's 0°C–70°C rating is insufficient.

Availability

UCC3817ADR 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 full production support.

Supply support for UCC3817ADR 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, embedded processing, and power management ICs, with leadership in high-reliability power conversion solutions.

The UCC3817ADR belongs to TI's UCCx81xA BiCMOS PFC controller family, designed specifically for cost-sensitive, high-efficiency active power factor correction in sub-300 W AC/DC power supplies compliant with IEC 61000-3-2.

FAQ

What is the operating temperature range for UCC3817ADR?

The UCC3817ADR is specified for operation from 0°C to 70°C ambient temperature. This commercial-grade rating makes it suitable for indoor consumer and computing applications but excludes extended industrial or automotive environments. For designs requiring –40°C to 85°C operation, the pin-compatible UCC2817AD is the appropriate alternative. All thermal metrics-including RθJA = 73.9°C/W for the SOIC package-are validated within this range.

Does UCC3817ADR support both continuous and critical conduction mode?

UCC3817ADR is optimized for average current-mode control in continuous conduction mode (CCM) boost PFC topologies. While its architecture can be adapted for transition mode with external modifications, the datasheet specifies CCM operation, including design equations, compensation guidelines, and test circuits for CCM. Critical conduction mode (CRM) implementations require different controllers such as the UCC38051, which are explicitly characterized for boundary-mode operation.

How does the OVP/EN pin function in UCC3817ADR?

In UCC3817ADR, the OVP/EN pin serves dual roles: as an overvoltage protection input (trip threshold = 1.07 × VREF + 500 mV hysteresis) and as an enable/disable control (disable threshold <1.9 V). When OVP is triggered, DRVOUT is latched off until VCC cycles or the fault clears. If pulled below 1.9 V, it also forces rapid discharge of the SS capacitor, ensuring immediate shutdown. This dual functionality simplifies system-level fault management without external logic.

What is the purpose of the VFF pin on UCC3817ADR?

The VFF (voltage feed-forward) pin on UCC3817ADR accepts a scaled RMS representation of the AC input voltage, generated externally by mirroring IAC through an RC filter. At low line (85 VAC), VFF ≈ 1.4 V; at high line (265 VAC), it rises to ≈4.7 V. This signal dynamically adjusts the multiplier gain to maintain constant power delivery across universal input ranges-enabling stable regulation and low THD without manual gain switching or microcontroller intervention.

Can UCC3817ADR be used with a bootstrap VCC supply?

Yes, UCC3817ADR supports bootstrap VCC supply configurations due to its integrated shunt regulator and low 150 µA start-up current. During startup, the internal shunt regulates VCC from a high-impedance resistive divider across the boost output, eliminating the need for an auxiliary winding or dedicated bias supply. Once running, VCC is sustained by the auxiliary winding or dedicated supply, with the shunt regulator automatically disabling above UVLO turn-on threshold.