Texas Instruments UCC28056ADBVT

Overview

UCC28056ADBVT from Texas Instruments is a 6-pin SOT-23 transition-mode (TM) and discontinuous conduction mode (DCM) power factor correction (PFC) controller for AC-DC front ends. It delivers <80 mW no-load input power at 230 VAC, supports up to 300 W PFC stages, and features valley-synchronized MOSFET turn-on, burst-mode operation with soft entry/exit, and dual output over-voltage protection. It enables PFC-always-on architectures in desktop computing, LED drivers, and industrial power supplies.

For engineers reviewing the UCC28056ADBVT datasheet, UCC28056ADBVT pinout, UCC28056ADBVT application, or UCC28056ADBVT equivalent, key selection criteria include its ultra-low standby power capability, multi-mode TM/DCM control logic, FET drain valley detection timing, integrated thermal shutdown, and compatibility with LLC controllers like UCC256403/4 for full-system efficiency optimization.

Technical Context

The UCC28056ADBVT implements mixed-mode control: it operates in transition mode at full load and automatically transitions into DCM at reduced load, reducing switching frequency while maintaining low THD and near-unity power factor. Its ZCD/CS pin performs dual functions-current sensing during DRV high and valley detection during DRV low-enabling synchronous turn-on without auxiliary winding.

Burst mode activates below 10% load using COMP voltage thresholds (VBSTFall = 0.5 V, VBSTRise = 0.625 V), with soft-entry/exit periods minimizing audible noise. The error amplifier features nonlinear transconductance gain (50 µS small-signal, 300 µS large-signal) and fast transient response without compromising line current distortion.

Key Specifications

Pinout & Package

UCC28056ADBVT is housed in a 6-pin SOT-23 package (2.90 mm × 1.6 mm body size) with exposed pad for thermal performance. Pin numbering follows standard DBV top-view orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UCC28056ADBVT, UCC28056A offers superior noise immunity and extended OVP2 functionality but requires minor layout review for ZCD routing; UCC28064A trades valley-synchronized efficiency for predictable EMI behavior and higher power scalability, necessitating different inductor design and gate drive sizing.

Availability

UCC28056ADBVT is available at Aetrix Electronics and suitable for desktop computing power supplies, LED driver front ends, and industrial AC-DC converters requiring stable component supply, long-term lifecycle support, and compliance with global energy standards.

Supply support for UCC28056ADBVT 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 decades of expertise in high-efficiency power conversion ICs.

The UCC28056 series belongs to TI's high-performance PFC controller product line, designed specifically for ultra-low standby power, multi-mode efficiency optimization, and seamless integration with LLC resonant controllers in compact AC-DC systems.

FAQ

What is the primary function of the ZCD/CS pin on the UCC28056ADBVT?

The ZCD/CS pin on the UCC28056ADBVT serves two critical roles: during DRV high, it monitors the voltage across the current sense resistor (RCS) for cycle-by-cycle over-current protection; during DRV low, it detects the MOSFET drain voltage waveform to identify zero-current crossing and valley points for synchronized turn-on. This dual functionality eliminates the need for an auxiliary winding on the boost inductor and enables precise valley switching across varying line and load conditions in the UCC28056ADBVT.

How does the UCC28056ADBVT achieve <80 mW no-load power at 230 VAC?

The UCC28056ADBVT achieves <80 mW no-load input power through ultra-low quiescent current (<46 µA startup, ~132 µA in burst-OFF state), multi-mode control that reduces switching frequency at light loads, and burst-mode operation with soft entry/exit that minimizes switching losses and audible noise. When paired with UCC256403/4 LLC and UCC24624 synchronous rectifier controllers, the UCC28056ADBVT enables a complete PFC-always-on system without auxiliary converters - directly enabling compliance with Energy Star 6.1 and DoE Level VI standards.

Does the UCC28056ADBVT support both TM and DCM operation, and how is mode transition managed?

Yes, the UCC28056ADBVT natively supports both transition mode (TM) and discontinuous conduction mode (DCM). It operates in TM at full load and automatically transitions into DCM as load decreases - reducing switching frequency while maintaining low THD and near-unity power factor. Mode transition is fully internal and requires no external configuration; the controller dynamically adjusts maximum on-time (TONMAX) based on line feed-forward gain levels (GFF0–GFF7), ensuring optimal efficiency across 85–265 VAC and 10–100% load in the UCC28056ADBVT.

What are the over-voltage protection mechanisms implemented in the UCC28056ADBVT?

The UCC28056ADBVT implements two independent over-voltage protection (OVP) mechanisms: OVP1 monitors the VOSNS pin with a typical threshold of 2.75 V (110% of 2.5-V reference) and 72-mV hysteresis; OVP2 monitors the ZCD/CS pin with a typical threshold of 1.125 V and is blanked for 620–820 ns after DRV falling edge to avoid false triggering. Both protections halt switching immediately and require restart via UVLO cycling or COMP discharge - providing redundant safety for regulated DC bus integrity in the UCC28056ADBVT.

Can the UCC28056ADBVT be used with a standard boost inductor without auxiliary windings?

Yes, the UCC28056ADBVT is explicitly designed to operate with a standard two-winding boost inductor - no auxiliary winding is required. Its ZCD/CS pin detects the MOSFET drain voltage waveform during non-conduction periods to identify valley points, enabling FET turn-on synchronization directly from the main switch node. This architecture reduces component count, PCB area, and cost while maintaining high efficiency and low EMI - a core design advantage confirmed in TI's UCC28056ADBVT application documentation and reference designs.