Texas Instruments UCC24650DBVR

Overview

UCC24650 from Texas Instruments is a 200-V secondary-side wake-up monitor IC for primary-side regulated (PSR) flyback power supplies, featuring 3% relative VDD droop detection, <50 µA typical supply current, 5–28 V monitoring range, and integrated 200-V wake-up switch - enabling zero-standby-power adapters and fast transient response in consumer chargers.

For engineers reviewing the UCC24650 datasheet, UCC24650 pinout, UCC24650 application, or UCC24650 equivalent, this device is selected for PSR systems requiring ultra-low standby loss (<5 mW), minimal output capacitance under 2-A load steps, and coordinated wake-up signaling with controllers like UCC28730.

Technical Context

The UCC24650 implements relative-droop detection by sampling and storing 97% of VDD at each power-cycle end via its PCD (Power Cycle Detect) circuit, then comparing real-time VDD against that stored reference. Its internal 200-V N-channel MOSFET drives 1-µs wake-up pulses into the transformer secondary at 33 kHz until primary switching resumes.

It integrates dual control functions: WAKE pin serves as both input (for detecting demagnetization timing) and output (for injecting wake-up current), while ENS provides open-drain enable/disable signaling to synchronous rectifier controllers based on cumulative and consecutive switching period thresholds (tENS = 57 µs typ., tDISS = 177 µs typ.).

Key Specifications

Pinout & Package

SOT-23 (DBV) 5-pin package, body size 2.92 mm × 1.30 mm, thermally optimized for low-power secondary-side mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary-side wake-up monitoring applications.

Compared with UCC24650, UCC24612DR integrates SR drive but sacrifices pin-level flexibility and independent ENS control, while NCP4354ADR2G offers lower cost at the expense of droop adaptivity, voltage range, and precision timing - making UCC24650 optimal for high-performance, wide-range PSR systems demanding zero-standby power and tight transient regulation.

Availability

UCC24650 is available at Aetrix Electronics and suitable for smartphone adapters, TV power supplies, home appliance SMPS, and industrial lighting drivers requiring stable component supply and long-term lifecycle support.

Supply support for UCC24650 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 power conversion ICs.

The UCC24650 belongs to TI's PSR ecosystem product line, designed specifically to enable zero-standby-power, low-component-count isolated flyback converters for consumer and industrial applications.

FAQ

What is the primary function of the UCC24650 in a PSR flyback design?

The UCC24650 acts as a secondary-side wake-up monitor that detects a ~3% relative droop in its VDD supply voltage and triggers a 1-µs, 33-kHz-repeating current pulse via its WAKE pin to alert the primary-side controller (e.g., UCC28730). This enables rapid recovery from heavy load transients while maintaining ultra-low standby power - a core requirement in modern energy-efficient PSR systems. The UCC24650 itself consumes only 41 µA typical at 5 V.

How does the UCC24650 achieve zero-standby-power performance?

The UCC24650 achieves <5-mW no-load input power by combining ultra-low quiescent current (41 µA typ. at 5 V), adaptive 3% relative-droop detection (eliminating constant polling), and intelligent ENS-driven disable of secondary circuits like synchronous rectifiers. Its internal 200-V wake-up switch operates only when needed, and its UVLO (4.0 V turn-on) ensures operation starts only when auxiliary rail voltage is stable - all contributing to verified zero-standby-power compliance in certified adapters.

Can the UCC24650 be used with PSR controllers other than the UCC28730?

Yes, the UCC24650 is compatible with any PSR controller capable of detecting its 1-µs, 20–27 mA wake-up pulse on the transformer primary side - including UCC28710, UCC28711, and third-party PSR ICs with dedicated wake-up input pins. The key requirement is that the primary controller must interpret the coupled WAKE pulse as a command to exit low-frequency standby and resume normal switching. Timing and amplitude compatibility is confirmed in TI's interoperability notes for UCC24650.

What is the role of the ENS pin on the UCC24650, and how is it timed?

The ENS pin is an open-drain output that enables or disables secondary-side circuits such as synchronous rectifier controllers. It transitions low after 63 consecutive power cycles exceeding tDISS (177 µs typ.), disabling the SR to cut standby loss. It returns high-impedance after 32 cumulative cycles below tENS (57 µs typ.), re-enabling the SR. This hysteresis prevents chatter during marginal load conditions and is fully documented in the UCC24650 electrical characteristics table (Section 6.7).

Does the UCC24650 require external components for basic operation?

No - the UCC24650 requires no external components for core wake-up and ENS functionality. Only two connections are mandatory: VDD (to monitored output rail) and WAKE (across secondary-side rectifier). GND completes the circuit. All timing, droop detection, current limiting, and logic are implemented internally. External series resistance on WAKE may be added only in high-dv/dt applications (>3700 V/s) to limit peak current per Absolute Maximum Ratings, but is not required for standard designs.