NXP Semiconductors TEA1705/1R

Overview

TEA1705/1R from NXP Semiconductors is a secondary-side transient controller IC for flyback SMPS, designed to enable ultra-low no-load power (97 µA typical supply current), fast output voltage drop detection (4.9 V typical Vdet), and minimal output capacitance in 5 V battery chargers. It integrates a MOSFET switch (2 Ω typical Ron) and clamp circuit (5.92 V typical Vclamp) to generate wake-up pulses via transformer coupling with primary controllers like TEA1720xT.

For engineers reviewing the TEA1705/1R datasheet, TEA1705/1R pinout, TEA1705/1R application, or TEA1705/1R equivalent, key selection considerations include its SOT23-3 package, 1.1 µs typical ton pulse width, 65 µs blanking time, integrated VCC clamp, and compatibility with NXP's GreenChip primary-side ecosystem for compact, high-power-density AC/DC adapters.

Technical Context

The TEA1705/1R operates as a secondary-side monitoring and wake-up signal generator in quasi-resonant or fixed-frequency flyback converters. Its CAP pin senses primary switching cessation via capacitor charging through an internal body diode, then triggers a controlled discharge pulse through an integrated MOSFET to induce a primary-side wake-up event.

It features a temperature-compensated bandgap reference for precise Vdet (4.9 V) and Vstartup (4.4 V) thresholds, plus a dedicated VCC clamp (5.92 V) with 26 Ω differential resistance to protect output capacitors during overvoltage transients - all implemented in a single SOT23-3 package without external bias winding or optocoupler.

Key Specifications

Pinout & Package

TEA1705/1R is housed in a plastic surface-mounted SOT23-3 package (TO-236AB), measuring 2.9 mm × 1.3 mm × 1.0 mm with gull-wing leads and standard thermal pad layout for FR-4 PCB mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary-side transient detection applications.

Compared with UCC24612-2QDR and MP6908GJ-Z, the TEA1705/1R delivers lowest system-level BOM count for 5 V flyback chargers due to its monolithic SOT23-3 integration of clamp, MOSFET, and precision detection - eliminating external components required by both alternatives.

Availability

TEA1705/1R is available at Aetrix Electronics and suitable for smartphone battery chargers, desktop PC standby supplies, media tablet adapters, and TV auxiliary power rails requiring stable component supply and long-term lifecycle support.

Supply support for TEA1705/1R 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer electronics.

The TEA1705/1R belongs to NXP's GreenChip SMPS controller family, engineered specifically to reduce no-load power, shrink output capacitance, and simplify flyback converter design for high-volume 5 V AC/DC power supplies.

FAQ

What is the primary function of the TEA1705/1R in a flyback power supply?

The TEA1705/1R serves as a secondary-side transient controller that monitors the 5 V output voltage and generates a wake-up pulse via the CAP pin when Vout drops below 4.9 V. This pulse is coupled to the primary side through the transformer to restart the primary controller (e.g., TEA1720xT), enabling ultra-low no-load power and reduced output capacitance. The TEA1705/1R performs this function without optocouplers or auxiliary windings.

Does the TEA1705/1R require an external MOSFET to generate the wake-up signal?

No, the TEA1705/1R integrates a MOSFET switch between CAP and GND with 2 Ω typical on-state resistance, eliminating the need for external active components. The internal MOSFET discharges the external communication capacitor to create the primary-side wake-up pulse. The TEA1705/1R also uses its internal body diode to recharge the capacitor during normal switching, making it a fully self-contained solution.

What is the role of the VCC clamp function in the TEA1705/1R?

The VCC clamp in the TEA1705/1R activates when the supply voltage exceeds 5.92 V, diverting excess current through a 26 Ω internal path to prevent overvoltage stress on the IC and downstream output capacitors. This feature protects against transformer leakage spikes and improves system reliability without requiring external Zener diodes. The TEA1705/1R's integrated clamp directly contributes to smaller, more robust 5 V SMPS designs.

Can the TEA1705/1R be used with primary controllers other than NXP's TEA1720xT?

Yes, the TEA1705/1R is compatible with any primary-side controller capable of detecting a transformer-coupled wake-up pulse, including third-party QR and CCM controllers. Its 1.1 µs pulse width and 65 µs blanking time are designed for interoperability, though optimal timing alignment and noise immunity are validated with NXP's TEA1720xT family. System-level validation is required when pairing TEA1705/1R with non-NXP primary ICs.

What package type and pin configuration does the TEA1705/1R use?

The TEA1705/1R uses a SOT23-3 (TO-236AB) plastic surface-mount package with three gull-wing leads: Pin 1 = VCC, Pin 2 = CAP, Pin 3 = GND. Its 2.9 mm × 1.3 mm footprint matches industry-standard SOT23 layouts, enabling drop-in replacement in existing 5 V charger designs. The TEA1705/1R's marking code is %4U, where % denotes the manufacturing site code.