Power Integrations TNY274PN

TNY274PN TinySwitch-III Product Summary

The Power Integrations TNY274PN is a member of the TinySwitch-III family, designed as an energy-efficient, highly integrated off-line flyback switcher IC for low-power AC-DC conversion applications. Packaged in an 8-lead DIP (PDIP-8C), the TNY274PN is renowned for its streamlined ON/OFF control scheme, selectable current limits, and extended power range capabilities. This device targets engineers and procurement specialists seeking cost-effective, reliable solutions for adapter, charger, auxiliary supply, and standby power circuits across consumer, industrial, and appliance domains.

Main Architecture and Key Functions of TNY274PN TinySwitch-III

Central to the TNY274PN is the integration of a 700 V power MOSFET switch with an advanced controller, enabling simplified system design and high performance. The controller manages regulation using ON/OFF control rather than traditional pulse width modulation, minimizing external component count and complexity. Core features include:

Selectable current limits via the BP/M pin capacitor, allowing adaptability for peak or continuous power or maximizing efficiency in thermally constrained designs.

Adaptive switching cycle on-time extension for improved low-line regulation and reduced bulk input capacitance.

Built-in frequency jittering (average 132 kHz oscillator with 8 kHz p-p jitter), lowering EMI and facilitating compliance with conducted and radiated standards.

Self-biasing operation drawing startup and steady-state power directly from the DRAIN pin, eliminating the need for external bias windings or components.

Advanced protection circuitry, including hysteretic thermal shutdown (typ. 142 °C threshold, 75 °C hysteresis), accurate overvoltage detection, and auto-restart to limit power during short-circuit or open loop faults.

TNY274PN TinySwitch-III Pinout and Working Principle

The TNY274PN presents a simplified pinout enabling efficient PCB layout and thermal management. Each pin supports core operational functions:

DRAIN: MOSFET drain connection, supplying internal current during both startup and operation.

BYPASS/MULTI-FUNCTION (BP/M): External bypass capacitor node for the internal 5.85 V regulator, current limit mode selection (by capacitor value), and overvoltage shutdown input via externally generated current.

ENABLE/UNDERVOLTAGE (EN/UV): Controls MOSFET switching and serves as line undervoltage sense; input current threshold governs switching enable/disable and load-dependent current limit state.

SOURCE: Power return and common control for the internal circuit, acting as the main path for device heatsinking to the PCB.

The device’s control logic samples the EN/UV pin at each clock cycle’s start, using input state and historical sequence to determine switching cycles and modulate the current limit states based on actual load, ensuring optimal efficiency and fast transient response.

Energy Saving and EcoSmart Features of TNY274PN TinySwitch-III

A defining feature of the TinySwitch-III family is its EcoSmart operation, ensuring ultra-low no-load and standby consumption. The TNY274PN supports international energy efficiency standards, achieving:

<150 mW no-load at 265 VAC without a bias winding

<50 mW no-load with external bias winding and resistor

Constant efficiency down to very light loads, meeting requirements such as CEC regulations and 1 W PC standby

The device’s ON/OFF control and load-adaptive switching make it an ideal candidate for designs demanding stringent energy-saving performance, even in charger, auxiliary supply, or standby system scenarios.

Power Handling, Safety, and Reliability in TNY274PN TinySwitch-III Applications

Safety, reliability, and robust performance are engineered into the TNY274PN:

Hysteretic thermal shutdown ensures auto-recovery after over-temperature fault, preventing board fatigue and minimizing the risk of continuous faults.

Auto-restart limits fault-mode power delivery to <3% of maximum, protecting transformer and secondary circuits during shorts or open loop events.

Output overvoltage shutdown and programmable line undervoltage detection can be configured with minimal external components for precise system-level protection.

The device’s low component count and extended creepage distances between high voltage pins increase field reliability, reduce PCB complexity, and support single-sided layouts.

Use Cases for the TNY274PN TinySwitch-III

The TNY274PN suits a broad range of applications requiring reliable, efficient low-power flyback conversion. Typical uses include:

Mobile device chargers/adapters (phones, PDAs, cameras, MP3 players)

Standby and auxiliary power supplies for PCs

DVD, set-top boxes, and low-power multimedia decoders

Industrial supplies, appliances, and meters

Engineers can reference standard and open-frame output power tables based on system operating conditions, online reference designs, or adapt example circuits featured for higher or lower output requirements by selecting appropriate transformer and external feedback networks.

Design Guidelines and Board Layout for TNY274PN TinySwitch-III Integration

Successful integration of the TNY274PN centers on a few crucial layout choices:

Use a single-point ground from the input filter capacitor to the copper area linked to all SOURCE pins, which doubles as the device’s main heatsink.

Place the BP/M pin capacitor as close as possible to its respective pins for effective decoupling.

Keep EN/UV pin traces short and away from high-voltage nodes.

Minimize primary loop and clamp circuit areas to reduce EMI. Prefer Zener or RCD clamps for DRAIN voltage protection, keeping related paths tight to the transformer and MOSFET.

For output diodes, maximize cathode copper area for heatsinking and minimize high-frequency loop length.

When using undervoltage lockout but operating in harsh environments or open-frame designs, add a high-value resistor (e.g., 390 kΩ) from EN/UV to SOURCE to guard against PCB leakage currents and startup issues.

Thermal Performance and Maximum Ratings for the TNY274PN TinySwitch-III

Thermal design is vital to leveraging the full power capability and reliability of the TNY274PN:

All SOURCE pins should be soldered to substantial copper area for efficient heat sinking, recommended to keep the pin temperature at or below 110 °C for maximum power and device longevity.

Absolute maximum ratings include DRAIN voltage up to 700 V, DRAIN peak current of 400 mA (750 mA during low-voltage events), EN/UV/BP/M pin voltages up to 9 V, and operating junction temperature between -40 °C to 150 °C.

Thermal resistance in PDIP-8C packages is typically 70 °C/W (to ambient) and 11 °C/W (to case), with performance depending on PCB copper area.

Package Details of TNY274PN TinySwitch-III Components

The TNY274PN is delivered in the standard PDIP-8C configuration, compliant with JEDEC MS-001-AB specifications for dual-in-line packages. This leverages ease of prototyping and cost-effective volume production, with pin spacing and lead geometry supporting robust soldering and thermal mounting practices.

Alternative or Replacement Options for the TNY274PN TinySwitch-III

The TinySwitch-III family offers adjacent models, providing a clear roadmap for up- or down-scaling power levels and current limits without redesigning the entire circuit:

TNY275PN (higher peak current capability: 560 mA) for greater output power

TNY276PN/TNY277PN/TNY278PN/TNY279PN/TNY280PN: progressively increasing peak current and output power ratings up to 1360 mA for TNY280PN

Current limit selection using BP/M pin capacitors allows certain family members to mimic the current limit of the next smaller or larger device for added design flexibility

Replacement selection depends on required output power, thermal headroom, and system architecture—engineers should consult the output power tables and family datasheets to optimize choice

Conclusion

The Power Integrations TNY274PN TinySwitch-III stands as a mature, versatile solution for energy-efficient, low-power AC-DC conversion. Its architecture and features simplify design, lower component count, and provide flexible protection and efficiency to meet global regulatory standards. With a breadth of selectable family members for varying power needs, robust safety and thermal management, and a proven suitability for charger, standby, industrial, and appliance supplies, the TNY274PN and its kin offer procurement and design engineers reliable options for next-generation compact power platforms.