Single Integrated Circuit Chip TNY275PG Energy Effi Cient Off Line Switcher

TNY274-280

TinySwitch-III Family

Energy-Effi cient, Off-Line Switcher With Enhanced Flexibility and Extended Power Range

Product Highlights

Lowest System Cost with Enhanced Flexibility​

Simple ON/OFF control, no loop compensation needed

Selectable current limit through BP/M capacitor value

Higher current limit extends peak power or, in open frame applications, maximum continuous power

Lower current limit improves effi ciency in enclosed adapters/chargers

Allows optimum TinySwitch-III choice by swapping devices with no other circuit redesign

Tight I2 f parameter tolerance reduces system cost Maximizes

MOSFET and magnetics power delivery Minimizes max overload power, reducing cost of transformer, primary clamp & secondary components ON-time extension – extends low line regulation range/hold-up time to reduce input bulk capacitance

Self-biased: no bias winding or bias components

Frequency jittering reduces EMI fi lter costs

Pin-out simplifi es heatsinking to the PCB

SOURCE pins are electrically quiet for low EMI

Enhanced Safety and Reliability Features

Accurate hysteretic thermal shutdown protection with automatic recovery eliminates need for manual reset

Improved auto-restart delivers <3% of maximum power in short circuit and open loop fault conditions

Output overvoltage shutdown with optional Zener

Line undervoltage detect threshold set using a single optional resistor

Very low component count enhances reliability and enables single-sided printed circuit board layout

High bandwidth provides fast turn on with no overshoot and excellent transient load response

Extended creepage between DRAIN and all other pins improves fi eld reliability

TinySwitch-III Functional Description

TinySwitch-III combines a high voltage power MOSFET switch with a power supply controller in one device. Unlike conventional PWM (pulse width modulator) controllers, it uses a simple ON/OFF control to regulate the output voltage.

The controller consists of an oscillator, enable circuit (sense and logic), current limit state machine, 5.85 V regulator, BYPASS/ MULTI-FUNCTION pin undervoltage, overvoltage circuit, and current limit selection circuitry, over-temperature protection, current limit circuit, leading edge blanking, and a 700 V power MOSFET. TinySwitch-III incorporates additional circuitry for line undervoltage sense, auto-restart, adaptive switching cycle ontime extension, and frequency jitter. Figure 2 shows the functional block diagram with the most important features.