TYN268PN Off-Line Switcher

The TYN268PN is an integrated off-lineswitching ICthat contains the controller and power switch in one package. It needs a minimum number of external components to implement a mains-powered flyback converter.

TYN268PN Pinout Description

Pin Number	Pin Name	Description
1	BP	旁通销内部5.8 v
2, 3	S	Power MOSFET source pins
4	EN/UV	IC enable, undervoltage detection pin
5	D	Power MOSFET drain pin
7, 8	S(HV RT)	Power MOSFET high voltage source return pins

Features

• Fully integrated off-line switcher
• Up to 23W output power
• 132kHz switching frequency
• Built-in current and overtemperature limit

Note:Complete technical details can be found in theTYN268PN datasheetlinked at the end of this page.

Equivalent for TYN238PN

TYN23x series

Other Off-Line Switchers

VIPer32, TYN274

How To Use TYN268PN

Designing an off-line (as in, powered off-line mains voltage) converter has always been a tricky task – apart from calculating various parts parameters, safety must also be taken into account. ICs like the TYN268PN make the job easier by integrating all the necessary control components and the power switch into one IC. Only a few external components are needed, including a transformer and some passives. An example application circuit is shown below.

The TYN268PN is treated mostly like ahigh-voltage power MOSFETconnected to the low side of the transformer. Only two extra pins are used – bypass pin for the internal power supply, to which a suitable capacitor must be connected, and the EN/UV pin which also serves as the feedback pin. The feedback network itself is anoptocoupler, which is turned on when the output Zener diode exceeds its breakdown voltage. An RC network is connected to the drain of the IC to prevent voltage spikes from damaging the internal power switch. The IC itself has an internal6.4V Zener diodeto clamp the drain-source voltage to safe limits. The current through the switch is internally limited to 500mA.

The DIP-8 package in which this IC comes is special as it lacks the seventh pin. This provides some clearance to prevent arcing between pins. The recommended PCB layout is shown in the figure below.

Applications

• Phone chargers
• Off-line power converters
• Battery backup trickle chargers
• High input voltage flyback converters

2D Model and Dimensions