LNK3205PD datasheet(10/28 Pages) POWERINT

10 / 28 page

Rev. P 06/22

LinkSwitch-TN2

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Quick Design Checklist

As with any power supply design, all LinkSwitch-TN2 designs should

be verified for proper functionality on the bench. The following

minimum tests are recommended:

1. Adequate DC Rail Voltage – Check that the minimum DC input

voltage does not fall below 70 VDC at maximum load, minimum

input voltage.

2. Correct Diode Selection – UF400x series diodes with reverse

recovery time of 75 ns or better are recommended only for

designs that operate in MDCM at an ambient of 70 °C or below.

For designs operating in continuous conduction mode (CCM) and/

or higher ambients, then a diode with a reverse recovery time of

35 ns or better, such as the BYV26C, is recommended.

3. Maximum Drain Current – Verify that the peak drain current is

below the data sheet peak drain specification under worst-case

conditions of highest line voltage, maximum overload (just prior

to auto-restart) and highest ambient temperature.

4. Thermal Check – At maximum output power, minimum input

voltage and maximum ambient temperature, verify that the

LinkSwitch-TN2 SOURCE pin temperature is 100 °C or below.

This ensures adequate margin due to variations in R

DS(ON) from

part to part. If the device temperature of the IC exceeds 85 °C

with ambient temperature of 25 °C, it is recommended the next

bigger device in the family should be selected for the application.

A battery powered thermocouple meter is recommended to make

measurements when the SOURCE pins are a switching node.

Alternatively, the ambient temperature may be raised to indicate

margin to thermal shutdown.

In a LinkSwitch-TN2 design using a buck or buck-boost converter

topology, the SOURCE pin is a switching node. Oscilloscope measure-

ments should therefore be made with probe grounded to a DC voltage,

such as primary return or DC input rail, and not to the SOURCE pins.

The power supply input must always be supplied from an isolated

source when doing measurements (e.g. via an isolation transformer).

LNK3205PD 데이터시트(PDF) 10 Page - Power Integrations, Inc.