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PIExpert support for LinkSwitch-LP and -TN

Posted by: mgcorr on
I am trying to design a universal input (100-277VAC) single output (3VDC) power supply. I went through the Product Selector Guide, and based on my criteria, it recommended the LinkSwitch-LP (Flyback) or LinkSwitch-TN (Buck). But, the New PI Expert Design Wizard does not offer either of these two chips for a new design. Is there a way to update PIExpert to include the LP or TN chips? I see XT is included. I'm using PIExpert Release 7.0.3.3 thanks Michael

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Submitted by PI-Spock on 10/08/2008

LinkSwitch-LP and LinkSwitch-TN are both supported by the PIXls spreadsheet application. PIXls spreadsheets offer more design flexibility, however it is intended for more experienced designers who know which parameters to tweak.

What is your specification (output power requirement?)

Depending on your answer I could suggest that you choose the Linkswitch-XT or TinySwitch-III family and use the automated PI Expert application to complete your design.

Submitted by mgcorr on 10/09/2008
This is to control an embedded processor and RF radio. There are three modes the processor and radio can be in - each drawing different current.

(1) The device is primarily in sleep mode, in which case it is drawing about 1mA total.
(2) The device will occasionally wake up to do some processing for a second or two, drawing about 35mA.
(3) Once the processing is complete, the device will transmit a few packets, drawing 165mA peak for 3-10ms for each packet. It will then go back to sleep for a few hours before waking up again.

So, the challenge seems to be designing a universal input power supply that is relatively efficient at such low operating currents.

thanks for your help
Michael
Submitted by PI-Spock on 10/09/2008

You did not mention weather or not this needs to be isolated power supply. If not I'd suggest you use LinkSwitch-TN. Otherwise you can use the LinkSwitch XT family.

I do not believe it needs to be isolated. What is the criteria for choosing whether or not it needs isolation? This is a simple line voltage power supply to a low power embedded wireless device.

As I understand, isolated circuits typically offer better performance, anyway. Is this true?

Submitted by PI-Spock on 10/10/2008

Isolation is for safety. If the application is such that it will not render itself to human contact (like in a exit sign in buildings) you can do without isolation. However if the application is for a charger or an adapter you do need safety.