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action of LNK302 current limit

Posted by: twood@yorkville.com on

In a previous design I remember a Power integrations part locking up after entering current limit, i don't remember what part. It would shut off and then not restart until after the input Voltage was reduced to a very low voltage. Since the power supply capacitors kept the voltage above that voltage for several minutes it was difficult to recover from this condition.  I am currently looking at using the LNK302 and want to be sure that this does not happen here. Does the LNK302 ever shut down and require the input voltage to be removed before it will restart?

 

Also is there a way to search for a topic like this in the forums?

Comments

Submitted by PI-Terry on 05/05/2014

Hi,

I think you are talking about the fault latch off. There are some products from PI that provide the latch off option for the cusomter, when a fault condition (for example, open loop or output short circuit.) created. The power supply will latch off (output disabled) at fault conditon, even the fault condition removed, it requires to disconnect the input voltage and wait the bus capacitor to be discharge to enable the power supply output.

For LNK 302, the power supply will go to auto restart under fault conditon, for example output short circuit and open loop. So as soon the the fault condition remove, the power supply will restart. It does not require the disconnection of the input line and wait for the discharge of the capacitor.  

Submitted by Vignesh E on 03/10/2015

Hi, I want to confirm the behavior of LNK302 for output short. I noticed the block diagram for LNK302 misses the block called "Auto restart counter" as compared to LNK304-306.

So will LNK302 get into hiccup mode for an output short? and will it start regulating output once short is removed? what are the typical duration for checking for a short?

Submitted by PI-Terry on 03/18/2015

Hi,
Thanks for contacting Power Integration.
You are right about the auto restart missing in LNK 302. If you can check the data sheet in detail, the LNK 302 does not include auto restart feature. That means the part will not get into hiccup mode during the output short circuit situation.
If you want to get this feature, LNK304 - 306 will be the better fit for you. Hope this is helpful for you.

Submitted by Vignesh E on 03/18/2015

Hi Terry,

Thanks for the reply. You mentioned in your previous reply that

"For LNK 302, the power supply will go to auto restart under fault conditon, for example output short circuit and open loop. So as soon the the fault condition remove, the power supply will restart. It does not require the disconnection of the input line and wait for the discharge of the capacitor. "

How will LNK302 know that output short is no longer there if it is not periodically attempting/sensing?

Submitted by PI-Terry on 03/20/2015

Hi,
I am sorry that I think I made the wrong reply. The correct statement should be: For LinkSwitch TN, except LNK 302, the power supply will go to auto restart under fault condition, for example output short circuit and open loop. So as soon the the fault condition remove, the power supply will restart. It does not require the disconnection of the input line and wait for the discharge of the capacitor
Sorry again if that created misunderstanding