Quote# QADE70E - Usage of LNK304DG at lower currents

Posted by: Adnan on 08/12/2019

***** Quote# QADE70E *****

Hello,
can you please advise on the following question of one of our customer's regarding the DC/DC converter P/N: LNK304DG ?
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I like to use the device in buck configuration with a DC voltage source.
It's not a typical application, but my question is if it's working with for example lower output current.

Is it possible to use the LNK304 with input voltages below 70V?
My required input voltage range is 60-167VDC, output voltage 12V, output current 100mA...
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Thank you very much.

Best regards
Adnan

Comments

It is possible to use LNK304 for input below 70V. In the LNK-TN datasheet. The general test circuit for all electrical data shown in page 9-11 is also shown in page 12. You will see that the test input voltage is a 50V dc source.

Link: https://ac-dc.power.com/sites/default/files/product_document/data_sheet/linkswitch-tn_family_datasheet.pdf

our customer returned with the following question. Can you please advise on this?:
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PN: LNK304DG: What are the limitations when using 50V input voltage?
Is there a limit of the max. output current? Or why is it mentioned to be >= 70V on Key Application Considerations on page5?
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Thank you very much.

Best regards
Adnan

Hello,

Can you please advise on our customer's follow-up question below?:
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PN: LNK304DG: What are the limitations when using 50V input voltage?
Is there a limit of the max. output current? Or why is it mentioned to be >= 70V on Key Application Considerations on page5?
---------

Thank you very much.

Best regards
Adnan

Hello,

Thank you very much.

Best regards
Adnan

Because LNK-TN family of devices is primarily used for buck converters, the output current will always be limited by the peak current limit of the IC, as shown in Table 1.

LNK-TN operates at 66khz only (with on-off control) and fixed peak limit, so you can expect the max power delivery to be limited at very low input voltages. Although the IC will operate down to 50V (meaning switching will still occur), it is optimized to be used within typical AC input ranges.