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TLV759P: Effciency

Nidhi P Shetty
Intellectual 735 points
Part Number: TLV759P
Other Parts Discussed in Thread: TPS7A91

Dear Sir/Madam

I'm searching for an LDO with more than 85%efficiency for converting 5V to 3.3V and 3.3V to 1.2V at 1A.

When I referred TLV759P I found that it suits my requirement. But in the datasheet efficiency is not mentioned. How can I get efficiency of this part?

Please help me in this concern.

Thank you

Regards

Nidhi P Shetty

  • 0
    TI__Guru 50090 points

    HI Nidhi,

    A good first order approximation for efficiency for any LDO/Linear Regulator is simply 100*VOUT/VIN. So for 3.3VOUT/5VIN the efficiency is actually closer to 66%. The key metric you need to be aware of especially for 1A regulators with large voltage drops is TJA this is a parameter to predict the die junction temperature based on the power dissipation. For example the TLV759P has a TJA of 80.3C/W so at 1A from 5 to 3.3 you drop 1.7V which dissipates 1A*1.7V or 1.7W.  80.3C/W*1.7W yields a 136.5C temperature rise above ambient. Meaning if your PCB ambient were at 25C, the die temperature would be 25C+136.5C or 161.5 which means you are over spec and likely going to enter thermal shutdown.

    Another 1A device we have is the TPS7A91. This has a TJA of 56.9C/W so here your temperature rise would only be 56.9C/W*1.7W= 96.73C which is still marginal but below the recommended maximum operating temperature.

    I hope this answers your question. If not, please let me know.