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TLV733P-Q1: thermal resistor computation

Part Number: TLV733P-Q1

Dear team,

My customer use our TLV733-Q1 in their design. Before they use WSON package which has smaller thermal resistor. This package is out of stock, so they plan to change to SOT-23 package. Now we have a concern, 

Ambient temperature is 95°C, RθJA=198.3°C/W, VIN-max=1.89V, VOUT_min=1.148V, IOUT_max=240mA

so the junction temperature = 95+198.3*(1.89-1.148)*0.24=130.3°C which is close to 150°C.

I am not sure whether this package is ok. The customer has no time to test this, so they want to know how big the risk is. Can we make the positive conclusion based on the computation? Or we have other more accurate methods?

Thanks & Regards,

Sherry

  • Hello Sherry,

                         Your calculations are correct. The device would work and all the parameters would hold under the operating conditions you have specified. The only issue/risk is that by operating the device at a larger ambient temperature, the part will age quickly. The JEDEC standard qualifies any IC to run for ~9 Years at a junction temp of 55C and to qualify a part to meet that standard all TI commercial devices qualify HTOL for 1000hrs at 125C (or 300hrs at 150C). At the operating conditions that you have specified, based on our translation, the device will work just fine for ~760 hours. Improving the Thermal Dissipation using better PCB layout can increase the life of the device. Please find attached an excel tool that can help you make some calculations. Thanks!2133.Customer Mission Profile Compared To Industry Standard Reliability Testing.xlsx

    Regards,

    Srikanth