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Original question:

TLV733P-Q1: TLV73312PQDBVRQ1 thermal issue

TLV733P: TLV733P power consumption and Heat

Kami Huang60
Genius 3830 points
Part Number: TLV733P

Dear Sir/Ms.

My customer measured her current actual power consumption, and I measured the following power consumption.

The current(real) power consumption of the customer:
4Vin to 3.3V/158mA
3.3Vin to 1.2V/107mA
Customers are worried about heat dissipation,
Since the customer is worried about heat dissipation, he wants to know the following information.

He chooses the package of SOT-23-5.
Package thermal dissipation
Calculate real temperature (base on real current)

In addition, I would like to ask, how to calculate the temperature rise?

Best Regards,

Kami Huang

  • 0
    TI__Expert 6825 points

    Hi Kami,

    I will get back to you by tomorrow with this.

    Thanks,

    Mark

  • 0 in reply to Mark Sellers
    TI__Expert 6825 points

    Hi Kami,

    Without knowing anything about your board it is difficult to provide an exact answer to your question, but you can get an estimate using the thermal information in our datasheet. 

    The junction temperature can be calculated by this equation Tj = Ta + Pd(TJA), where Tj is junction temperature, Ta is ambient temperature, Pd is power dissipation (Vin - Vout)*Iout, and TJA is the junction to ambient thermal resistance.

    The first scenario will give you a 25C rise from ambient temperature and the second scenario will give you a 51C rise from the ambient temperature.

    Regards,
    Mark

  • 0 in reply to Mark Sellers
    Genius 3830 points

    Hello Mark,

    The customer told me that the PD under different ambient temperatures is different. But this is different from what I know. I would like you to ask if this is what it looks like? There are also customers who want to know the following parameters.

    TLV73333PDBVR
    Package / Case: SOT-23-5
    Power Dissipation(mW) (Ta=25℃) =? 
    Power Dissipation(mW) (Ta=85℃) =? 

    TLV73312PDBVR
    Package / Case: SOT-23-5
    Power Dissipation(mW) (Ta=25℃) = ?
    Power Dissipation(mW) (Ta=85℃) = ?

    Best Regards,

    Kami Huang

  • 0 in reply to Kami Huang60
    TI__Expert 6825 points

    Hi Kami,

    The power dissipation will not change unless you change your Vin, Vout, and Iout conditions. The junction temperature of the device can be calculated as Tj = Ta + Pd(TJA), where Tj is junction temperature, Ta is ambient temperature, Pd is power dissipation (Vin - Vout)*Iout, and TJA is the junction to ambient thermal resistance.

    As you can see the Power dissipation and Junction to ambient thermal resistance are constants so the only variable here is the ambient temperature.

    You will still get a 25C rise for their first scenario and a 51C rise for the second scenario. For the second scenario the ambient temperature would have to stay below 75C.

    TLV73333PDBVR
    Package / Case: SOT-23-5
    Power Dissipation(mW) (Ta=25℃) -> Junction temperature = 50C
    Power Dissipation(mW) (Ta=85℃) -> Junction temperature = 110C

    TLV73312PDBVR
    Package / Case: SOT-23-5
    Power Dissipation(mW) (Ta=25℃) -> Junction temperature = 75C
    Power Dissipation(mW) (Ta=85℃) -> Junction temperature = 135C

    Thanks,

    Mark