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LM61495-Q1: Thermal shutdown, Current limit during dropout operation.

Yassine Damoh
Prodigy 180 points
Part Number: LM61495-Q1

Hello,

I have two questions related to the LM61495-Q1:

- The maximum junction temperature stated as 150oC, but the thermal shutdown tripping threshold is 168oC Nom. can you please elaborate on that ?

- What's the efficiency of the device when the input voltage is too low to provide the desired output voltage (for example 9V input and 11V output setting) - Is there any additional current limitation when the device is operating in such mode ?

Thanks,

Yassine 

  • 0
    TI__Genius 12525 points

    Hi Yassine,

    Thank you for your questions. 

    The maximum junction temperature is the maximum temperature that the device can operate properly at. This is also the maximum storage temperature for the device. The thermal shutdown tripping threshold is the temperature in when the device will shut down regardless of the input conditions of the device. This prevents the device from regulating its output at all until the device falls below a certain temperature. Between 150 C and this thermal shutdown tripping threshold, the device is not in thermal shutdown and can have an output. However as this operating temperature would be above the recommended operating temperature, TI would advise against operating the device above 150 C regardless. More information about thermal shutdown can be found in section 8.3.14 of the datasheet.

    Once the device has an input voltage that is too low to provide the output voltage desired, the part is considered in dropout. Efficiency is still defined by the same equations as in normal conditions, but TI generally does not provide these as these devices are not designed to operate in dropout. However in general lower currents will allow for higher output voltages in dropout. See figures 9-21 to 9-28 in the datasheet for more insight or section 8.4.3.5 for more information on dropout.

    Thank you,

    Joshua Austria