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CLC001: Specification of thermal resistance

Part Number: CLC001
Other Parts Discussed in Thread: LMH0001,

Hi,

I would like to ask you some questions about thermal resistance as below.

My customer has been simulating the behavior with thermal.

Q1) θja and θjc value of Absolute max ratings (datasheet 3 page)

Are both data (θja=125℃/W, θjc=105℃/W) actual data or simulation data?

Q2) IDD data (datasheet 3 page)

The specification of IDD is 115mA(max) @Vsdo=800mVpp, includes load current.

Do you have the IDD data without line load, just only device power consumption?

Q3) Thermal design consideration

Would you tell me any considerations to do thermal design?

If you give me anything information to design, it will be very helpful for me.

Thank you for your support.

Best Regards,  

  • Hi,
    Could you support this issue?
    Any advice would be very helpful.
    Thanks!
  • Greetings Takumi-San,

    1). These parameters were determined by our packaging group based on the actual device device data/power.

    2). Data Sheet IDD:

    Please note 115mA is with 75 ohm load on the output. There is an AC coupling Capacitor between the device load and the BNC connector. Therefor there will not be any DC current going toward the load. 

    3). As you noted this device has high theta ja. For a lower theta ja you can consider LMH0001. This part has lower value for theta ja and additionally it has thermal pad for heat dissipation.

    Regards,,nasser

  • Hi Nasser-san,

    Thank you so much for your kind reply!

    I understood.

    Regards,

  • Hi Nasser-san,

    Let me ask you some additinal questions from my customer as below again please?

    Q1) Measurement condition of θja, θjc

    The customer tried to calculate the increasing temperature which is raised by CLC001 with 115mA IDD.

    That is to say,

        As VDD = 3.3V and IDD = 115mA, the power dissipation of this device is around 0.38W.

        And as θja = 125℃/W, the increasing temperature is around 47.5℃ (0.38 x  125 = 47.4375℃)

    In case of room temperature is 25℃, the environment temperature becomes 72.5℃ (25 + 47.5).

    The operating temperature of this device is from -40℃ to +85℃.

    The head room is about +12.5℃ @25℃ and this value seems to be very severe for actual products to adopt...

    How do you think of this result?

    The customer thinks that θja can be changed by some conditions of PCB design (quality, thermal via/pattern, etc).

    So could you tell me the measurement conditions when you determined θja/jc value, if possible? 

    Q2) IDD value

    The IDD specification is 70mA(Typ) and 115mA(Max).

    What is the condition to become 115mA? (Rush current?)

    And about 70mA, could you teach me how to calculate? (Or is this value actual measurement value??)

    Thank you very much for your support!

    Best Regards,

        

  • Hi,
    If it is not easy to explain/reply me about my question, would you advise me something documents like a design guide to help design PCB?
    Any your advice would be very helpful for me.
    Thanks!
  • Hi Takumi-San,

    1). You can increase Rref resistor value to lower the output voltage swing to about 740mV. This will reduce current consumption.

    2). To get a better thermal performance, can you use LMH0001 instead of CLC001?

    Regards,,nasser

  • Hi Nasser-san,

    Thank you so much for your reply.

    I see, I will ask the customer to consider to use LMH0001 instead of CLC001.

    Regards,