5 Replies Latest reply on Sep 22, 2019 10:39 PM by PradiptaB_11

# FM25W256-G Power dissipation required

Hi,

We are using "FM25W256-G" in our design.We require power dissipation of this ic under typ,min and max conditions for thermal analysis.Also require "RθJB-Thermal resistance between Junction to Board" which is not available in the datasheet.Kindly help us to get the same asap.

• ###### 1. Re: FM25W256-G Power dissipation required

Hi,

You can use the Pd = VDD * IDD formula to calculate power dissipation of the device. For example if typical VDD is applied to the IC the max current consumption at 1 MHz is 0.25 mA. So max power dissipation at this voltage will be

Pd = 3.3 * 0.25 = 0.825 mW

Similarly you can calculate Pd at other voltages(min, max).

You can also measure the current consumption at the supply pin and calculate power dissipation as an alternative.

Let me check for the RQJB value internally.

Thanks,

• ###### 2. Re: FM25W256-G Power dissipation required

Hi,

Thank you for your response Pradipta. Please let me know the Junction to Board RQJB asap.That would be of great help & please let me know why RQJB data is not mentioned in the datasheet?

Regards,

Vishal.A

• ###### 3. Re: FM25W256-G Power dissipation required

Hi Vishal,

We only mention the Theta Ja and Theta Jc parameter in the datasheet for the product line. That is how it was composed.

The theta Jb for the part will be 135 C/W.

Thanks,

• ###### 4. Re: FM25W256-G Power dissipation required

Hi,

May i know the parts maximum Junction temperature Tj ?

• ###### 5. Re: FM25W256-G Power dissipation required

Hi,

The TJmax = Maximum Junction temperature. This is the maximum temperature that the device tolerates to guarantee
reliable operation. The system designer needs to ensure that T
J < TJmax to guarantee reliability.

For FRAM it is 125 C.

Thanks,