# LMK00308: Maximum power consumption

Part Number: LMK00308
Other Parts Discussed in Thread: LMK00105

Hello team,

I received a question from my customer about maximum power consumption of LMK00308.

In the datasheet, the calculation of power consumption is described in 11.2.

But is there a maximum regulation of total power consumptions?

Also, can a device like LMK00105 calculate the same way?

Best Regards,

Ryotaro Fukui

• Hello Fukui-san,

There is no maximum power consumption specification.  The reason is that once you calculate the power, you can then calculate the thermal.  Given the worst case ambient of 85 deg C.  The example in section 11.2 performs the thermal calculation and finds that the junction temperature would be 111 deg C given the theta-ja of 31.4 deg C/W. and device power dissipation of 817 mW.

* For the same example, given the maximum junction temperature of 125 deg C and theta-ja = 31.4 deg C/w, you could dissipate a max power of (125 deg C - 85 deg C) / 31.4 deg C/W = 1.27 W.
* But suppose your theta-ja which is PCB design specific, is lower than 31.4 deg C.  Then the maximum power you can consume is higher.
* Suppose your theta-ja is higher than 31.4 deg C.  Then the maximum power you can consume is lower.

This applies for any device including LMK00105.

73,
Timothy

• Hello Timothy-san,

Thank you for sharing materials about thermal calculations. This material was just what they are looking for. As it could be use it on other devices, so we would like to make effective use of it for other projects too.