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LM5122-Q1: LM5122-Q1 Power losses

Bhargav jani
Intellectual 340 points
Part Number: LM5122-Q1
Other Parts Discussed in Thread: LM25117-Q1

Hello, 

I am currently working with LM5122-Q1 IC for designing a boost-buck stage DC-DC power supply design. I am currently working on placing my components on my circuit board (Perfboard). The question is choosing the correct heat sink for the circuitry. I read in the datasheet, regarding the shutdown mode if the junction temperature goes above 160 degrees. My input voltage spec are from Vin - 10V to 24V and Output from 12V to 14.5V and output current upto 5A.

The second stage is the LM25117-Q1 not directly next to the same board (Board 1 where along with LM5122-Q1, with microcontroller and its other passive components).

Is it really necessary to place a heat sink with the N channel MOSFETS or shut down mode will take care of the IC in case 

Regards

Bhargav 

  • 0
    TI__Guru* 78400 points
    Not every circuit require a heat sink, and it depends on your board thermal performance. You should estimate the power dissipations in the IC, the FETs and the power inductor, and make sure none of them exceeds its max temperature limit. The IC internal thermal shutdown can take care of itself if you don't want to do anything extra, but you should pay attention to the FETs and inductor temperature.