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heating

Yuri Gershov
Prodigy 10 points
Part Number: DS125DF410
Other Parts Discussed in Thread: LMH5401, LMH6401, DS30EA101,

Good day

My design build from three identical channels, each build is chain based on LMH5401-LMH6401-DS30EA101. Between LMH5401 and LMH6401 DC-coupling, between LMH6401 and DS30EA101 AC coupling. The inputs of  common-mode voltage VOCM of LMH5401 and LMH6401 are connected together to source 2.5V stabilized and connection of these component to power is single source 5V (Vs- and GND connected together)

Component DS30EA101 is powered from 2.5V source.

All three channels (chains) connected to inputs of one component DS125DF410 powered from 2.5V source and coupling between outs of LMH6401 and inputs of DS30EA101 is AC.

Not found any instability of parasitic generation (has been use spectrum analyzer up to 3GHz with antenna sniffer

All three channels and retimer DS30EA101 placed on multi-GND PCB and all pads of devices are connected to GND planes (internal and on Print side). The area is appr. 15-20 sq. cm but board is more bigger.

The area is hot appr 60-70deg Celsius. It is not high temperature? What is the possible reason for this temperature? How we can to decrease the temperature with method other than heat dissipation area increase?

Thank you very much

  • 0
    TI__Mastermind 25415 points

    Hello Yuri,

    You mentioned there are no signs of oscillation and are not using high voltage supplies, do you see any concerning high power drawn (supply current) from any of the devices? Having three of each of those components leads to about a typical of about 2.2W of power consumption, and these devices do not have exposed thermal pads. Would you be able to share a schematic?

    In your multi-GND PCB design you most likely have vias going though the internal layers. It would help to run them though to the bottom layer which will dissipate the heat faster; but, this is not the most significant factor in dissipating the heat. It mostly depends more on surface area of the copper plane, the number and size of the vias. If you would like more information on the topic, here are some app notes with more insight: Thermal Design, PowerPad, Layout, PowerPad Brief. 

    Thank you,

    Sima