Cingular cell phone service - Thermal solution for handheld devices with plastic enclosures

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Thermal solution for handheld devices with plastic enclosures

veeresh

2007-11-12, 4:33 am

Hi,
I'm integrating an HSDPA module - HC25 from siemens to PXA270. This
entire setup would sit into a plastic body without airflow .
This module takes 2.7Watts of power while transmitting HSDPA
packets. There is not much clearance to put heatsink.

Can you please advice me to ensure the operation at 55 degrees?

thanks and regards,
Veeresh

isw

2007-11-12, 12:33 pm

In article <1194862060.647369.71680@k35g2000prh.googlegroups.com>,
veeresh <veereshin@gmail.com> wrote:

> Hi,
> I'm integrating an HSDPA module - HC25 from siemens to PXA270. This
> entire setup would sit into a plastic body without airflow .
> This module takes 2.7Watts of power while transmitting HSDPA
> packets. There is not much clearance to put heatsink.

A heatsink won't do much good anyway if there's no thermal connection to
outside air.

> Can you please advice me to ensure the operation at 55 degrees?

You didn't say what the total average power dissipation of the unit is,
nor did you mention the size of the box. Both of those matter a lot.

Isaac

veeresh

2007-11-13, 4:33 am

On Nov 12, 11:14 pm, isw <i...@witzend.com> wrote:
> In article <1194862060.647369.71...@k35g2000prh.googlegroups.com>,
>
> veeresh <veeres...@gmail.com> wrote:
>
> A heatsink won't do much good anyway if there's no thermal connection to
> outside air.
>
>
> You didn't say what the total average power dissipation of the unit is,
> nor did you mention the size of the box. Both of those matter a lot.
>
> Isaac

Thanks for the response :-)
the module's surface area is about 50mm X 34mm. This is shielded on
one side which face towards PCB, and I've provided few thermal vias on
this side. The other side has a ground plane that is facing towards
towards the plastics, with about 0.5mm or less clearance.
Average power dissipation would be about 1W during voice calls and
about 2.7W during HSDPA packet transfers.. Is it possible to infer the
temperature rising curve assuming that HSDPA packet transfer would
last for maximum of 5 minutes?

PCB size is approximately 108mm X 100mm with two ground planes and 0ne
power plane. The module has four mounting holes that are grounded.

ciscodsl

2007-11-20, 4:33 am

On Nov 12, 11:26 pm, veeresh <veeres...@gmail.com> wrote:

> Average power dissipation would be about 1W during voice calls and
> about 2.7W during HSDPA packet transfers..

You better plan for some type of air flow inside a box with that much
power inside. Best mount a fan in there.

ciscodsl

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