Question about cc2520-cc2591EM_Schematic

stones yang

Other Parts Discussed in Thread: CC2520

Hi,everyone

when I look at cc2520-cc2591EM_Schematic,I found that fifteen pin and twenty-first pin in cc2520 connect to power.Below is the picture from cc2520-cc2591EM_Schematic.

While in cc2520 datasheet fifteen pin,eighteen pin and twenty-first pin are "NC".Please see the picture from the cc2520 datasheet.

Anybody can explain why for me?Thanks in advance.

Regards,

stone

over 14 years ago

0 Tor-inge over 14 years ago

TI__Expert 3205 points

These pins are only connected as it simplifies layout and inprove ground close to RF.

Tor-Inge

0 stones yang over 14 years ago in reply to Tor-inge

Expert 1080 points

Hi,Tor-Tnge

I can not understand completely.These pins are connected to power,not ground.so how to improve ground close to RF?I think it is easier that these pins are not connected than they are connected to power.Could you explain for me?Thanks in advance.

Regards,

Stones

0 Tor-inge over 14 years ago in reply to stones yang

TI__Expert 3205 points

Hi stones

The NC pins are not connected internally in the chip allowing supply routing to pin 16 and 20 through these pins (15, 21). This shortens supply routing and frees board area close to C21 and C41. This area freed allows more ground in-between the RF nodes and the supply lines. This intermediate ground area reduce coupling between supply lines and RF nodes. The increased ground area also allows more ground via connections close to chip. Added ground vias and short supply routing improve decoupling effectiveness and reduces unintentional radiation.

Tor-Inge

0 stones yang over 14 years ago in reply to Tor-inge

Expert 1080 points

hi Tor-Inge

I looked the PCB once again,I don't think it will shorten the power supply routing.

Regards,

stones

0 Fredrik K over 14 years ago in reply to stones yang

TI__Guru** 106705 points

Stones,

If pin 15 and 21 were not connecte to Vcc the power routing would have to go around the pins. This would have reduced the ground plane between the RF lines and the power line and also required somewhat longer power traces.

/Fredrik

0 stones yang over 14 years ago in reply to Fredrik K

Expert 1080 points

hi,Fredrik

Thanks for your reply very much.Knowing about this way of design,I have to acknowledge that TI employee design circuit very comprehensively.Perfect!I must follow you.

Regards,

stones

0 stones yang over 14 years ago in reply to Fredrik K

Expert 1080 points

Hi,Fredrik

However the CC2520 reference in "swrr054" pin 15 and 21 are not connected to power.

Regards,

Stones

0 Fredrik K over 14 years ago in reply to stones yang

TI__Guru** 106705 points

In other words, the CC2520-CC2591 design is slightly better than the CC2520 design.

/Fredrik

0 Evgeniy Podoshvelev over 11 years ago in reply to Tor-inge

Prodigy 50 points

Please tell me what program opens this file format, with PCB trace? The files are here - http://www.ti.com/tool/cc2520-cc2591em_rd
you can download it here http://www.ti.com/lit/zip/swru190.
The first format PCB than open? And CPA CSA than open formats? And what other files?

0 Fredrik K over 11 years ago in reply to Evgeniy Podoshvelev

TI__Guru** 106705 points

Hi Evgeniy,

The CAD files are from Zuken Cadstar.

/Fredrik

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