In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

[b]Sparks,[/b]

yes, you are definitely right, the DIL arrangement actually requires less real estate on the "motherboard" than the square arrangement. I had better made the calcualtions you did, before posting :-)

Nevertheless, what I meant was that a DIL48-sized board does possibly not have enough real estate to allow routing of all SX48 pins to the corresponding pins of a DIL48-sized PCB. I found that it can be done when you turn the SX48 by 45° (like Peter did).

The attached picture shows my design. Please note that I did not assign the SX48 pins 1:1 to the DIL pins. This is because I wanted to keep the traces for OSC1 and OSC2 as short as possible. Except of the SX48 and the two filter caps, there are no other components on this board because it is my idea to make an "SX48 DIL plug'n play' version allowing to access all I/O pins without any restrictions.

Whenever the traces connected to a high-speed device like the SX48 become longer (i.e. antennas), my "EMI alarm light" goes on. This is the main reasoon why I gave up the 1:1 pin assignment idea to allow for shorter traces for OCS1 and OSC2. I have also added two filter caps between the Vdd and Vss signals, and added a Vss plane almost all over the bottom side, and a Vdd plane covering as much space as possible on the top side. These two planes make an additional low-impedance capacitor between Vdd and Vss helping to reduce EMI.

Although I could have reduced the DIP package's pin-count by only providing only one pin for Vdd and Vss each, I have decided to keep the original number of four pins for Vdd and Vss each. This adds some freedom for selecting the power pins on the DIL48 socket. Nevertheless, for lowest impedance and EMI reduction, I suggest connecting them all to the supply potentials on the motherboard.

The minimum lead width is 10 mils, and the minimum spacing is 8 mils. So, this is not a typical design for a "home-brew" PCB but a professional PCB manufacturer can do it. The board size is approx. 2.4" x 0.7".

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