QFN-16 (RSA) footprint?

John Mielke said:

Hello,

The QFN-16 (RSA) packaging of MSP430G2452 seems to have incorrect drawing in one page of the datasheet.

From page 62 of the datasheet, we see that pitch is 0.65mm, then since each edge has 4 pins the center to center distance between the first and four pin is 1.95mm. Add the two halves of pad width which also includes the solder mask expansion width, the distance between outer edges of the pin on each side is 1.95+0.35+2x0.07(solder mask expansion) =2.44mm.

But on page 61, this distance is shown as 2.7±0.1mm, even the smaller 2.6mm value is still substantially larger than 2.44 calculated from page 62.

Do we have an official CAD footprint or gerber file for this package?

The 2.7 mm you referenced is correct but part of a poorly drawn diagram.  The distance measured between the outer edges of the pins should be 2.3 mm.  The 2.7 mm actually refers to the distance between the outer edges of the thermal pad.  I have submitted a request for us to make this more clear.  Thank you for bringing it to our attention.

Here's a simple proof to show which dimensions to rule out.  Let's assume that the 0.65 mm spacing is correct.  The space between centres of for four pins is 1.95 mm.  Now let's test the idea that the edge to edge distance of the pins is 2.7 mm.  This means that the width of one pin needs to be 2.7-1.95 mm = 0.75 mm.  With pin spacing of 0.65 mm and a pin width of 0.75 mm, the pins would overlap so this cannot be true.

We do have a schematic and footprint library for Eagle CAD.  As a cross reference I measured some dimensions for the RSA16 used in the MSP430G2452.  This verifies the pin spacing as 0.65 mm.  The distance between the outer edges of the pads is within a reasonable margin of error from 2.44 mm you referenced (2.5 mm).  You can also see that the thermal pad edges (2.7 mm) extend beyond the pin edges like they should.

John Mielke said:

Is there any design example of G series device, preferable MSP430G2302? We are reviewing the schematics and it would be best to have an official example to look at side-by-side.

Try the MSP430 LaunchPad.  For the MSP430G2302, I suggest you start your development with the MSP-EXP430G2 using the MSP430G2302IN20.  You will find the schematic in the MSP-EXP430G2 LaunchPad Experimenter Board User's Guide in the section, "MSP-EXP430G2 Hardware."  An alternative is to use the use the MSP-FET430U28A with the MSP430G2302IPW20.