PDA

View Full Version : MAX6955 package confusion...



Nak
12-20-2009, 06:45 AM
Hi all,

I recently picked up a MAX6955 LED display driver and am trying to i/f with my Propeller (hence making this post on-topic!). However I am mightily confused by the packaging vs. specs of this IC... I have in my hands a 40-pin DIP package, but the spec sheet describes a 36-pin package that looks like a DIP but is labelled something else, and a 40-pin square surface-mount package that is clearly not the droid I'm looking for...

I'm lost. Am I supposed to be working with one of the two pinouts below, or something completely different!?!

Edit: Photo of chip attached. http://forums.parallax.com/images/smilies/smurf.gif

Post Edited (Nak) : 12/20/2009 1:43:52 AM GMT

hover1
12-20-2009, 06:56 AM
It look's like it's not available in 40 Pin "rectangle" package. What I think you have is the 36 pin chip. Not normal pinout, but there just the same.they are the same chip.



Jim


Nak said...
Hi all,

I recently picked up a MAX6955 LED display driver and am trying to i/f with my Propeller (hence making this post on-topic!). However I am mightily confused by the packaging vs. specs of this IC... I have in my hands a 40-pin DIP package, but the spec sheet describes a 36-pin package that looks like a DIP but is labelled something else, and a 40-pin square surface-mount package that is clearly not the droid I'm looking for...

I'm lost. Am I supposed to be working with one of the two pinouts below, or something completely different!?!

Post Edited (hover1) : 12/20/2009 1:14:18 AM GMT

Nak
12-20-2009, 07:05 AM
Hey hover1: So, would you map the 36-pin layout pin numbers to the 40-pin package pin numbers? Thus moving 19 (V+) and 20 (OSC) to the left side of the package? Or would you expect the physical layout to be preserved, leaving pins 19-22 of the 40-pin package unconnected?

PS: Is there a safe way to probe at the pins of an IC and tell if they're not connected to anything?

hover1
12-20-2009, 08:18 AM
Count the pins first. Could be 36.

I'm not understanding what you are asking. You would connect the pins of the Max device to the correct pins on the Propeller Chip.

You have notˇattached a schematic or PCB layoutˇthat I think you might be refering to.

ˇ Nak said...
Hey hover1: So, would you map the 36-pin layout pin numbers to the 40-pin package pin numbers? Thus moving 19 (V+) and 20 (OSC) to the left side of the package? Or would you expect the physical layout to be preserved, leaving pins 19-22 of the 40-pin package unconnected?

PS: Is there a safe way to probe at the pins of an IC and tell if they're not connected to anything?

Nak
12-20-2009, 08:26 AM
Hi hover1: There is an attachment on my first post that shows the 36-pin DIP-looking package pinout and the 40-pin surface mount package pinout. This was copied straight from the Maxim spec sheet. What I have, though, is a 40-pin DIP package. I have counted the pins several times to be sure! I simply have no idea what pins do what on this 40-pin package.

hover1
12-20-2009, 08:31 AM
Could you take a picture of the top of the chip?



Jim




Nak said...
Hi hover1: There is an attachment on my first post that shows the 36-pin DIP-looking package pinout and the 40-pin surface mount package pinout. This was copied straight from the Maxim spec sheet. What I have, though, is a 40-pin DIP package. I have counted the pins several times to be sure! I simply have no idea what pins do what on this 40-pin package.

Nak
12-20-2009, 08:42 AM
Pic attached to first post. http://forums.parallax.com/images/smilies/smile.gif

kuroneko
12-20-2009, 08:51 AM
Seems that the APL variant comes in 40 pin PDIP.

Nak
12-20-2009, 08:54 AM
TY TY TY!!! Now I can finally get on to playing with my propeller! http://forums.parallax.com/images/smilies/smile.gif

hover1
12-20-2009, 01:30 PM
Good news!