We are evaluating low end 32 bit USB (device only) uCs. Ideally, we want 64K flash and 30 I/Os in 48 pins. So far, these are possible choices: Are there any other we should like into?
AT32UC3B164 64K 28 two I/O short LPC1343FBD48,151 32K 40 no 48 pins in 64K NUC120LD3AN 128K 31 unproven product/company
How much less than an inch? I used a 100 pin TQFP on a board only
0.85" wide. A 64 pin TQFP is only 12 mm wide which is only about half an inch of board space. The 64 pin package has pins on 0.5 mm pitch while the 44 pin package has pins on 0.8 mm pitch. So the size ends up being the same, 12 mm sq!
Did I miss something or are you excluding the 64 pin package by mistake?
Just FYI, the 48, 64 and 100 pin LQFP and TQFP parts are all 0.5 mm pitch. The 44 pin LQFP is the oddball on 0.8 mm pitch. I think the
The new RX-621 comes in 100 pin TQFP (only 16mm wide, 0.63 inch) and has host and device USB (one port, configurable either way), 256k-512k flash, and 64k-96k RAM. It's 32-bit, and runs at up to 100 MHz. Might be overkill for your purposes, but it fits :-)
If you're really space constrained, there's an 85-pin TFLGA version that's only 9mm square.
I can do 64 or 100 pins with more pcb space and/or finer design rules. But there are plenty of 48 pins to work with for now. Bigger chips tend to have more stuffs and more expensive anyway.
I can't say I am following you. If the problem is a routing issue, how is that impacted by the number of pins on the part? You are willing to work with a 44 pin LQFP which is the exact same size as the
64 pin LQFP, just with different pin pitches, so there is no reason it would need more board space.
I see you have included 44 pin LQFPs in your list, but your layout shows a 48 pin LQFP which is smaller. I also see what look like via holes bigger than the pin pitch which is 0.5 mm or >20 mil. Can't you save some board space by using smaller via holes?
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