>From the Tuesday design review I still have the following redlines to work on:
   Ensure all devices follow the Rocket Names naming guidelines.
   Ensure that all lines in the schematic have properly descriptive names.
   Run BOM and prepare a parts list (ensure all parts carried over from prior 
design are still available).

The current schematic is in git, under the "lv2-node5" directory as 

There are also the following 7 items that I would be happy to have feedback on:

1) U281 Binary ripple counter used to divide the 12MHz clock down to 1.5MHz for 
sync of the SPS and HAP switching regulators.
    Issue:  At 5V for VDD the part can only handle a max input frequency of 
3.5MHz. The specified part can handle up to 12MHz, but only with Vdd=15V.
    Solution: Replace with a 3.3V, 12MHz (or higher) divider circuit. Perhaps 
similar to the SN54LV163A (binary counter, fmax=50MHz @VDD=3.3V, use Qb and 
clock) from TI.

2) CAN transceiver: MCP251x
    Issue: Not a 3.3V part.
    Solution: Replace with 3.3V CAN transceiver.  These are hard to find, but 
it looks like TI makes a few, though none in a package smaller than 8pin SOIC. 
A good choice appears to be the SN65HVD234 from TI

3) U283 Reset controller, used to hold the reset signal until the SPS or HAP 
has reached stable output
    Issue: Is this part and its associated circuitry needed?
    Solution: Just like the LPC1248, the LPC2368 has brownout circuitry built 
into the IC. That said the justification given by the 2006 Capstone team still 
appears to be valid.

4) U282 USB transient noise suppressor
    Issue: The part is an SOT23 package, not DFN. That said the SOT-6 is still 
a pretty small part, just not leadless.
    Solution: Possible to look up a new part available in a DFN package. The 
existing part is available in SOT23, BGA, SSOP, and PDIP.
5) Small "cut-able" jumpers
    Issue: in several places, there are small cut-able jumpers in the 
schematic, is there a standard symbol for this? Is it a good idea to cut traces 
on the board in the first place?
    Solution: Use two zero ohm resistors, mark one as a do not place. If 
desired, resistor can be removed and soldered on in the alternate position, 
resulting in lower possibility of board damage and higher reliability during 

6) USB High Speed Select
    Issue: Can the LPC2368 drive the voltage and current needed to get the bus 
to act in High Speed Mode?
    Solution: Probably, Need to look up the USB2.0 spec to be sure. The LPC2368 
can output +2.9V (VDD-0.4V) at -4mA on its GPIO pins. 
7) Everything Else
    Issue: Time consuming
    Solution: Time machine, I checked, TI still doesn't make one, neither do 
Micrel, Linear, On-semi, IBM, or Intel.

Ken Z (capstone2009)


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