USB Audio 2.0 Reference Design, XS1-L2 Edition Hardware Manual (1.6) 31/32
19
Board Revision Changes
This sections lists the changes between revisions of the PCB.
19.1
Changes From 1V0 To 1V1
•
Swapped R62 and R66 silkscreen labels to correct error.
•
Removed GPIO test points and added GPIO connector
•
Split digital I/O to use seperate ports, rather than outputs being identical and the input
being selected by a switch.
•
Added testpoints for new digital I/O signals.
•
Added PLL AUX LED.
•
Added power sequencing to power supplies.
•
Moved R75, C75 and 13M oscillator to add power sequencing.
•
Changed layout of 1V0 SMPS.
•
Changed L2 footprint to improve solderability.
•
General tidy up and minor track changes.
19.2
Changes From 1V1 To 1V2
•
Added buffer for MIDI I/O to correct 5V going into XS1-L2 I/Os.
•
Added pull ups on MIDI signals to stop startup glitches.
•
Added 47pf cap to slow coax output and tidied up digital out layout.
•
Redesigned coaxial input for better performance and reduced cost.
•
Moved the optical input track away from the 1V0 SMPS inductor.
•
Moved bulk 1V0 decoupler (C93) across to far corner of L2.
•
Changed most 0402 decouplers to 0603.
•
Changed layout of the 13M oscillator.
•
Added 5 more ground test points (next to CLK, VBUS, MIDI, DIGITAL IN and DIGITAL
OUT).
•
Added silkscreen labels to all test points, apart from the codec signals in the middle of
the board.
•
Added silkscreen labels for 5V DC, POWER SW, USB, XSYS and GPIO.
•
Moved around R19, R52 and C34 to make it in line with other analogue outputs.
•
Tidied up teardrops and changed them to curved shape.
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