Issues in rev 2 from 22 Mar 2020 #1
Description
BOM/PCB:
C26/28 (/31/46/210 [209/48/49/50/... ?]) 100nF C0G not awailable in 0805, only in 1206 (C0G preferred in signal path and for critical blocking), alternative is paralleled 2x 47nF in 0805 (as bodge on top of each other)
(C46 marked as foil in schematic -> C0G
all C0G should be marked in BOM/Schematic)
BOM (see used BOM@mouser) :
U3: has to be ATMEGA48(P)A
R1, R2, R9, R12, R35: 5k -> 4.99k (E96)
U7: has to be DG408DY
U5: has to be SN74LV4053AD(R)
X1: 12MHz (preferred, 16MHz possible -> needs FW change)
R7: 100R (is 100)
PCB:
DRC gave me some errors, which I corrected for fabrication of PCB @ JLCPCB
Zener TP is underneath C13
Programming headers 10P: standard programming plug does not fit (C207 to close)
Programming headers 10/6P: No markings visible for Pin1 (if both are populated the standard programming plugs do not fit)
Remarks
Removed differential frontend (LTC2057 & OP07), it happily oscillated
Did not populate U20, U1, C37, U202, Q2, R84 JP
Due to changes in revs by Kleinstein the current FW does not work OOTB:
Input GND S8 DG408 are different -> can be addressed in FW (already did that)
ADC0 connection had to be swapped to ADC1 -> can be addressed in FW