diff --git a/atusd/ERRATA b/atusd/ERRATA index 5c7ce42..4004deb 100644 --- a/atusd/ERRATA +++ b/atusd/ERRATA @@ -17,3 +17,16 @@ Version 20100908: - SPI activity causes the PLL to unlock. Specifically, toggling nSEL does this. + +- work-around on second 20100908 board: replace the resistive divider with + a capacitative divider. See sim/cdiv.sch. This is a simple BOM change: + + C7 -> 0 R + R3 -> 33 pF + R4 -> 220 pF + +- considering that the clock input has a Vpp of only 400-500 mV, we should + have a ground plane also under as much of the the clock circuit as + possible. + +- via between pins 1 and 32 is too close to the chip for DIY PCBs diff --git a/atusd/sim/cdiv.sch b/atusd/sim/cdiv.sch new file mode 100644 index 0000000..84269a5 --- /dev/null +++ b/atusd/sim/cdiv.sch @@ -0,0 +1,47 @@ + + + + + + + + + + + + + + + + + + + + <.DC DC1 1 120 40 0 36 0 0 "26.85" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "no" 0 "150" 0 "no" 0 "none" 0 "CroutLU" 0> + <.TR TR1 1 310 40 0 57 0 0 "lin" 1 "0" 1 "1 us" 1 "10000" 0 "Trapezoidal" 0 "2" 0 "1 ns" 0 "1e-16" 0 "150" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "26.85" 0 "1e-3" 0 "1e-6" 0 "1" 0 "CroutLU" 0 "no" 0 "yes" 0 "0" 0> + + + + + + <100 340 100 400 "" 0 0 0 ""> + <220 280 220 320 "Vout" 250 270 17 ""> + <220 380 220 400 "" 0 0 0 ""> + <100 200 100 280 "" 0 0 0 ""> + <100 200 120 200 "" 0 0 0 ""> + <180 200 220 200 "" 0 0 0 ""> + <220 200 220 220 "" 0 0 0 ""> + + + + <"Vout.Vt" #0000ff 0 3 0 0 0> + + + <"V1.It" #0000ff 0 3 0 0 0> + + + <"Vout.Vt" #0000ff 0 3 1 0 0> + + + +