FMC TDC 1ns 5cha - Hardware issueshttps://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues2019-02-12T11:26:22Zhttps://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/1V3-1 - EEPROM type not compatible with VITA 57.12019-02-12T11:26:22ZDimitris LampridisV3-1 - EEPROM type not compatible with VITA 57.1In order to comply with VITA 57.1 standard, the FMC EEPROM needs to be
changed to 24C02.https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/2V3-0 - Mechanical: PCB breakout tabs too long2019-02-12T11:26:22ZTomasz WlostowskiV3-0 - Mechanical: PCB breakout tabs too longThe breakout pads on the PCBs received from recent batch(es) are too
long, sometimes preventing insertion of two TDCs on a SVEC (see the
photo).
Make them shorter in the future cards, please :)
### Files
* [IMG_20130924_155630.jpg](/uploads/0041ebc3b7be23148c14d9332ff1315f/IMG_20130924_155630.jpg)https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/3V3-1 - Add 10mm spacers,replace FMC front panel kit2019-02-12T11:26:23ZErik van der BijV3-1 - Add 10mm spacers,replace FMC front panel kitThe standoffs are not in the BOM file
[EDA-02290-V3-1\_arrangement-mat](http://edms.cern.ch/file/1283037/1/EDA-02290-V3-1_arrangement-mat.pdf).
They are needed and even shown in
[EDA-02290-V3-1\_arrangement](http://edms.cern.ch/file/1283037/1/EDA-02290-V3-1_arrangement.pdf).
Replace the Xtech FMC front panel kit, the two spacers and the four
hexalobular screws by the following ELMA kit reference:
21M280-2
The ELMA 21M280-2 kit contains:
\- 1 FMC front panel
\- 1 O-ring
\- 2 10mm spacers
\- 8 M2.5x6mm screwshttps://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/4V3-1 - Wrong Manufacturer PN in BOM for C5, C13-21, C272019-02-12T11:26:23ZNicolas VoumardV3-1 - Wrong Manufacturer PN in BOM for C5, C13-21, C27Actually, the design office did something wrong in the creation of the
capacitor TPSB476K006R0250 in the Altium library. There are two
manufacturer part number in the parameters of the component. In the
actual BOM, Manufacturer part number is "GENERIC
CTE3528-21\_47UF\_6.3V\_10%\_LESR0250" instead of "AVX
TPSB476K006R0250".Nicolas VoumardNicolas Voumardhttps://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/6V3-0 - Change stackup2019-02-12T11:26:24ZErik van der BijV3-0 - Change stackup- Verify proposal for a new stackup.
### Discussion
-----
- JGR: Some nets of the bus TDC\_D\[27..0\] were routed in the inside
layers with 8 mils of track width. According to my calculations, in
this inside layers the impedance is about 67 Ω \> 50 Ω +/- 10%. This
impedance step may degrade the signal quality. I'd prefer to
propose, if you believe it needed, another PCB stack-up to fit
better the 50 ohms impedance requirement without having to change
the routing.
- NV: Please explain… We can also enlarge the tracks on the internal
layers and/or (don’t know if it’s possible) to grow up the internal
layers thickness.
- EB: To check in a future version.
- JGR: I'd like to propose for this series (December 2012 - EB) this
PCB stack-up as an alternative (see the image below). Using it you
can achieve an impedance of about 50-55R for single ended internal
layers, improving the signals quality.
- NV: I cannot see the image… ;-).
- EB: To check in a future version. Do not change the PCB
specification and produce as specified. The differences in
impedances are too low to validate a change now.
-----
EB: I checked the differences in stackup between the original design
files and the ones that Wurth is proposing (see attached file).
Basically there is
- a slight difference in prepreg thickness at L1/L2 and L5/L6 (150 vs
163 um).
- a large difference in the other thicknesses L2/L3 and L4/L5 (500 vs
200 um) and L3/L4 (150 vs 570 um)
I believe that there nothing critical on this card, but still would like
the production version to be as similar as possible to our prototype and
therefore we should follow our original design files.
-----
### Files
* [7S_tarjeta_TDC_6_layer_standard_1_6.pdf.pdf.pdf](/uploads/fa04a3cfb89ccd23c7369d4d3ca1a04b/7S_tarjeta_TDC_6_layer_standard_1_6.pdf.pdf.pdf)
* [Proposal.gif](/uploads/ae54cd6470892f3d54a98ea5325bc83d/Proposal.gif)https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/7V3-0 - Track width not as defined. Verify layout.2019-02-12T11:26:24ZErik van der BijV3-0 - Track width not as defined. Verify layout.- Verify and correct track width of signals. Verify layout.
### Discussion
-----
- JGR: The “Layer Stack Up Detail” table indicates a line width/gap of
0.23/0.30 mm for 50/100 Ω at the top and bottom layers, but finally
the single ended tracks were routed with 0.203 mm (8 mils) width and
~56 Ω
- NV: I don’t think it’s the case for all the lines, but changing the
tracks between TDC chip and FMC connector to 10 mils can be easily
achievable.
- EB: Recommend to change in a future version
-----
- JGR: Some nets of the bus TDC\_D\[27..0\] were routed in the inside
layers with 8 mils of track width. According to my calculations, in
this inside layers the impedance is about 67 Ω \> 50 Ω +/- 10%. This
impedance step may degrade the signal quality. I'd prefer to
propose, if you believe it needed, another PCB stack-up to fit
better the 50 ohms impedance requirement without having to change
the routing.
- NV: Please explain… We can also enlarge the tracks on the internal
layers and/or (don’t know if it’s possible) to grow up the internal
layers thickness.
- EB: To check in a future version.
-----
- JGR: Some signals (TDC\_IN\_FPGA\[5..1\] and differential pairs by
example) were routed too close. It may cause crosstalk problems. I
would recommend using the 3W separation rule where possible.
- NV: This is the case for many other signals, not only TDC\_IN\_FPGA.
Not very easy to route those lines elsewhere -\> too much vias
around…
- EB: To check in a future version.
-----
- NV: Other things on routing: (if a version 4 is planned)
- On C21, enlarge the tracks on both sides.
- Enlarge the tracks of the TDC\_STOP \[1-5\] to 10-12mils on the
bottom side.
- A few more decoupling capacitors can be placed directly under
the TDC chip (bottom layer). Pins 81, 82 and 86.
- Looking at TDC chip, on the right side of pin 86, there is a via
(x: 4662.5mil, y: 4600mil) there is a small piece of track that
can be removed.
- On VDDC\_TDC, a 100nF decoupling capacitor could be added near
pin 1 of TDC chip.
- To check in a future version.
-----https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/9V3-0 - Add pull-down R on unused LVPECL inputs TDC2019-02-12T11:26:25ZErik van der BijV3-0 - Add pull-down R on unused LVPECL inputs TDC- Add pull-down R on unused LVPECL inputs
### Discussion
-----
TDC.SchDoc:
- JGR: TDC datasheet recommends using 10KΩ pull-down resistor in not
used LVPECL inputs.
- NV: I agree if we plan to go on a version 4. It works well also
without any pull-down resistors.
- EB: Recommend to change in a future version.
-----https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/11V3-0 - Add more decoupling to AD9514 and AD5662 DAC2019-02-12T11:26:26ZErik van der BijV3-0 - Add more decoupling to AD9514 and AD5662 DAC- Add more decoupling to AD9514 and AD5662 DAC
### Discussion
-----
- JGR: I think that the AD9514 chip has few decoupling capacitors.
- NV: I agree. Adding more decoupling can only produce a better clock.
One can be added on pins 38-41, 30-31-32, 11-12, but again, the
whole manufacturing data has to be redone (version 4).
- EB: Recommend to change in a future version.
<!-- end list -->
- JGR: The AD5662 DAC doesn't have any decoupling capacitor.
- NV: Adding a 100nF cap will not kill us if we plan to go to version
4.
- EB: Recommend to change in a future version.
-----https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/12V3-0 - Replace 10uF/16V Capacitor by Sanyo type2019-02-12T11:26:26ZErik van der BijV3-0 - Replace 10uF/16V Capacitor by Sanyo type- Replace 10uF/16V Capacitor by Sanyo type
### Discussion
-----
Power\_supply.SchDoc:
- JGR: C25 rated voltage is 16V. It's connected to the P12V0, so it
will be stressed at 75. I think, as a good policy of design, all
components must be bellow of the 50 of theirs rated voltage and
dissipation power. This will decrease the failure rate of the board.
- NV: I totally agree with this if we can get the same capacitor value
with the same ESR and the same case size (A). In this case, all
other capacitors of the same type (i.e. C68) have to be replaced as
well. But AVX say in the datasheet that the recommended derating
should be less than 80% of the rated voltage. This means that the
capacitor can handle up to 12.8V. The only replacement part I found
with a quick search is the Kemet T491A106M020AT, but its ESR is too
high (5 Ohm). If we want to use a B case capacitor of the same type,
some components have to be displaced, and whole manufacturing data
has to be redone (version 4).
- EB: Leave design as is. According to the above
(http://www.avx.com/docs/catalogs/tcj.pdf), we are within the
recommended derating. Also, this particular board does not get hot.
In the Fine delay design that really heats up, we have used specific
capacitors from Sanyo for their good life-time under high
temperature operation. C25 is 10uF, 16V and could be replaced by
this type that is used on the Fine Delay card:
SANYO 16TQC10M ±20% 10uF 16V ESR 0R1 Solid Tantalum Chip Capacitor.
Type B.
Unfortunately the 16TQC10M is a Type B package (1210) and not Type A
(1206).
(The other type we use is
SANYO 10TPB47M ±20% 47uF, 10V ESR 0R07 Tantalum Solid Capacitor with
Conductive Poly-mer. Type B.)
Recommend to change in a future version.
- JGR: Maybe we can use X7R capacitors like this one (or
similar):
http://www.digikey.es/product-detail/en/C3216X7R1E106M/445-7706-1-ND/2733778
X7R capacitors have low ESR and are cheaper than tantalum or
aluminium capacitors. Some DCDC applications need a minimal ESR, but
I think this isn't the case.
- NV: I agree replacing the 10uF by the X7R as you propose.
- EB: Leave design as is. Recommend to change in a future version. See
2.3
-----https://ohwr.org/project/fmc-tdc-1ns-5cha-hw/issues/16V3-0 - C30/C31: replace by higher voltage version.2019-02-12T11:26:29ZErik van der BijV3-0 - C30/C31: replace by higher voltage version.Two capacitors are used at a higher voltage than their specification.
- Replace C30 and C31 by 22uF/20V TPSB226K020R0400 (new BOM item)
Discussion:
-----
FMC\_Connector.SchDoc:
- JGR: C30 and C31 capacitors (47uF ± 20% ) are rated at 6,3V but
connected to P12V0.
- NV: I agree this is not good\!\!\! I couldn’t find a 47uF with more
than 16V, But we can replace the two capacitors by 22uF/20V (see
TPSB226K020R0400 at Farnell). They have the same footprint, but not
the same height.
- EB: Replace C30 and C31 by 22uF/20V TPSB226K020R0400
-----Nicolas VoumardNicolas Voumard