[Halld-cal] Fwd: Resistor values for Bcal readout module

Elton Smith elton at jlab.org
Mon Jun 18 14:11:14 EDT 2012


I am copying this e-mail from Jack McKisson to the mail list for 
reference as it defines the parameters for the final iteration of the 
readout boards. The new boards to check the final configuration are 
being built with these values.

Cheers, Elton.

-------- Original Message --------
Subject: 	Resistor calculations
Date: 	Thu, 14 Jun 2012 16:55:43 -0400
From: 	Jack McKisson <jem at jlab.org>
To: 	Fernando J Barbosa <barbosa at jlab.org>, Yi Qiang <yqiang at jlab.org>, 
Carl Zorn <zorn at jlab.org>, Elton Smith <elton at jlab.org>, Chris Stanislav 
<stanisla at jlab.org>
CC: 	Nick Sandoval <sandoval at jlab.org>, Jim Fochtman <fochtman at jlab.org>

I've recalculated the resistor values for the BCAL SiPM bias circuits based on the following parameters.

Production version 5.00 KΩ(25°C) 0.5% thermistors US Sensor 502JG2E
Vop = 1.15V above breakdown (Nominal Hamamatsu data sheet Vop value (averaged for 16 elements in array) + 0.250V)
Nominal steps preferred for Vsupply = 0.500V
Nominal operating temperature +5.0°C

The value of Rlin is unchanged
Rlin = 6.49K 0.1%

I was able to keep the value of R2 unchanged
R2 = 86.60KΩ 0.1%

R2 Trim values have changed:
R2A = 162 Ω 1%
R2A = 324 Ω 1%
R2A = 649 Ω 1%
R2A = 1.30 KΩ 1%

Values for the Rs trim are also unchanged from the first test set values*

RsA = 41.2 Ω 1%
RsA = 82.5 Ω 1%
RsA = 165 Ω 1%
RsA = 332 Ω 1%

The minimum Vsupply appears to be 74.500 V*
The maximum Vsupply appears to be 76.000 V*

*I am running these values against multiple SiPM sets to observe the set point error distribution. An adjustment of the Rs Trim values or of the Vsupply points may be required (+/- 0.3 V) to center that error distribution. While the Rs Trim values may change I believe that the R2 Trim values are now settled if the above parameters remain unchanged.


On Jun 14, 2012, at 12:25 PM, Fernando J Barbosa wrote:

>  Hi Jack,
>  We are using the final thermistors.
>  The optimal bias voltage is 1.15V above breakdown, as per the recent email from Yi.
>  Thanks and best regards,
>  Fernando
>  On 6/14/2012 12:12 PM, Jack McKisson wrote:
>>  Fernando,
>>  I've run the calculations again for the new breakdown voltage but there is another thing I wanted to check before I start building the database for resistor value selection.
>>  I'm assuming that for this build we are using the final thermistors. They have a different B0 value from the thermistors used for the first round of readout testing. Can you confirm those thermistors have been updated to the final production type?
>>  And a double check of the correct voltage for Vop. What voltage is desired for Vop - expressed as the change from the Vop listed in the Hamamatsu data sheet?
>>  Jack
>>  On Jun 6, 2012, at 10:07 AM, Fernando J Barbosa wrote:
>>>  Hi Jack,
>>>  Yes, there have been changes to the PCB. The layout was changed a bit on the bias distribution side and now we have two U and D. So, you will need to extract the required information from the new versions.
>>>  We went ahead and ordered the 86.6k (0.1%) due to long lead times and in case we were to keep it. I am not sure if Elton has contacted you but he would like to operate the SiPMs at 1.2V above breakdown. So, definitely a change.
>>>  I would appreciate if you could send us the new resistor values as soon as possible due to long lead times on the high precision resistors.
>>>  Thanks and best regards,
>>>  Fernando
>>>  On 6/6/2012 9:41 AM, Jack McKisson wrote:
>>>>  Fernando,
>>>>  I'm out on travel today and again on Friday. On Thursday I'll make a point
>>>>  to review the PCB files and the procedures for generating jumper settings.
>>>>  Am I to understand there have been PCB changes in the last 2 weeks?
>>>>  More importantly perhaps, has there been a change in the operation voltage
>>>>  I should use to generate the jumper selections? If there has been a change
>>>>  it could affect the best value for that one larger value (86.600K
>>>>  currently) resistor.
>>>>  Jack
>>>>>  Hi Jack, Yi,
>>>>>  I was reviewing my notes and I realized I was incorrect in my request.
>>>>>  We will build two new BCAL modules instead of refurbishing the
>>>>>  prototypes at this time. Therefore, we will need 80 new SiPMs, two (U
>>>>>  and D) jumper drawings and Excel files within the next two weeks.
>>>>>  For production, we will need to start having these (SiPMs and docs) in
>>>>>  early August.
>>>>>  Thanks and best regards,
>>>>>  Fernando
>>>>>  On 6/3/2012 9:51 PM, Fernando J Barbosa wrote:
>>>>>>  Hi Jack, Yi,
>>>>>>  We now have two distinct BCAL PCBs: U and D. U is as before; D is has
>>>>>>  mirrored bias (compared to U) for SiPMs 1 through 8. They are similar
>>>>>>  otherwise.
>>>>>>  BCAL U:
>>>>>>  SiPMs 1&    2 - bias 1
>>>>>>  SiPMs 3&    4 - bias 2
>>>>>>  SiPMs 5&    6 - bias 3
>>>>>>  SiPMs 7&    8 - bias 4
>>>>>>  BCAL D:
>>>>>>  SiPMs 1&    2 - bias 2
>>>>>>  SiPMs 3&    4 - bias 1
>>>>>>  SiPMs 5&    6 - bias 4
>>>>>>  SiPMs 7&    8 - bias 3.
>>>>>>  The other SiPMs are biased as before, per row (1 to 4, 1 to 4). Note
>>>>>>  that biases 1 - 4 for the U side are still distinct from those on the
>>>>>>  D side (different supply channels).
>>>>>>  The reason for this is that we want to have the same BCAL elements
>>>>>>  active during calibration by LEDs and and cosmics. We will need
>>>>>>  groupings and jumper drawings that take this into account and we,
>>>>>>  thus, need 48 for the U side and 48 for the D side.
>>>>>>  We plan to have one each of PCBs U and D ready to install into the
>>>>>>  mini-BCAL modules in within three weeks for tests before production.
>>>>>>  These will also implement the new assembly hardware, including high
>>>>>>  precision resistors and spec thermistors. So, the final version.
>>>>>>  Jack, the final drawings are available and I would appreciate if you
>>>>>>  could re-generate them for the new boards. We should plan to have
>>>>>>  jumper drawings ready by early August.
>>>>>>  Thanks and best regards,
>>>>>>  Fernando
>>  Jack McKisson
>>  Detector and Imaging Group
>>  jem at jlab.org

Jack McKisson
Detector and Imaging Group
jem at jlab.org

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