Cronologic xTDC4, Руководство пользователя

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Pin Name
1 +3.3 V
2 - 9 reserved/NC
10 GND
Table 2.2: Pinout of connector C3.
2.3 xTDC4 Functionality
The xTDC4 is a “classic” common start time-to-digital converter. It records the time difference
between leading or trailing edges on the start input and the stop inputs. Each stop channel A-D
can be enabled individually. The accuracy of the acquired timestamps is approx. 8 ps. The
timestamps are recorded in integer multiples of a bin size of 13
. 02083 ps (76 . 8 GHz). The data
acquisition can be limited to rising or falling signal transitions. Transitions of the input signals
are called hits. To reliably detect hits the signal has to be stable for at least 500 ps before and
after the edge. Between multiple hits on a stop channel a deadtime of approx. 5 ns occurs.
Within this deadtime further hits on the stop channel are reported with a coarse timestamp
only. The maximum trigger rate on the start channel is 4 MHz.
2.3.1 Grouping and Events
In typical applications a start hit is followed by a manifold of hits on e.g. a detector. The
hits recorded are managed in groups (which are called in some applications “events”). Figure
2.4 shows a corresponding timing diagram. The user can define the range of a group, i.e. the
time window within which hits on the stop channels are recorded, in software. Hits occurring
outside of that time window are discarded. The maximum recording range for a group is 218
µs .
Different ranges can be set for each of the 4 stop channels by setting corresponding channel.start
and channel.stop values in the channel configuration. The values need to be set as multiples of
13
. 02083 ps. A value of 768 corresponds, for example to a time of 10 ns.
Start
A
B
C
D
channel[i].start
channel[i].stop
Figure 2.4: Acquired hits are merged to groups as explained in the text.
2.4 Performing a firmware update
After installing the xTDC4 device driver, a firmware update tool is available. By choosing
“FirmwareGUI.exe” a firmware update can be performed. After invoking the application a
cronologic GmbH & Co. KG 5 xTDC4 User Guide