TDC-GPX acam messelectronic gmbh, TDC-GPX Datasheet - Page 49

• Manufacturer Part Number: TDC-GPX
• Description: Precision Time Interval Measurement
• Manufacturer: acam messelectronic gmbh

5.6 MTimer
There is an internal timer available for internal use.
The main application will be setting a dedicated time
interval between 25ns and 204.7 µs after which the
interrupt flag is set. The period is set in ‘MTimer’,
register 7, in multiples of Tref. The maximum delay is
8191 * Tref = 204.7 µs. The timer can be started by
a Stop and/or Start signal. This is set in ‘MTimerStart’
and ‘MTimerStop’, register 4. Setting Bit ‘TimerFlag’,
register 12, the interrupt flag is set when the timer
stops.
5.7 Interrupt Flag
The user can select on which event(s) the interrupt
flag is set.
The selection is done in register 12, Bits 13 to 25, by
unmasking the dedicated bits. They are combined by
an Or-Gate to the interrupt flag.
Selectable events are
5.8 Error Flag
The user can select on which event(s) the error flag is
set.
The selection is done in register 11, Bits 16 to 26, by
unmasking the dedicated bits. They are combined by
an Or-Gate to the error flag.
Selectable events are
5.9 Testinputs
For test purpose a set of three TTL inputs can be mul-
tiplexed to the measuring circuit by setting Bit Gtest in
register 3. The test inputs have the same functionality
as the measure inputs, but can only handle a minimum
pulse width of 5ns and a minimum edge-to-edge dis-
tance of 20ns.
5.10 M-Mode Timing &
Resolution
TDC-GPX is working in resolution adjust mode.
The intrinsic delay parameters vary with voltage, tem-
perature and process tolerance. The resolution adjust
unit uses the voltage depency to compensate for tem-
perature and process variations. The following table
lists the derating factors.
Hit FIFOs 1, 2 …or/and 8 are full
Interface FIFOs 1 or/and 2 are full
PLL not locked
All Hit FIFOs empty
End of Mtimer
Hit FIFOs 1, 2 …or/and 8 are full
Interface FIFOs 1, 2 …or/and 8 are full
PLL not locked
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49
With the stabilization of the resolution by the resolu-
tion adjust mode, the voltage of the core decreases
with decreasing temperature, and increases with in-
creasing temperature. The setting should be done in a
way that at maximum operating temperature the
maximum core voltage is reached, and that minimum
core voltage is reached at minimum operating tem-
perature. With this method you get two limits:
Best case process, deepest temperature, lowest volt-
age: 0.74 x 0.889 x 1.2 = 0.789
Worst case process, highest temperature, highest
voltage: 1.31 x 1.17 x 0.91 = 1.394
The BIN size is calculated as BIN
standard deviation in M-Mode is basically limited by the
noise of the measuring unit and has been measured
with 10 ps + 8 ps * t/µs.. The BIN size has no real
influence on this.
The pulse width limit is minimum 1.5 ns, limited by the
input buffers.
The measurement range depends on the M-Mode bin
size and the coarse counter. Its typical value is:
INL
As a speciality of M-Mode the integral non-linearity
shows a deviation of the measured to the real time
interval in the near range. The width and height of the
non-linear range depends linearily on the MSet value.
Range
Derating by
Voltage
Temperature
Process
2
23
BIN
R
Mode
0.889 at –
40°C
Minimal
0.91 at 3.6V
0.74
MSet
1
TDC-GPX
R-Mode
1
/MSet. The
Maximal
1.2 at 2.85V
1.17 at
+125°C
1.31
7
( s
MSet
31
)