TDC-GPX acam messelectronic gmbh, TDC-GPX Datasheet - Page 24

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

2.3 I-Mode Basics
In this mode TDC-GPX offers
Figure 18: Measurement timings
Par.
*with int. start retrigger
Input circuitry
The detailed input structure is shown in Figure 17:
Input circuitry. Each input separately can be set to be
sensitive to rising or falling edge. This is done in regis-
ter0, TRiseEn[8…0] and TFallEn[8…0]. The LSB stands
for the TStart input, the MSB TStop8 input. A zero in
the channel bit for TRiseEn and TfallEn at the same
time disables the channel.
All inputs can be disabled by hardware, the stop inputs
in pairs (pin ‘StopDis1’ disables inputs TStop1 and
TStop2, etc.). They also can be disabled by Software
setting the ‘Disable’ bits in register 2. The TDC-GPX
offers the possibility to disable the Stop inputs auto-
matically until a Start is coming in. This is set by Stop-
DisStart = ‘1’ in register 5.
t
t
t
t
t
r r ,
ph
ss
pl
ff
8 stop channels referring to 1 start channel,
Each of typ. 81 ps resolution
5.5 ns pulse-pair resolution
Start-retrigger up to 7 MHz
Unlimited measuring range with internal start re-
trigger
All inputs of LVTTL type
Selectable rising/falling edge sensitivity for all
channels
Several disable possibilities for all channels
Start
Stop
**5.2 ns
0 ns min
1.5 ns
1.5 ns
Min.
Time (Condition)
acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de
6.9 ns max.
5.5 ns typ.
t
ph
*unlimited
t
ss
Asynchronous
9.4 µs
Max.
t
#
ph
Start
**with StopDisStart = 1
measured
t
Start01
Positive pulse width
Negative pulse width
Start to Stop
edge to edge
#
pl
@ 87 ps resolution
t
rr
t
Start# 1
ff
Description
(N+1) * 25ns
fixed
Start# 2
24
S t a r t R e t r i g g e r
After an initial start event, the TDC-GPX can generate
its own internal starts. This is controlled by the pa-
rameter “StartTimer” in register 4. The start retrigger
rate may not exceed 7 MHz.
Single Start
StartTimer = 0 switches off the internal Start genera-
tion. In this mode the measuring range is limited to 2
BIN
TStart will be ignored.
Internal Start Retrigger
The period of the start repetition is programmable in
multiples of the 40 MHz reference clock between
(4+1) and (255+1) x 25ns (Register 4: Start-
Timer[7…0]).
The time interval between the initial, external start and
the first internal one will vary. It is therefore measured
and stored as ‘Start01’ in register 10. It can be read
out from this register as a 17 Bit integer in multiples
of BIN.
The time intervals between following starts are fixed
and referred to as (N +1) x Tref. Additionally, there is
an 8 Bit counter for the start number (Start#). The
start number is added to the output data.
A further option is to feed the highest bit of the Start
counter to the IrFlag output pin by setting register 11,
Bit 26 Start#U to one. With this signal the intenal
start number counter can externally be extended to
any size.
The internal start retrigger allows an unlimited
measuring range for the TDC-GPX.
External Start Retrigger
A further option is to retrigger the Start externally.
This option is activated by setting StartTimer = 1 (Reg
4) and StartRetrig = 1 (Reg 5). The further behavior is
the same as for the internal start retrigger. The
maximum retrigger frequency is typically 7 MHz. The
time interval between two Starts is measured and
stored in the “Start01” register. This value is reason-
able only if the delay between two Start pulses does
not exceed the measuring range of 2
Figure 19
(N+1) * 25ns
fixed
10.6 µs (@ BIN = 81 ps). Further pulses at
Start# 3
TDC-GPX
time
1 7
BIN
10.6 µs.
1 7