TDC-GPX acam messelectronic gmbh, TDC-GPX Datasheet - Page 15

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

1.6 Power supply
1.6.1 Resolution adjust
In principle the high resolution of the TDC-GPX is de-
rived from the internal gate propagation times. The
gate propagation time depends upon voltage, tempera-
ture and the manufacturing process. Due to this de-
pendency the resolution normally is not known and
must be calculated via calibration measurements. In
addition, the resolution is not stable, it sways with
voltage and temperature. This does not apply using the
resolution adjust mode for the TDC-GPX. In this mode
the resolution of the TDC-GPX is adjusted quartz-
accurately and absolutely temperature stable via
Phase Locked Loop The phase locked loop (PLL) regu-
lates the core voltage of the TDC-GPX so that the reso-
lution is set exactly to the programmed value.
The BIN size is calculated as follows:
BIN
BIN
BIN
BIN
R
I
G
M
Mode
Mode
Mode
Mode
5*47 µF
acam-messelectronic gmbh - Am Hasenbiel 27 - D-76297 Stutensee-Blankenloch - Germany - www.acam.de
T
BIN
BIN
BIN
216
ref
I
I
R
2
Mode
Mode
Mode
hsdiv
refclkdiv
3.3 V
1
1
2
3
MSet
Schottky (BAT47)
5*47 µF
Vddo
Vdde
Vddo
Vddo
Vddo
Vddo
Vdde
Vdde
Vdde
Vdde
Vdde
1
Vsso
1
Vddc
Vssc
Vddc
TDC-GPX
Vssc-h
5*47 µF
Vddc Vddc Vddc
Vssc-o
Figure 15
Vsse
15
40 MHz reference
Vddc-h
Vddc-o
RefClk
Phase
Tref = 25ns (40 MHz reference clock)
RefClkDiv, HSDiv
The adjustment range of the resolution can reach
values from –40 % up to +9 % of the normal resolu-
tion at 3.3 V and 25 °C. If environmental conditions
lead to very large adjustments the locked-state can be
lost. Then the PLL changes to floating resolution until
the conditions allow the PLL to lock again.
Figure 15 shows the recommended external circuit for
the regulation loop.
Note: See also application note AN013.
Example:
RefClkDiv = 7 and HSDiv = 183 give the follow-
ing resolution:
I-Mode
G-Mode
R-Mode
>= 50 mil
2*47 µF
2K2
80.9553 ps BIN
40.4776 ps BIN
26.9851 ps BIN
10R
1K3
10 µF
close to the regulator
Register 7
electrolytic, e.g.
tantalum
1K8
LM1117
adj.
Vo
TDC-GPX
5.0 V
Vi
10 µF