Microchip LN-CSAC-SA65 handleiding
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LN-CSAC Model SA65-LN User’s Guide
DS50003805A-page 22 2024 Microchip Technology Inc. and its subsidiaries
2.9.1 Manual Synchronization
In Manual Synchronization mode (default), the LN-CSAC ignores any signal present on
the PPSEXT (pin 9) until commanded. When a synchronization command is received
(see Section 3.3.4 “1 PPS Synchronization (S)”), the PPSOUT is synchronized to
the next rising edge of PPSEXT to appear on pin 9.
This mode is applicable to configurations where the LN-CSAC is embedded in a sys-
tem where a 1 PPS reference signal is always present, but not always reliably accurate
or stable (such as a GPS receiver). The host microprocessor may command the
LN-CSAC to synchronize after it has verified the state-of-health of the 1 PPS reference
source (for example, after querying lock state of a GPS receiver).
To manually synchronize the LN-CSAC from Clockstudio, make sure that a valid 1 PPS
reference is connected to the 1 PPS reference input and click Sync Now on the 1 PPS
Tab (Figure 2-5). The LN-CSAC synchronizes to the next rising edge of PPSEXT
detected on pin 9.
2.9.2 Automatic Synchronization
In Automatic Synchronization mode, the LN-CSAC synchronizes PPSOUT to every
PPSEXT rising edge that appears on pin 9. In this mode, synchronization may be per-
formed by connecting a reference 1 PPS signal to pin 9 without needing to issue the
synchronization command. Automatic synchronization can be enabled/disabled
through bit 3 (0x0008) in the mode register (see Section 3.3.3 “Set/Clear Operating
Modes (M)”).
This mode can be useful, for example, in cases where the host system does not com-
municate with the LN-CSAC and uses gating of the PPS to indicate validity.
To enable Automatic Synchronization from Clockstudio, select the Enable Auto Sync
checkbox on the 1 PPS panel and click Apply (see Figure 2-5).
2.10 1 PPS DISCIPLINING
In order to achieve higher-resolution synchronization of PPSOUT as well as frequency
calibration of the LN-CSAC, the LN-CSAC incorporates a simple proportional-integral
(PI) disciplining algorithm.
Based on the measurements of the TIC, the disciplining algorithm adjusts the
LN-CSAC’s microwave synthesizer through the digital tuning value (steer, observed
from the telemetry string). The algorithm steers the frequency so as to simultaneously
discipline both the time- and frequency-error of the LN-CSAC to that of the external ref-
erence, ultimately achieving accuracies of <5 ns and 1 × 10
–12
, respectively. Note that,
unlike the !FA and !FD commands, there is no software limitation upon the disciplined
value of steer.
Disciplining can be enabled/disabled through bit 4 (0x0010) in the mode register (see
Section 3.3.3 “Set/Clear Operating Modes (M)”). The time constant of the steering
algorithm is user selectable through the !D or !d the command (see
Section 3.3.5 “Set 1 PPS Disciplining Time Constant (D)”).
Note: Automatic Synchronization mode and Disciplining mode (see
Section 2.10 “1 PPS Disciplining”) are mutually exclusive. Enabling
either in the mode register disables the other.
Note: Both mode settings and time constants set via the !D command are
non-volatile, that is, preserved across power cycles.
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Productinformatie
| Merk | Microchip |
| Model | LN-CSAC-SA65 |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 6392 MB |
