System information

Page 60 9530/8530 Manual Version 4.7
15. Appendix H - External Clock
9530/8530 External Clock Operation
The 9530 pulse generator has a special external clock circuit that allows for external clock
synchronization when using clock sources that have very narrow pulse widths and amplitudes.
The circuit was designed to be used on the output of a photo-diode or equivalent current
source. The clock function will still operate if a voltage source is used if the parameters stated
below are observed.
Parameter:
Minimum
Maximum
Pulse Width
100ps
-
Pulse Amplitude
1V
rms
5V
rms
Current Amplitude
9.8mA
rms
49mA
rms
Input Impedance
102Ω
Frequency
10MHz
100MHz
*Note: These specifications are preliminary and subject to change.
Using the external clock function:
Enter the system menu pages and find the clock menu page. Enter the clock source
menu by pressing the page button until the clock source page is reached.
Select the source to External Osc or External PLL.
Adjust the threshold level to trigger between 10% and 30% of the High-Z input
amplitude of the external clock source. For example when clock source is connected
to a 1MΩ input of an oscilloscope.
Adjust the rate to match the frequency of the external clock source.
A “?” will appear if the system does not lock onto the external clock source when in
External PLL mode. Possible causes are:
o Threshold level not adjusted correctly.
o External clock source not present.
o External clock has excessive jitter.
o Amplitude of external clock is changing.
Figure 1: System Display Screen Shot