52
| Technical Specifications
|
Ultra
Version M 22-April-2012
4.0 External Trigger Signal Requirements
External triggering will not function properly unless the external signal
applied to the ICE450 input connector meets the specified requirements:
•
The signal generator must be set up to drive the ICE450 50
Ω
input.
Figure 22 shows a signal generator driving the external trigger input of
the ICE450.
•
The external flashlamp input to the ICE450 has an impedance of 50
Ω
.
In order for Vi to be 5V, the signal generator must drive 50mA into the
trigger input.
•
If it is not clear that the signal generator is driving the signal properly,
measure the trigger signal using the method shown in Figure 23.
Connect to the trigger signal circuit using a BNC “tee”. Verify that the
oscilloscope input is in high-impedance mode (greater than 1 M
Ω
).
•
The duration of the signal must be at least 100μs. If the signal from the
external generator does not meet the required parameters, adjust or
replace the generator until it does.
•
Figure 24 shows the required characteristics of the flashlamp trigger
signal.
CAUTION:
To maintain a fast rise time and therefore minimal jitter, the
Q-Switch input is not optically isolated and does not have over-voltage
protection circuitry. Do not apply voltages greater than 5V to prevent
damage to sensitive components.
Figure 22
Signal Generator to Trigger Circuit
Vg
Vi
Signal Generator
50
Ω
ICE450
Trigger Circuit
Figure 23
Preferred Method of Measuring Trigger Signal
BNC “T-connector”
RJ-58 (50
Ω
) coax
cable
Signal Generator
ICE450
Oscilloscope,
high-impedance input
Figure 24
Required Characteristics of Flashlamp and Q-Switch Trigger Input Signals
Symbol Parameter
Min.
Max. Unit
VIL
Input low voltage
0.0
0.8
V
VIH
Input high voltage
3.0
5.0
V
TR
Rise time
1
μs
TW
Pulse width
100
μs
VPK
Peak voltage
5.5
V
T
R
V
IH
V
IL
0 V
T
W
V
IH
V
PK
