22
7
General description
Two modes of operation are provided for the light output:
Pulse (strobe)
—
the output is pulsed once per trigger. One trigger input is used
as a trigger. The delay from trigger to pulse, the pulse duration and the
brightness can all be set.
Switched
—
a trigger input can be used to switch the output current on and
off. The sense of the trigger signal can be active high or active low.
The set-up is non-volatile, so the VCT6-T20 will resume the same operation
after a power cycle.
7.1
Pulse and duty cycle limits
In both pulsed and switched mode, the pulse width and duty cycle are internally
limited to prevent damage to the light.
The brightness, pulse width, and duty cycle can all be set, in accordance with
the table below:
Output brightness
850nm Variant
White variant
Allowed pulse
width
Allowed
duty cycle
Allowed pulse
width
Allowed duty
cycle
0% to 20%
3ms
6%
3ms
3%
21% to 30%
3ms
6%
2ms
3%
31% to 50%
3ms
3%
2ms
2%
51% to 100%
2ms
3%
1ms
1%
For example, if the brightness is set to 40%, then an 850nm variant VCT6 will not
allow pulses greater than 3ms long.
With 1ms pulses, if a trigger occurs less than 33ms after a previous trigger (so
that the duty cycle would be greater than 3%), the trigger is ignored.
If necessary, the VCT6 will limit the duty cycle by increasing the re-trigger delay.
When the VCT6 internal temperature gets too high, the allowed duty cycle is
reduced, and an
Event 149
code is generated.