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Starter Kit Instruction Manual Appendix 58
• As a rule of thumb, the overall dissipated power
(sum of DC Bias current dissipation and pulse
current dissipation) must never be higher than
the average dissipated power given by the high-
est current / voltage / temperature combina-
tion sp e cified in the datasheet.
Take into account that the average dissipated
power for a given pulse current I, pulse voltage
U, and duty cycle d is given by d x I x U,
whereas the dissipated power due to a Bias
current IB is given by IB x U. (U is the voltage
on the laser, but it is safe for this calculation
of Bias curr e nt dissipation to use the voltage
on the LDD pulser input.)
Current and voltage ranges of the Bias-T cir-
cuit
Since the input stage of the Bias-T is a bipo-
lar transistor, applied voltage must be higher
than about 0.6V to start Bias current. The in-
put stage has maximum voltage limit of 2.6V,
but the laser itself may be destroyed at lower
Bias-T control voltage already, therefore the
maximum rating has to be checked with the
abovementioned rules and together with Alpes
Lasers SA.
The monitor output (if available) a llows mea-
surement of applied DC Bias current: Its volt-
age divided by 10OΩ gives Bias current. In
general, Bias current can be in the range of
0.1A, but this must be checked with Alpes
Lasers SA before.
CAUTION !
Avoid reverse polarity on the input!