THORLABS LD2000R, Руководство пользователя

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OEM Laser Diode Driver Chapter 5: Operating the LD2000R
Page 10 0187-D01
5.2. Setting the Feedback Resistor
The LD2000R is configured at the factory for a maximum feedback gain. This gain
setting is appropriate for lasers that have low monitor currents in the range of 20
to 120

A.
For most lasers, the photodiode current is greater than 120

A and the feedback
gain will have to be reduced to drive the laser at full drive current. This can be done
by following the procedure below.
1. Determine the appropriate feedback gain using the following calculation:
𝑅
𝐹 𝐸𝑋𝑇
=
20,000
(8,000𝐼
𝑀𝑂
− 1)
where R
F EXT
is the external gain setting resistor to be added in ohms and
I
MON
is the monitor current for a particular laser in Amps.
2. Pick the nearest standard value resistor (0.25 W, 5% or better).
3. Connect R
F EXT
across pins 8 and 12 of the LD2000R.
SHOCK WARNING
The LD2000R uses CMOS circuitry to minimize power drain. Use anti-static
precautions while handling the LD2000R to prevent permanently damaging
the device.
0.1 1 10
0.1
1
10
10 0
1 10
3
RFext vs. PD Monitor Current
PD Monitor Current (mA)
R
F
ext
(
koh
m
s)