© 2018
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WLD SERIES LASER DIODE DRIVERS
SAFE OPERATING AREA CALCULATION
The Safe Operating Area of the WLD driver is determined
by the amount of power that can be dissipated within the
output stage of the driver. If that power limit is exceeded,
permanent damage can result.
!
Do not operate the WLD driver outside of
the Safe Operating Area curve.
Operating the WLD driver outside of the
SOA voids the warranty.
Refer to the Wavelength Electronics website for the most
up-to-date SOA calculator for our products. The online tool
is fast and easy to use, and also takes into consideration
operating temperature.
www.teamwavelength.com/support/design-tools/soa-ld-calculator
SOA charts are included here for quick reference, however
we recommend you use the online tools instead.
Follow these steps to determine if the driver will be operating
within the SOA.
•
Refer to the laser diode datasheet to find the maximum
voltage (V
MAX
) and current (I
MAX
) specifications
• Calculate the voltage drop across the controller:
V
DROP
= V
S
- V
MAX
(V
S
is the power supply voltage)
• Mark V
DROP
on the X-axis, and extend a line upward
• Mark I
MAX
on the Y-axis, and extend a line to the right
until it intersects the V
DROP
line
• On the X-axis, mark value of V
S
• Extend a diagonal line from V
S
to the intersection of the
V
DROP
and I
MAX
lines; this is the Load Line
• If the Load Line crosses the Safe Operating Area line at
any point, the configuration is not safe
If the SOA Calculator indicates the WLD will be outside of the
Safe Operating Area, the system must be changed so that
less power is dissipated within the driver. See Wavelength
Electronics Application Note
for information on shifting the Load
Line.
After changing any of the operating parameters, recalculate
the SOA to make sure the driver will operate safely. If you
have questions, or run into difficulties calculating the SOA,
contact Wavelength Electronics for assistance.
WLD3343 SOA Chart:
SAFE OPERATION
UNSAFE OPERATION
0.5
1.0
1.5
2.0
2.5
0
1
2
3
4
5
6
7
8
9
10 11 12 13
0
Voltage Across WLD3343 (V)
Current (A)
Figure 20. SOA for WLD3343 with thermal washer, heatsink,
and fan.
WLD3343HB SOA Chart:
SAFE OPERATION
UNSAFE OPERATION
2
3
4
5
6
1
0
0
0.5
1.0
1.5
2.0
2.5
Voltage Across WLD3343HB (V)
Current (A)
Figure 21. SOA for WLD3343HB with thermal washer,
heatsink, and fan.
WLD3343-3A SOA Chart:
SAFE OPERATION
UNSAFE OPERATION
1
2
3
4
5
6
7
8
9
10 11 12 13
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Voltage Across WLD3343-3A (V)
Current (A)
Figure 22. SOA for WLD3343-3A with thermal washer,
heatsink, and fan.
