
Thermoelectric Cooler Control
Application Notes
Cooler +
10K
-5V
TIP-120
10K
LM-358
10 uF
TIP-125
Cooler
-
+5V
100K
10K
(for 25oC)
10M
330
+5V
T
A l aser diode can b e damaged by an
overdrive condition or a very short duration
transient spike. It is advisable to protect the
laser diode by providing a slow-start circuit
to ramp the driver current to the appropriate
DC level. Commercial drivers are available in
circuit form.
The monitor photodiode in this device reads
the optical power from the rear facet of the
laser diode. This technique provides a very
good indication of the level and stability of
the optical power that is coupled from the
front facet of the laser into the optical fiber.
The current from the monitor diode should
be used in a d ynamic feedback loop to
control the laser drive current and thus
maintain a constant optical output level.
This laser package incorporates a Peltier-
effect thermoelectric cooler (TEC). It is
imperative that the TEC is running when the
laser chip is operating to prevent thermal
damage to the laser. The thermistor that
measures 10 Kohms at 25
o C is mounted
close to the laser chip to provide feedback to
the temperature controller. A simple drive
circuit f or the T EC is included in this
document.
10-4400-0012 Rev. A
0.60
[15.2]
SC Connector
FC/PC and FC/APC Connectors
ST Connector
0.50
[12.7]
0.10 [2.54]
0.25
[6.4]
0.36
[8.9]
0.04 [1.0]
0.82
[20.8]
0.30
[7.6]
0.018
[0.46]
0.75
[19.1]
0.28 [7.1]
Note: Connectors are not drawn to scale.
1.0 meter nominal fiber length
1
2,3,4,6,13
5
7
8
9
10
11,12
14
Cooler anode (+)
No connection
Ground, laser anode (+)
Detector cathode (-)
Detector anode (+)
Laser cathode (-)
Ground
Thermistor
Cooler cathode (-)
1
2,3,4,6,12,13
5
7
8
9
10
11
14
Cooler anode (+)
No connection
Ground, laser anode (+)
Detector cathode (-)
Detector anode (+)
Laser cathode (-)
Ground, thermistor
Thermistor
Cooler cathode (-)
Pin
Function
F SERIES
Pin
Function
G SERIES
Pin Assignments
1.00
[25.4]