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QCL500, QCL1000, QCL1500 Low Noise Quantum Cascade Laser Drivers
PAGE 10
QCL1500-00400-D
AC(L) AC(N)
FG
-V
+V
AC(L) AC(N)
FG
-V
+V
16
18
17
V+
POWER
GROUND
V-
**R=150k
:
On 20 pin connector
POSITIVE SUPPLY
NEGATIVE SUPPLY
OPERATING PROCEDURES, continued
** If ground is somewhere tied to earth ground (e.g. at a DAQ card), tie common point to
ground through high resistance to avoid triggering safety circuits.
•
AC: In to both power supplies
•
AC Safety ground #1: Connect two FG terminals
•
AC Safety ground #2: Connect FG to AC chassis ground
•
Common Ground: Connect between -V of positive supply and +V of negative supply
•
Attach to the QCL driver - V+, POWER GROUND, V -
4. Attach dual power supplies
For safety, it is important that your power supply integrate an effective current limit circuit. Ground
loops can be avoided by choosing a power supply with the chassis not tied to ground. WEI offers
switching power supplies (PWRPAK-24V), a 20 pin cable (WCB311), and a power supply kit (WCB312)
to simplify setup. Twist wire pairs to minimize noise. See TDK/Lambda instruction manual for
mounting and other design considerations. Here is an example schematic and wiring diagram for
power supply setup:
Figure 8
Example power supply wiring
3. Wire Test Load
To become familiar with the QCL driver operation, we recommend that you wire a test load fi rst. This
can be as simple as a resistor. We recommend a metal fi lm, TO-220, 50 W, as a typical test load. Two
vendor numbers are: Caddock MP850-10.0-1% (Digikey part number MP850-10.0-F-ND) or Ohmite
TCH35P10R0JE (Digikey part number TCH35P10R0JE-ND)
The QCL driver is not designed to operate with the QCL pins shorted. Safe Operating Area thermal
limits will be exceeded. The following schematic shows an example test load and wiring.
10
:
, 50 W
metal film
resistor
QCL + *
Pin 19
QCL -
Pin 20
* Internally grounded
Figure 7
Example test load