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WLD3393
PAGE 11
WLD3393-00400-K
STEP 9: MONITOR THE LASER DIODE AND PHOTODIODE CURRENTS
The input connector includes three signals for externally monitoring the WLD3343 laser driver output.
IMON, PMON, and PDM allow for monitoring of laser diode current and power intensity depending on
the selected mode of operation. The voltages at IMON, PMON, and PDM are all referenced to the
common terminal (COM) on the input connector.
IMON provides a mechanism for externally monitoring the laser diode current. IMON is available at all
times in both CC and CP modes. In the 200 mA range, V
IMON
has a transfer function of 106 mA / V. In
the 2.0 A range, V
IMON
has a transfer function of 1.2 A / V. Table 3 summarizes this data.
PMON provides an external indication of the laser diode intensity by measuring photodiode current.
Since PD+ and PD- on the WLD3343 are shorted together in CC mode, PMON will only monitor
photodiode current in CP mode. When operated in the 200
A range, V
PMON
has a transfer function
of 100
A / V. When operated in the 2 mA range, V
PMON
has a transfer function of 1 mA / V. Table 4
summarizes this data.
PDM provides a mechanism for monitoring photodiode current in either CC or CP mode. While PMON
monitors the feedback used by the control electronics to maintain constant power of the laser, PDM
is an external monitor that is independent of the control electronics of the WLD3343. The transfer
function for V
PDM
to I
PD
is the same as for the PMON signal. PDM is accessible on the terminal block.
200 mA Range
2.0 Amp Range
200
μ
A Range
2 mA Range
LDI = V
IMON
* 106 [ mA ]
LDI = V
IMON
* 1.2 [ AMPS ]
PDI = V
PMON *
100 [
μ
A ]
PDI = V
PMON
[ mA ]
Wire Color
Function
PIN #
BLUE
ORANGE
RED
BLACK
WHITE
GREEN
1
2
3
4
5
6
PGND
VS
VDD
COM
P MON
I MON
Table 2: Input Cable Color Code
Table 3: Convert IMON Voltage to Laser Diode Current
Table 4: Convert PMON or PDM Voltage to Photodiode Current
CONFIGURING THE EVALUATION BOARD
