Wavelength Electronics PLD10000, Техническое описание и руководство по эксплуатации

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PLD10000/PLD12500 LASER DIODE DRIVER
ONBOARD ADJUSTMENTS AND CONTROLS
Onboard controls are on the top of the PLD and must be
set according to the operation mode. The controls are
illustrated in Figure 10 .
MODE
P
L
I
H
OUT
LIM I
PLD10000 Laser Diode Driver
PD RNG
+5V
Analog In
P Monitor
I Monitor
Common
Lim I Mon
Lim I Stat
LD Enable
PD Aux
Aux V+
GND
LD Anode/
+LD Supply
LD Cathode
PD Anode
PD Cathode
N/C
13
14
15
16
17
18
19
20
21
22
23
24
12
11
10
9
8
7
6
5
4
3
2
1
ENBL
OUT
ADJ
LIM I
ADJ
Output Adjust (12-turn)
Current Limit
Adjust (12-turn)
Output Enable LED
(Green = ON)
Current Limit Status
LED (Red = LIMIT)
Operating Mode *
PD Range *
L = 15 – 500 µA
H = 50 – 5000 µA
P = Constant Power
I = Constant Current
* DO NOT change switch positions while the output is
enabled; Doing so may damage the laser diode.
!
Figure 10. PLD Driver Adjustments and Controls
SET THE CONTROL MODE
Set the MODE switch to P (left) for Constant Power-mode
operation (CP), or to I (right) for Constant Current-mode
(CC). CP-mode operation requires a photodiode feedback
loop from the laser diode.
!
D
o noT swiTch The conTroL moDe whiLe The ouTpuT is
enabLeD anD Driving a Laser DioDe
. T
he Laser DioDe
may be DamageD or DesTroyeD
.
SET THE PHOTODIODE RANGE
Two photodiode feedback current ranges are available on
the PLD drivers. Reference the datasheet for your laser
diode to find the nominal photodiode current, and set the
PD RANGE switch as follows:
• L (left) = Low Range, PD current 15 – 500 µA,
Type A and B lasers only
• H (right) = High range; PD current 50 – 5000 µA
! D
o noT swiTch The
pD r
ange whiLe The ouTpuT is
enabLeD anD Driving a Laser DioDe
. T
he Laser DioDe
may be DamageD or DesTroyeD
.
CALCULATE THE MONITOR VOLTAGES
Refer to the datasheet for your laser to determine the
maximum forward current, and calculate the LIM I Monitor
voltage using this equation and the transfer function found
in Table 2 :
V
Lim I Mon
= I
LIMIT
/ Transfer Function
If you are using the PLD in Constant Current mode, calculate
the monitor voltage for the drive current setpoint. Refer
to the datasheet for your laser to determine the nominal
forward current, and calculate the I Monitor voltage using
the transfer function found in Table 2 :
V
I_MON
= I
LD
/ Transfer Function
If you are using the PLD in Constant Power mode, calculate
the P Monitor voltage. Refer to the laser diode datasheet
to determine the nominal photodiode current at the desired
operating point. Calculate the P Monitor voltage using the
transfer function found in Table 2 :
V
P_MON
= I
PD
/ Transfer Function
SET THE CURRENT LIMIT
Connect the positive lead of the digital voltmeter to the
LIM I Mon pin, or to the LIM I MON test point on the evaluation
board. Connect the negative lead to the COMMON terminal.
Reference Figure 5 for switch and control locations on
the PLD and PLD10EV board, and configure the PLD and
evaluation board:
• Set the POWER switch to ON
• Set the OUTPUT switch to LASER DISABLE
• Set the MONITOR switch to I MONITOR
• Set the OUTPUT ADJUST trimpot to zero by turning at
least 12 turns counter-clockwise.
• Turn the CURRENT LIMIT ADJUST trimpot clockwise
until the value on the digital multimeter matches the
V
Lim I Mon
value calculated above.
Switch off power on the evaluation board, then switch off the
power supply.
The PLD controllers trip the current limit circuit below the
expected limit level, by 0.2 V on the monitor. To trip the
current limit at exactly the desired current level, refer to Set
the Current Limit More Accurately on page 13 .