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25

WLD SERIES LASER DIODE DRIVERS

TROUBLESHOOTING

PROBLEM

POTENTIAL CAUSES

SOLUTIONS

Driver will not switch on

Improperly configured power 

supply

Standalone:

 Carefully check the wiring diagram according to  

page 13

 and 

page 14

.

Evaluation Board:

 See 

page 18

 for details regarding power supply 

connections.

Output will not enable

ENABLE pin not held low

Standalone:

 Refer to the SHD pin specifications in 

Table 1

 and 

make sure this pin is held at zero volts or left floating.

Evaluation Board:

 Ensure that the ENABLE switch is fully rockered 

to the ON position.

Laser output power too 

low in Constant Current 

mode

Laser current setpoint too low

Increase the setpoint by increasing the voltage at Pin 2 (V

SET

).

Evaluation Board:

 The setpoint can be increased using the onboard 

SET trimpot, and/or using the SET input on the terminal strip.

Laser current limit too low

Standalone:

 Refer to 

page 11

 for instructions on setting the laser 

driver current limit.

Evaluation Board:

 Refer to 

page 19

 for instructions on setting the 

laser driver current limit.

Laser driver is compliance 

limited

Check the laser diode specifications to determine the forward 

voltage (V

F

). Make sure that the WLD is not compliance limited. 

Refer to the Electrical Specifications table on 

page 6. 

If the 

driver is compliance limited, V

DD

 may need to be increased. 

Verify that the WLD will be operating within the Safe Operating 

Area if V

DD

 is increased.

Laser does not reach 

desired output in 

Constant Power mode

Photodiode feedback current 

is out of range for the WLD

Refer to the laser diode datasheet to determine the approximate 

photodiode (PD) current at the desired output power level. If the PD 

current exceeds the chosen WLD photodiode current range, either:

Standalone:

 see 

page 12

 for instructions on how to properly set 

the photodiode current range by choosing R

PD

.

Evaluation Board:

 see 

page 17

 for instructions on how to increase 

the PD RANGE jumper value.

Modulation is not working

V

SET

 improperly configured

Standalone:

 See 

page 15

 for details for modulating using V

SET

.

Evaluation Board:

 See 

page 20

 for proper evaluation board 

configuration for modulation.

Cannot zero the trimpots

Evaluation Board:

 The trimpots that are installed on the 

WLD33ND-EV are 12-turn trimpots. This means that after 12 full 

turns counterclockwise, they will be set to zero, even though they 

will turn continuously.

Photodiode feedback is 

inaccurate

Improperly configured R

PD

 or 

PD RANGE jumper

Standalone:

 see 

page 12

 for instructions on how to properly 

choose the photodiode current range by choosing R

PD

.

Evaluation Board:

 see 

page 17

 for instructions on how to change 

the PD RANGE jumper value.

Transfer functions are 

inaccurate

Improperly configured 

 

CC/CP Mode

If CC/CP Mode is improperly configured, this can lead to 

inaccuracies in the transfer functions. 

Standalone:

 See 

page 13

 or 

page 14

 for proper wiring 

diagrams.

Evaluation Board:

 Make sure the MODE switch is fully rockered to 

the desired operating mode.

Содержание WLD33ND

Страница 1: ...oard switches connectors and trimpots make the configuration and operation simple Input and output cables are also included with the WLD33ND EV The WLD33ND is excellent for VCSELs electro optical equi...

Страница 2: ...n tools wld calculator 1 2 3 4 5 6 7 14 13 12 11 10 9 8 TOP VIEW SHD VSET IMON PMON MODE LIM GND VDD PD PD OUTA RS OUTB RS Shutdown Laser Diode Output Current Setpoint Voltage Input Laser Diode Curren...

Страница 3: ...AD VS 2 5 1 ILIM and the power rating of the resistor is found by PRLOAD I2 LIM RLOAD 2 For example if VS is 12 V and the current limit is 2 A then RLOAD needs to be 4 75 with a power rating of 19 W T...

Страница 4: ...nnected between this pin and Pin 7 GND limits the maximum amount of forward current through the laser diode See page 11 for more information 7 GND Power Supply Ground Connect the VDD power supply grou...

Страница 5: ...or 2 mA POWER SELECT Separate or tied power supplies Configures the WLD33ND EV to either use separate VS and VDD supplies or to tie the VS and VDD connections for single supply operation VSET SOURCE...

Страница 6: ...se Time 100 ns ILD Full Scale Fall Time 200 ns ILD Full Scale Bandwidth 2 2 MHz CC Sine Wave 2A Slow Start Delay Time 0 24 sec Slow Start Ramp Time 0 01 sec Leakage Current 3 0 mA Noise Ripple 22 26 1...

Страница 7: ...TAMBIENT 25 C Max Internal Power Dissipation Heatsink Fan 9 9 10 W TAMBIENT 25 C Heatspreader Temperature Rise TAMBIENT 25 C 30 C W No heatsink washer fan 21 5 C W With WHS302 Heatsink WTW002 Thermal...

Страница 8: ...erence between the two signals It may be useful to remember that you do not directly set the drive current setpoint instead you adjust a voltage signal that represents the output current The voltage a...

Страница 9: ...1 1 times the maximum laser diode current plus 150 250 mA for the electronics The HB offers low voltage operation for use with a Lithium ion battery or other low voltage power supplies PREVENT DAMAGE...

Страница 10: ...NSE CC 1 00 4 ILDMAX ILDMAX CONSTANT POWER RSENSE CONSTANT CURRENT RSENSE 50 mA 25 00 20 00 125 mA 10 00 8 00 250 mA 5 00 4 00 500 mA 2 50 2 00 1 25 A 1 00 0 80 2 2 A 0 57 0 45 WLD33ND 3A WLD33ND 3L O...

Страница 11: ...y calculate the value of RLIM use Equation 7 and Table 4 for the values of and RLIM ILDLIM RSENSE 1 7 1 ILDLIM RSENSE 1 LASER DIODE TYPE MODE Type A B CC 282 2 85 Type A B CP 350 3 35 Type C CC 290 2...

Страница 12: ...connections TYPE A B TYPE C GND GND RPD RPD VDD OR OR CONSTANT CURRENT TYPE A B TYPE C PD PD GND GND VDD VDD PD PD 7 7 13 13 12 12 14 14 OR PIN 11 WLD33ND WLD33ND OR PIN 10 RPD RPD CONSTANT POWER Figu...

Страница 13: ...ured for Constant Current operation Constant Power 1 2 3 4 5 6 7 14 13 12 11 10 9 8 WLD33ND LASER DIODE DRIVER VDD RPD RLIM 1 TIE GROUND CONNECTIONS DIRECTLY TO PIN 7 RSENSE ENABLE DISABLE IMON PMON 0...

Страница 14: ...A 438 m 5 01 Figure 10 Type C laser configured for Constant Current operation Constant Power 1 2 3 4 5 6 7 14 13 12 11 10 9 8 WLD33ND LASER DIODE DRIVER RPD RLIM 1 TIE GROUND CONNECTIONS DIRECTLY TO P...

Страница 15: ...IPD VPIN2 10 2 RPD MONITORING THE LASER DIODE CURRENT PIN 3 Pin 3 IMON produces a voltage proportional to the current flowing through the laser diode Equation 11 provides a transfer function for conv...

Страница 16: ...ELECTRONICS WLD33ND EV ONLY 0N FAN PMON SET 2 5 PDM CP COM LIM WITH ENABLE VS IMON OFF C USE 1 Index Marker WLD 33ND Sockets Mode Switch Output Current Enable Disable Switch Fan Power Input Cable Conn...

Страница 17: ...o available options are the 200 mA or the 2 A position PD RANGE Jumper Set the PD RANGE jumper on the bottom of the WLD33ND EV to either the 200 A or the 2 mA range depending on the specifications of...

Страница 18: ...efer to the WHS302 WTW002 WXC303 and or the WXC304 datasheets for assembly instructions Fan Connections Connect the fan leads to the and fan power positions on the terminal block and secure with a sma...

Страница 19: ...ast twelve turns counter clockwise OFF Adjust the LIM trimpot at least twelve turns clockwise ON D Apply power to the WLD33ND EV and enable the output current by switching the enable switch to the ON...

Страница 20: ...nt controls the output of the WLD33ND The setpoint voltage can be adjusted using the onboard SET trimpot applying an external setpoint voltage or by summing the two signals The VSET SOURCE jumper must...

Страница 21: ...the onboard toggle switch The output is enabled when the green ON LED indicator is lit see Figure 13 You can also remotely enable the WLD33ND by connecting a control signal to a via See Figure 19 Thi...

Страница 22: ...t maximum output current at this supply voltage is 170 mA 200 mA range or 1 7 A 2 A range BANDWIDTH OPTIMIZATION WITH THE WLD33ND EV EVALUATION BOARD To improve bandwidth shorten the cables Expect 1 8...

Страница 23: ...ects the VDROP line On the X axis mark value of VS Extend a diagonal line from VS to the intersection of the VDROP and IMAX lines this is the Load Line If the Load Line crosses the Safe Operating Area...

Страница 24: ...E VDD PDM VA VA R4 332 VA VA R17 499 R16 4 99K R23 1 00M R24 1 00M R22 1 00M R14 1 00M R7 1 00K R9 1 00K R8 1 00K R10 1 00K R6 1 00K 2 3 1 8 4 U4A AD8032 5 6 7 8 4 U4B AD8032 2 3 1 8 4 U2A AD8032 5 6...

Страница 25: ...hin the Safe Operating Area if VDD is increased Laser does not reach desired output in Constant Power mode Photodiode feedback current is out of range for the WLD Refer to the laser diode datasheet to...

Страница 26: ...an be installed in a socket soldered to a PCB Two 7 pin SIP sockets are required Wavelength recommends Sullins PPPC071LFBN RC Socket WEIGHTS WLD33ND 0 6 oz WHS302 Heatsink 0 5 oz WXC 303 4 0 3 oz PIN...

Страница 27: ...Molex 43645 00400 57 2 2 25 39 6 1 56 11 2 0 44 28 7 1 13 1 875 47 63 4 8 0 19 2 25 57 1 2 38 60 5 1 875 47 63 2 25 57 1 1 3 0 05 4 4 0 17 2 48 62 9 4 0 0 156 4 8 0 19 The WLD33ND connects to the eva...

Страница 28: ...UE PGND 2 ORANGE VS 3 RED VDD 4 BLACK COM 5 WHITE VM1 6 GREEN VM2 CABLING SPECIFICATIONS These cables are included with the WLD56ND EV Evaluation Board WTC3293 00101 INPUT CABLE MOLEX 43645 0400 MICRO...

Страница 29: ...er are expressly prohibited from reverse engineering decompiling or disassembling this product NOTICE The information contained in this document is subject to change without notice Wavelength will not...

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