Wavelength Electronics FL591FL User manual

ORDERING INFORMATION
PART NO DESCRIPTION
FL591FL Evaluation board with FL500
EASY SETUP SAVES YOU TIME
The FL591FL allows you to quickly and easily prototype your
laser diode driver system using our popular FL500 laser
diode driver chip.
The FL591FL can be congured to drive a single 500 mA
output, or two 250 mA independent outputs by setting
onboard jumpers. The drivers operate in Constant Current
or Constant Power modes.
Onboard current setpoint and limit trimpots mean no external
electronics are required to operate the drivers. Simply
connect the power supply and laser diodes, and you’re ready
to go.
ACCURATELY PROTOTYPE YOUR
LASER CONTROL SYSTEM
The FL591FL features low-noise electronics and low
quiescent current, and the feedback and monitor signals
allow you to accurately characterize your laser controller.
You can transfer the FL500 prototype conguration directly
to your custom laser control system with no surprises.
The FL500 is commonly used in hand-held, portable, and
space constrained applications. The small size and light
weight makes the FL500 ideal for airborne applications,
and the dual-channel output is perfect for sighting-and-
detection applications.
FEATURES AND BENEFITS
• Accurately and efciently characterize the FL500
in your application environment
• Includes FL500 Laser Driver chip already installed
• Utilizes all the safety features of the FL500
»Adjustable current limits
»Slow-start laser diode protection
»Brownout protection
• Onboard trimpots adjust output current and
current limits
• Drive two independent 250 mA channels or a
single 500 mA output
• Switches set the operating mode to Constant
Current or Constant Power
• Operates Type A and Type B Laser Diodes
• Output Enable switch, LED status indicators
• Power and Output cables included
CONTENTS
QUICK CONNECT GUIDE 2
PIN DESCRIPTIONS 4
ELECTRICAL SPECIFICATIONS 6
SAFETY INFORMATION 7
OPERATING INSTRUCTIONS 8
TROUBLESHOOTING 11
TECHNICAL SUPPORT INFORMATION 12
MECHANICAL SPECIFICATIONS 17
CERTIFICATION AND WARRANTY 18
PAGE
Applies to Product Revisions A through C
© February 2017
406-587-4910
www.teamWavelength.com
FL591FL
Laser Diode Driver
DATASHEET AND OPERATING GUIDE
Distributor
[email protected]m
www.amstechnologies-webshop.com

© 2017 www.teamWavelength.com 2
FL591FL LASER DIODE DRIVER
QUICK CONNECT GUIDE
!
ItIs ImperatIve that you verIfy the unIt wIll operate
wIthIn the Internal heat dIssIpatIon safe operatIng
area (soa).
operatIng the drIver outsIde the soa may damage or
destroy the drIver and/or laser.
Visit the Wavelength Electronics website for the most accurate,
up-to-date, and easy to use SOA calculator:
http://www.teamwavelength.com/support/calculator/soa/soald.php
Figure 1 is the top view of the FL591FL, illustrating the
onboard switches, trimpots, and connectors.
When shipped from the factory, the FL591FL is congured to
operate with two independent 250 mA outputs. For information
on conguring the FL591FL to drive a single 500 mA output,
refer to page 9.
Figure 2 is the Quick Connect diagram for the FL591FL
illustrating operation as a two-channel laser diode driver. Two
different laser wiring types are shown.
Current Monitor, I
MON1
Power Monitor, PMON1
LD1 Monitor Ground
Current Monitor, IMON2
Power Monitor, PMON2
LD2 Monitor Ground
LD1 Output
Connector
LD2 Output
Connector
Mode
Switches
Current Limit
Trimpots
Power Supply
Connector
Analog Input
BNC Connectors
Output Enable
Switch
ENABLE
DIS
INPUT 1
INPUT 2
TRIMPOT
TRIMPOT
BNC
BNC
VSET 1
VSET 2
GND
GND
LD1 MODE
CC CP CP CC
LD2 MODE LIM 1 LIM 2
LDA
LDA
PDA
PDA
LDC
LDC
LD 1
MON
1
DS
VS
GND
]ON
]OFF
]ONE
]TWO
]OFF
]ON
LD 2
]S
]P
POWER
RPD1
RPD2
FL500
J4
Figure 1. FL591FL Top View
Figure 2. FL591FL Quick Connect Wiring Diagram
Channel LD1 Output 1
Channel LD1 BNC
Optional External
Setpoint (0 to 2 V)
Channel LD2 BNC
Optional External
Setpoint (0 to 2 V)
OPEN or 3 to 5 V = DISABLE
GND = LD ENABLE
GND
VS
DMM
ENABLE
DIS
INPUT 1
INPUT 2
TRIMPOT
TRIMPOT
BNC
BNC
VSET 1
VSET 2
GND
GND
LD1 MODE
CC CP CP CC
LD2 MODE LIM 1 LIM 2
LDA
LDA
PDA
PDA
LDC
LDC
LD 1
MON
1
DIS
VS
GND
]ON
]OFF
]ONE
]TWO
]OFF
]ON
LD 2
]S
]P
1. Common-Cathode configuration.
2. Laser Anode and Photodiode Cathode common.
Channel LD2 Output 2
POWER
RPD1
RPD2
FL500
J4

© 2017 www.teamWavelength.com 3
FL591FL LASER DIODE DRIVER
QUICK CONNECT GUIDE, CONTINUED
The FL591FL is compatible with Type A and Type B lasers,
but will not drive Type C lasers; see Figure 3.
Type A Laser Diode Type B Laser Diode Type C Laser Diode
Common
Cathode
Laser Diode Anode &
Photodiode Cathode Common Isolated Photodiode
Short the
Laser Diode Anode
to Photodiode Cathode
Common
Anode
Laser Diode Cathode &
Photodiode Anode Common
Figure 3. Laser Type Diagrams
Recommended simulated laser loads are shown in Figure 4.
To determine the actual drive current, measure the voltage
drop across the 1 Ω resistor. Do not insert an ammeter in
series with the output circuit; doing so may cause instability in
the control loop.
24 Ω
1N4001
1N4001
2N3906
0.33 µF
PDA
LDA
LDC
1N4001
1N4001
LDC
LDA
1 Ω, 2 W
Constant Current Mode Constant Power Mode
The 24 Ω resistor typically
produces approximately 30 mA
laser driver current. Vary the
resistor value to change the
output current.
1 Ω, 2 W
Figure 4. Laser Driver Test Loads

© 2017 www.teamWavelength.com 4
FL591FL LASER DIODE DRIVER
PIN DESCRIPTIONS
Table 1. Pin Descriptions and Wire Colors
PIN NAME CABLE
COLOR PIN DESCRIPTION
Connectors LD1, LD2; Cable FL591-00102-A
1LDA Red
Laser Diode Anode connection. When used in 2x–250 mA mode, LD1 and LD2
are independent and isolated from each other. When used in 500 mA mode, the
current is output via connector LD1 only.
2PDA White
Photodiode Anode connection. When used in 2x–250 mA mode, LD1 and LD2
are independent and isolated from each other. When used in 500 mA mode, the
current is output via connector LD1 only.
3 LDC Black
Laser Diode Cathode connection. When used in 2x–250 mA mode, LD1 and LD2
are independent and isolated from each other. When used in 500 mA mode, the
current is output via connector LD1 only.
Connector J4, Cable FL591-00101-A
1 DIS White
Laser diode shutdown / interlock input, optional. The onboard Enable switch must
be set to ENABLE when this external enable function is used.
TTL-compatible. Enable = Ground; Disable = OPEN or 3 to 5 V.
2 VS Red Power supply positive terminal.
3 GND Black Ground connection for power supply input.
Connectors INPUT 1, INPUT 2
Inner VSET1, VSET2 Positive connection for the external setpoint voltage signal
Shield GND Ground connection for the external setpoint voltage signal
Connector MON, Six-Pin Header
1 IMON1, Current Monitor LD1 laser current monitor output. The signal on this pin is proportional to the
actual laser output current. Transfer function shown in Table 2.
2 PMON1, Power Monitor LD1 photodiode current monitor output. The signal on this pin is proportional to
the photodiode current. Voltage range 0 to 2 V. Transfer function shown in Table 2.
3 LD1 Monitor Ground Low current return for LD1 monitors. Do not use for high current return.
4 IMON2, Current Monitor LD2 laser current monitor output. The signal on this pin is proportional to the
actual laser output current. Transfer function shown in Table 2.
5 PMON2, Power Monitor LD2 photodiode current monitor output. The signal on this pin is proportional to
the photodiode current. Voltage range 0 to 2 V. Transfer function shown in Table 2.
6 LD2 Monitor Ground Low current return for LD2 monitors. Do not use for high current return.

© 2017 www.teamWavelength.com 5
FL591FL LASER DIODE DRIVER
Table 2. Monitor Transfer Functions
FUNCTION OUTPUT
CONFIGURATION TRANSFER NOTE
Current Output Monitor,
IMON1 and IMON2
Separate 0.125 A / V The voltage on IMONx is proportional to the current
output on that channel
Current Output Monitor,
IMON1 + IMON2
Parallel
When operating the FL591FL as a single channel 500 mA driver,
monitor the output current on both IMON1 and IMON2. The total output
current monitor voltage is determined by summing the voltage
measured on both monitors, using the equation:
ILD = (VIMON1 + VIMON2) * 0.125
Current Limit Monitor,
ILIM1 and ILIM2
Separate 0.125 A / V Adjust ILIM1 and ILIM2 to set the current limit on each
channel. See page 9.
Current Limit Monitor, ILIM1 Parallel 0.250 A / V
Adjust only ILIM1 to set the current limit when the
FL591FL is operated in parallel-output mode.
See page 9.
Power Monitor,
PMON1 and PMON2
Separate 500 μA / V 1The voltage on PMONx is proportional to the
photodiode current on that channel.
Power Monitor, PMON1 Parallel 500 μA / V 1
When operating the FL591FL as a single channel
500 mA driver, the photodiode current is monitored
on PMON1.
1. The photodiode feedback transfer function can be changed. See page 12 for details.
Table 3. Setpoint Transfer Functions
OPERATING
MODE
INPUT
CONFIG.
OUTPUT
CONFIG.
VSET TRANSFER
FUNCTION NOTES
Constant
Current
One
Separate 0.125 A / V
Measure the voltage on the VSET1 testpoint; adjust the VSET1
trimpot to set the output current on both channels. The VSET2
trimpot is not used.
Parallel 0.250 A / V
Measure the voltage on the VSET1 testpoint; adjust the VSET1
trimpot to set the output current on both channels. The VSET2
trimpot is not used.
Two
Separate 0.125 A / V
Measure the voltage on the VSET1 and VSET2 testpoints; adjust the
VSET1 and VSET2 trimpots to set the output current level for each
channel.
Parallel 0.125 A / V
The VSET1 and VSET2 voltages drive each channel independently.
The output currents sum. Measure the voltages on the VSET1
and VSET2 testpoints separately, and add them to determine the
effective output current.
Constant
Power
One
Separate 500 μA / V 1
Measure the voltage on the VSET1 testpoint; adjust the VSET1
trimpot to set the photodiode current setpoint. The VSET2 trimpot is
not used.
Parallel 500 μA / V 1
Measure the voltage on the VSET1 testpoint; adjust the VSET1
trimpot to set the photodiode current setpoint. The VSET2 trimpot is
not used.
Two Separate 500 μA / V 1
Measure the voltage on the VSET1 and VSET2 testpoints; adjust the
VSET1 and VSET2 trimpots to set the photodiode setpoint for each
channel.
Parallel __ This conguration is not allowed.
1. The photodiode feedback transfer function can be changed. See page 12 for details.

© 2017 www.teamWavelength.com 6
FL591FL LASER DIODE DRIVER
ELECTRICAL SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS SYMBOL
DUAL-
CHANNEL
OPERATION
SINGLE-
CHANNEL
OPERATION
UNIT NOTE
Supply Voltage VS3 to 9 VDC
Max LD Output Current ILD (2x) 250 (1x) 500 mA
Laser Driver Internal Power Dissipation PMAX 1 W per channel 2 W total W TAMBIENT = 25ºC
Case Operating Temperature TOPR -40 to 85 ºC
Case Storage Temperature TSTG -55 to 125 ºC
Weight 1.7 oz 47.6 g
Size 2.97 x 2.50 x 1.07 inches 75.5 x 63.5 x 27.1 mm
LASER DRIVER
SPECIFICATIONS SYMBOL DUAL- CHANNEL
SINGLE-
CHANNEL UNIT NOTE
CONSTANT CURRENT CONTROL
Short Term Stability, 1 hour 35 to 40 ppm TAMBIENT = 25ºC
Long Term Stability, 24 hours 50 to 75 ppm TAMBIENT = 25ºC
CONSTANT POWER CONTROL
Short Term Stability, 1 hour 0.009 % TAMBIENT = 25ºC
Long Term Stability, 24 hours 0.02 %
OUTPUT
Peak Current IMAX 250 - 260 500 - 520 mA
Compliance Voltage VS – (0.5 * VSET) V IMAX = 500 mA
Rise Time 300 nsec ILD = 500 mA
Fall Time 300 nsec ILD = 500 mA
3dB Bandwidth, Constant Current 500 kHz Sinewave input signal
Delayed Start 100 msec
Slow Start Ramp 15 mA / msec
Depth of Modulation 99 % 100 kHz sinewave
POWER SUPPLY
Power Supply Voltage VS3 to 9 V
Quiescent Current, VS100 mA at VS= 9 V
V SET INPUT
Input Impedance 51.1 Ω
Input Voltage Range VSET1, VSET2 0 to 2 V
Damage Threshold VSET < -0.3, VSET > (VS+ 0.3) V
NOISE
Noise and Ripple (RMS) 3µA ILD = 100 mA
Leakage Current with output disabled
50
100
150
µA
VSET = 0 V
VSET = 1 V
VSET = 2 V

© 2017 www.teamWavelength.com 7
FL591FL LASER DIODE DRIVER
THEORY OF OPERATION
The FL591FL employs Wavelength’s FL500 laser diode
control chip, and can drive a single output up to 500 mA or
dual outputs up to 250 mA each.
When operating with two separate outputs, the FL591FL can
be congured to use a single setpoint to drive both outputs
to the same current, or use separate setpoint signals to
drive each current source independently.
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 setpoint voltage is
controlled by the onboard trimpot or by an external input.
The current source continually monitors the actual output
current, compares it to the setpoint, and adjusts the current
if there is a difference between the two signals.
As current is driven through the load, there is a voltage drop
across the load because of the impedance. As the current
increases the voltage drop may increase to the point that it
reaches the Compliance Voltage limit of the current source.
Once that occurs the current source is no longer able to
increase the current driven to the load even if you increase
the setpoint.
The current sources can be operated in Constant Current
(CC) mode or in Constant Power (CP) mode. In CP mode,
the photodiode (PD) current is used in the feedback loop,
and the driver adjusts the output current in order to keep the
PD current constant.
The laser driver includes features that help protect your
laser and make the driver more versatile in a wide array of
applications:
• The current limit is set by an onboard trimpot and
protects the laser from over-current conditions.
• Slow-start delays the current ramp by 100 msec,
and then ramps the current to setpoint at a rate
of 15 mA / msec.
• The photodiode feedback control loop allows for
Constant Power operation whereby the driver adjusts
the laser forward current in order to maintain a constant
photodiode current.
SAFETY INFORMATION
SAFE OPERATING AREA — DO NOT EXCEED
INTERNAL POWER DISSIPATION LIMITS
Before attempting to operate the FL591FL, it is imperative
that you rst determine that the FL500 will operate within the
Safe Operating Area (SOA). Operating the unit outside of
the SOA may damage the controller or the laser. Operating
outside of the SOA will void the warranty.
Go to the Wavelength Electronics website for the most
accurate, up-to-date, and easy to use SOA calculators:
http://www.teamwavelength.com/support/calculator/soa/soald.php
SOA charts are included in this datasheet for quick reference
(page 15), but we recommend you use the online tools
instead.
!
toensure safe operatIon of the fl591fl drIver, It
Is ImperatIve that you determIne If the fl500 Is
goIng to be operatIng wIthIn the Internal heat
dIssIpatIon safe operatIng area (soa).

© 2017 www.teamWavelength.com 8
FL591FL LASER DIODE DRIVER
OPERATING INSTRUCTIONS
The rst step in operating the controller is to wire it, and
connect a test load. It is critical to properly set the drive
current limit before connecting a laser.
We recommend using a test load until you are familiar with
operation of the driver and have congured it to safely power
your laser. A test load design is provided on page 3.
NECESSARY EQUIPMENT
The following equipment is the minimum necessary to
congure the FL591FL for basic operation.
• FL591FL controller, plus included cables
• VS – power supply for the laser driver electronics and the
laser diode; must be rated for 1.1-times the maximum
laser drive current plus 100 mA quiescent current
• Digital multimeter, 4-½ digit resolution recommended
• Test Load (recommended)
• Laser diode
• Connecting wires
SAFE OPERATING AREA AND
THERMAL DESIGN CONSIDERATIONS
SOA charts are included in this datasheet for quick reference,
but we recommend you use the online tools instead. Refer
to the SOA calculator for the FL500.
http://www.teamwavelength.com/support/calculator/soa/soald.php
!
toensure safe operatIon of the fl591fl
controller, It Is ImperatIve that you determIne If the
unIt Is goIng to be operatIng wIthIn the Internal heat
dIssIpatIon safe operatIng area (soa).
PREVENT DAMAGE FROM
ELECTROSTATIC DISCHARGE
Before proceeding, it is critical that you take precautions to
prevent electrostatic discharge (ESD) damage to the driver
and your laser. ESD damage can result from improper
handling of sensitive electronics, and is easily preventable
with simple precautions.
Enter the search phrase “ESD Precautions for Handling
Electronics” in an internet search engine to nd information
on ESD-safe handling practices.
We recommend that you always observe ESD precautions
when handling the FL591FL and laser diodes.
ONBOARD CONTROLS AND MONITORS
Figure 5 shows the jumpers and switches that congure the
FL591FL operating mode.
Mode
Switches
Current Limit
Trimpots
Output Configuration
Jumper (JP2)
Current Limit
Testpoint
ENABLE
DIS
INPUT 1
INPUT 2
TRIMPOT
TRIMPOT
BNC
BNC
VSET 1
VSET 2
GND
GND
LD1 MODE
CC CP CP CC
LD2 MODE LIM 1 LIM 2
LDA
LDA
PDA
PDA
LDC
LDC
LD 1
MON
1
DIS
VS
GND
]ON
]OFF
]ONE
]TWO
]OFF
]ON
LD 2
]S
]P
RPD1
RPD2
FL500
POWER
Output Enable
Switch and LED
Power ON LED
Input Configuration
Jumper (JP1)
Current Monitor, IMON1
Power Monitor, PMON1
LD1 Monitor Ground
Current Monitor, IMON2
Power Monitor, PMON2
LD2 Monitor Ground
Output Disable
Power Supply VS
Power Supply Ground
J4
Figure 5. FL591FL Conguration Controls
The FL591FL can be congured to drive two separate
250 mA outputs with tied or separate setpoints, or a single
500 mA output controlled by a single setpoint.
The control mode—Constant Current or Constant Power—
is set by onboard switches. The current limit for each
channel is set by the trimpots.
SET THE INPUT CONFIGURATION JUMPER
The Input Conguration Jumper (JP1), located between
the BNC connectors, determines whether a single setpoint
signal controls the output current, or if two independent
input signals are used to control each output separately.
Refer to Table 4. Set the jumper to position ONE for single
setpoint operation; set the jumper to position TWO for
independent input signals.
Table 4. Jumper Conguration Overview
JP1 INPUTS
ONE Input 1 controls both output channels
TWO Setpoint signals are separated
* When JP1 is set to position ONE, the FL591FL references
the setpoint signal on Input 1. Any setpoint signal on Input 2
is disregarded.
When the FL591FL is delivered, the default conguration is
to use two independent input signals (jumper set to TWO).

© 2017 www.teamWavelength.com 9
FL591FL LASER DIODE DRIVER
SET THE OUTPUT CONFIGURATION JUMPER
The Output Conguration Jumper (JP2), located between
the output connectors, determines whether the outputs are
paralleled to drive up to 500 mA output on a single channel,
or separate to drive up to 250 mA on two channels.
When the driver outputs are separate, connect each laser
diode to the respective output connector, LD1 and LD2.
When the driver outputs are paralleled, each channel
drives one-half of the total output current. When operating
in parallel driver mode, use output connector LD1 to drive
current to the load.
When the FL591FL is delivered, the default conguration
is with two separate 250 mA output channels (jumper set
to “S”).
WIRE THE POWER SUPPLY AND TEST LOAD
Wire the FL591FL power supply according to Figure 2, use
the test load shown in Figure 4.
When the power supply is switched on, power is applied
to the FL500 and the POWER LED will illuminate, but the
output current is not enabled.
SET THE DRIVE CURRENT LIMITS;
SEPARATE OUTPUT CONFIGURATION
First calculate the VLIM voltage; use the transfer function on
page 5 according to your input/output conguration:
VLIM = ILIMx / Transfer Function (Separate) (V)
Connect the DMM to the LIM1 testpoint and the GND
testpoint, and apply power to the FL591FL. Adjust the LIM1
trimpot until the voltage displayed on the DMM matches the
VLIM value calculated above. Turn the trimpot clockwise to
increase the current limit.
Connect the DMM to the LIM2 testpoint, and set the current
limit on channel two using the same procedure.
SET THE DRIVE CURRENT LIMITS;
PARALLEL OUTPUT CONFIGURATION
If the FL591FL is congured to drive paralleled outputs, the
current limit is set using the LIM1 trimpot only.
First calculate the VLIM voltage; use the transfer function on
page 5 based on your input/output conguration:
VLIM = ILIM1 / Transfer Function (Parallel) (V)
Connect the DMM to the LIM1 testpoint and the GND
testpoint, and apply power to the FL591FL. Adjust the LIM1
trimpot until the voltage displayed on the DMM matches the
VLIM value calculated above.
CONFIGURE FOR CONSTANT CURRENT OR
CONSTANT POWER MODE
The FL591FL will drive lasers in Constant Current mode or
Constant Power mode. Constant Power mode operation
requires photodiode feedback from the laser.
To congure channel one for Constant Current mode
operation, set the LD1 MODE switch to CC (left); for
Constant Power mode set the switch to CP (right). Set
channel two in the same manner.
!
donot change swItch posItIons whIle power Is
applIed to the fl591fl. doIng so may damage the
laser. remove power from the fl591fl board
before changIng mode swItch posItIons.
If the FL591FL outputs are paralleled and operated in
CP-mode, the signal on the channel one photodiode is used
in the control feedback loop.
When the FL591FL is delivered, the default conguration is
Constant Current mode on both channels.
SET THE INPUT SIGNAL CONFIGURATION
Figure 6 shows the setpoint adjust section of the FL591FL.
ENABLE
DIS
INPUT 1
INPUT 2
TRIMPOT
TRIMPOT
BNC
BNC
VSET 1
VSET 2
GND
LD1 MODE
CC CP
]ON
]OFF
]ONE
]TWO
]OFF
]ON
Channel 2 Controls
V
SET Testpoints
Channel 1 Controls
LD1 MODE
CC CP
FL500
Figure 6. Current Setpoint Section
The drivers can be congured to reference only the signal
input on the BNC connector, only the onboard trimpot, or
the sum of the two signals. This versatility allows the driver
to be congured with a bias current set by the trimpot, and
an external modulation signal input on the BNC.

© 2017 www.teamWavelength.com 10
FL591FL LASER DIODE DRIVER
Congure the setpoint jumpers per Table 5. Channels one
and two are congured independently.
Table 5. Setpoint Jumper Conguration
TRIMPOT BNC EFFECT
OFF OFF This setting results in no setpoint input
signal; Do not use this setting
ON Reference only the BNC signal
ON
OFF Reference only the onboard trimpot
ON Add the BNC signal to the onboard
trimpot setpoint value
When the FL591FL is delivered it is congured to reference
only the onboard trimpot setpoint signals.
CONNECT THE CURRENT AND
POWER MONITORS
Connector J4, the screw terminal at the top of the board,
includes outputs for monitoring the drive current and
photodiode currents of both channels. Wire the DMM per
Figure 2 on page 2 to monitor these signals. The
transfer functions are listed in Table 2 on page 5.
ENABLE THE OUTPUT CURRENT
In order to enable the output current, two conditions must
be met simultaneously:
• The DIS pin on the power connector must be grounded.
• The output ENABLE switch must be set to ENABLE.
Channels one and two are enabled simultaneously, whether
the FL591FL is in separate- or parallel-output mode. When
the output is enabled, the LED next to the ENABLE switch
will illuminate.
The output is disabled by oating the DIS pin or applying
a 3 – 5 VDC signal, or by setting the ENABLE switch to
DISABLE.
ADJUST THE OUTPUT CURRENT SETPOINT IN
CONSTANT CURRENT MODE
Calculate the VSET voltage value using the equation below.
Use the proper CC-mode transfer function for dual- or
single-channel operation (see Table 2).
VSET = ILD / Transfer Function (V)
Connect the positive lead of the DMM to the VSET1 testpoint,
and the negative lead to the GND testpoint and adjust the
VSET1 trimpot until the voltage value on the DMM matches
the value calculated above. Turning the trimpot clockwise
increases the output current.
Repeat the process on the second channel if operating in
dual-channel mode.
ADJUST THE OUTPUT CURRENT SETPOINT IN
CONSTANT POWER MODE
In Constant Power mode, the drive current is not set directly.
Rather, the photodiode current setpoint is calculated and
set; the controller adjusts the output current in order to
maintain the required photodiode current.
Refer to the laser diode datasheet to nd the photodiode
current at the desired optical output power level. Then
calculate the VSET voltage value using the equation below,
and the CP-mode transfer function listed in Table 2.
VSET = IPD / Transfer Function (V)
Connect the positive lead of the DMM to the VSET1 testpoint,
and the negative lead to the GND testpoint and adjust the
VSET1 trimpot until the voltage on the DMM matches the
VSET voltage. Turning the trimpot clockwise increases the
Constant Power setpoint current.
Repeat the process on the second channel if operating in
dual-channel mode.
RECONFIGURE FOR YOUR APPLICATION
Once you are familiar with the operation of the FL591FL,
switch off the output and power supplies, and remove
the test load. Wire your laser diode according to the wire
diagram shown in Figure 2 on page 2.

© 2017 www.teamWavelength.com 11
FL591FL LASER DIODE DRIVER
TROUBLESHOOTING
PROBLEM POTENTIAL CAUSES SOLUTIONS
Driver will not switch on Improperly congured power
supply
Carefully check the wiring diagram on page 2. Make sure the power
supply polarity is not reversed.
Power supply voltage too low Check the electrical specications on page 6 and make sure the power
supply is within the required voltage range to operate the FL591FL.
Output will not enable Improperly congured Enable
switch on the FL591FL
The DIS pin on the Power connector must be grounded AND the switch on
the FL591FL must be set to ENABLE.
Power supply voltage too low Check the electrical specications on page 6 and make sure the power
supply is within the required voltage range to operate the FL591FL.
Driver not working properly
in constant current, parallel-
output mode
Jumpers congured incorrectly Check page 9 to make sure the output jumper is set properly.
Improper output wiring
conguration
Check that the connections to the laser diode are made via output
connector LD1.
Laser output power too low
in Constant Current mode
Laser current setpoint too low Increase the setpoint either by adjusting the trimpot, or by increasing the
signal voltage on the input connector.
Laser current limit too low Refer to page 9 for instructions on setting the laser driver current limit.
Laser driver is compliance limited Check the laser diode specications to determine the forward voltage
(VF). Make sure that the FL591FL is not compliance limited. Refer to the
Electrical Specications table on page 6.
Laser does not reach desired
output in Constant Power
mode
Current limit too low Check the laser diode datasheet to determine the approximate laser drive
current at the desired optical power output level. Then verify that the current
limit is set slightly higher than that. Refer to page 9 for instructions on
setting the laser driver current limit.
Photodiode feedback current is
out of range for the FL591FL
Refer to page 12 for information on adjusting the photodiode current
range.

© 2017 www.teamWavelength.com 12
FL591FL LASER DIODE DRIVER
ADJUST THE PHOTODIODE CURRENT RANGE
The maximum photodiode current input is 1 mA, but the
range can be adjusted by changing a resistor on the
FL591FL circuit board. The location of the resistors is shown
in Figure 7. The default resistor value is 1 kΩ ±1%.
Figure 7. Photodiode Feedback Resistors
GND LIM 1LIM 2
LDA
LDA
PDA
PDA
LDC
LDC
LD 1
LD 2
]S
]P
RPD1
RPD2
FL500
Channel 1
PD Resistor
Channel 2
PD Resistor
Calculate new resistor values based on the expected
maximum photodiode current using this equation:
RPD = 1 / IPMON (Ω)
To convert the VPMON value to photodiode current, use this
equation:
IPMON = VPMON / (2 * RPD) (A)
TECHNICAL SUPPORT
INFORMATION
This section includes useful technical information on these
topics:
• Adjust the Photodiode Current Range
• FL591FL Schematic
• Safe Operating Area Calculation

© 2017 www.teamWavelength.com 13
FL591FL LASER DIODE DRIVER
PDFB1
PDFB2
PSET1
PSET2
S2
CC/CP1
S3
CC/CP2
D8
LM4040-2.5
5
43
Q4A
2
1 6
Q4B
MMDT3946
R84
249
2
31
W
CW CCW
R82
2.0K
C46
10uF
C47
10uF
R81 182
VCC
2 3
1
84
U4A
AD8032
2 3
1
84
U6A
AD8032
VCC-U4
VCC-U6
VEE-U6
R78
1.05K
Q1
BSS138
VCC
R27
499
R28
499
VCC
R61 10.0
VCC
1
GND
2
RST
3
VSET1
4
GND
5
VSET2
6LDC2 7
LDC2 8
PGND 9
PGND 10
LDC1 11
LDC1 12
U5
FL500
PDA1 PDA2
VS
LDA2LDA1
LDC
3PDA
2LDA
1
J1
LD Con
n
LDC
3PDA
2LDA
1
J2 LD Con
n
1
2
3
JP2
VS-U7
IMON1
IMON2
VEE-U7
R57
1.0
R48
1.0
2
3
1
84
U7A
AD8032
5
6
7
U7B
AD8032
C17
10uF
C16
10uF
C26
10uF
C48
10uF
D10
LM4040-2.5
5
43
Q5A
2
1 6
Q5B
MMDT3946
R96 249
2
31
W
CW CCW
R92 2.0K
C49 10uF
C50 10uF
R91 182
VCC
5
6
7
U4B
AD8032
5 6
7
U6B
AD8032
R90
1.05K
C51
10uF
D7 1N4148
D9
1N4148
VSET2 VSET1
VS
EN 1
GND3
VS 2
J4 Power
2
1
3
S1 SPDT Toggle
C19 100uF
C18
100uF
1
2
3
JP1
LDC2
IMON1 IMON2
PMON2 PMON1
MONITORS
1
2
3 4
5
6
J3
TP7 Test Point
D2
SML-LXT0805GW
D1
TP6 (VIA) Test Point
TP5 (VIA)
Test Point
R20
1.0
R21
1.0
R77
1.0K
R76
1.0K
R85 1.0K
R75
1.0K
R83
1.0K
R89
1.0K
R88
1.0K
R87
1.0K
R97
1.0K
R93
1.0K
R60
20.0k
R56
20.0k
R54
20.0k
R45
20.0k
R49
1.0K
R58
1.0K
R98 2.0K
R86
2.0K
R53
4.99K
R44
4.99K
R59
4.99K
R55
4.99K
TP2
LIM1
TP4
LIM2
LDA1
FL591FL SCHEMATIC, PAGE 1

© 2017 www.teamWavelength.com 14
FL591FL LASER DIODE DRIVER
2
31
W
CW CCW
R101
2.0K
C53
10uF
1
2
3
JP3
1
2
3
JP4
R80
51.1
R79
51.1
2 3
1
84
U8A
AD8032
5 6
7
U8B
AD8032
VEE-U8
VCC-U8
5
43
Q6A
2
1 6
Q6
B
MMDT3946
R99 182
C52
10uF
D12
LM4040-2.5
2
31
W
CW CCW
R110
2.0K
C56
10uF
1
2
3
JP5
1
2
3
JP6
R118
51.1
R112
51.1
2 3
1
84
U9A
AD8032
5 6
7
U9B
AD8032
VEE-U9
VCC-U9
5
43
Q7A
2
1 6
Q7
B
MMDT3946
R108 182
C55 10uF
D14
LM4040-2.5
VEE-U1
VEE-U3
PDA1
VS-U1
VCC-U3
PMON1
PSET1
PDR1
C1
0.012uF
C4
0.022uF
2 3
1
84
U1A
AD8032
2 3
1
84
U3A
AD8032
PDFB1
PDA2
PMON2
PSET2
PDFB2
PDR2
C14
0.012uF
C20
0.022uF
5 6
7
U1B
AD8032 5
6
7
U3B
AD8032
D1
1
1N4148
D1
3
1N4148
VSET1
VSET2
P2 BNC
P1
BNC
VEE
VS
VEERAW
R8
1.0
R16
1.0
R12 10.0
R13 10.0
C12
10uF
C5
0.47uF
C9
0.47uF
C6
4.7uF
C10
10uF
VS
VEE
Filter for U1
VS-U1
VEE-U1
VCC
VEE
Filter for U3
VCC-U3
VEE-U3
VCC
VEE
Filter for U6
VCC-U6
VEE-U6
VS
VEE
Filter for U7
VS-U7
VEE-U7
C21
0.1uF
C28
0.1uF
C22
0.1uF
C29
0.1uF
C23
0.1uF
C30
0.1uF
C24
0.1uF
C31
0.1uF
R63
10.0
R67
10.0
R64
10.0
R68
10.0
R65
10.0
R69
10.0
R66
10.0
R70
10.0
VCC
VEE
Filter for U8
VCC-U8
VEE-U8
C35
0.1uF
C36
0.1uF
R72
10.0
R73
10.0
VCC
VEE
Filter for U9
VCC-U9
VEE-U9
C37
0.1uF
C38
0.1uF
R94
10.0
R95 10.0
VRAW
VCC
Filter for U4
VCC-U4
C25
0.1uF
R62
10.0
VCC
C13
100uF
VCC
VCC
C57
22uF C54 22uF
C3
22uF
C8
22uF
R103
1.0K
R105 1.0K
R104
1.0K R114 1.0K
R113
1.0K
R115
1.0K
R106 1.0K
R107
1.0K R116 1.0K
R117
1.0K
R2
1.0K
R3
1.0K
R4
1.0K
R7
1.0K
R17
1.0K
R18
1.0K
R19
1.0K
R24
1.0K
R23
1.0K
R25
1.0K
R6
1.0K
R9
1.0K
R1
100k
R14
100k
R102 2.0K R111 2.0K
R109
499 R100
499
TP3
VSET2
TP1
VSET1
TP11
VSET GND
C11
22uF
C7
22uF
R10 1.0K
R26
1.0K
TP4 (VIA) Test Point
FL591FL SCHEMATIC, PAGE 2

© 2017 www.teamWavelength.com 15
FL591FL LASER DIODE DRIVER
1.02.03.04.05.06.07.08.09.0
0.00
0.05
0.10
0.15
0.20
0.25
Voltage (V)
Current (A)
VDROP VS
IMAX
Load Line
Figure 8. Example SOA Chart, FL591FL Laser Driver
1.02.03.04.05.06.07.08.09.0
0.00
0.05
0.10
0.15
0.20
0.25
Voltage (V)
Current (A)
Figure 9. SOA Chart,
FL591FL Operating as a 250 mA Driver
3.04.05.06.07.08.09.0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Voltage (V)
Current (A)
Figure 10. SOA Chart,
FL591FL Operating as a 500 mA Driver
SAFE OPERATING AREA CALCULATION
Before attempting to operate the FL591FL, it is imperative
that you rst determine that the FL500 driver will operate
within the Safe Operating Area (SOA). Consult the
instructions for calculating the FL500 Safe Operating Area
online at:
http://www.teamwavelength.com/support/calculator/soa/soald.php
If you have any questions about the Safe Operating Area
calculator, call the factory for free and prompt technical
assistance.
!
ItIs ImperatIve that you verIfy the unIt wIll operate
wIthIn the Internal heat dIssIpatIon safe operatIng
area (soa).
operatIng the controller outsIde the soa may
damage or destroy the fl591fl and/or loads.
We recommend using the online SOA calculators rather
than the charts provided here. The online calculators take
into consideration operating temperature.
Follow these steps to use the SOA Chart to determine if the
FL591FL will be operating safely. Refer to the example SOA
chart in Figure 8. Room temperature SOA charts for the
FL591FL are shown in Figure 9 and Figure 10.
• Determine the VSsupply voltage for the laser driver. For
this example assume VS= 8 VDC.
• Refer to the laser datasheet to nd the voltage (VF) at
the required drive current, and maximum current (IMAX)
specications. For this example, assume VF= 1.8 V and
IMAX = 200 mA.
• Calculate the voltage drop across the controller:
VDROP = VS – VF
• Mark VDROP on the X-axis, and extend a line upward
• Mark IMAX on the Y-axis, and extend a line to the right
until it intersects the VDROP line
• On the X-axis, mark the supply voltage (VS)
• Extend a diagonal line from VSto the intersection of the
VDROP and IMAX lines; this is the Load Line
• If the Load Line crosses the Safe Operating Area line at
any point, the conguration is not safe
If the SOA calculator indicates the FL591FL will be outside
of the Safe Operating Area, the system must be changed
so that less power is dissipated within the driver. See
Application Note AN-LDTC01: The Principle of the Safe
Operating Area for information on shifting the Load Line.
After changing any of the parameters, recalculate the
SOA to make sure the controller will operate safely. If you
have questions, or run into difculties calculating the SOA,
contact Wavelength Electronics for assistance.

© 2017 www.teamWavelength.com 16
FL591FL LASER DIODE DRIVER
CABLE SPECIFICATIONS
POWER CABLE -- FL591-00101-A; INCLUDED WITH FL591FL
1
3
2
Molex 43645-0300 Terminal Housing
Molex 43030-007 3mm Micro-Fit Terminal
1 - DIS
2 - VS
3 - GND
18” Long, 22 AWG
OUTPUT CABLE -- FL591-00102-A; TWO INCLUDED WITH FL591FL
1
3
2
1 - LDA
2 - PDA
3 - LDC
Molex 43645-0300 Te rminal Housing
Molex 43030-007 3mm Micro-Fit Terminal
18” Long, 22 AWG

© 2017 www.teamWavelength.com 17
FL591FL LASER DIODE DRIVER
MECHANICAL SPECIFICATIONS
11.99
.47
15.11
.60
27.10
1.07
[46.984]
1.850
5.08
.20
57.15
2.25
[53.333]
2.100
5.08
.20
63.50
2.50
18.38
.72
75.53
2.97
.188
4 PLS
The FL500 chip is convection reflow process compatible
(not vapor phase).
FL500
Figure 11. FL591FL Mechanical Dimensions
All dims in [mm] inches; Tolerance ±5%

© 2017 www.teamWavelength.com 18
FL591FL LASER DIODE DRIVER
CERTIFICATION AND WARRANTY
CERTIFICATION
Wavelength Electronics, Inc. (Wavelength) certies that this
product met its published specications at the time of shipment.
Wavelength further certies that its calibration measurements are
traceable to the United States National Institute of Standards and
Technology, to the extent allowed by that organization’s calibration
facilities, and to the calibration facilities of other International
Standards Organization members.
WARRANTY
This Wavelength product is warranted against defects in materials
and workmanship for a period of one (1) year from date of shipment.
During the warranty period, Wavelength will, at its option, either
repair or replace products which prove to be defective.
WARRANTY SERVICE
For warranty service or repair, this product must be returned to the
factory. An RMA is required for products returned to Wavelength
for warranty service. The Buyer shall prepay shipping charges to
Wavelength and Wavelength shall pay shipping charges to return
the product to the Buyer upon determination of defective materials
or workmanship. However, the Buyer shall pay all shipping
charges, duties, and taxes for products returned to Wavelength
from another country.
LIMITATIONS OF WARRANTY
The warranty shall not apply to defects resulting from improper
use or misuse of the product or operation outside published
specications. No other warranty is expressed or implied.
Wavelength specically disclaims the implied warranties of
merchantability and tness for a particular purpose.
EXCLUSIVE REMEDIES
The remedies provided herein are the Buyer’s sole and exclusive
remedies. Wavelength shall not be liable for any direct, indirect,
special, incidental, or consequential damages, whether based on
contract, tort, or any other legal theory.
REVERSE ENGINEERING PROHIBITED
Buyer, End-User, or Third-Party Reseller 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 be liable for errors contained
herein or for incidental or consequential damages in connection
with the furnishing, performance, or use of this material. No part of
this document may be translated to another language without the
prior written consent of Wavelength.
SAFETY
There are no user-serviceable parts inside this product. Return the
product to Wavelength Electronics for service and repair to ensure
that safety features are maintained.
LIFE SUPPORT POLICY
This important safety information applies to all Wavelength
electrical and electronic products and accessories:
As a general policy, Wavelength Electronics, Inc. does not
recommend the use of any of its products in life support
applications where the failure or malfunction of the Wavelength
product can be reasonably expected to cause failure of the life
support device or to signicantly affect its safety or effectiveness.
Wavelength will not knowingly sell its products for use in such
applications unless it receives written assurances satisfactory
to Wavelength that the risks of injury or damage have been
minimized, the customer assumes all such risks, and there is no
product liability for Wavelength. Examples of devices considered
to be life support devices are neonatal oxygen analyzers, nerve
stimulators (for any use), auto-transfusion devices, blood pumps,
debrillators, arrhythmia detectors and alarms, pacemakers,
hemodialysis systems, peritoneal dialysis systems, ventilators of
all types, and infusion pumps as well as other devices designated
as “critical” by the FDA. The above are representative examples
only and are not intended to be conclusive or exclusive of any
other life support device.
REVISION HISTORY
DOCUMENT NUMBER: FL591-00400
REV. DATE CHANGE
F Nov 2012 Update datasheet for FL591FL
product enhancement
G March 2014 Claried reow compatibility
HJune 2014 Updated Transfer Functions
I February 2017 Updated max supply voltage value
Distributor
[email protected]m
www.amstechnologies-webshop.com