THORLABS IP500 User manual

IP500
500 mA Laser Diode
Controller
User Guide

IP500 Laser Diode Controller
Table of Contents
Chapter 1 Overview ............................................................................ 1
1.1. Features ........................................................................ 1
Chapter 2 Setup and Operation ........................................................ 2
2.1. Connections ................................................................... 2
2.2. Operation ...................................................................... 4
2.2.1. Automatic Constant Current Control (ACC).................................4
2.2.2. Automatic Constant Power Control (APC)...................................5
2.2.3. Analog Modulation.......................................................................6
2.2.4. Remote Control Inputs.................................................................7
2.3. Alarms and Troubleshooting.......................................... 7
2.4. Remote Monitoring ....................................................... 8
2.5. Accessories .................................................................... 8
Chapter 3 Specifications ................................................................... 9
Chapter 4 Regulatory ....................................................................... 12
Chapter 5 Thorlabs Worldwide Contacts....................................... 13

IP500 Laser Diode Controller Chapter 1: Overview
Rev I, December 1, 2015 Page 1
Chapter 1 Overview
The IP500 is a universal 500 mA board level driver. Designed for use within higher
level assemblies, while being value priced as a laboratory diode driver. This
versatile device can easily and safely control all Laser Diode / Photo Diode pin
configurations in 5.6 mm and 9 mm lasers. Operating in constant current or
constant power mode, this driver can be enabled on the board itself or over a
remote switch connection. Connections are provided for remote interlocks and
remote monitoring. Wire harnesses for all required connections are provided with
the unit.
1.1. Features
Accepts photodiode feedback currents of up to 2.0 mA.
Pin configurations and operating modes are easily set using on board
jumpers.
Current and power limits are set using individual 25-turn potentiometers.
Current or power is adjusted using a 25-turn potentiometer.
Easily accessible test points allow analog monitoring of the injection
current and photodiode feedback current as well as the current and
power limit settings.
Laser diode inputs are shorted during idle operation to protect the
device.
Three indicators display whether the laser is enabled, operating at
current limit, or in an alarm shutdown condition.
Automatic alarmed shutdown when laser connection is open or
reversed.
Operates from ±5 VDC.
Analog modulation up to 50 kHz.
Separate ENABLE switch turns laser on and off, no need to power down
the entire unit.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Page 2 3037-D02
Chapter 2 Setup and Operation
2.1. Connections
Wiring harnesses have been provided to make the proper connections from the
IP500 to its power source and the laser diode to be driven. One harness has a
three-pin connector mate the other has a four-pin connector mate.
The wire harness made with the 3-pin connector should be connected to J1 of the
IP500 and the ±5 V power supply. Connect to the power supply as follows:
Power Supply
Jumper
Wire Color
Designation
J1-1
Red
+5 V
J1-2
Black
Common
J1-3
Yellow
-5 V
The wire harness made with the 4-pin connector should be connected to J2 of the
IP500 and the Laser Diode to be driven. Connect the Laser Diode as follows:
Laser Diode
Jumper
Wire Color
Designation
J2-1
Purple
Laser Cathode of Anode Grounded Diode or
Laser Anode of Cathode Grounded Diode
J2-2
Black
Laser Anode Ground or Laser Cathode Ground
J2-3
Black
Monitor Photodiode Cathode
J2-4
Orange
Monitor Photodiode Anode
Note: Either the monitor photodiode cathode or monitor photodiode anode MUST
be connected to ground somewhere in this system. Typically this is done at the
laser diode package itself on a common pin. To eliminate errors due to wire losses,
always return the photodiode ground connection on the wire provided. Do not use
a common wire for the photodiode and laser diode ground currents.
If the photodiode is completely isolated from the laser diode, install a wire jumper
into J3 of the IP500 to fix the ground connection to the photodiode cathode.
Refer to Figure 1 on Page 3 for the schematic diagram detailing the laser diode
connections and the correct setting for the JMP1 ground jumper.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Rev I, December 1, 2015 Page 3
Figure 1 Laser Diode Connections

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Page 4 3037-D02
2.2. Operation
2.2.1. Automatic Constant Current Control (ACC)
1. Set JMP1 to either “AG” for laser diodes with grounded anodes or “CG”
for laser diodes with grounded cathodes. JMP1 is located on the left side
of the unit. Always disable the laser driver prior to changing modes.
2. Set JMP2 to “ACC” for constant current operation. JMP2 is located on the
left side of the unit. Always disable the laser driver prior to changing
modes.
3. Apply power to the unit.
4. Using a digital multimeter measure the ILIM Test point with respect to the
TP GND Test point (all measurements will be with respect to TP GND).
Adjust the ILIM ADJ potentiometer for the maximum current that the laser
must be limited to. The transfer function is 1 V = 1 A, with a maximum
adjustment of approximately 0.500 V or 500 mA.
5. If a monitor photodiode (MPD) is connected, measure the PLIM Test point
and adjust the PLIM ADJ pot for the maximum MPD current expected.
The transfer function is 1 V = 1 mA, with a maximum adjustment of 2.5 V
or 2.5 mA.
When operating in ACC the PLIM (power limit) function is still active if the
MPD current reaches the limit point. This is especially helpful if the laser
is to be operated at varying temperatures where the efficiency may
change to the point where the operating current will overdrive the laser.
The PLIM will always keep the laser in a safe operating area when
properly set.
If no MPD is connected always set the PLIM ADJ fully clockwise.
6. The P/I ADJ Pot will allow adjustment of the laser drive current from 0 mA
to the ILIM set point or 500 mA max. When turning on a laser for the first
time it is suggested that this pot be set fully counter-clockwise.
7. Press and release the ENABLE switch.
8. The green LD ON indicator will turn on.
Note: There will always be a delay until full power of approximately 2 to
3 seconds before any current can flow to the laser diode.
9. Adjust the P/I ADJ potentiometer clockwise to increase the injection
current of the laser diode. The Ild Test point provides an analog read back
of the actual laser current, 1 V = 1 A. The Ipd Test point provides an
analog read back of the photodiode monitor current, 1 V = 1 mA and can
be used to gauge the relative output power of the laser.
10. Pressing the ENABLE switch while the laser is operating will turn off the
laser current.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Rev I, December 1, 2015 Page 5
If the ALARM indicator turns ON see Section 2.3 “Alarms and Troubleshooting” on
Page 7.
Note: If the ILIM setting is below approximately 10 mA the I LIMIT LED will be ON,
this is normal.
If the current is adjusted to its maximum limit then the I LIMIT indicator will turn
ON. This indicator is active when the injection current is approximately 95% of the
maximum limit.
If the photodiode is connected and the PLIM is set to a value requiring less than
the maximum current set by ILIM, the I LIMIT indicator will NOT turn ON and the
unit will operate in constant power at the power limit level set by PLIM.
While operating in APC Mode, if the power is adjusted to its maximum limit then
the injection current will not increase even though the potentiometer has more
adjustment.
If the PLIM is set to a value that requires a higher level of drive current than ILIM
is set to, the I LIMIT indicator will turn ON and the unit will operate in constant
current at the current limit level.
2.2.2. Automatic Constant Power Control (APC)
Photodiode feedback current is required in APC mode.
1. Set JMP1 to either “AG” for Laser Diodes with Grounded Anodes or “CG”
for Laser Diodes with Grounded Cathodes. JMP1 is located on the left
side of the unit. Always disable the laser driver prior to changing modes.
2. Set JMP2 to “APC” for Constant Current operation. JMP2 is located on
the left side of the unit. Always disable the laser driver prior to changing
modes.
3. Apply power to the unit.
4. Using a digital multimeter measure the ILIM Test point with respect to the
TP GND Test point (all measurements will be with respect to TP GND).
Adjust the ILIM ADJ potentiometer to the maximum laser current limit.
The transfer function is 1 V = 1 A, with a maximum adjustment of
approximately 0.500 V or 500 mA.
When operating in APC the ILIM (current limit) function is still active if the
laser current reaches the limit point.
5. Measure the PLIM Test point and adjust the PLIM ADJ pot for the
maximum MPD current expected. The transfer function is 1 V= 1 mA, with
a maximum adjustment of 2.5 V or 2.5 mA.
6. The P/I ADJ Pot will allow adjustment of the Monitor Photodiode current
from 5 uA to the PLIM set point or 2 mA max. When turning on a laser for
the first time it is suggested that this pot be set fully counter-clockwise.
7. Press and release the ENABLE switch.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Page 6 3037-D02
8. The green LD ON indicator will turn ON. If the ALARM indicator turns ON
see “Alarms and Troubleshooting” below. If the I LIMIT indicator turns ON
immediately press the ENABLE switch and refer to “Alarms and
Troubleshooting”.
9. Adjust the P/I ADJ potentiometer clockwise to increase the MPD current.
The IPD Test point provides an analog read back of the actual MPD
current, 1 V = 1 mA.
10. Pressing the ENABLE switch while the laser is operating will turn off the
laser current.
While operating in APC Mode, if the power is adjusted to its maximum limit then
the injection current will not increase even though the potentiometer has more
adjustment.
If the PLIM is set to a value that requires a higher level of drive current than ILIM
is set to, the I LIMIT indicator will turn ON and the unit will operate in constant
current at the current limit level.
If the photodiode is connected incorrectly or the connection is opened, the I LIMIT
indicator will turn ON and the unit will operate in constant current at the current
limit level.
2.2.3. Analog Modulation
The amplitude of the laser injection current can be varied over time by connecting
a signal generator to the BNC connector J3 on the IP500. It is recommended that
the unit be configured to operate in ACC mode whenever analog modulation is
used.
J3 can also be used as a remote analog input, allowing the user to program the
laser injection current from 0 to 500 mA by applying a 0 to 10 VDC signal. The
transfer function being 50 mA per 1 V.
The P/I ADJ pot must be set fully counter-clockwise prior to using this input.
For 100% depth of modulation set the P/I ADJ pot fully counter-clockwise and
apply a sinewave input to J3. The peak-to-peak amplitude must equal ILIM / 0.05
and a DC offset equal to 0.5 of the amplitude must be applied (the signal should
always be above 0 V).
The depth of modulation can be decreased by increasing the P/I ADJ pot to provide
a DC current offset, and then adjusting the peak-to-peak amplitude to stay within
the ILIM range. The ILIM circuit will limit the average current to the ILIM setting
and the I LIMIT indicator will turn on when the average current exceeds the ILIM
setting.
The ILD Test point will provide the average current level when modulating.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Rev I, December 1, 2015 Page 7
2.2.4. Remote Control Inputs
In addition to the automatic shutdown features, the IP500 also has a number of
remote enable and lockout functions accessible on J4 of the unit. The standard
unit provides a shunt jumper installed in J4 Pins 5-6. This is the remote lockout
input and must be shorted in order for the unit to be ENABLED. A summary of the
J4 functions is provided for reference. A mating wire harness is available from
Thorlabs, Inc. should you decide to incorporate these features (refer to
Accessories for more information):
Pin
Description
J4-1
Remote Enable Input
J4-2
Remote Enable Return (common to ground)
Momentarily connecting J4-1 to J4-2 will allow remote enable and disable the unit.
Leave unconnected when not using.
Pin
Description
J4-3
Key lock Input
J4-4
Key Lock Return (common to ground)
A closed connection across J4-3 to J4-4 will prevent the unit from being ENABLED.
Leave unconnected when not using.
Pin
Description
J4-5
Remote Interlock Input
J4-6
Remote Interlock Return (common to ground)
An open connection across J4-5 to J4-6 will prevent the unit from being ENABLED.
These two points must be connected for unit to operate.
All connections to J4 must be made using isolated or dry contacts (i.e. switches or
relays with no potentials on the contacts).
2.3. Alarms and Troubleshooting
This unit contains circuitry that will automatically shut down the laser driver if any
of the following conditions are met:
The laser diode anode and cathode connections are reversed.
The laser diode connection is broken or an open circuit exists.
The operating voltage (Vop) of the laser exceeds approximately 3.3 V.
If an alarm shutdown occurs the ALARM indicator will turn ON and the LD ON
indicator will turn OFF, remove power from the unit, correct the problem, and
reapply power to the unit. Pressing the ENABLE switch once will turn the ALARM
indicator OFF. Pressing it again will re-enable the unit.

IP500 Laser Diode Controller Chapter 2: Setup and Operation
Page 8 3037-D02
In addition to the alarm shutdown, the IP500 will also shutdown (or not allow
ENABLE) if any of the following conditions exist or occur:
The Key lock Inputs (J4-3 and J4-4) are shorted together.
The Remote Interlock Inputs (J4-5 and J4-6) are open circuit.
The -5 V power supply is below approximately -4 V (-3.6 V typical).
As mentioned above, the I LIMIT indicator will turn ON when the laser injection
current exceeds 95% of the ILIM setting. This could be due to a number of
conditions summarized here:
The current or power has been adjusted to a point that requires an
injection current of greater than 95% of the current limit setting.
The Photodiode is reverse connected (in PMODE operation).
Identified by a negative level at the IPD Test point.
The Photodiode is not connected (in PMODE operation).
Identified by 0 V at the IPD Test point.
The Photodiode is short-circuited (in PMODE operation).
Identified by 0 V at the IPD Test point.
The ILIM pot is set full CCW (minimal).
2.4. Remote Monitoring
J5 has been reserved as an I/O port for specialized applications incorporating the
IP500. Refer to the attached engineering support drawing and contact a Thorlabs
engineer for more specific information on using these connections.
2.5. Accessories
The IP500 is shipped with the wire harness mates for J1 and J2. Youmay purchase
spare or replacement harnesses from Thorlabs as well as a suitable wire harness
for J4. The part numbers are listed below:
Wire Harness Descriptions
Jumper
Description
Connector Description
J1
DC Input Wires
Molex 70543-0002
J2
LD Wire Harness
Molex 70543-0003
J3
Modulation Input
BNC
J4
Status Wire Harness
Molex 70543-0005
J5
Test Points
Standard 0.1” Spaced Header