PICOLAS LDP-CWL 90-10 User manual

User Manual
LDP-CWL 90-10
(preliminary)
PicoLAS GmbH
Burgstr. 2
52146 Würselen
Germany
Phone: [phone]
Fax: [phone]
E-mail: [email protected]e
Web: www.picolas.de
Rev. 2201

2
Table of Contents
Description of Connections ......................................................................................................................4
Pin Assignments and Description of the MOLEX Pin Header ...................................................................5
How to get started (quick start without PLB-21)......................................................................................7
How to get started with a PLB-21.............................................................................................................7
Dos and Don’ts .........................................................................................................................................8
Absolute maximum Ratings......................................................................................................................8
Ordering Options / Product Changes .......................................................................................................8
Current Regulator.....................................................................................................................................9
Current Limiter .........................................................................................................................................9
External Setpoint....................................................................................................................................10
Test Load ................................................................................................................................................10
Power Supply..........................................................................................................................................10
Cooling....................................................................................................................................................10
Over temperature Shutdown .................................................................................................................11
Mechanical Dimensions..........................................................................................................................12
Power on Self Test..................................................................................................................................13
Controlling the Driver.............................................................................................................................13
Controlling the Driver using a PLB-21.....................................................................................................14
Menu Structure ......................................................................................................................................14
If an Error occurs ....................................................................................................................................15
Controlling the Driver via a PC................................................................................................................15
Introduction............................................................................................................................................15
Description of the RS-232 Interface .......................................................................................................16
The Serial Text Interface.........................................................................................................................17
Structure.................................................................................................................................................17
Commands for the serial text interface..................................................................................................18
If an Error Occurs....................................................................................................................................19
The PicoLAS Protocol..............................................................................................................................20
Structure.................................................................................................................................................20
General Commands................................................................................................................................21
Commands for the Driver.......................................................................................................................22
Register Description ...............................................................................................................................27
Description of the LSTAT Register ..........................................................................................................27
Description of the ERROR Register.........................................................................................................28
Please pay Attention to all Safety Warnings!
Symbols used in this manual:
Risk of electrical hazard
Please pay special attention
Do not
Valuable information, remark

3

4
Description of Connections
All connectors on the LDP-CWL 90-10 are protected against ESD as described by the
human body model.
The following drawing shows all connections that are available to the user.
Connector
Description
VCC
Supply voltage 24 V
GND (next to VCC)
Supply ground
LD+
Positive laser diode output (anode)
GND (next to anode
on the right side)
Negative laser diode output (cathode) ground.
Do not use the input ground!
LDP-C BOB
connector
Mini MOLEX Connector for analogue / TTL control of the driver
(see below)
RS-232 / PLB-21
connector
Mini-MOLEX connector for RS-232 communication or the
PLB-21 (see below)
CAN Bus
Provides a CAN bus interface corresponding to CAN 2.0
(not implemented in the preliminary version)
VCC
GND
LD anode
GND
4 holes for heat sink
(3.1 mm trough)
Left: RS-232 / PLB connector (pin 1 marked), Middle: LDP-C BOB connector (pin 1 marked), Right: CAN-Bus
connector (pin 1 marked)

5
Pin Assignments and Description of the MOLEX Pin Header
The connector is a MOLEX_908140008, a suitable female connector would be a MOLEX
- 90327-0308 like Farnell 673160.
Pin Number
Description
Direction
Comments
1 (marked in red)
reserved
Do not connect!
2
reserved
Do not connect!
3
I-Soll
Input
Scale: depending on configuration
4
Enable-Ext
Input
0 V = disabled, 3.3 V = driver enabled
5
Pulser-Ok
(“pulser” is
used here as
a synonym
for driver)
Output
0 V = laser diode driver not ok or power
up self test not passed yet; 3.3 V = driver
ok / test passed
6
GND
Output
7
I-Diode
Output
Current monitor output (20 A/V)
8 (left)
+ 3.3 V
(via 10 R)
Output
Can be used to connect with pin 4
to enable the driver, please use a switch
for safety reasons

6
The connector is a MOLEX_908140004, female connector MOLEX - 90327-0304 like
Farnell 673146.
Pin Number
Description
Direction
Comments
1 (marked in red)
+12 V
Output
Only for the use with the PLB-21, prevent
any overload or short! (max. 100 mA)
2
TXD
I/O
RS-232 standard serial interface
3
RXD
I/O
RS-232 standard serial interface
4 (left)
GND
Output
The connector is a MOLEX_908140004, female connector MOLEX - 90327-0304 like
Farnell 673146.
Pin Number
Description
Direction
Comments
1 (marked in red)
n.c.
Not connected
2
CAN +
I/O
CAN +
3
CAN -
I/O
CAN -
4 (left)
GND
Output

7
How to get started (quick start without PLB-21)
Step
What to do
Note
1
Unpack your device.
2
Connect a load to the output.
Screw connectors are on the right side.
Pay attention to the polarity when
connecting a diode.
For tests the load might be a resistor
or a dummy diode.
3
Apply the supply voltage. Connect the
VCC input on the upper left to your
power source (fix your wires with the
screws at the connector).
Apply supply voltage of +24 V at
“VCC” with respect to GND. Make
sure there is no voltage surge that
could destroy the unit when
switching the power supply on!
4
Wait until “pulser-ok” is high
(“pulser” is used here as a synonym for
driver).
Pin 5 with respect to pin 6 must
change from 0 V to 3.3 V.
5
Apply the current setpoint.
6
Set enable pin “high”.
Apply 3.3 V to pin 4 of the BOB
connector. The current will ramp up
now.
7
Check
If the driver is not properly cooled, it
will shut down.
How to get started with a PLB-21
Step
What to do
Note
1
Unpack your device.
2
Connect the PLB-21.
Use the PLB-21 pin header and the
special cable.
3
Apply the supply voltage. Connect the
VCC input on the upper left to your
power source (fix your wires with the
screws at the connector).
Apply any voltage between +15 V
and +24 V to “VCC” with respect to
GND.
The voltage must be at least 7 V
higher than the expected compliance
voltage of the laser diode.
Make sure there is no voltage surge
that could destroy the unit when
switching the power supply on!
4
Wait until “pulser-ok” is high (pin5).
(“pulser” is used here as a synonym for
driver.)
Pin 5 with respect to pin 6 must
change from 0 V to 3.3 V.
5
Apply the current setpoint.
Use the PLB-21 to switch from
external to internal setpoint and set
the setpoint by turning the dial.
6
Set enable pin “high” (pin 4).
Apply 3.3 V to pin 4 of the BOB
connector. The current will ramp up
now.
7
Check
If the driver is not properly cooled, it
will shut down.

8
Dos and Don’ts
Never make a short at the output. This will not do any harm to the laser driver but
will result in an incorrect current measurement.
Keep the connection between power supply and driver as well as the connection
between driver and laser diode as short as possible.
Mount the driver on an appropriate heat sink. The driver will shut down under
overtemperature circumstances. Depending on the desired current a slight airflow
across the black coils on top is necessary. Please keep the temperature of these
devices below 85 °C
This diver uses a “low-side” current sensing technique. The GND of the VCC
terminal is the not same as the GND of the LD terminal, hence a connection
between these two is not recommended.
The driver is for cw operation only.
Never disconnect or connect the load while the driver is operational. This will
destroy the driver and / or the connected load.
Make sure that the control ground is connected to the supply ground. Any
unexpected current flow through the control board may damage the driver.
Never use the power stage without the assembled controlling unit!
Absolute maximum Ratings
▪Supply voltage range: +24 V
▪Maximum input current: 100 A
▪Maximum laser diode output current: 90 A
▪Maximum laser diode compliance voltage: 12 V (up to 18 Volts possible, but no
support)
▪BOB connector input and output voltages: 0 V to 3.3 V (terminals are 5 V proof)
▪BOB connector output currents: 1 mA
▪Auxiliary 3.3 V supply voltage output current: 30 mA (pin 8 of BOB connector
planned for Rev 2.1)
▪Auxiliary 12 V supply voltage output current: 100 mA (pin 1 of PLB-21
connector)
▪Operating temperature: 0 .. 55 °C
Ordering Options / Product Changes
▪LDP-CWL 90-10 or LDP-CWL 90-10-S50 yields the standard unit with the
scaling 5 V = 90 A
▪LDP-CWL 90-10-S33: Input scaling is 0 .. 3.3 V correspond to 0 .. 90 A. The first
units were shipped with this scaling. If you require this furthermore, please order
with the -S33 option.
Note: This affects the analog input only.

9
Current Regulator
The driver is equipped with a linear current regulator, which can drive up to 90 A. The following diagram
gives a simplified technical overview:
As shown in the diagram a DC-DC converter is used to generate the voltage required to
drive the laser diode. It can be configured via software between 2 V and 20 V or
controlled automatically.
Manual: When the voltage is chosen manually it must be at least 1.5 V higher than
the laser diodes compliance voltage. This will decrease the rising edge of
the output current. However, if it is not high enough, the driver will not be
able to reach the set point current.
Auto: In this mode, the driver will set the voltage automatically to minimize the
power losses in the output stage but will lead to a slower rising edge.
Current Limiter
The driver is equipped with a software based current limiter. This can be used to configure
a maximum valid current setpoint (analog and digital) which cannot be overstepped.

10
External Setpoint
An external voltage can be applied to the driver which defines the setpoint current. The
scaling of this voltage depends on the version of the driver. See datasheet for more
information.
In order to switch between external and internal setpoint the bit 6 of the LSTAT register
must be altered. Please note that this only works if the driver is disabled!
The external setpoint voltage is converted by an analog to digital converter into a digital
value. The resolution of this converter is 10 bit. This may lead to some current jitter as this
resolution is not equal to the current resolution of 0.1 A.
The input impedance on this input pin is greater or equal to 10 kOhms.
Test Load
A common method to test the driver is to connect a regular silicon rectifier diode to the
driver output. Attention has to be paid to the junction capacitance of the diode. Only fast
recovery diodes (or similar) have a low parasitic capacitance as laser diodes have. To
achieve reasonable test results the parasitic elements of the test diode and the connection
must be very similar to a laser diode approach. Regular silicon rectifier diodes have a
junction capacitance of several microfarads and are not a suitable test load! The use of
these diodes will yield in incorrect current measurement at the pulse edges!
Power Supply
The power supply must be able to cover the output power plus the internal power losses (please
see next section).
Cooling
The driver has to be mounted on a heat sink to ensure proper operation and prevent an
overtemperature shutdown. It produces thermal losses depending on the selected voltage
and output current. The actual losses can be estimated by using the following equation:
SLDLDdcdcinLPIVVIP ++ −= )(72.0
where
LP
Thermal dissipation loss in W
inI
Input current
dcdcV
Capacitor voltage in V
LDV
Compliance voltage of the LD in V
LDI
Laser diode current
SP
Static operation losses ~ 5 W