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

11
Over temperature Shutdown
To protect itself, the driver automatically shuts down if its temperature rises above 80 °C.
This condition is latched and the appropriate bit in the ERROR register is set. To re-enable
the driver the ENABLE pin must be toggled (set low and then high).

12
Mechanical Dimensions
All dimensions are in millimetres (mm).
Position
(vertical)
Dimension (mm)
Position (horizontal)
Dimension (mm)
A
61
H
4.8
B
59.6
I
6.6
C
55.9
J
9.3
D
51.7
K
18.3
E
38.1
L
20.6
F
22.8
M
34.8
G
5.1
N
45.2
S
16.2
O
53
T
32.8
P
113.3
Q
115
R
120

13
Power on Self Test
Each time the driver is powered up, it performs a test of its internal safety features. The
driver cannot be enabled until a self test has been performed successfully. The
PULSER_OK signal will be pulled high when the test has been successful.
The test will take less than 5 seconds, but can take up to 15 seconds due to internal time-
outs if any failures are detected.
Controlling the Driver
The driver can be operated stand alone, with a PLB-21 or a PC connected to it via a serial
link (RS-232 interface, for USB you need an USB RS-232 adaptor). It remembers all
settings from the last time it had been powered on, unless configured to load default values
on power-on. In latter case it loads pre-configured settings each time the power is applied.
Connecting a digital control to the driver does not alter the internal settings.
No digital control (factory default)
If no digital control (PLB-21 or serial link to PC) is attached, only the BOB connector
could be used to control the driver. If configured so, the pin 10 at the BOB connector
(“Isetpoint“) can be used to control the setpoint current. To enable the output pin 7 at the
BOB connector (“ENABLE”) must be set HIGH. If an error occurs (e.g. overtemperature),
the driver will be disabled and the pin 1 of the BOB connector (“PULSER_OK”) is pulled
low. The “enable” pin has to be toggled to enable the driver again.
PLB-21
If a PLB-21 is attached to the driver, it can be used to control the behavior of the driver.
The PLB-21 may ask for a driver to download. This must be confirmed with “yes” in
order for the PLB-21 to work properly. This must always be done when the PLB-21 was
connected to any other PicoLAS product. After the download all operating parameters can
be accessed using the PLB-21. For a detailed description see chapter PLB-21 below.
RS-232
If the driver is connected to a PC using a serial cable, all operating parameters can be
accessed via a serial RS-232 terminal program or the PicoLAS protocol. The PLB-21 is
automatically disabled if a serial connection is established. For a detailed description of
the serial text protocol and the PicoLAS protocol see below.
PC
If the driver is connected to a PC, all operating parameters can be accessed via a serial RS-
232 terminal program or the PicoLAS protocol. For a detailed description of the serial text
protocol and the PicoLAS protocol see below.

14
Controlling the Driver using a PLB-21
When the PLB-21 is connected the first time to the driver, the user is asked to download a
new firmware driver. This must be confirmed with “yes” in order for the PLB-21 to work
properly.
Menu Structure
The following diagram shows the structure of the PLB-21 menu which affects the driver.
All entries are described in detail. All other menu entries are described in the PLB-21
manual. For detailed instructions see the PLB-21 manual.
Menu root -Pulsgen
oCur(ext/int)
oCur Limit
oCap
-Config
oCurrent
oVCap mode
-
-Temp
oTemp 1
oTemp 2
oTemp 3
oTemp Off
-Defaults
oDef. pwron
oLoad defaults
oSave defaults
Pulsgen
In this menu the setpoint current can be modified.
Cur (ext/int)
This value defines the setpoint current.
When using the internal setpoint, the value can be modified by the user.
When using the external setpoint, the value shown is measured value supplied at pin 3 of
the BOB connector. The display is updated every few seconds, so it is not accurate when
using analog modulation.
Cur Limit
This value defines the software current limitation value. Please see section “Current
Limiter”for more details.
Cap
This value defines the precharge voltage for the linear current regulator. In the manual
mode, this value can be modified.

15
Config
Current
The driver can either use an internal digital set point or an external analogue signal. This
can be set here
VCap mode
This can be set to manual or auto.
Temp
The driver is equipped with several an onboard temperature sensors. The actual measured
temperatures of the PCB as well as the shutdown temperature can be monitored here.
Defaults
The driver can load a default setting each time it powers up or the user commands it to do
so. This is done within this submenu.
Def. pwron
When enabled, the driver loads the saved settings each time it powers up.
Load
When activated via turning the Jogdial or the ENTER key all internal registers are
changed to the previously saved values. The output stage has to be re-enabled via the
L_ON bit or the FIRE Key afterwards
Save
When activated via turning the Jogdial or the ENTER key all internal registers are stored
into an internal EEprom for later usage.
If an Error occurs
If an error occurs during operation the pulse output is switched off, the “pulser_ok_ext”
signal on the BOB connector is pulled low and a message is displayed on the PLB-21. If
no other action is described on the display, a toggle of the ENABLE pin resets the error
condition and re- enables the driver.
Controlling the Driver via a PC
Introduction
When the driver is connected to a PC, it allows communications over a serial text interface
as well as the PicoLAS protocol. While the text interface is designed for communication
with a terminal program, the PicoLAS protocol is designed as a system interact protocol.

16
The switching between the two protocols occurs automatically as soon as the driver
receives a certain sequence. The corresponding commands are:
•PING for the PicoLAS protocol
•“init” followed by <Enter> for the text interface
Description of the RS-232 Interface
The driver implements a standard RS-232 interface. It can be connected to a PC using a
three-wire connection. For USB connection you need a USB RS-232 adaptor (USB-serial
adapter).
The connection settings are:
Baud rate
115200
Data bits
8
Stop bits
1
Parity
even

17
The Serial Text Interface
The following section describes the structure and the commands of the text interface.
Structure
Every command that is sent to the driver must be completed with a CR (Carriage Return =
Enter). It consists of a command word followed by one or more parameters. If the
command has been executed successfully a “00” is sent, otherwise a “01”. If there is an
error pending, the response will be “10”, otherwise “11”. If the command requires an
answer parameter, this parameter is sent before the confirmation is given.
Exampe1:
The user would like to read out the actual setpoint current:
User input: gcur<Enter>
Output of the driver: 12.2<CR><LF>
00<CR><LF>
Example 2:
The user would like to set a new setpoint current:
User input: scur 25.7<Enter>
Output of the driver: 25.7<CR><LF>
00<CR><LF>
Input is done in ASCII code and is case sensitive. Every terminal can be used which
supports this standard.

18
Commands for the serial text interface
The following table contains a command reference for the driver.
Command
Parameter
Answer
Description
scur
Current in A
--
Sets the pulse current to the indicated
value. A dot is used as decimal point.
No more then one decimal place is
used! (12.225 is the same as 12.2)
gcur
--
Current in A
Outputs the present output current
gcurmin
--
Current in A
Outputs the minimum output current
gcurmax
--
Current in A
Outputs the maximum output current
scurlimit
Current in A
Current in A
Sets the current limiter to the given
value in A. A dot is used as decimal
point. No more then one decimal place
is used! (12.225 is the same as 12.2)
gcurlimit
--
Current in A
Outputs the actual current limiter value
gcurlimitmin
--
Current in A
Outputs the minimum current limiter
value
gcurlimitmax
--
Current in A
Outputs the maximum current limiter
value
cur_ext
--
--
Use external current setpoint
cur_int
--
--
Use internal current setpoint
slstat
32 bit number
--
Sets the LSTAT register to the value
glstat
--
32 bit number
Outputs the LSTAT register
gserial
--
serial number
Returns the device serial number
gname
--
device name
Returns the devices internal name
ghwver
--
hardware version
Prints out the hardware version
gswver
--
software version
Prints out the software version
ps
--
current settings
Prints out an overview of all settings
loaddefault
--
--
Loads previously saved settings
savedefault
--
--
Saves the current settings as defaults
enautoload
--
--
Enables the autoload feature
disautoload
--
--
Disables the autoload feature
gtemp1
--
Temperature in
°C
Returns the temperature of sensor 1
gtemp2
--
Temperature in
°C
Returns the temperature of sensor 1
gtemp3
--
Temp. in °C
Returns the temperature of sensor 1
gtempoff
--
Temperature in
°C
Returns the temperature at which the
device will shut down

19
If an Error Occurs
If an error occurs during operation the driver output is switched off and the return value of
a command is no longer “00” or “01” but “10” or “11”. Errors have to be acknowledged
with a toggle of the ENABLE signal (switch off and on again), otherwise switching on
again of the LDP-CW output is not possible. For more details see the description of the
ERROR register.
To retrieve the error, use the gerr command for the content of the ERROR register or the
gerrtxt command for a human readable form.
Command
Parameter
Answer
Description
gtemphys
--
Temperature in
°C
Returns the temperature at which the
device will restart after thermal
shutdown
gtempwrn
--
Temperature in
°C
Returns the temperature at which the
device will warn about reaching its
thermal limit
gadcidiode
Current in [A]
gadcudiode
--
Voltage in [V]
Returns the actual measured
compliance voltage
gadcuin
--
Voltage in [V]
Returns the actual measured supply
voltage
gadcvcap
--
Voltage in [V]
Returns the actual measured capacitor
voltage
gadcvds
--
Voltage in [V]
Returns the actual measured voltage
drop over the linear stage

20
The PicoLAS Protocol
The following section describes the structure and valuable commands of the PicoLAS
protocol.
Structure
Each transmission consists of 12 bytes –called a frame in the following –that must be
sent consecutively. Otherwise the system times out and the transmission must start again
from the beginning.
A frame has a fixed structure. The first two bytes describe the command, the following
eight bytes the parameters, followed by one reserved byte and one checksum byte. The
checksum is calculated out of the first 11 bytes that are linked by a bitwise XOR.
Thus a frame has the following structure:
Byte
Meaning
1
Bit 8-15 of the command
2
Bit 0-7 of the command
3
Bit 56-63 of the parameter
4
Bit 48-55 of the parameter
5
Bit 40-47 of the parameter
6
Bit 32-39 of the parameter
7
Bit 24-31 of the parameter
8
Bit 16-23 of the parameter
9
Bit 8-15 of the parameter
10
Bit 0-7 of the parameter
11
Reserved, always 0x00
12
Checksum
A properly received frame must be acknowledged by the recipient with an answer that is
also a frame. If the acknowledgement does not occur the command has not been processed
and the sending procedure should be repeated.
If the recipient recognizes the command as valid, but not the parameters, it will answer
with an ILGLPARAM (0xFF12) as command.
In the case the recipient receives an invalid command it will answer with UNCOM
(0xFF13).
If a faulty checksum is recognized, the answer is RXERROR (0xFF10). If this error occurs
often, the connection should be checked.
Using the REPEAT (0xFF11) command the recipient can instruct the sender to send the
most recent frame again.