User Manual - Schulz Electronic GmbH
Contents
1. Pic LAS FOCUSSING POWER TO THE POINT Command s for the driver The following table contains a list of the commands which the LDP CW supports in addition to the generally applicable commands An explanation of the individual commands and its parameters follows afterwards Command Sent Frame Received Frame Command Parameter Command Parameter GETTEMPOFF 0x0001 0 0x0050 64 bit value GETTEMPACT 0x0002 0 0x0050 64 bit value SETTEMPOFF 0x0003 40 80 C 0x0050 64 bit value GETCUR 0x0010 0 0x0051 64 bit value SETCUR 0x0011 Refer to description 0x0051 64 bit value GETOCUR 0x0012 0 0x0051 64 bit value SETOCUR 0x0013 Refer to description 0x0051 64 bit value GETSIMMER 0x0014 0 0x0059 64 bit value SETSIMMER 0x0015 Refer to description 0x0059 64 bit value GETMESSSIGNALS 0x0017 0 0x005C 64 bit value GETLSTAT 0x0020 0 0x0052 32 bit value GETERROR 0x0021 0 0x0055 32 bit value GETREGS 0x0022 0 0x0057 64 bit value SETLSTAT 0x0023 Refer to description 0x0052 32 bit value SAVEDEFAULTS 0x0027 0 0x005E 0 LOADDEFAULTS 0x0028 0 0x005E 0 GETPREV 0x0029 0 0x005F 32 bit value GETSOFTSTEP 0x003A 0 0x005B 32 bit value SETSOFTSTEP 0x003B Refer to description 0x005B 32 bit value The following table contains additional commands which apply only to the LDP C variants Command Sent Frame Received Frame Command Parameter Comman2. DOWER Pic LAS User Manual LDP C CW 120 80 20 40 PicoLAS GmbH Company for Innovative Power Electronics und Laser Technology Kaiserstra e 100 52134 Herzogenrath Schulz W Electronic Tel 49 0 2407 563 58 0 Schulz Electronic GmbH B Dr Rudolf Eberle Stra e 2 Fax 49 0 2407 563 58 29 D 76534 Baden Baden A E Fon 49 7223 9636 30 E Mail infoGpicolas de Fax 49 7223 9536 90 27 vertrieb schulz electronic de Web www picolas de kk ctronic de Pic LAS FOCUSSING POWER TO THE POINT Table of Contents Table of Contents nase n taat ben M qu es uam ede pue umi dus nude 2 Description of Connections and Jumpers enmennmennmennnennnenennnennennennnn nenn 3 interface Specifications eier legte gu Vase haa k 4 Timing DIagram zer T MEE 6 DOS and DON sr Em 8 Functional Description e ie ettet erint hence ceu ee le UAE E 9 I sKom MEE 10 Power Suppl yisi MTS 10 Rolo Ne ta cance eg AE EEE a 10 Over Temperature Shutdown eere erre e rn enr n nennen nnns 11 s it Stat ae Mt M i 11 Mechanical Dimensions utei otto teen ense patate queden 11 Power ON SEI test unseren ee een 12 Controlling the AVE itaalia ttt ana een 13 Trigger Modes a 4 42 28 a ern A Heer 13 Controlling the LDP C 120 20 using a PLB 21 ssssssssssssss eee 15 Controlling the EDP C 120 20 via USB ict etr tee pde dde tex dens 18 Register description i ote nee ee
3. the value can be modified by the user When using the external setpoint the value shown is measured value supplied at Pin 10 of the BOB connector The display is updated every few seconds so it is not accurate when using analogue modulation Simmer A Simmer current is not available with a LDP C series when using trigger modes internal or external Trigger The LDP C supports various trigger modes These are selected in this Submenu Trigger Possible values are internal external and cw Please note that any change disables the output Edge This value defines the speed of the rising edge Possible ranges from 0 to 255 The smaller the value is the smaller is the rise time It is not used in CW mode Config The LDP C has some additional safety features which can be user enabled This is done within this Submenu Occur not in HW version 1 2 Using the F1 key an additional over current protection can be enabled If enabled the LDP C disables automatically if the output current rises below the given maximum value The display shows the actual value and it can be modified using the jogdial If disabled the display will just read disabled Scut If enabled the LDP C disables automatically if a shortcut on the output clamps during operation is detected Please note that this feature will not operate properly when the setpoint current is modulated or a compliance voltage below 1 volt is used Noload If enabled
4. 21 is connected the first time to the driver the user is asked to download a new driver This must be confirmed with yes for working the PLB 21 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 Pulseparameter o Width o Reprate o Cur int ext o Simmer Trigger o Mode o Edge Config o Occur not in HW version 1 2 o Scut o Noload o SStart Defaults o Def pwron o Load defaults o Save defaults Temperature o BDev Off o Temp 1 o Temp2 o Temp 3 Measurement o Uin o Udiode o IDiode 15 Pic LAS FOCUSSING POWER TO THE POINT Pulseparameter In this menu point can be modified the setpoint current and simmer current See the device specific datasheet for detailed information Width This value defines the width of the pulses generated by the internal pulse generator if the internal trigger is used It is measured in steps of 0 1us Reprate This value defines the repetition rate of the pulses generated by the internal pulse generator if the internal trigger is used It is measured in steps of 1 Hz Cur int ext This value defines the setpoint current It can be switched between internal int and external ext setpoint by pressing the F1 key When using the internal setpoint
5. chapters Soft start and Timing Diagram for more details LDP C The LDP C series can be configured by the user for internal external or CW trigger CW When the CW mode is configured the LDP C behaves like the LDP CW series See above for more details 13 Pic LAS FOCUSSING POWER TO THE POINT External The output stage is controlled by the PULSE signal Like the CW mode the current regulator is controlled by the ENABLE signal and L_ON bit but the output stage is controlled separately Hence the user can enable the internal current flow but wait for the soft start to be finished before enabling the output stage This will lead to a very low rise time compared to the soft start The actual rise time can be configured using the digital control Please see the chapters Soft start and Timing Diagram for more details Internal The output stage is controlled by an internal pulse generator which can be enabled disabled using the L_ON bit in the LSTAT register The PULS input is not used The values for pulse width and repetition rate can be configured via USB or the PLB 21 Please see the chapters Soft start and Timing Diagram for more details 14 Pic LAS FOCUSSING POWER TO THE POINT Controlling the driver using a PLB 21 To control the driver with a PLB 21 it must be connected via the enclosed cable The PLB 21 will not work if the USB and the PLB 21 are connected at the same time When the PLB
6. ernennen 29 Pic LAS FOCUSSING POWER TO THE POINT Description of Connections and Jumpers The following drawing shows all connections which are available to the user O O PLB 0o 1S UO m di OO S Mini USB type B LD J V F in N LD C GND ib 6 NA BOB connector edgewise LDP C BOB See section interface specifications for detailed information Break out board Connector connector PLB Connector for PLB 21 protected against polarity reversal Vin Supply voltage 5 24V GND Supply ground LD Positive laser diode output anode Use both connectors parallel for high currents LD Negative laser diode output cathode Do not connect to ground Use both connectors parallel for high currents Mini USB Mini USB connector for connecting the driver with a computer For a more convenient use of the driver e g in laboratory use we recommend the optional available product accessory LDP C BOB Please see LDP C BOB manual for further details Pic LAS FOCUSSING POWER TO THE POINT Interface Specification The following figure shows the input and output signals of the external analogue BOB connector enable 10 Control 8 BOB pulse gt Connector 6 5 i 10K 100pF 5V GND 4 3 4K7 4700 L ulser_ok 2 1 470R 100pF Functional Description of BO
7. is the updated repetition rate GETEDGE The return value contains the actual value of the SETEDGE This command sets 28 PICeLAS FOCUSSING POWER TO THE POINT Register description Description of the LSTAT Register The following list contains a description of the individual LSTAT bits These can be read with GETLSTAT and written with SETLSTAT With SETLSTAT a complete 32 bit word must always be written Thus to change individual bits first the register must be read out with GETLSTAT then the desired bits changed and then with SETLSTAT passed again to the LDP CW Bit Name Read Write Meaning 0 L ON Read write Switch on off the pulse output Note that this bit is automatically set high every time the driver is powered on 1 2 TRG MODE Read Write Trigger mode O external pulse input 1 internal pulse generator 2 CW mode In case of a LDP CW this is always read 2 3 ISOLL EXT Read Write When 1 the external setpoint current is used 4 INIT COMPLETE Read The power on test is performed successfully 5 PULSER OK Read Indicates that the driver is in no error condition 6 ENABLE OK Read Indicates that the external enable is given 7 SHORTCUT CHECK Read Write When 1 the driver will check for an shortcut on the output clamps during operation 8 NOLOAD CHECK Read Write When 1 the driver will check for open output clamps during operation 9 OVERCURRENT CHECK Rea
8. runtime measurement information Uin This shows the measured value of the supply voltage Udiode This shows the measured value of the compliance voltage of the connected load The output must be enabled for a correct result Please note that this is not a real time measurement If the Setpoint is modulated the display may show incorrect values In that case use the signal of the analogue current monitor at pin 9 on the BOB connector with appropriate measurement equipment Idiode This shows the measured value of the current flow through the connected load f 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 17 Pic LAS FOCUSSING POWER TO THE POINT Controlling the driver via USB Introduction In addition to the PLB 21 the driver also has a USB interface to communicate with a computer laptop This interface allows communications over a serial text interface as well as using 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 The switching between the two protocols occurs automatically as soon as the driver receives a certain sequence The corres
9. AILED Read Self test failed 23 Reserved Read Reserved 31 30 Pic LAS FOCUSSING POWER TO THE POINT 31
10. B Connector Interface Pic LAS FOCUSSING POWER TO THE POINT Isetpoint This input signal is used to provide an analogue setpoint value In order to use the analogue setpoint this must be configured via USB or PLB Please see the device specific datasheet for the scaling Idiode This signal is used as an output of the internal current shunt It provides near real time measurement of the output current Please see the device specific datasheet for the scaling Master Enable MEN The Master Enable provides a safety interlock which disables the driver when pulled low This signal must be pulled high by the user for the driver to start up If the signal is low when the driver is powered on it will not work properly It is recommended that the user also disables the ENABLE after disabling MEN Otherwise the will be a current overshoot on the connected load When no safety interlock is needed this signal can be connected to pin 2 of the BOB connector Enable The ENABLE signal enables disables the driver during normal operation The ENABLE signal must be pulled low by the user in order for the driver to start up If the signal is high when the driver is powered on it will not work properly After the user applies the ENABLE signal the internal current regulator ramps the current flow to the configured setpoint in a configured amount of time soft start Pulse This signal is only used by the LDP C It provides fast access to the output sta
11. GETSOFTSTEPS command see above GETPULSEWIDTHMINMAX The return value contains the minimum and maximum pulse width of the internal pulse generator combined in a single 64bit value The data format is bit meaning format 0 31 minimum width O 1us unsigned int32 32 63 maximum width 0 1us unsigned int32 GETPULSEWIDTH The return value contains the actual pulse width of the internal pulse generator in steps of 0 1us SETPULSEWIDTH 27 Pic LAS FOCUSSING POWER TO THE POINT This command sets the pulse width of the internal pulse generator to the given value in steps of 0 1A The value must be within the borders defined by the minimum and maximum values given by the GETPULSEWIDTHMINMAX command The return value is the updated pulse width GETREPRATEWIDTHMINMAX The return value contains the minimum and maximum repetition rate of the internal pulse generator combined in a single 64bit value The data format is bit meaning format 0 31 minimum reprate Hz unsigned int32 32 63 maximum reprate Hz unsigned int32 GETREPRATE The return value contains the actual repetition rate of the internal pulse generator in steps of 0 1us SETREPRATE This command sets the repetition rate of the internal pulse generator to the given value in Hz The value must be within the borders defined by the minimum and maximum values given by the GETREPRATEMINMAX command The return value
12. ation over output current 10 Pic LAS FOCUSSING POWER TO THE POINT Over Temperature Shutdown To protect the Laser Diode and the driver itself the pulser automatically disables itself if its temperature rises above the configured shutdown temperature This condition is latched and the pulser will not start working until temperature drops five degrees below the shutdown temperature and the ENABLE pin is toggled During the over temperature shutdown the PULSER_OK output Pin 1 of the BOB Connector is pulled low The shutdown temperature can be modified using a PLB 21 or via the USB connector Soft Start The driver implements a soft start mechanism which is activated every time the output is enabled via the ENABLE pin or the L_ON bit in the LSTAT register This mechanism ramps up the current output from zero the setpoint in a configurable amount of time Mechanical Dimensions Over all height 69 0 mm All dimensions in mm Oberseite 11 Pic LAS FOCUSSING POWER TO THE POINT Power on self test Each time the driver is powered up it performs a test of its internal safety features The MEN pin has to be HIGH while the ENABLE pin has to be LOW for the self test to work properly Changing either of the signals during the self test will result in a failure The driver cannot be enabled until a self test is performed successfully The PULSER_OK signal will be pu
13. command returns the value of the ERROR register For a complete description of this register see below 26 PICeLAS FOCUSSING POWER TO THE POINT GETREGS This command returns the value of the LSTAT and ERROR register combined in a single 64bit value The lower 32bit represents the LSTAT register the upper 32bit the ERROR register SETLSTAT This command sets the LSTAT register to the given value The return value contains the new register value SAVEDEFAULTS This command saves all settings to an internal EEProm LOADDEFAULTS This command loads previously saved settings into the driver SETPREV This command returns the version of the current regulator parameters The data format is bit meaning format 0 15 revision minor unsigned int16 16 30 revision major unsigned int16 31 63 reserved GETSOFTSTEPS The return value contains the minimum maximum and actual soft start delay in steps of 166us The data format is bit meaning format 0 15 maximum current 166us unsigned int16 16 30 minimum current 166us unsigned int16 31 47 setpoint current 166us unsigned int16 48 63 reserved SETSOFTSTEPS This command sets the soft start delay to the given value in steps of 166us The value must be within the borders defined by the minimum and maximum values given by the GE7SOFTSTEPS command The return value contains the same data as in the
14. d Parameter GETPULSEWIDTHMINMAX 0x0030 0 0x0053 64 bit value GETPULSEWIDTH 0x0031 0 0x0053 32 bit value SETPULSEWIDTH 0x0032 32 bit value 0x0053 32 bit value GETREPRATEMINMAX 0x0033 0 0x0054 64 bit value GETREPRATE 0x0034 0 0x0054 32 bit value SETREPRATE 0x0035 32 bit value 0x0054 32 bit value GETEDGE 0x0036 0 0x0058 8 bit value SETEDGE 0x0037 8 bit value 0x0058 8 bit value 24 Pic LAS FOCUSSING POWER TO THE POINT Description of the Individual Commands GETTEMPOFF The return value contains the average temperature as well as the individual values of all tree temperature sensors The data format is bit meaning format 0 15 average temperature C signed int16 16 30 temperature sensor 1 C signed int16 31 47 temperature sensor 2 C signed int16 48 63 temperature sensor 3 C signed int16 GETTEMPACT The return value contains the warning and cool down hysteresis values as well as the maximum minimum and current value of the shutdown temperature The values for warning and hysteresis are subtracted from the shutdown value to calculate the actual borders The data format is bit meaning format 0 7 warning threshold C signed int8 8 15 hysteresis threshold C signed int8 16 30 maximum shutdown temperature C signed int16 31 47 minimum shutdown temperature C signed int16 48 63 actual shutdown tem
15. d Write When 1 the driver will check for an over current on the connected load during operation 10 CW ONLY Read Indicates that only CW operation is possible TRG MODE 2 11 MEN Read Indicates that the MEN is given 12 DEFAULT ON PWRON Read Write When 1 the driver will load the default values at each power up 13 31 Reserved Read Reserved 29 Pic LAS FOCUSSING POWER TO THE POINT Description of the ERROR Register The following list contains a description of the individual bits of the ERROR register A 1 as a bit leads to a deactivation of the drivers output Bit 3 is excluded of this directive as it is just a warning The Bits 1 6 and 10 12 are cleared every time the ENABLE pin is set low All other bits are cleared by toggling the main power If any self test related error condition persists a hardware failure is possible The bit 20 indicates that the ENABLE pin was set high during power on It must remain low until the pulser_ok_ext signal or the related bit in the LSTAT register is set high The bit 21 indicates that the MEN pin was set low during power on Is must set high during power on Otherwise the self test will fail Bit Name R W Meaning O TEMP SENSOR FAIL Read One or more temperature sensors failed 1 TEMP OVERSTEPPED Read Maximum temperature overstepped 2 TEMP HYSTERESIS Read Devic
16. e is cooling down Temperature needs to drop below maximum 10 3 TEMP WARN Read Device temperature 5 before shutdown 4 LOAD SHORT Read Shortcut on the output clamps detected 5 LOAD NONE Read No connected load detected 6 OVERCURRENT Read Maximum current overstepped 7 PHASE UNCAL Read Device is not properly calibrated Please contact your distributor 8 SHUT UNCAL Read Device is not properly calibrated Please contact your distributor 9 I2C FAIL Read Internal communication error Please contact your distributor 10 VCC LOW Read Supply voltage below minimum 11 VCC HIGH Read Supply voltage above maximum 12 VCC DROP Read Supply voltage drops during operation 13 CROWBAR ALWAYS OPEN Read Indicates a defect crowbar Please contact your distributor 14 CROWBAR_ALWAYS_CLOSE Read Indicates a defect crowbar Please contact your distributor 15 HST ALWAYS OPEN Read Indicates a defect safety switch Please contact your distributor 16 HST ALWAYS CLOSE Read Indicates a defect safety switch Please contact your distributor 17 Reserved Read Reserved 18 CFG CHKSUM FAIL Read Indicates an incorrect configuration Please contact your distributor 19 AUTO IOFFSET FAIL Read Indicates an internal error Please contact your distributor 20 ENABLE DURING POWERUP ENABLED Read Enable was high during power on 21 MEN DURING POWERUP DISABLED Read MEN was low during power on 22 POST F
17. eter is always 0 the answer parameter too IDENT This command is used to determine the device ID of an attached recipient It has no effect on the condition of the recipient The parameter is always 0 The answer contains the ID GETHARDVER Instructs the driver to send back the version number of its hardware The parameter is always 0 The answer contains the hardware version number The format of the answer is 0x000000 lt major gt lt minor gt lt revision gt In other words one byte for each of the three elements of the version number As example version 1 2 3 has the parameter 0x00000001 0203 GETSOFTVER Instructs the driver to send back the version number of its firmware The parameter is always 0 The answer contains the software version of the recipient The format of the answer is 0x000000 lt major gt lt minor gt lt revision gt In other words one byte for each of the three elements of the version number As example version 2 3 4 has the parameter 0x000000020304 GETSERIAL Instructs the driver to send back its serial number If O is sent as parameter the answer contains the number of ASCII digits of the serial number otherwise the respective position of the serial number is sent in ASCII format GETIDSTRING Instructs the driver to send back its name If O is sent as parameter the answer contains the number of digits of the string otherwise the respective position of the serial number is sent in ASCII format 23
18. figurable ta ts rise time 1us depends on the inductance of the connected load to tio t13 t14 te t7 fall time depends on the inductance of the connected load t11 t12 tis te tig t20 t7 tig rise time after depends on the inductance of the MEN toggle connected load Pic LAS FOCUSSING POWER TO THE POINT Dos and Don ts Never ground any lead of the output This can yield an incorrect current regulation Never use any grounded probes at the output This will immediately destroy the driver and the probe Never make a short at the output This will not do any harm to the laser driver but will yield in an incorrect current measurement Keep connection between power supply and the driver as well as the connection between driver and laser diode as short as possible Mount the driver on an appropriate heat sink Pic LAS FOCUSSING POWER TO THE POINT Functional Description The driver operates with three parallel buck converters S1 S2 D1 D2 L1 S3 S4 D3 D4 L2 S5 S6 D5 D6 L3 Every single converter has an independent control loop with a current sensor Imeas1 Imeas2 and Imeas3 The set point current that is pretended by the user is evenly spread over all three converters The current through the laser diode is measured directly at the output pins with a shunt Inductor current additional current of all three phases laser diode current and compliance voltage a
19. ge and can be used to pulse the output current It actual usage depends on the configured trigger mode Please see chapter Trigger modes for more details Pulser ok This signal informs the user about any error condition It is pulled low by the driver when no internal error is detected Udiode This signal is used to determine the compliance voltage of the connected load It provides near real time measurement Please see the device specific datasheet for the scaling setpoint mm meh nde om i SSS a en Ss 6 dim c at cami air Ame an ccc EHE 22 M M A een lec 0 L d i L setpoint ee u pe lint Oe 71 MM 7 77 77 0 J r E RM e PULS i ane 2 A a 2 1 4 10 The following diagram shows the effect of the MEN ENABLE and PULSE input signals to the internal end Pic LAS FOCUSSING POWER TO THE POINT S us on S 8 A B C 25 LM P H H I H H gg pe a en E E to ti t ts ta ts ts t te to ti ta t12 tiatia tistis tir tis tig tap t ETE E T Pic LAS FOCUSSING POWER TO THE POINT meaning min max avg notes to t Power on self test 2 55 14s 4s t2 t3 ENABLE delay 650us 5 5ms t3 tg soft start 166us 4 3ms user con
20. is command sets the over current shutdown current to the given value in steps of 0 1A The value must be within the borders defined by the minimum and maximum current values given by the GETOCUR command The return value contains the same data as in the GETOCUR command see above GETSIMMER The return value contains the minimum maximum and actual setpoint value of the simmer current in steps of 0 1A The data format is bit meaning format 0 15 maximum simmer current 0 14 unsigned int16 16 30 minimum simmer current 0 1A unsigned int16 31 47 actual simmer current 0 1A unsigned int16 48 63 reserved SETSIMMER This command sets the actual simmer current to the given value in steps of 0 1A The value must be within the borders defined by the minimum and maximum simmer current values given by the GETSIMMER command The return value contains the same data as in the GETSIMMER command see above GETMESSSIGNALS The return value contains the measurement values of the input voltage output voltage and output current The data format is bit meaning format 0 15 input voltage 0 1V unsigned int16 16 30 output voltage 0 1V unsigned int16 31 47 output current 0 1A unsigned int16 48 63 reserved GETLSTAT This command returns the value of the LSTAT register For a complete description of this register see below GETERROR This
21. lled high when the test was successful The test will take less than 5 seconds but can take up to 15 seconds due to internal time outs if any failure is detected The following diagram shows the individual tests and the approximate time it will take S Open S Close in Min min and Vin lt Vin max 70us 5 Open S Close Temperature sensors ok 70us Up lt 0 5V and Uc lt 1V TOus So Open PULSER OK z1 S Close PULSER OK 0 Set ERROR bits 140ms 12 Pic LAS FOCUSSING POWER TO THE POINT Controlling the driver The driver can be operated stand alone with a PLB 21 or a PC connected to it via USB It remembers all settings from the last time it was powered on unless it is configured to load default values on power on In this case it loads pre configured settings each time the power is toggled 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 USB is attached only the BOB Connector could be used to control the driver If configured so the pin 10 at the BOB connector lsetpoint can be used to control the setpoint current To enable the output pin7 at the BOB connector ENABLE must be set HIGH If an error occurs e g over temperature the driver will be disabled and the pin 1 of the BOB connector PULSER OK is pulled low The e
22. nable pin has to be toggled to enable the driver again When using the LDP C series the ENABLE pin enables the driver but not the current output Pin6 of BOB connector PULSE directly controls the current output in that case The PULSE input does not trigger a soft start Hence the configured setpoint current applies as fast as possible to the output 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 USB If the driver is connected to a PC using an USB cable all operating parameters can be accessed via a serial RS232 terminal program or the PicoLAS protocol The PLB 21 is automatically disabled if a USB connection is established For a detailed description of the serial text protocol and the PicoLAS protocol see below Trigger Modes LDP CW The LDP CW series has no different trigger modes The PULSE input signal is not used The output stage as well as the current regulator is controlled by the ENABLE signal and the L ON bit in the LSTAT register Every time the output is enabled the driver performs a soft start and ramps up the output current Please see the
23. o longer 0 or 1 but 10 or 11 Errors have to be acknowledged with a toggle of the ENABLE signal otherwise switching on again of pulse output is not possible For more details see the description of the ERROR register To retrieve the error use the gerror command for the content of the ERROR register or the gerrtxt command for a human readable form 21 Pic LAS FOCUSSING POWER TO THE POINT The PicoLAS Protocol The following section describes the structure and possible commands of the PicoLAS protocol Structure Each transmission consists of 12 bytes called a frame as follows which 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 which 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 mus
24. perature C signed int16 SETTEMPOFF This command sets the over temperature shutdown temperature to the given value The value must be within the borders defined by the minimum and maximum temperature values given by the GETTEMPACT command The return value contains the same data as in the GETTEMPOFF command see above GETCUR The return value contains the minimum maximum and actual setpoint value in steps of 0 1A The data format is bit meaning format 0 15 maximum current 0 1A unsigned int16 16 30 minimum current 0 1A unsigned int16 31 47 setpoint current 0 1A unsigned int16 48 63 reserved SETCUR This command sets the current setpoint to the given value in steps of 0 1A The value must be within the borders defined by the minimum and maximum current values given by the GETCUR command The return value contains the same data as in the GETCUR command see above 25 Pic LAS FOCUSSING POWER TO THE POINT GETOCUR The return value contains the minimum maximum and actual over current shutdown value in steps of 0 1A Please note that this feature must be enabled in the LSTAT register The data format is bit meaning format 0 15 maximum current 0 1A unsigned int16 16 30 minimum current 0 1A unsigned int16 31 47 shutdown current 0 1A unsigned int16 48 63 reserved SETOCUR Th
25. ponding commands are e PING for the PicoLAS protocol e init followed by Enter for the text interface If the LDP C 120 20 and the USB interface are both connected at the same time then only the USB interface can be used As soon as the USB connection is connected to a computer then the LDP C 120 20 switches automatically over to this Description of the USB Interface The USB connection of the driver emulates a virtual COM port under Windows The necessary drivers can be downloaded free of charge under http www ftdichip com Drivers VCP htm or they are already included in the current Linux kernels The virtual COM port created by this can be addressed like a regular one The connection settings are Baud rate 115200 Data bits 8 Stop bits 1 Parity even 18 Pic LAS FOCUSSING POWER TO THE POINT The Serial Text Interface The following section describes the structure and commands of the text interface Structure Every command that is sent to the drivermust be completed with a CR Enter It consists of a command word followed by a parameter If the command was successfully executed a 0 is sent otherwise a 1 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 Example The user would like to read out the actual setpoint current User input gcurrent lt Enter g
26. re pre processed and then lead to the external BOB connector An enable input as well as a status output are available Several security features protect the laser diode and driver from damage D8 protects the laser diode from reverse currents S7 could short the output pins and the bypass diode D7 protects the driver in case of a load failure To protect the laser diode during start up of the driver S0 remains opened until the supply voltage has reached a stable level In case of a failure the control unit disables the driver A soft start mechanism slowly rises the current after an over temperature shutdown or at start up GND Operation Principle of LDP C 120 20 driver Element Function SO Security Switch C1 S1 S2 S3 S4 S5 S6 D1 Buck Converter D2 D3 D4 D5 D6 L1 L2 L3 co Input Buffer Capacitor 57 Shunt Mosfets Short Output D7 D8 Laser diode and driver protection diodes Shunt LD current monitor Pic LAS FOCUSSING POWER TO THE POINT Test Load A common method to test the driver is to connect a regular silicon rectifier diode to the driver output Here has to be paid attention 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 rec
27. t 32 bit number Outputs the LSTAT register gerror 32 bit number Outputs the ERROR register gerrtxt error text description of every pending error stempoff Temperature in C Changes the shutdown temperature to the passed value gtempoff Temperature in C Outputs the current shutdown temperature gtempoffmin Temperature in C Outputs the minimum shutdown temperature gtempoffmax Temperature in C Outputs the maximum shutdown temperature curext use external current setpoint curint use internal current setpoint gserial serial number Returns the device serial number ps current settings Prints out an overview of all settings loaddefault loads previously saved settings savedefault saves the current settings as defaults ghwver hardware version prints out the hardware version gswver software version prints out the software version gpver parameter version prints out the parameter version shortcut 1 0 1 Enables the shortcut protection 0 Disables the shortcut protection overcurrent 1 0 1 Enables the over current protection 0 Disables the over current protection noload 1 0 1 Automatically disabled the output if no load is detected see text for more details 0 Leave the driver enabled if load fails ssoftstart 32 bit number 32 bit number sets the soft start time to the given number multiplied by 166us gsoftstart 32 bit n
28. t Output of the LDP CW 12 2 lt CR gt lt LF gt O lt CR gt lt LF gt Example 2 The user would like to set a new setpoint current User input scurrent 25 7 lt Enter gt Output of the LDP CW 25 7 lt CR gt lt LF gt O lt CR gt lt LF gt Input is done in ASCII code and is case sensitive Every terminal can be used that supports this standard Commands for the LDP C CW The following table contains a command reference for the LDP CW series These commands are also implemented in the LDP C series Command Parameter Answer Description scurrent Current in A Sets the pulse current to the indicated value A dot is used as decimal point No more then on decimal place is used 12 22 is the same as 12 2 gcurrent Current in A Outputs the present output current gcurrentmin Current in A Outputs the minimum output current gcurrentmax Current in A Outputs the maximum output current gsimmermin Current in A Outputs the minimum simmer current gsimmermax Current in A Outputs the maximum simmer current Ssimmer Current in A Sets the output current to the indicated value gsimmer Current in A Outputs the present simmer current 19 Pic LAS FOCUSSING POWER TO THE POINT Command Parameter Answer Description lon Activates the output loff Deactivates the output slstat 32 bit number Sets the LSTAT register to the value glsta
29. t be acknowledged by the recipient with an answer which is also a frame If the acknowledgement does not occur then 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 then it will answer with a ILGLPARAM OxFF12 as command In the case that the recipient receives an invalid command it will answer with UNCOM OxFF13 If a faulty checksum is recognized then the answer is RXERROR OxFF10 If this error occurs often then the connection should be checked Using the REPEAT OxFF11 command the recipient can instruct the sender to send the most recent frame again 22 PICeLAS FOCUSSING POWER TO THE POINT General Commands The following list contains an overview of the general commands which are supported by every product from PicoLAS which makes use of this protocol The explanation of the individual commands is given further below Command Name Sent Frame Answer Frame Command Parameter Command Parameter PING OxFEO1 0 OxFFO1 0 IDENT OxFEO2 0 OxFF02 ID GETHARDVER OxFEO6 0 OxFFO6 Version GETSOFTVER OxFEO7 0 OxFFO7 Version GETSERIAL OxFEO8 0 20 OxFFO8 Refer to description GETIDSTRING OxFEO9 0 20 OxFFO9 Refer to description PING This command is used to determine the presence of a connected driver and to initialize its interface It does not change any registers The command param
30. the LDP C disables automatically if the load has been disconnected during operation Please note that this feature will not operate properly if the setpoint current is modulated SStart The value shown here is the time span in which the LDP C raises its output current to the given setpoint when enabled 16 Pic LAS FOCUSSING POWER TO THE POINT Config 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 Temperature The LDP C 120 20 is equipped with several temperature sensors In this submenu the actual and shutdown temperatures can be read and modified All values are in C Dev Off This shows the user defined shutdown temperature If the LDP C 120 20 reaches this temperature during operation the output will be disabled and an error message is displayed It can be modified within 40 80 C Temp 1 3 This shows the actual temperatures measured by the sensors of the LDP C 120 20 Measurement This submenu holds some
31. tifier 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 To obtain a good pulsing performance with the driver it requires an appropriate power supply PSU The PSU has to supply the power which is delivered to the laser diode and also the losses in the driver itself Besides this the laser diode power varies strongly when the output current is modulated Although the driver is equipped with a large input capacitance of 12 mF to buffer these power peaks the power supply has to deliver the required power fast enough to avoid input voltage drops For excessive modulation of the output current the PSU output impedance as well as the line impedance between PSU und pulser has to be as low as possible When the input voltage drops below 11 5 V the driver shuts down automatically To remove this condition the enable line has to be toggled Cooling The driver produces up to 130 W of losses Thus the base plate has to be mounted on a heat sink to ensure proper operation and prevent an over temperature shutdown If working with high currents above 90 A it is recommended to cool the power inductors as well This can be achieved easily by placing the pulser with its heat sink in the air flow of a fan W P loss 20 40 60 80 100 120 I out A e power dissipation Power dissip
32. umber returns the current soft start time in steps of 166us 20 Pic LAS FOCUSSING POWER TO THE POINT The following table contains all commands for the LDP C 120 20 series These are not implemented within the LDP CW 120 20 Command Parameter Answer Description spulse pulse width in us pulse width in us Sets the pulse width to the indicated value A dot is used as decimal point No more then on decimal place is used gpulse pulse width in us Outputs the present pulse width gpulsemin pulse width in us Outputs the minimum pulse width gpulsemax pulse width in us Outputs the maximum pulse width sreprate repetition rate in Hz repetition rate in Hz Sets the repetition rate to the indicated value greprate repetition rate in Hz Outputs the present repetition rate grepratemin repetition rate in Hz Outputs the min repetition rate grepratemax repetition rate in Hz Outputs the max repetition rate strgmode 0 2 0 2 P the trigger mode to the indicated value 0 external trigger input 1 internal trigger 2 CW mode gtrgmode 0 2 Outputs the current trigger mode sedge 0 255 0 255 modifies the rise time of the leading edge smaller is faster gedge 0 255 Outputs the current rise time Ifan Error Occurs If an error occurs during operation the pulse output is switched off and the return value of a command is n
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