PICOLAS LDP-V 03-100 V4.0 User manual

1
User
Manual
PicoLAS GmbH
Burgstr. 2
52146 Würselen
Germany
Phone: [phone]
Fax: [phone]
E-mail: [email protected]
Web: www.picolas.de
Rev. 1910
LDP
-
V 0
3
-
10
0
V4.0

2
Table of Contents
Product Overview..........................................................Fehler! Textmarke nicht definiert.
Important Information ...........................................................................................................4
How to get started..................................................................................................................5
How to connect the LDP-V 03-100.......................................................................................6
Operating Range Diagram.....................................................................................................7
Maximum Duty Cycle vs. Output Current ............................................................................8
Current Droop vs. Pulse Duration .........................................................................................8
Typical Performance of the LDP-V.......................................................................................8
Internal Structure of the LDP-V............................................................................................9
How to use the internal HV-DC Supply..............................................................................10
Pulse Output ........................................................................................................................10
Trigger Input........................................................................................................................10
Trigger Output Monitor.......................................................................................................11
Absolute maximum Ratings ................................................................................................12
Mechanical Details of the Baseplate ...................................................................................12

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4
Important Information
With respect to version 4.0, we performed the following changes compared with the versions
3.3 or older:
1) There is no option to provide an external HV-DC voltage to the board. Pin 2 of the
main pin header is out of function. Please use the internal HV; it is powerful enough
for all parameters.
2) The trigger signal can only be provided via the SMC connector. Pin 6 of the pin
header has got no connection. If you use a PLCS-21 due to the very high speed
signals, you will need a SMC-SMC cable. This will be shipped free of charge upon
request (one for each PLCS-21).
3) The maximum internal high voltage is reduced to be max. 80 V. If the voltage is
displayed with a PLCS-21 via a PLB-21 operation unit or a PC interface it will show
100 V at a real internal setting of 80 V. Please interpret this is as 100 % and scale all
values accordingly. This is done to keep a backward compatibility to all previously
delivered PLCS-21 devices. The max. current of 3 A will be achieved below 75 V.

5
How to get started
Step What to do Check
1 Unpack your device.
2 Make a short at the output.
3 Turn the high voltage to the lowest value
(turn poti fully counterclockwise).
4 Connect a pulse source with the desired
pulse width to the selected triggering
input.
E.g. 100 ns, 100 Hz reprate.
5 Connect your scope. Select 50 Ohm termination, trig on
neg. falling edge, 200 mV/div.
6 Apply the supply voltage.
Security advice: Do not touch any leads
of the output or the output capacitors as
they are connected to a high voltage of up
to 100 V.
Connect a 15 .. 24 V DC power
supply to the pin header. See page
5 for details.
Note: Some supplies have a
voltage overshoot during turn
on/turn off. This may damage the
device.
7 Adjust the value of the desired pulse
current (turn the poti clockwise until the
current reaches the desired level).
8 Disconnect the supply, remove the short at
the output and assemble the laser diode
(polarity!).
9 Reconnect the supply and check the
optical output of your laser diode.
Note: The actual current is always
some percent lower than the value
of step 7. Adjust the current with
help of the poti.
Do not use PLCS-21 with a higher supply voltage than 15 V. If you use the PLCS-21 with
higher voltage than 15 V the device will be damaged.

6
How to connect t e LDP-V 03-100
Connections via Pin header:
Pin Name Description
1 GND Ground return
2 Currently not
used Do not use
3 GND Ground return
4 +15 V Supply voltage, connect to a power supply
5* Disable_Poti Disables the internal HV setpoint poti when set high
6 Pulse_In Trigger input into 50 Ohm
7 Disable Not connected
8* U-Monitor High voltage monitor output (scale: 40 mV/V) for supervising
the actual high voltage
9 NTC Internal 10 kOhm NTC versus GND for temperature
monitoring (B-value: 3620)
10* Currently not
used Do not use
Trigger Input:
The trigger input requires a signal level of 5 V and is terminated with 50 Ohm.
Current Monitor Output:
The current monitor output has a scale of 2 A/V with a negative signal output. It has a
source impedance of 50 Ohm and must be terminated with 50 Ohm to achieve the correct
scale.
Rogowski coil
Laser diode
connection
Current monitor output
into 50 Ohm
Poti to adjust value of
HV-DC
Pin 10
Pin header
Pin 2
Trigger input SMC

7
Laser Diode Connection:
The laser diode can either be connected via the mounting holes on the top side of the
pulser (inner hole: anode, outer hole: cathode) or at the rectangular pads on top (anode)
and bottom (cathode) of the pulser.
Security Advice: Do not touch any leads of the output or the output capacitors as they are
connected to a high voltage of up to 100 V.
Do not use PLCS-21 with higher supply voltage than 15 V. If you use the PLCS-21 with
higher voltage than15 V, the device will be damaged.
Operating Range Diagram
LDP-V 03-100: Max. reprate vs. pulse width (internal HV, with cooling)
1
10
100
1.000
10.000
0 100 200 300 400 500 600 700 800 900 1000
Pulsewidth in ns
Repetition rate in kHz
0,5 A 1,0 A 1,5 A 2,0 A 2,5 A 3,0 A 3,5 A
LDP-V 03-100: Max. reprate vs. pulse width (internal HV, without cooling)
1
10
100
1.000
10.000
0 100 200 300 400 500 600 700 800 900 1000
Pulsewidth in ns
Repetition rate in kHz
0,5 A 1,0 A 1,5 A 2,0 A 2,5 A 3,0 A 3,5 A

8
Maximum Duty Cycle vs. Output Current
The following tables show the maximum allowable duty cycle depending on a given
output current.
With active cooling of the baseplate:
Output current
in A Typical high voltage in V External displayed HV in V Max. duty cycle with int. HV
0
.
5
12.7
15.9
1.00
1.
0
24
30
0.
40
1.
5
35,3
44.1
0.
18
2.
0
46,6
58.2
0.
10
2.
5
57,9
72.4
0.
06
3.
0
69,2
86.5
0.
04
3.
5
80
100
0.
03
Without cooling of the baseplate:
Output current
in A Typical high voltage in V External displayed HV in V Max. duty cycle with int. HV
0.
5
12.7
15.9
1.00
1.
0
24
30
0.
40
1.
5
35,3
44.1
0.
18
2.
0
46,6
58.2
0.
10
2.
5
57,9
72.4
0.
06
3.
0
69,2
86.5
0.
04
3.
5
80
100
0.
03
Current Droop vs. Pulse Duration
The table below shows the absolute output current droop (in A) versus pulse length. Pulse
durations shorter than one microsecond are not considered as the droop is typically lower
than 1%. Pulse duration in µs
Current in A
1
5
10
0.
3
<1%
<1%
<1%
1
.
0
<1%
<1%
0.
0
12
A
2
.
0
<1%
0.
024
A
0.
056
A
3
.
0
0.
024
A
0.
054
A
0.
088
A
Typical Performance of t e LDP-V
The table below shows the typ. achieved pulse performance using different pulse sources.
Signal source Typ. output rise time
( 0 .. 2 A) Typ. output rise time ( 2 .. 3 A)
Rectangular pulse signal
(<100 ps rise time) 900 ps 1.1 ns
PLCS-21 with SMC-
SMC trigger cable 900 ps 1.8 ns
PLCS-21 on top of the
driver 920 ps 2.7 ns
Low performance signal
generators > 5 ns > 5 ns

9
Internal Structure of t e LDP-V
The LDP-V series generates the pulses by a simple but efficient principle. First, the
storage capacitors (C
S
) are charged, whether through the internal HV-DC supply or an
external high voltage source. When a pulse is applied at the trigger input, the high speed
mosfet opens and the current flows from the capacitor through the laser diode, mosfet and
current sense resistors. At the end of the pulse the mosfet closes again and the current
stops. The generated current depends on the applied high voltage, the laser diode
compliance voltage and its differential resistance.
The following formula gives a good estimation of the laser diode current depending on the
pulser’s high voltage supply U
HV
, the laser diode compliance voltage U
comp
and its
differential resistance R
diff
:
diff
compHV
LD
R
UU
I+
−
≈6.23
The laser diode current is measured with current sensing resistors (current monitor output)
and with the galvanically isolated Rogowski coil. The trigger input provides full control of
the driver’s pulsing capability to the user. The required DC high voltage can either be
applied through an external voltage source or it can be generated with the integrated HV-
DC supply. The internal supply is controlled by the HV setpoint poti. A voltage monitor
(pin 8) provides feedback of the high DC voltage.
The Diode D
RP
prevents the laser diode from reverse currents; a 10kR NTC provides the
possibility to monitor the pulser temperature. An overtemperature protection is NOT
integrated on the driver.
Rogowski-Coil
Rogowski-Coil
Current-Monitor
Trigger SMC
Pin 2: + HV
Pin 4: +15 V
Pin 9: NTC
Pin 6: Trigger
Pin 1,3: GND
15 V
18 .. 90 V
50 R
10K
+HV-Adjust-Poti
Driver
++++
- - - -
LD
Pin 5: Disable Poti
Pin 10: Ext. HV setpoint
Pin 7: Disable
Pin 8: U-Monitor
R
CS
C
S
R
CL
D
RP
50 R

10
How to use t e internal HV-DC Supply
The LDP-V series provides a high power (up to 15 W / 1 A / 80 V) internal high voltage
supply. To adjust the laser diode current to the desired value follow the steps below.
Note: Make sure that the solder junction is done to activate the HV-DC supply.
1. Turn the poti fully counterclockwise
2. Apply the 15 .. 24 V supply voltage
3. Start pulses
4. Measure the diode current
5. Adjust the level of the high voltage supply (hence the level of the current) by
turning the poti clockwise
Security Advice:
Do not touch any leads of the output or the output capacitors as they are connected to a
high voltage of up to 80 V.
Pulse Output
The LDP-V series provides ultra rapid pulse rise and fall times in the region of several
nanoseconds. However, pulse rise and fall depend on the parasitic stray inductance of the
cabling to the laser diode. Direct connection without any kind of wires to the module is
absolutely necessary for best results. For detailed information about the effect of the laser
diode connection on the pulse shape please refer to PicoLAS Application Notes
“Impedance of Diodes” and “LD-Connections”.
Typical pulse rise and fall times of LDP-V 03-100 (scale: 1 A/Div)
Trigger Input
The trigger input, both on the pin header and the SMC jacket, is terminated with 50 Ohm
to ground. The trigger source has to be able to provide a signal level of 5 V with a 50 Ohm
load.

11
< 200 ps
Τ
r
Τ
j
4,5 .. 5,2 V
0 .. 0,2 V
T 1 ns .. 10 µs
puls
Time
Voltage
C
B
A
Trigger signal demands
Notes:
A: Exceeding 0.2 V during pulse pause will cause a non proper turning off and
thermal damage.
B: If the trigger altitude is below 4.5 V the device will not turn on properly and can
not carry the full current. Exceeding 5.2 V can damage the power stage and will
yield in µs-trailing after turn off.
C: To achieve best rise times the rise time of the trigger must be as short as possible.
Shortest pulse durations are guaranteed with rise times below 200 ps. There is no
“Schmitt-Trigger” inside the LDP-V 03-100.
Trigger Output Monitor
The trigger output signal is generated with an integrated, isolated Rogowski coil and
provides an ultra fast galvanically isolated signal. The signal shape is proportional to the
derivative of the load current. It can be used for a current response triggering signal and
has no delay to the load current. Combined with an integrator it is possible to use this
signal for a galvanically isolated current monitor. The isolation barrier is suitable for
voltages up to 100 V and prevents unwanted ground loops.
Signal of the Rogowski coil:
"True" load current
Positive edge at pulse begin
Negative edge at pulse end

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Absolute maximum Ratings
Supply voltage range: 12 .. 26 V
Max. output current U-monitor, NTC: 1 mA
Input voltage range Disable_Poti: 0 .. 5 V
Input voltage range trigger input, disable: 0 .. 15 V
Security Advice:
Do not touch any leads of the output or the output capacitors as they are connected to a
high voltage of up to 80 V.
Mec anical Details of t e Baseplate
All dimensions in millimetres.