PICOLAS LDP-AV 4N55-90 User manual

User
Manual
LDP
-
AV 4N55
-
90
PicoLAS GmbH
Burgstr. 2
52146 Würselen
Germany
Phone: [phone]
Fax: [phone]
E-mail: [email protected]
Web: www.picolas.de
Rev. 1911

2
Table of Contents
Product Overview..........................................................................................................3
How to use the Manual..................................................................................................4
Dos and Don’ts..............................................................................................................5
How to get started..........................................................................................................6
Connection of the Laser Diode......................................................................................7
How to connect the Driver ............................................................................................8
Pulse Input.....................................................................................................................9
Channel Selection..........................................................................................................9
Power Supply Requirements .......................................................................................10
Trigger Output Monitor...............................................................................................10
Current Consumption ..................................................................................................11
Cooling ........................................................................................................................11
Power Losses...............................................................................................................11
Recommended Operating Conditions..........................................................................12
Absolute maximum Ratings (destroying limits)..........................................................12
Output Power...............................................................................................................13
Mechanical Dimensions ..............................................................................................14

3
LDP-AV D06-N20

4
How to use the Manual
Notice: Depending on the final application and operation regime, this unit must be
assembled onto a heat sink or may stay non-cooled. Improper cooling may cause
damage to the electronic components.
Before powering on your driver unit read this manual thoroughly and make sure you
have understood everything.
Caution: High voltages up to 100 V are present at several PCB components. Do not
touch during operation.
Please pay attention to all safety warnings.
If you have any doubts or suggestions, please do not hesitate to contact us!

5
Dos and Don’ts
Never ground any output connector.
Never use any grounded probes at the output.
Do not connect your oscilloscope to the output!
This will immediately destroy the driver and the probe!
Do not connect voltages in reverse polarity to the device as there is no built-in
protection circuit.
Do use power-up sequencing: Allow the +5 V supply voltage to fully ramp up before
applying any other voltages (HV; Trigger Input).
Do not use mechanical force on the PCB components as they are fragile. Resulting
damages are not covered by warranty.
Beware: Some lab power supplies cause excessive ringing during powering on and
off. These may damage the unit!
Do keep connecting cables between power supply and driver as short as possible.

6
How to get started
Step What to do Check
1 Unpack your device.
2 Attach the laser diode to the driver. Please see section “Connection of
the Laser Diode” for further
details.
3 Assemble the driver onto an appropriate
heat sink. This step may only be omitted if
the stress to the driver is kept very low.
See section “Power Losses” for
further information on thermal
dissipation.
4 Connect GND, +5 V and +HV to the
10 pin Micro-Match connector. Keep the
power supply off.
Please see section “How to
connect the Driver” for further
details.
5 Connect the pulse generator to the SMA
trigger input jack. Ensure that no pulse is fed before powering up the unit.
6 Carry out the power-up sequence as
follows:
1) Fully ramp up the +5 V rail
2) Enable the +HV supply
Then, feed a pulse signal to the input
terminal. For example 5 V amplitude,
100 µs pulse width and 1 kHz repetition
rate.
Security advice: Do not touch the
PCB components near the laser
diode since they may carry high
voltages up to 100 V.
Note: Observe the drivers limits as
in section “Power Losses” to avoid
overloading the driver.
7 Check the optical output of your laser
diode.
8 Turn off sequence:
Disable the pulse generator and then turn
off all power sources (+5 V and +HV).

7
Connection of the Laser Diode
Figure 1: Dimensions of bonding pads for the laser diode
The LD- and LD+ pads are located in the upper edge of the driver. For the standard
dimensions please refer to the dimensions in Figure 1.
Many elements and parasitic “stray” components may affect the performance of the driver
unit. The stray inductance of the load connected to the driver is very important. The term
“load” not only includes the diode itself but also the packaging (bond wires!) and the
connection between the driver and the diode. However, PicoLAS has no influence on these
parts.
Refer to the PicoLAS Application Notes “Impedance of Diodes” and “LD-Connections”
for more information on parasitic elements and their effect on the pulse shape.
If you need different pad sizes for your laser diode, please do not hesitate to contact
us. Customized pad layouts are possible for adapting the dimensions of your load.
LD-
1.6 x 4.4 mm²
LD+
4 pads with
0.7 x 0.3 mm²
Distance between LD+ and
LD- pad: 0.9 mm
Ch0
Ch1
Ch2
Ch3

8
How to connect the Driver
Figure 2: Layout of the LDP-AV 4N55-90
Signals of the 10 pin Micro-Match header (connector 1):
Pin
Name Description
1 +5 V +5 V supply voltage, connect to a stabilized power supply.
2 GND Ground return
3 Trigger input The trigger input requires a signal of 5 V and is terminated with
50 Ohms.
4 Sync out Sync out signal; Rogowski coil
5 /INH Leave this pin floatend for normal operation. Connect to logic
level high to turn all channels off.
6 BIT0 Binary channel selection A.
7 BIT1 Binary channel selection B.
8 GND Ground return
9 GND Ground return
10 HV External high voltage supply input (0 .. 95 V)
Security Advice:
Do not touch any leads of the output or the output capacitors as they can carry high
voltages of up to 100 V.
Connector 1
1
2
3
4
5
6
7
8
9
10
1
2
3
4
LD Pads

9
ulse Input
The trigger generator must be capable of delivering 5 V into 50 Ohms and at least 1 µs in
pulse width. The internal Schmitt-Trigger prevents unstable trigger response.
Note: It is recommended to keep the trigger pulse width within the range of 1 µs .. 100 µs.
The LDP-AV 4N55-90 has an internal short pulse sharpener included. This feature assures
a constant pulse width.
Channel Selection
This driver includes an internal multiplexer which allows to select a specific channel thus a
laser diode. For the selection of one specific laser diode see following table:
BIT1 BIT0 Channel / laser diode
0 0 0
0 1 1
1 0 2
1 1 3
Table 1: Description – How to select a specific channel
Figure 3: Close up of the laser diode footprint and their indicators
This driver is capable for individual coding methods. Therefore the LDP-AV 4N55-90
features the ability of fast channel selection up to 1 MHz.
If you need a flash driver instead of a sequential driver, please do not hesitate to
contact us. Customized driver topologies are possible.
Ch3
Ch1
Ch0
Ch2

10
ower Supply Requirements
The driver requires a stabilized +5 V supply (used by control logic).
Adhere to the power-up sequence as follows:
1) Fully ramp up the +5 V rail
2) Enable the HV supply
3) Apply trigger signal
Should you aim to connect a large number of driver units to a single power supply the high
start-up current spikes can be taken care of by using an additional capacitor bank and hard
power switching at its output. Failure to meet this requirement may cause the gate driver
circuitry to stay in a faulty state.
To reveal that you have to feed the power supply +5 V or +HV in, there are two blue LEDs
included. They indicate that the power supply is turned on.
Figure 4: Close up of the laser diode driver and LEDs
Note: The +HV laser diode supply can be interrupted at any time e.g. for safety reasons by
the customer.
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.
5 V LED
HV LED

11
Current Consumption
Quiescent currents
Supply input Conditions Min. Max. Unit
+5 V 4.8 V .. 5.2 V TBD TBD mA
HV 0 V .. 95 V 5 500 mA
Trigger signal present
Supply input Conditions Typ. Max. Unit
+5 V 4.8 V .. 5.2V 0.3 25 mA
Cooling
The driver is base plate cooled only. Please assemble the entire unit to a heat-sink which is
capable to take out the heat.
The heat-sink is suitable if the system temperature does not exceed the maximum operating
limits.
ower Losses
Due the structure of this driver the power losses of this driver can be approximately
estimated with following equation
AWVItfVP
HVoutpwrepHVLOSS
/05.0⋅+⋅⋅⋅≈
++
Where
LOSS
PTotal average power consumption [W]
+HV
VHigh voltage supply [V]
rep
fRepetition frequency [Hz]
pw
tOptical pulse width [s]
out
IOutput current [A]

12
Recommended Operating Conditions
Supply voltages Min. Typ. Max. Unit
HV+ 0 - +95 V
+5 V +4.75 +5.0 +5.2 V
Trigger input Min. Typ. Max. Unit
HIGH level input voltage
@ Zin=50 Ω4.8 5 +5.2 V
LOW level input voltage
@ Zin=50 Ω0 - +0.8 V
Pulse width 1 2 100 µs
Repetition rate - - 200 kHz
Channel selection Min. Typ. Max. Unit
BIT0 / BIT1 input logic
high +2.0 +5.0 +5.2 V
BIT0 / BIT1 input logic low +0.8 - +0 V
Address transition time
- - 1.0 MHz
Absolute maximum Ratings (destroying limits)
Supply voltages Min. Max. Unit
HV+ 0 +95 V
+5 V 0 +5.2 V
Trigger input Min. Max. Unit
Trigger signal voltage,
unterminated 0 +5.2 V
Trigger Signal:
Note that the maximum ratings for both pulse width and repetition rate depend
on the actual high voltage supply (HV). See section “Power Losses” for guidance.

13
Output ower
Figure 5: Output power of the LDP-AV 4N55-90 in relationship to the HV voltage; measured with the
SPL PL90_3
The LDP-AV 4N55-90 was tested with the SPL PL90_3 from OSRAM. The maximum
current of this laser diode is 40 A. In total we expected that this driver can reach an output
current up to 360 A or 90 A each channel.
Many elements and parasitic “stray” components may affect the performance of the driver
unit. The stray inductance of the load connected to the driver is very important. The term
“load” not only includes the diode itself but also the packaging (bond wires!) and the
connection between the driver and the diode. However, PicoLAS has no influence on these
parts.
Refer to the PicoLAS Application Notes “Impedance of Diodes” and “LD-Connections”
for more information on parasitic elements and their effect on the pulse shape.

14
Mechanical Dimensions
Figure 6: Mechanical dimensions of LDP-AV 4N55-90