PICOLAS LDP-QCW 150 User manual

User Manual
LDP-QCW 150
PicoLAS GmbH
Burgstrasse 2
52146 Würselen
Phone: [phone]
Fax: [phone]
E-Mail: [e-mail]
Web: www.picolas.de
Before powering on your unit, read this manual thoroughly and make sure
you understood everything.
Please pay attention to all safety warnings.
If you have any doubt or suggestion, please do not hesitate to contact us!

2
Table of Contents
Please pay attention to all safety warnings!
Pulse current
Please pay attention to all safety warnings!
Valuable information, remark
Do not
Please pay special attention
Risk of electrical hazard

3
How to use the Manual
Remark: The LDP-QCW 150 described in this manual is a primarily baseplate cooled
laser diode driver. Improper cooling may cause an internal overtemperature shutdown.
Heat sink cooling with fans: Depending on the final application and operation regime a
sufficient airflow created by the fans through the heat sink must be possible.
Please refer to section “Cooling” for more details about the thermal power losses during
operation.
You may use a passive or an active air/water cooler.
Before powering on your unit, read this manual thoroughly and make sure you understood
everything.
Please pay attention to all safety warnings.
If you have any doubt or suggestion, please do not hesitate to contact us!

4
Overview
The LDP-QCW 150 (LDP-QCW for short) is a high power linear regulated laser diode driver.
It supports the following features:
o Supports up to 30 V compliance voltage
o Linear output driver for rectangular current pulses with ripple < 1 %
o Multiple trigger modes for external and internal triggering
o Interlock input for safety
Technical Specifications
*1: The compliance voltage strongly correlates to the pulse current and pulse duration.
Output current 1 .. 150 A
Compliance voltage 0 .. 30 V *1
Min. pulse duration < 10 µs
Max. pulse duration 1 ms
Max. repetition rate 1 kHz
Max. duty cycle 10 %
Max. rise time TBD
Current overshoot < 5 % (depending on
regulator settings)
Pulse trigger input Analog Interface: TTL
Connectivity Analog interface,
RS-232
Supply voltage 24 .. 48 V DC
Max. power dissipation TBD
Dimensions in mm 120 x 76 x 40
Weight 0.3 Kg
Operating temperature 0 to +55 °C

5
Functional Description
The driver uses a DC-DC converter to load a capacitor bank to a defined voltage. It can
provide a maximum voltage of 34 V to load the storage capacitor bank Cb.
A P-I regulator using T1 and T2 are controlling the current flow through the laser diode. These
regulators are triggered by an internal timing generator that is triggered by either an external
trigger signal or via software through the RS-232 interface.
Several security features protect the laser diode and the driver from damage. D1 protects the
laser diode from reverse currents. The switch S1 is automatically opened when an internal
failure or an interlock condition is detected.
Operation Principle of LDP-QCW Driver
Element Function
C1 Input buffer capacitor
Cb Capacitor bank
S1 Security switch
D1 Laser diode protection diode
T1, T2 Current regulation MosFET
Shunt LD current monitor

6
Current Regulator
The LDP-QCW implements a proportional integral (PI) regulator to control the current flow
through the connected load. The following diagram shows a simplified layout:
Depending on the chosen operating mode the user has the possibility to modify all relevant
parameters to a specific need. This is done through the digital interface (RS-232). See below
for more information.
PicoLAS implemented an active nonlinearity compensation of the output stage. This speeds
up the device, prevents excessive current overshoots and yields a better accuracy with high
impedance loads.
The influence of this part of the regulator can be user defined and is called FFwd.
However, the interconnection between the voltage and the current flow on the output is
calibrated during fabrication. This is used in operating mode 1. So, it is not necessary to
change this value if only these operating modes are used. If needed, it can be adjusted
between the values 0 to 7.5 by the customer.
Be careful if changes are performed with the FFwd value. The effect is high and may
cause damage to the connected load if not adjusted properly. Wrong settings are not
covered by warranty.

7
Description of available Connectors

8
Mechanical Dimension

9
Analogue Interface Specifications
The following figure shows the input and output signals of the external analogue BOB
connector.
The LDP-C BOB (Breakout board) is recommended for easy testing of the driver. It will
be replaced in the application by your machine interface.
Functional Description of BOB Connector Interface

10
Pin Description (numerical assorted)
Pin 1: Pulser OK
The state of this signal indicates weather the driver is ready (5 V) or it has an error pending
(0 V).
Pin 2: 5 V
This pin provides 5 Volts for external usage. Please note that the load should not exceed 10
mA, otherwise the voltage will drop.
Pin 3: GND
This pin is connected to ground.
Pin 4: Udiode
This signal provides near real time measurement of the laser diodes compliance voltage. The
scaling is 10 Volts per Volt measured into 1 MOhm.
Pin 5: GND
This pin is connected to ground.
Pin 6: Pulse
This signal is used in the external end external controlled trigger mode. Connect your external
trigger source to this pin. The signal amplitude should be within 3 to 6 Volts.
Pin 7: Enable
This signal is used to enable / disable the current output of the driver during operation.
It must be pulled low to reset an error condition or to re-enable the driver after Master Enable
was pulled low.
Pin 8: Master Enable
This signal is used as an interlock safety feature that disables the complete driver if set to 0 V
during operation. In order to re-enable the driver after this emergency shutdown the enable
signal must first set to 0 V.
If this feature is not required this pin can be connected to pin 2 (5 V).
Pin 9: Idiode
This signal provides near real time measurement of the laser diodes current flow. The scaling
is 200 Amperes per Volt measured into 1MOhm.
Pin 10: Isetpoint
This pin is not used in this driver.