AMS Illuminator Eval Kit User guide

Brand: AMS

Model: Illuminator Eval Kit

Type: User guide

User Guide

UG001008

Illuminator Evaluation Kit

User Manual

EVALKIT_Illuminator

v1-00 • 2021-Mar-09

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Illuminator Evaluation Kit

Content Guide

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Content Guide

1 Introduction ................................... 3

1.1 Kit Content .................................................... 3

1.2 Ordering Information .................................... 4

1.3 Safety Information ........................................ 4

2 Specifications Overview ............... 5

2.1 Board Architecture ........................................ 5

2.2 Main Features .............................................. 6

2.3 Absolute Maximum Ratings .......................... 7

2.4 Performance Characteristics ........................ 7

3 Hardware Description ..................10

3.1 Board Settings ............................................ 10

3.2 External Connections ................................. 10

3.3 Controls and Indicators .............................. 12

3.4 Mechanical Interface .................................. 12

3.5 External Power Supply ............................... 13

4 Getting Started .............................16

4.1 Illuminator Connection and the Influence of

Inductance .................................................. 16

4.2 Setup of a Safe Starting Condition ............. 16

4.3 How to Set the Laser Supply Voltage ........ 17

4.4 How to Measure the Laser Current and Its

Voltage Drop............................................... 18

4.5 How to Minimize Readout Offset ................ 19

4.6 How to Connect the VCSEL Illuminator ..... 21

4.7 How to Set the Bias Current ....................... 24

4.8 How to Set the Pulsed Current Amplitude .. 25

4.9 How to Set the PWM Oscillator .................. 27

4.10 How to Connect a Camera Master Strobe

Signal .......................................................... 28

4.11 How to Connect a Fast LVDS Trigger ........ 30

5 How to Operate the Board ........... 32

5.1 Possible Thermal Issues ............................ 32

5.2 Connecting Oscilloscope Probes ............... 33

5.3 Measuring the Cathode Voltage ................. 33

5.4 Taking Confidence Using a Resistive

Dummy Load .............................................. 34

5.5 Measuring a Starboard-Mounted Laser with

1 μs Pulse Length ....................................... 39

5.6 Measuring a Socket-Mounted (or Soldered)

Laser with 1 μs Pulse Length ..................... 45

6 Troubleshooting .......................... 51

6.1 Red LED DL1 is ON: Driver Fault ............... 51

6.2 Yellow LED DL4 is ON: Board-Level Error . 51

6.3 No Current: Check Electrical Integrity of

Output ......................................................... 52

6.4 Sudden Board-Level Error While Using

LVDS .......................................................... 52

7 Annex ............................................ 53

7.1 Board Settings Configurations .................... 53

7.2 External Connections ................................. 54

7.3 Controls and Indicators ............................... 55

8 Revision Information ................... 57

9 Legal Information ......................... 58

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Illuminator Evaluation Kit

Introduction

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1 Introduction

The illuminator evaluation kit EVALKIT_Illuminator intends to provide a flexible hardware interface to

drive laser diodes in different application contexts using 2D based imaging systems as well as 3D

time-of-flight systems.

With the kit, the user is able to drive most of ams’ illuminator modules to allow the user to evaluate

easily the performances of the product.

It is the user’s responsibility to take care of the eye safety compliance at system level.

1.1 Kit Content

The shipment box of the Illuminator Evaluation Kit contains the following items:

● The Illuminator Evaluation Kit board

● The external AC/DC power adapter in its own cardboard box

● A small plastic bag with a 1 Ω high power resistor to use as a dummy load for testing

The shipment box does not include the C13 wall plug so it is on the user to get the suitable C13 plug

fitting with the region.

Figure 1:

Pictures of the Kit Content

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1.2 Ordering Information

Ordering Code

Description

EVALKIT_Illuminator

Illuminator Evaluation Kit

1.3 Safety Information

The device is only intended for laboratory testing use by trained

personnel. Use by general public users has to be avoided.

Even during normal operation of the device, the heatsink and

some of the parts mounted on the board could become hot, with

temperature up to 110°C for specific components.

Provide stable mechanical mounting of the device and assure

proper ventilation.

Do not touch the device during operation and allow sufficient time

to cool down after shut-down before handling it.

The device is intended to drive high power laser diodes, which

can be harmful to eyes.

Check the compliance of the experimental setup to all present

laser safety regulations before operating the device.

Wear protection glasses while operating.

This electronic product is subject to disposal and recycling

regulations that vary by country and region: check for applicable

rules on your site.

In general, do not dispose waste electronic equipment in standard

waste receptacle.

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Specifications Overview

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2 Specifications Overview

2.1 Board Architecture

The Illuminator Evaluation Kit intends to provide a flexible hardware interface to drive VCSEL diodes

in different application contexts. It allows to independently set a pulsed modulation current and a

continuous bias current, using trimmers or applying external control voltages.

A variety of digital interfaces allow to apply an external strobe signal, which sets both pulse rate and

duty cycle. An on-board oscillator at 100 kHz is also present, which provides variable duty cycle PWM

and interacts with the external strobe signals with an AND logic. On-board analogue electronics

makes easier to interface to an external oscilloscope to acquire the laser current waveform, as well as

the voltage drop across the laser.

The device requires a single external supply and internally generates all the voltages required by the

different electronics parts.

The board is based on the integrated laser driver circuit iC-HG30 from IC-Haus.

Figure 2:

Block Diagram of the Illuminator Evaluation Kit

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Specifications Overview

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2.2 Main Features

The main features of the Illuminator Evaluation Kit are listed as follows:

● Laser driving:

● Constant current operation

● Up to 20 A pulsed current and up to 1 A bias current, with independent analogue settings

● Selectable external or internal current control

● Adjustable anode supply voltage to optimize speed or to support the external connection

of multiple lasers in series (low-speed applications)

● Laser triggering:

● Differential input trigger for high-speed applications (Time-of-Flight) up to 100 MHz

● Camera Master strobe inputs for 2D Camera applications

● On-board PWM oscillator, 100 kHz, 0−100% duty cycle

● Laser connection

● Screw terminal block suitable for externally mounted devices

● Soldering pads (socket-mount option) intended for high-speed applications, if using lasers

with specific or compatible footprints as shown in Figure 3.

● Signal outputs for the electrical laser parameters, with different scales and bandwidth

● 24 V nominal supply voltage

● External AC/DC adapter included

● On-board ON/OFF sliding switch

● Operating ambient temperature range: 0 to 40 °C (non-condensing)

● Restrictions may apply depending on the set laser current and modulation parameters

● Over-temperature protection operates

● Use of the provided heatsink is compulsory

Figure 3:

Module Bottom Pads Footprints Compatibility with the Kit Soldering Pads

TARA2000-AUT / EGA2000 PMSILPlus

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2.3 Absolute Maximum Ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to

the device. These are stress ratings only. Functional operation of the device at these or any other

conditions beyond those indicated under “Operating Conditions” is not implied. Exposure to absolute

maximum rating conditions for extended periods may affect device reliability.

Figure 4

Absolute Maximum Ratings of the Illuminator Evaluation Kit

Symbol

Parameter

Min

Max

Unit

Comments

Electrical Parameters

pulsed

Pulsed Laser Current

(With Heatsink)

Pulse length 10 ns

Average duty cycle < 2%

No bias

supply

Supply Voltage

biased

Biased Laser Current

(With heatsink)

Temperature Ranges and Storage Conditions

(1)

Operating Ambient Temperature

°C

STRG

Storage Temperature Range

-20

°C

NC, op

Operating Relative Humidity

(non-condensing)

NC, STRG

Storage Relative Humidity

(non-condensing)

(1) By design, not actually tested

2.4 Performance Characteristics

Figure 5:

Electrical Parameters

Parameter

Conditions

Min

Typ

Max

Unit

External Supply Voltage

Operating Mode

Constant current controller

Star-board-mounted VCSEL

Pulsed Current

(see Figure 27 for setting)

With heatsink in still air at 20 °C

Anode voltage V

driver

= 6 V

Frequency 100 kHz

Duty cycle 50%

No bias

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Parameter

Conditions

Min

Typ

Max

Unit

Anode voltage V

driver

=6 V

Frequency 100 kHz

Duty cycle 10%

No bias

Socket-mounted VCSEL

Pulsed Current

(see Figure 27 for setting)

With heatsink in still air at 20°C

Anode voltage V

driver

=20 V

Pulse length 10 ns

Average duty cycle < 2%

No bias

Anode voltage V

driver

=6 V

Frequency 100 MHz

Duty cycle 50%

No bias

Anode voltage V

driver

=6 V

Frequency 100 kHz

Duty cycle 50%

No bias

Anode voltage V

driver

=6 V

Frequency 100 kHz

Duty cycle 20%

No bias

VCSEL Bias Current

(2)

(With heatsink in still air at 20 °C)

Bias enabled (board jumper)

1.5

Pulse current setting with a voltage

Internal

12-turn Trimming Potentiometer

External Range

External Bandwidth

(1)

MHz

Bias current setting with a voltage

Internal

12-turn Trimming Potentiometer

External Range

External Bandwidth

(1)

MHz

VCSEL anode voltage range (V

driver

)

5.3

21.3

VCSEL anode voltage setting

Internal

12-turn Trimming Potentiometer

VCSEL current readout

TP15 Scale

Bandwidth

(1)

100

mV/A

MHz

TP15 Scale

Bandwidth

(1)

1000

0.2

mV/A

MHz

TP8 Scale

Bandwidth

(1)

2.5

300

mV/A

MHz

VCSEL Anode-Cathode voltage

readout

TP14 Scale

Bandwidth

(1)

500

mV/V

MHz

TP10 Scale

Bandwidth

(1)

450

mV/V

MHz

Thermal Resistance Driver/Ambient

With heatsink

°K/W

Without heatsink

°K/W

(1) By design, not actually tested

(2) Heat dissipation due to bias current reduces pulsed maximum current and/or duty cycle

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Figure 6:

Mechanical Parameters

Parameter

Value

Unit

Driver Overall Dimension

(included heatsink and components height)

115 x 95 x 23

Driver weight

270

External AC/DC adapter dimensions

125 x 50 x 31.5

External AC/DC weight

300

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Hardware Description

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3 Hardware Description

3.1 Board Settings

The setting flexibility of the Illuminator Evaluation Kit is ensured with the on-board jumpers in order to

set different configurations. The below picture helps locating them on the board and in the Annex

chapter of this document is showing a detailed table list for the board configurations.

Figure 7:

Location of the Configuration Jumpers on the Board

3.2 External Connections

In order to allow the user to use easily the evaluation kit, the board has several input and output

connections as shown on the picture below. Several ground-loops, sequentially numbered with a

prefix “GND”, are located in different positions on the board to ease ground connection of any external

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equipment. The Annex chapter of this document is showing a detailed table list to describe further the

different external connections.

Figure 8:

Location of Board Connectors

In the annex, there is a table listing the signals available on the pins of the status connector J2.

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3.3 Controls and Indicators

The board has also different controls and light indicators as shown in the figure after. The Annex

chapter of this document is showing a detailed table list to describe controls and indicators on the

board.

Figure 9:

Location of Board Controls and Indicators

3.4 Mechanical Interface

The Figure 10 below shows the position of the mechanical fixing holes for an easy-handling of the

board as follow:

● Four pass-through M4 holes provided to mount the board on a suitable base

● Two pass-through M4 holes usually intended to fix the board onto its heatsink

● Two pass-through M3 holes intended as fixings to better attach the heatsink

● Two pass-through M2 holes intended to mount the optional laser socket or to be used as further

auxiliary fixings to better attach the heatsink

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Figure 10:

Mechanical Interface

3.5 External Power Supply

An AC/DC adapter is delivered with the Illuminator Driver to provide the required 24 V supply. The

Figure 11 below shows how to connect it to the green J1 socket, and the main specifications.

Figure 11:

Power Supply and Its Specifications

In case the user has to use a different supply within the experimental set-up, here follow some more

information about the power requirements.

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● Supply input socket: Phoenix Contact MSTBA_2,5/2-G-5,08 (P/N 1757242)

● Mating plug: MSTB_2,5/2-ST-5,08 (P/N 1757019)

● Wiring: See below (board protected against polarity inversion)

● Power consumption: Application dependent, see below

Figure 12:

Connection of the Supply Input

About power consumption, let’s define that Stand-by refers to being the board powered-on without any

trigger or strobe applied and with the laser bias current disabled. The connected load is thus not

operating in any way. In this condition, current consumption depends mainly on the setting of the

supply voltage to the laser. The Figure 13 below shows the typical trend of the current drained from an

external supply at 24 V versus the set laser voltage value. Note that, on the supply voltage range,

some dependence of the stand-by current on the external voltage exists, but it is usually within

±10 mA. Looking at the stand-by current level may be useful as an at-a-glance check that nothing

anomalous is occurring.

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Figure 13:

Typical Value of the Current Drained in Stand-by From a 24 V External Supply

Operating power consumption depends on the setting of the laser voltage, on the laser current and on

the pulse duty cycle. The following formula can be used to estimate it at the nominal 24 V supply:

[mA] ≈ I

+ ( I

LCW

+ I

* P

) * V

driver

/ 24

where I

is the current drained from the external supply, I

is the stand-by current, I

LCW

the laser bias

current, I

the peak value of the pulsed component of the laser current, P

the pulse duty cycle,

assumed rectangular, and V

driver

the laser supply voltage.

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Illuminator Evaluation Kit

Getting Started

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4 Getting Started

This section introduces general concepts about the use of the Illuminator Evaluation Kit and provides

information about basic operations. All of this will be then put together presenting some real measures

taken using the board.

4.1 Illuminator Connection and the Influence of Inductance

Laser connection considerations apply to any Illuminator Driver application, whether it uses long

pulses at a relatively low frequency or requires short pulses at a high switching rate. The most

important aspect is to keep the connection inductance as low as possible. The presence of stray

capacitance is important too. The design of the board layout kept as a priority to minimize these stray

parameters.

● Direct soldering of the laser on the board allows to get the best performance in terms of speed,

but not practical when different devices have to be tested and compared. The use of the socket

mounting option leads to very similar results and offers much more flexibility. These options are

especially suited for 3D ToF applications.

● Using the screw terminal block is easy, but wiring adds much stray inductance. This solution is

more suitable for 2D camera applications, which use longer pulse lengths. However, always

keep the wires as short as possible. Also examine the contribution of the external mount, which

will add some stray capacitance too.

The main effect of inductance and capacitance is to reduce the switching speed, putting a lower bound

to the usable pulse length. They thus limit the minimum duty cycle in PWM applications or the

maximum pulse rate in ToF systems. In general, an external connection is not suitable whenever

pulses shorter than about 400 ns are involved.

It should also be considered that, whatever the pulse length, the inductance can reduce electronics

reliability. In fact, since the switching edges of the laser current are fast, large voltage peaks occur that

can exceed the maximum voltage rating of the driver. See next relevant sections about how to connect

a laser.

4.2 Setup of a Safe Starting Condition

Preparing a new test setup requires following a sequence of steps designed to ensure the safety of

both the operator, preventing the exposure to a dangerous level of laser light, and the board itself,

avoiding any possible electrical damage.

Follow the below steps to start from a safe condition, whatever the foreseen application is:

● Verify that all the jumpers are correctly set for the experiment you intend to perform

● Mount the driver on a stable mechanical support

● Slide SW1 switch to OFF position (Figure 12)

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● Remove any load from the J18 terminal block

● If there is a laser, welded or in the socket, and it is not advisable to remove it, wear

protective goggles in case of accidental laser emission

● Check the voltage of the external power supply

● Connect the external power supply to J1 (Figure 12)

● Switch-on the external power supply

● Slide SW1 switch to ON position and check LED DL3 lit

● Set to a minimum the pulsed current control, checking the value at J12 with a voltmeter.

Depending on your configuration (Figure 14 below):

● Turn counter-clockwise R58 until voltage reading at J12 is less than 500 mV

● Check the external voltage applied to TP6 (white), possibly measuring it at J12

● In case a bias current is not required, open the J16 jumper and skip next step

● In case a bias current is required, start setting to a minimum the related control, checking the

value at J14 with a voltmeter. Depending on your configuration (Figure 14 below):

● Turn counter-clockwise R61 until voltage reading at J14 is less than 500 mV

● Check the external voltage applied to TP7 (orange), possibly measuring it at J14

Figure 14:

Setting Bias and Pulse Currents

4.3 How to Set the Laser Supply Voltage

The voltage level at the VCSEL anode can be set at any voltage in the specified range (see Figure 7).

The required minimum value depends on the voltage drops due to the standard device operation and

to inductance. A 6 V minimum is typical, which computes as:

● 2 V required for the proper operation of the current controller

● 2-3 V to account for VCSEL cathode-anode voltage, depending operating current

● 1 V or larger, to account for inductive falls when switching

With pulse lengths shorter than some hundreds of ns, a higher anode supply voltage helps to get a

better optical pulse shape, with faster fronts. The main drawback comes from the higher thermal load

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that may make difficult to keep the driver cold. The actual setting will thus be a compromise between

speed and the device operating temperature.

To set the voltage:

● Check SW1 is ON and LED DL3 lit

● Turn trimmer R95 clock-wise to increase, opposite to decrease (Figure 15 below)

● Measure voltage at TP4 (yellow) with a voltmeter

Figure 15:

Setting Laser Voltage Supply (V

driver

)

4.4 How to Measure the Laser Current and Its Voltage Drop

You can conveniently measure the laser current and the cathode to anode voltage at some test points,

which differ for the measurement scaling and bandwidth figure 16 reports the gains to convert the

voltage readings at the measuring point and the typical value of the measuring bandwidth. About listed

measures, note that:

● Current scales refer to the use of the standard 0R02 (20mΩ) value for the R15 resistor

● All test points to be read using high impedance scope probes or a digital multimeter

Figure 16:

Gain and Bandwidth of the Measuring Points

Test Point

Description

Gain

TP8 (blue)

“Fast” Current Readout

5 mV/A

300 MHz

TP15 (purple)

“Slow” Current Readout

100 mV/A (J46 open)

2 MHz

“Slow” Current Readout

1 V/A (J46 closed)

0.2 MHz

TP10 (yellow)

“Fast” Laser Voltage Readout

100 mV/V

450 MHz

TP14 (green)

“Slow” Laser Voltage Readout

1 V/V

10 MHz

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Test Point

Description

Gain

TP4 (yellow)

TP3 (brown)

Direct reading of voltage across

the current sensing resistor.

Compute current as:

Voltage difference (TP4 – TP3) / (R15 value)

Depends

on used

equipment

Do not connect any of these test points to ground.

Use high impedance multimeter or differential-mode scope probes.

Any misuse can damage the board.

Especially when dealing with short pulses, always consider the rated response bandwidth of the used

test point. To get a complete and reliable information, we suggest the use of an oscilloscope to

measure both the faster and the slower outputs, which helps to recognize bandwidth limitations too.

You can also use a simple voltmeter, connected to the “slow” test points, to get some information

about the laser voltage and current, but limitations exist in this case. The voltmeter only gives an

average value of the parameter value, so a compensation and possibly further measures are needed

to estimate maximum and minimum values.

4.5 How to Minimize Readout Offset

Electronics voltage offset affects the “Slow” readouts for both the laser voltage and the laser current.

Measuring the peak-to-peak amplitude of the waveforms is free of any offset problem. However, a

non-zero baseline badly affects getting data with a simple digital voltmeter and can annoy watching to

oscilloscope traces. The driver has two separate controls to compensate for these offsets, although,

depending on operating conditions, they could be only minimized but not nulled.

To get the minimum readout offset follow this procedure:

● Slide SW1 switch to OFF position (Figure 12)

● Do not apply any trigger or strobe signal

● Possibly open J17 jumper to be sure of this (Figure 17 below)

● Do not apply any bias current

● Possibly open J16 jumper to be sure of this (Figure 17 below)

Figure 17:

Disabling any Trigger and Bias (Opening J17 and J16)

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● Set the wished current measure gain using J46 (Figure 16 and Figure 19)

● Short the J18 contacts using a short wire (Figure 18)

Figure 18:

Shirting J18

● Slide SW1 switch to ON position (Figure 12) and check LED DL3 lit

● Set the laser supply voltage at the wished value (section “How to set the laser supply voltage”)

● Note that the offset of both the readout voltages usually changes toward negative values

when the laser supply voltage increases to a higher level

● Minimize the offset of the TP15 (purple) current measure output (see Figure 19)

● Measure offset at TP15 with a voltmeter

● Adjust R126 to minimize voltmeter reading

Figure 19:

Adjusting TP15 Gain and Offset

● Minimize the offset of the TP14 (green) voltage measure output (Figure 20)

● Measure offset at TP14 with a voltmeter

● Adjust R138 to minimize voltmeter reading

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AMS Illuminator Eval Kit User guide

AMS Illuminator Eval Kit User guide

AMS Illuminator Eval Kit User guide

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