www.osram.com/ledset
Application guide.
The LEDset interface.
CONTENTS
General notes:
As the specifi cations of the applied components are subject to change, OSRAM does not take
liability for the technical accuracy of the application solutions shown in this application guide.
For current specifi cations, please refer to the data sheets of the respective components.
Please also note that LED standards are changing rapidly and that this application guide can
therefore only refl ect the status of the listed standards on the date published. Please check the
latest edition of any standard at the following websites or with your national trade association.
www.cenelec.org
www.cen.eu
www.iec.ch
2
CONTENTS
1. Introduction 4
1.1. Features and benefi ts 5
2. LEDset specifi cations 6
2.1. General overview 6
2.2. LEDset characteristic 7
2.2.1. General description 7
2.2.2. Implementation in the OSRAM ECG 8
2.3. Technical details 9
2.3.1. Bias current (Iset) 9
2.3.2. +12Vset 9
2.3.3. Fault protection 9
2.3.4. Insulation 9
2.3.5. Color coding 10
2.3.6. Cable length 10
2.3.7. Fault conditions/troubleshooting 10
2.3.7.1. Incorrect wiring 10
2.3.7.2. Missing control wire (Vset) 10
2.3.8. Connection of multiple ECGs 11
3. LEDset applications 12
3.1. Current setting 12
3.1.1. Setting by external resistor 12
3.1.2. Step dimming (StepDIM) 15
3.2. Local dimming 17
3.2.1. Potentiometer application 17
3.2.2. Light sensor application 18
3.2.2.1. Using OSRAM DIM
MICO/PICO 18
3.2.2.2. Using customized sensors 19
3.2.2.3. General notes on local
dimming: LEDset, “current set”
combination 20
3.3. Thermal derating 22
3.3.1. Overtemperature protection 24
3.3.1.1. Application solution 1 –
TMP300 solution 24
3.3.1.2. Application solution 2 –
LM26 solution 26
3.3.1.3. Application solution 3 –
NPC SM6611 solution 27
3.3.1.4. Application solution 4 –
SI S-5841 solution 28
3.3.1.5. Application solution 5 –
MM3488 solution 29
3.3.1.6. Application solution 6 –
TC620(1) solution 30
3.3.1.7. General notes on IC
temperature switches:
choice and usage 33
3.3.2. Overtemperature protection
(discrete NTC) 34
3.3.2.1. Application solution 1 –
overtemperature protection
by comparator 34
3.3.2.2. Application solution 2 –
overtemperature management
by comparator:
two-step output 36
3.3.2.3. Application solution 3 –
overtemperature management:
continuous derating
and switch-off 38
3.3.2.4. Application solution 4 –
LEDset and current set
combination: direct NTC
connection 40
3.3.2.5. Application solution 5 –
overtemperature management:
microcontroller
(MCU) approach 42
3.4. +12Vset auxiliary supply 46
3.4.1. Aesthetic use 46
3.4.2. Active cooling 47
3.5. Constant lumen output 48
3.6. Combination of features 49
3
INTRODUCTION
1. Introduction
LED technology is changing the world of general lighting. In
luminaire design, however, the various benefi ts of LEDs, e.g.
their high level of fl exibility in operating luminaires, can only
be achieved with perfectly matched control gears. This is fur-
ther complicated by the rapid improvement of the effi cacy
and current capability of LED technologies, which asks for
even greater adaptability of the corresponding control gears.
Purpose of this application guide:
The purpose of this application guide is to provide basic techni-
cal information on the LEDset interface, focusing on application
solutions that illustrate the specifi c functions of this new inter-
face and show how these can be used. The application solutions
demonstrate that the LEDset interface opens up many opportu-
nities for customizing your LED-based luminaire: the simplicity
and fl exibility of LEDset gives you the freedom to develop new
luminaire system features.
OPTOTRONIC
this demand for greater adaptability by supporting a wide
power and current range and by their future-proof design,
which makes them ready for coming LED generations.
®
control gears with LEDset interface can meet
4
1.1. Features and benefi ts
INTRODUCTION
LEDset helps you to meet important market requirements:
• Future-proof solutions in terms of lumen output
• Long-life operation
• Customization of the luminaire
• Energy saving
OPTOTRONIC
®
+12Vset
Signal (Vset)
GNDset
Power lines
LED module
In combination with OSRAM LED power supplies, the
LEDset interface offers full fl exibility and a future-proof
system with the following features and benefi ts:
• Current setting
• Thermal protection
• High current accuracy
• Auxiliary supply 12 V
• Local dimming
• Simple wiring
Current
setting
• By resistor
Figure 1: LEDset application features.
Local
dimming
• With lin/log
potentiometer
• StepDIM
Overtemperature
derating
Auxiliary
supply
• For control
logic (µc, IC)
on the LED
module
• For 12 V lowpower LED
module
Constant
lumen output
5
LEDset SPECIFICATIONS
2. LEDset specifi cations
2.1. General overview
LEDset is a 3-wire analog control interface designed for
OPTOTRONIC
allows setting the output current of the electronic control
gear (ECG) by providing a highly accurate voltage reference
(Vset) to the ECG. Thanks to the control accuracy and sim-
plicity of LEDset, control gears become highly adaptable and
can cover a wide range of applications. The output current
can be set/dimmed by a passive device (e.g. resistor) or by
an external imposed-voltage control signal.
Moreover, the interface gives more freedom in the design of
customized systems by providing a stabilized 12 V auxiliary
voltage (+12Vset) that can supply an active circuit, for exam-
ple on the LED module, extending a simple temperature-
dependent current derating circuit to a more complex micro-
controller-based fl ux control.
®
constant-current LED power supplies. It
The main features of the LEDset interface can be
summarized as follows:
• Output current setting interface for constant-current ECGs
• 3-wire interface
– +12Vset: Stabilized 12 V auxiliary voltage (+/-10 %)
– Vset: Voltage reference in the range of 0 to 12 V (+10 %)
– GNDset: Ground reference of the LEDset interface
• Output current setting by analog input voltage control (Vset)
– For current setting, the Vset control voltage is within the
range of 10 V
– The LEDset characteristic is a fi xed relationship between
the Vset voltage and the percentage of the maximum
nominal current of the control gear (relative coding)
• High-output LED current accuracy
– Overall control system provides an Inom
of up to +/-5 %
– Accurate bias current generator on Vset for very precise
current setting via passive control (fi xed/variable resistor)
• 12 V auxiliary output (+12Vset) for the supply of electronic
ICs/circuits or the control of a fan (future extension)
• ECGs can be used in a wide power and current operating
range
tolerance
max
Figure 2: LEDset interface wiring (block diagram).
6
2.2. LEDset characteristic
LEDset SPECIFICATIONS
2.2.1. General description
With the LEDset interface, the output current can be defi ned
relative to the maximum nominal output current of the control
gear.
The basic relationship between the LEDset voltage (Vset)
and the ECG output current (Iout) is defi ned by the following
equation:
Iout Inom
max
(Vset 1)
9
where Inom
is the maximum nominal output current of
max
the ECG and Vset voltage is the voltage between Vset and
GNDset.
The relationship is valid for values of Iout that are within
the current range of the control gear, i.e. between Imin
and Inom
max
.
The generic Iout versus the Vset characteristic is shown in
fi gure 3.
Figure 3: Generic Iout vs. Vset characteristic.
Designation of lines:
Blue line: Ideal case
Orange line: Typical real ECG behavior with Imin
limitation and no turn-off capability
0 < Vset < Vmin
Vmin < Vset < 10 V
10 V < Vset < 11 V
11 V < Vset < +12 Vset (or Vset, open)
Table 1: LED output current as function of Vset.
Iout = lmin or lout = 0 (see chapter 2.2.2. for details)
Iout according to LEDset relationship
Iout = Inom
max
Iout = Imin (i.e. Iout = 0 if the ECG has a turn-off capability)
7
LEDset SPECIFICATIONS
Note:
Vmin is the Vset voltage value corresponding to the minimum
deliverable current (Imin) of the ECG. The Imin is specifi ed in
the datasheet of the applied ECG. Based on the LEDset rela-
tionship between Iout and Vset, it is possible to calculate the
typical Vmin of the ECG.
2.2.2. Implementation in the OSRAM ECG
Based on the general LEDset specifi cation, two different
LEDset implementations can currently be found in constant-
current OSRAM ECGs (for details, please refer to the data-
sheet of the specifi c product).
Example:
When using the OT 35/220-240/700 with a nominal current
of 700 mA, the minimum current is 100 mA (according to the
datasheet of the ECG) and the Vmin is as follows:
Vmin Vmin9 + 1 2.28 V
Imin
Inom
Basically, the two cases differ due to the minimum current
limitation of the ECGs. An ECG’s turn-off capability – rather
than the minimum current holding between Vmin and 0 V –
makes the difference between the cases.
The following diagrams describe the different cases imple-
mented in OSRAM LEDset ECGs:
Figure 4a: Case I. Figure 4b: Case II.
Product examples:
3DIM + LEDset (LT)
OT 45/220-240/700 3DIMLT E
OT 90/220-240/700 3DIMLT E
8
LEDset
OT 90/220-240/700 LT E
Product examples:
LEDset (LT) + current setting (CS)
OT 35/220-240/700 LTCS
OT 45/220-240/700 LTCS
2.3. Technical details
This chapter gives a general overview of the technical details
of the LEDset interface. For further details and deviations
from this basic information, please refer to the datasheet
and instruction sheet of the respective control gear.
LEDset SPECIFICATIONS
2.3.4. Insulation2.3.1. Bias current (Iset)
The LEDset interface is an active interface since the Vset in-
put can actually generate a constant current output (bias
current), allowing the Vset voltage to be achieved through
“passive” circuits (e.g. current setting by resistor, light sen-
sors etc.).
The integrated current generator provides a very stable bias
current (Iset) of 274 µA over the complete operating range of
the control gear. Thanks to this feature, unwanted current
variations due to temperature changes, which occur in many
ECGs with similar control interfaces, can be avoided.
2.3.2. +12Vset
The stabilized 12 V auxiliary voltage is able to supply a
current of up to 15 mA (laux). The voltage accuracy is within
a tolerance of ±10 %. A future power extension will provide
an even greater capability to supply more powerful loads
(such as an external fan for active cooling applications).
For details regarding the maximum allowable output power,
please refer to the datasheet and instruction sheet of the
respective control gear.
All ECGs with LEDset interface have the following minimal
insulation barriers:
Primary
circuit
Primary
circuit
Secondary
circuit
LEDset
Table 2: Insulation barriers of LEDset ECGs.
There is no galvanic insulation between the LEDset interface
and the secondary circuit.
Note: If the LEDset ECG is to be used in a system that must
be classifi ed as SELV (Safety Extra-Low Voltage), any circuit
connected to the LEDset interface of an SELV or SELV-
equivalent control gear can only be used if double-insulated
from the mains.
–
Depending
on the ECG
Depending
on the ECG
Secondary
circuit
Depending
on the ECG
–
No insulation
LEDset
Depending
on the ECG
No insulation
–
2.3.3. Fault protection
The +12Vset is protected against short circuit (+12Vset –
GNDset). Vset is protected up to the 12 V + 10 %.
The LEDset interface has no specifi c protection against elec-
trostatic discharge (ESD). Therefore, it is recommended that
any circuit (e.g. accessible potentiometer) connected to the
LEDset interface port has a proper insulation against touch-
able parts.
Moreover, the negative pole of the LED load (LED-) must not
be connected to the GNDset terminal.
9
LEDset SPECIFICATIONS
2.3.5. Color coding
The color coding for the connector of the LEDset interface is
defi ned as follows:
LED+ Red
LED-
LEDset GNDset Gray
LEDset Vset
LEDset +12Vset
Table 3: Color coding.
LED+ and LED- are the power outputs of the control gear.
The position and order of the terminals can vary between the
different LEDset ECG types.
Black
Violet
Blue
2.3.7. Fault conditions/troubleshooting
2.3.6. Cable length
The maximum length of LEDset cables should not exceed
2 m. Further limitations to cable length generally derive from
EMI emission or immunity issues or directly from product
specifi cation details. For detailed information, please refer to
the datasheet or instruction sheet of the respective LEDset
control gear.
2.3.7.1. Incorrect wiring 2.3.7.2. Missing control wire (Vset)
The LEDset interface has been designed to inherently pro-
tect itself and the LED module against incorrect wiring on the
secondary side of the control gear. Incorrect connections
between LED+ and Vset or GNDset can irreversibly damage
the ECG.
Other possible incorrect wirings on the secondary side do
not affect the operation of the ECG once they are removed
(irrespective of problems regarding the connected external
LEDset ECGs).
LEDset is an interface intended for the current setting and
thermal management of an LED module. If the Vset terminal
is not connected to the control unit, the thermal protection of
the LED module and its correct current setting will not work.
This fault condition may result in an undetected overheating
of the LED module. In order to protect the LED module in
this condition, the absence of a control signal (Vset open or
Vset ≥ 11 V) is detected and the ECG is shut down or set to
its minimum current (see fi gure 3).
10
LEDset SPECIFICATIONS
2.3.8. Connection of multiple ECGs
Depending on the LEDset control gear, the Vset signals can
be connected in parallel to set the current of multiple ECGs
by a resistor. This connection is allowed in case of a local
dimming application on a luminaire supplied by more than
one ECG.
In general, if n is the number of ECGs to be connected to-
gether to a local dimmer or current setting resistance, Rset/n
is the resistance value to be considered (where Rset is the
value needed to set the current of one single ECG).
Example: an offi ce luminaire with two ECGs locally dimmed
by a 22 kΩ potentiometer.
Figure 5 shows a parallel connection of two LEDset inter-
faces. The interfaces share a resistor Rset, with which it is
possible to set the output current. Current setting by external
resistor is explained in detail in chapter 3.1.1.
Figure 5: Parallel connection of two LEDset interfaces.
11
LEDset APPLICATIONS
3. LEDset applications
3.1. Current setting
3.1.1. Setting by external resistor
If the application requires a specifi c fi xed output current, the
easiest way to set the output current is to apply a resistor
between Vset and GNDset.
Figure 6: Current setting by external resistor.
As mentioned in chapter 2.3.1., the LEDset interface is an
active interface that is able to generate a constant current
output (Iset) and thus allows the use of “passive” circuits
(e.g. resistor) to achieve the setting voltage (Vset).
The resistor can be placed either on the terminal block of the
ECG or on the LED module (plug-and-play solution but with
two additional wires that have to be considered for cabling
design).
As a function of the LEDset interface, the Vset value is
related to the percentage of the ECG’s maximum nominal
current.
(Vset 1)
9
100
12
Iout
Inom
[%]
max
This means that the absolute value of the output current
depends on the maximum nominal current of the ECG.
Setting the output current Iout
700 mA will differ from setting the same Iout on an ECG with
Inom
= 1500 mA.
max
on an ECG with Inom
max
max
=
The following table shows the output current values obtained by applying
a 1 % resistor (from E96 series unless otherwise specifi ed) for two different
ECGs with a nominal current of 700 mA and 1500 mA, respectively.
LEDset APPLICATIONS
Rset – E96 series
Vset [V] Iout/Inom [%] Inom [mA] = 700 Inom [mA] = 1500
(unless otherwise
specifi ed)
0 0.0 0 0 0
3830 1.0 1 4 8
7500 2.1 12 82 176
11300 3.1 23 163 349
14700 4.0 34 235 505
15000 4.1 35 242 518
19100
20000 (E24)
5.2 47 329
5.5 50
348
706
747
21000 5.8 53 370 792
23200 6.4 60 417 893
25500
27000 (E24)
7.0 67 466
7.4 71
498
998
1066
28000 7.7 74 519 1112
30100 8.2 81 564 1208
34000
36500 (E48)
9.3 92 647
10.0 100 700 1500
1386
38300 > 10.0 100 700 1500
39000 (E24)
> 10.0 100
700 1500
40200 (and up to 60000) > 10.0 100 700 1500
Table 4: Current setting by external resistor.
For more information, please see the notes on page 14.
13
LEDset APPLICATIONS
Note 1: The E96 series covers a wide range of values. The
table contains only some sample values of this series. Please
check the standard E96 series to fi nd the value best suited
for meeting your current setting requirements.
Note 2: The values given above are calculated without con-
sidering the possible power and/or output voltage and/or
minimum output current limitations which depend specifi cally
on the output characteristics of the chosen ECG. Please
refer to the respective product datasheet.
Note 3: The resistor tolerance has an effect on the accuracy
of the current setting. Available standard tolerances are 5 %,
2 %, 1 %, 0.5 %, 0.25 % and 0.1 %. LEDset ECGs are de-
signed to provide up to 5 % of the overall control accuracy
(Rset – Iout) if Rset is a resistor with a tolerance of up to 1 %.
If higher than 1 %, the tolerance of Rset must be considered in
the Iout tolerance calculation.
Note 4: Since the Iset current value is very low, the power
rating of the resistor is not an issue to be considered when
selecting the resistor (considering a maximum value of
50 kΩ
Note 5: If the value of the commercial resistor differs too
much from the calculated resistance, connecting resistors in
series/parallel might help to obtain the precise required value.
Note 6: It is not recommended to set the Vset by dividing
the +12Vset voltage by a resistor divider. This setting is in
fact more complicated. Moreover, the stated accuracy toler-
ance of ±5 % for the overall control system may not be lon-
ger achieved because it is directly affected by the +12Vset
voltage tolerance which is ±10 %.
PRset = 3.8 mW).
Example:
This example is meant to help in choosing the most suitable commercial resistor for a given system.
The calculation applies to an OT 35/220-240/700 LTCS in LEDset confi guration to set an output current of 580 mA.
Starting from the basic relationship:
Vset 1 + 9 8.33 V
Iout
where Iout = 580 mA and Inom
= 700 mA
max
Inom
Therefore:
Rset 30.87 kΩ
Vset
where Iset = 274 µA
Iset
Looking at available values of commercial resistors (i.e. E96 series), 30.9 kΩ is the best choice.
The recalculated real current setting would be:
Vset
14
Rset
Iset
8.47 V
and therefore Iout = 580.7 mA
3.1.2. Step dimming (StepDIM)
Based on the previous chapter (3.1.1.), the current setting
by resistor can be easily extended by an additional step dim-
ming function. By switching between two external resistance
values, the output current can be changed to two different
levels (i.e. one to set the nominal current to 100 % and one
to step down to 40 %). Shorting the Vset to GNDset allows
turning off the LED module while the ECG is still supplied
with mains voltage.
LEDset APPLICATIONS
Possible solutions are shown in the following block diagram:
7a: Manual solution. 7b: Relay-based solution.
Figure 7: Step dimming by two resistor values.
For more information, please see the note on page 16.
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