MLX90615SSG-DAA Melexis Inc, MLX90615SSG-DAA Datasheet - Page 25

• Manufacturer Part Number: MLX90615SSG-DAA
• Description: THERMOMETER IR DUAL 3V MED TO-46
• Manufacturer: Melexis Inc

Specifications of MLX90615SSG-DAA

• Featured Product: MLX90615 Series Infrared Thermometers
• Sensing Temperature: -40°C ~ 115°C
• Output Type: PWM, SMBus™
• Voltage - Supply: 2.6 V ~ 3.6 V
• Accuracy: ±0.5°C
• Package / Case: TO-46-4 Metal Can
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

- When considering reflow soldering, measure the temperature profile of the top of the can and keep the peak
temperature as low as possible.
- Please contact Melexis in case you intend to use a reflow soldering process for through hole devices to
verify your soldering process design.
Melexis is contributing to global environmental conservation by promoting lead free solutions. For more
information on qualifications of RoHS compliant products (RoHS = European directive on the Restriction Of
the use of certain Hazardous Substances) please visit the quality page on our website:
http://www.melexis.com/quality.asp
The MLX90615 is RoHS compliant
Electronic semiconductor products are sensitive to Electro Static Discharge (ESD).
Always observe Electro Static Discharge control procedures whenever handling semiconductor products.
When I measure aluminium and plastic parts settled at the same conditions I get significant errors on
aluminium. Why?
Different materials have different emissivity . A typical value for aluminium (roughly polished) is 0.18 and for
plastics values of 0.84…0.95 are typical. IR thermometers use the radiation flux between the sensitive
element in the sensor and the object of interest, given by the equation
Where
ε
α
σ is the Stefan-Boltzmann constant,
A
F
T
element) and the object temperature that we need.
Note that these are all in Kelvin, heat exchange knows only physics.
When a body with low emissivity (such as aluminium) is involved in this heat transfer, the portion of the
radiation incident to the sensor element that really comes from the object of interest decreases – and the
reflected environmental IR emissions take place. (This is all for bodies with zero transparency in the IR band.)
The IR thermometer is calibrated to stay within specified accuracy – but it has no way to separate the
incoming IR radiation into real object and reflected environmental part. Therefore, measuring objects with low
emissivity is a very sophisticated issue and infra-red measurements of such materials is a specialised field.
What can be done to solve that problem? Look at paintings – for example, oil paints are likely to have
emissivity of 0.85…0.95 – but keep in mind that the stability of the paint emissivity has inevitable impact on
measurements.
It is also a good point to keep in mind that not everything that looks black is “black” also for IR. For example,
even heavily oxidized aluminium has still emissivity as low as 0.30.
How high is enough? Not an easy question – but, in all cases the closer you need to get to the real object
temperature the higher the needed emissivity will be, of course.
With the real life emissivity values the environmental IR comes into play via the reflectivity of the object (the
sum of Emissivity, Reflectivity and Absorptivity gives 1.00 for any material). The larger the difference between
3901090615
Rev 002
q
1
1
a-b
1
1
14 ESD Precautions
15 FAQ
=
and ε
is the absorptivity of the sensor (in this case),
and T
and A
is the shape factor,
ε
1
.
α
2
2
2
1
are the emissivity of the two objects,
.
are known temperature of the sensor die (measured with specially integrated and calibrated
are the surface areas involved in the radiation heat transfer,
( )
T
1
4
.
σ
.
A
1
.
F
a
−
b
−
ε
2
.
( )
T
2
4
.
σ
.
A
2
,
Page 25 of 28
Infra Red Thermometer
12 Oct 2010
Data Sheet