MLX90632 FIR sensor
Datasheet
Features and Benefits
Application Examples
Small size of 3x3mm
High precision non-contact temperature
measurements
Easy to integrate
Factory calibrated
Body temperature measurement
External ambient and object temperature
calculation
Non-contact thermometer for mobile and
IoT application
Standard measurement resolution 0.02°C
Temperature sensing element for
residential, commercial and industrial
building air conditioning
Medical measurement resolution 0.01°C
Supply voltage of 3.3V, supply current
1mA (sleep current less than 2.5uA)
Industrial temperature control of moving
parts
I2C compatible digital interface
Software definable I C address with 1 LSB
bit external address pin
Home appliances with temperature
control
Healthcare
Field of View of 50°
Livestock monitoring
Default refresh rate 0.5s, configurable
between 16ms and 2s
https://github.com/melexis/mlx90632library
Integrated post-calibration option
2
Figure 1: Image of MLX90632
MLX90632 FIR sensor
Datasheet
Description
The MLX90632 is a non-contact infrared temperature sensor in a small SMD SFN package. The device is factory
calibrated with calibration constants stored in the EEPROM memory. The ambient and object temperature can
be calculated externally based on these calibration constants and the measurement data.
A major strength of the MLX90632 is that these temperature differences around the sensor package will be
reduced to a minimum. However, some extreme cases will influence the sensor.
The accuracy of the thermometer can be influenced by temperature differences in the package induced by
causes like (among others): hot electronics behind the sensor, heaters/coolers behind or beside the sensor or by
a hot/cold object very close to the sensor that not only heats the sensing element in the thermometer but also
the thermometer package.
In the same way, localized thermal variations -like turbulence in the air- will not generate thermal noise in the
output signal of the thermopile.
The MLX90632 is available in two different versions: standard and medical accuracy.
Both versions are calibrated in the ambient temperature range from -20 to 85˚C.
The difference between both versions is visible in accuracy and the object temperature range.
The medical version is factory calibrated with an accuracy of ±0.2˚C within the narrow object temperature range
from 35 to 42˚C for medical applications. This version also allows Extended range operation. This measurement
type option is implemented in order to give additional range to the medical devices. The object temperature
range is limited from -20 to 100˚C. For more information see Section 11.2.
On the other hand, the standard version covers an object temperature range from -20 to 200˚C but offers an
accuracy of ±1˚C.
It is very important for the application designer to understand that these accuracies are guaranteed and
achievable when the sensor is in thermal equilibrium and under isothermal conditions (no temperature
differences across the sensor package).
The typical supply voltage of the MLX90632 is 3.3V. For the I2C communication with the master microcontroller,
two versions of the sensor are available, working either at 3.3V or 1.8V I2C reference voltage.
The communication to the chip is done by I2C in fast mode plus (FM+).
Through I2C the external microcontroller has access to the following blocks:
RAM memory used for measurement data, in this document mainly referred to as ‘storage memory’
EEPROM used to store the trimming values, calibration constants and device/measurement settings
Based on this data, the external microcontroller can calculate the object temperature and if needed the sensor
temperature.
An optical filter (long-wave pass) that cuts off the visible and near infra-red radiant flux is integrated in the sensor
to provide ambient light immunity. The wavelength pass band of this optical filter is from 2 till 14µm.
MLX90632 FIR sensor
Datasheet
Contents
Features and Benefits................................................................................................................................ 1
Application Examples ................................................................................................................................ 1
Description ................................................................................................................................................ 2
1. Ordering Information ............................................................................................................................ 5
2. Glossary of Terms .................................................................................................................................. 6
3. Absolute Maximum ratings .................................................................................................................... 7
4. Pin definitions and descriptions ............................................................................................................. 8
5. Electrical characteristics ........................................................................................................................ 9
6. Detailed General Description............................................................................................................... 10
6.1. Block diagram.................................................................................................................................... 10
6.2. Description ........................................................................................................................................ 10
7. Memory map ....................................................................................................................................... 11
7.1. Product ID.......................................................................................................................................... 14
7.2. Product Code (0x2409) ..................................................................................................................... 15
7.3. Customer Data storage Area (0x24C0 to 0x24CF) .......................................................................... 15
8. Control and configuration.................................................................................................................... 16
8.1. Measurement control....................................................................................................................... 16
8.2. Device status ..................................................................................................................................... 18
8.3. Measurement settings...................................................................................................................... 19
8.3.1. Refresh rate................................................................................................................................. 19
9. I2C commands ..................................................................................................................................... 21
9.1. I2C address......................................................................................................................................... 22
9.1.1. Slave Address change flow ......................................................................................................... 22
9.1.2. Slave Address change example .................................................................................................. 23
9.2. Addressed read ................................................................................................................................. 24
9.3. Addressed write ................................................................................................................................ 25
9.4. Global reset ....................................................................................................................................... 25
9.5. Addressed reset ................................................................................................................................ 26
9.6. EEPROM unlock for customer access .............................................................................................. 26
9.7. Direct read......................................................................................................................................... 26
10. Operating Modes............................................................................................................................... 27
11. Temperature calculation ................................................................................................................... 29
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11.1. Medical measurement ................................................................................................................... 29
11.1.1. Pre-calculations ........................................................................................................................ 30
11.1.2. Ambient temperature .............................................................................................................. 30
11.1.3. Object temperature ................................................................................................................. 31
11.1.4. Example Medical measurement Temperature Calculation .................................................... 31
11.2. Extended range measurement ...................................................................................................... 36
11.2.1. Pre-calculations ........................................................................................................................ 36
11.2.2. Ambient temperature .............................................................................................................. 37
11.2.3. Object temperature ................................................................................................................. 37
11.2.4. Example Extended range measurement Temperature Calculation ....................................... 39
12. Performance characteristics .............................................................................................................. 43
12.1. Accuracy .......................................................................................................................................... 43
12.1.1. Standard .................................................................................................................................... 43
12.1.2. Medical ...................................................................................................................................... 44
12.2. Field of View (FoV) .......................................................................................................................... 45
12.3. Noise ................................................................................................................................................ 46
13. Mechanical Drawing .......................................................................................................................... 47
13.1. Package dimensions ....................................................................................................................... 47
13.2. PCB footprint................................................................................................................................... 48
14. Application schematic........................................................................................................................ 49
14.1. 3V3 I2C mode .................................................................................................................................. 49
14.2. 1V8 I2C mode .................................................................................................................................. 50
15. Software ............................................................................................................................................ 51
16. Standard information regarding manufacturability of Melexis products with different soldering
processes............................................................................................................................................ 52
17. ESD Precautions................................................................................................................................. 53
18. Application comments ....................................................................................................................... 53
19. Table of figures .................................................................................................................................. 54
20. Disclaimer .......................................................................................................................................... 55
21. Contact Information .......................................................................................................................... 55
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MLX90632 FIR sensor
Datasheet
1. Ordering Information
Product
Temperature Code
Package
Option Code
Packing Form
MLX90632
S
LD
BCB-000
RE
MLX90632
S
LD
DCB-000
RE
MLX90632
S
LD
DCB-100
RE
Table 1 : Ordering codes for MLX90632
Legend:
Temperature Code:
S: from -20°C to 85°C sensor temperature
Package Code:
“LD” for SFN 3x3 package
Option Code:
XYZ-123
X: Accuracy
B: Standard accuracy
D: Medical accuracy
Y: Pixel type
C: High stability version
Z: Field Of View
B: 50 degrees
2
1: I C level
0: 3V3
1: 1V8
2-3:
00: Standard configuration
xx: Reserved
Packing Form:
“RE” for Reel
Ordering Example:
“MLX90632SLD-DCB-000-RE”
For a FIR Sensor type in SFN 3x3 package with medical accuracy, Field Of View of
50 degrees and 3V3 I2C level, delivered in Reel.
Table 2: Coding legend
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MLX90632 FIR sensor
Datasheet
2. Glossary of Terms
POR
Power On Reset
IR
InfraRed
2
IC
Inter-Integrated Circuit
SDA
Serial DAta – I C compatible communication pins
SCL
Serial CLock – I C compatible communication pins
ACK / NACK
Acknowledge / Not Acknowledge
SOC
Start Of Conversion
EOC
End Of Conversion
FOV
Field Of View
Ta
Ambient Temperature measured from the chip – (the package temperature)
To
Object Temperature, ‘seen’ from IR sensor
SFN
Single Flat pack No-lead
TBD
To Be Defined
LSB
Least Significant Bit
MSB
Most Significant Bit
EMC
Electro-Magnetic Compatibility
ESD
Electro-Static Discharge
HBM
Human Body Model
CDM
Charged Device Model
2
2
Table 3: List of abbreviations
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Datasheet
3. Absolute Maximum ratings
Parameter
Symbol
Min.
Typ.
Max.
Unit
Supply Voltage, (over voltage)
VDD
5
V
Supply Voltage, (operating)
VDD
3.6
V
Reverse Voltage
VR
-1.5
V
VADDR
VDD + 0.6
V
Address-pin Voltage
Operating Temperature Range,
TA
-20
+85
°C
Storage Temperature Range,
TS
-40
+105
°C
ESD Sensitivity
-
HBM (acc. AEC Q100 002)
2
kV
-
CDM (acc. AEC Q100 011)
750
V
-
Air discharge (acc. IEC61000-4-2)
+4
kV
-
Contact discharge (acc. IEC61000-4-2)
+2
kV
10
μA
DC current into SCL
DC sink current, SDA pin
20
mA
DC clamp current, SDA pin
25
mA
DC clamp current, SCL pin
25
mA
EEPROM re-writes
10
Table 4: Absolute maximum ratings
Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute maximum rated conditions for extended periods may affect device reliability.
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Datasheet
4. Pin definitions and descriptions
Figure 2: MLX90632 TOP view
Pin #
Name
Direction
Description
1
SDA
In/Out
I C Data line
2
VDD
POWER
Supply
3
GND
GND
Ground
4
SCL
In
I C Clock line
5
ADDR
In
LSB of I C address
2
2
2
Table 5: Pin definition
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Datasheet
5. Electrical characteristics
All parameters are valid for TA = 25 ˚C, VDD = 3.3V (unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
3
3.3
3.6
V
0.5
1
1.4
mA
1.5
2.5
uA
Supplies
External supply
VDD
Supply current
IDD
No load
Sleep current
IDDpr
No load, erase/write EEPROM
operations
Power On Reset
POR level
VPOR_up
Power-up (full temp range)
1.3
2.4
V
POR level
VPOR_down
Power-down (full temp range)
1.1
2.1
V
VPOR_hys
Full temp range
200
500
mV
TPOR
Ensure POR signal
20
ms
Tvalid
After POR
POR hysteresis
VDD rise time (10% to 90% of
specified supply voltage)
Output valid
(result in RAM)
64
ms
2
I C compatible 2-wire interface
2
I C Voltage
VI2C
I C version = 1.8V
2
I C version = 3.3V
1.65
3
Input high voltage
VIH
Over temperature and supply
Input low voltage
VIL
Output low voltage
VOL
2
1.95
3.6
V
V
0.7*VI2C
VI2C+0.5
V
Over temperature and supply
-0.5
0.3*VI2C
V
Over temperature and supply
0
0.4
V
VDD+0.5
V
0.5
V
1
μA
Address pin voltage (“1”)
VADDR,HI
2
Address pin voltage (“0”)
VADDR,LO
0
ADDR leakage
IADDR, leak
1.8
VDD
VDD
SCL leakage
ISCL, leak
VSCL=3.6V, Ta=+85°C
1
μA
SDA leakage
ISDA, leak
VSDA=3.6V, Ta=+85°C
1
μA
SCL capacitance
CSCL
10
pF
SDA capacitance
CSDA
10
pF
Slave address
SA
Factory default, ADDR-pin grounded
3A
hex
Table 6: Electrical characteristics
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MLX90632 FIR sensor
Datasheet
6. Detailed General Description
6.1. Block diagram
Figure 3: Block diagram
6.2. Description
The MLX90632 is a far infrared, non-contact temperature sensor which is factory calibrated to a high
accuracy. Internally, electrical and thermal precautions are taken to compensate for thermally harsh external
conditions. The thermopile sensing element voltage signal is amplified and d igitized. After digital filtering,
the raw measurement result is stored in the RAM memory. Furthermore, the MLX90632 contains a sensor
element to measure the temperature of the sensor itself. The raw information of this sensor is also stored in
RAM after processing. All above functions are controlled by a state machine. The result of each
measurement conversion is accessible via I2C.
The communication to the chip is done by I2C in fast mode plus (FM+). The requirement of the standard is to
run at frequencies up to 1MHz. Through I2C the external unit can have access to the following blocks:
Control registers of internal state machines
RAM (96cells x 16bit) for pixel and auxiliary measurement data, in this document mainly referred to
as ‘storage memory’.
EEPROM (256cells x 16bit) used to store the trimming values, calibration constants and various
device/measurement settings.
From the measurement data and the calibration data the external unit can calculate both the sensor
temperature and the object temperature. The calculation allows the customer to adjust the calibration for
his own application in case an optical window or obstructions are present.
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Datasheet
7. Memory map
Some bits in the registers below are Melexis reserved. Those bits need to be read and masked, prior to
writing operation.
Access
Address
Name
Description
EEPROM
Read-only
0x2405
ID0[15:0]
Chip version
Read-only
0x2406
ID1[15:0]
Chip version
Read-only
0x2407
ID2[15:0]
Chip version
Read-only
0x2408
ID_CRC16
CRC
Read-only
0x2409
EE_PRODUCT_CODE
Sensor information
-
-
Read-only
0x240B
EE_VERSION
EEPROM version
Read-only
0x240C
EE_P_R [15:0]
P_R calibration constant (16-bit, Least Significant Word)
Read-only
0x240D
EE_P_R [31:16]
P_R calibration constant (16-bit, Most Significant Word)
Read-only
0x240E
EE_P_G [15:0]
P_G calibration constant (16-bit, Least Significant Word)
Read-only
0x240F
EE_P_G [31:16]
P_G calibration constant (16-bit, Most Significant Word)
Read-only
0x2410
EE_P_T [15:0]
P_T calibration constant (16-bit, Least Significant Word)
Read-only
0x2411
EE_P_T [31:16]
P_T calibration constant (16-bit, Most Significant Word)
Read-only
0x2412
EE_P_O [15:0]
P_O calibration constant (16-bit, Least Significant Word)
Read-only
0x2413
EE_P_O [31:16]
P_O calibration constant (16-bit, Most Significant Word)
Read-only
0x2414
EE_Aa [15:0]
Aa calibration constant (16-bit, Least Significant Word)
Read-only
0x2415
EE_Aa [31:16]
Aa calibration constant (16-bit, Most Significant Word)
Read-only
0x2416
EE_Ab [15:0]
Ab calibration constant (16-bit, Least Significant Word)
Read-only
0x2417
EE_Ab [31:16]
Ab calibration constant (16-bit, Most Significant Word)
Read-only
0x2418
EE_Ba [15:0]
Ba calibration constant (16-bit, Least Significant Word)
Read-only
0x2419
EE_Ba [31:16]
Ba calibration constant (16-bit, Most Significant Word)
Read-only
0x241A
EE_Bb [15:0]
Bb calibration constant (16-bit, Least Significant Word)
Read-only
0x241B
EE_Bb [31:16]
Bb calibration constant (16-bit, Most Significant Word)
Read-only
0x241C
EE_Ca [15:0]
Ca calibration constant (16-bit, Least Significant Word)
Read-only
0x241D
EE_Ca [31:16]
Ca calibration constant (16-bit, Most Significant Word)
Read-only
0x241E
EE_Cb [15:0]
Cb calibration constant (16-bit, Least Significant Word)
Read-only
0x241F
EE_Cb [31:16]
Cb calibration constant (16-bit, Most Significant Word)
Read-only
0x2420
EE_Da [15:0]
Da calibration constant (16-bit, Least Significant Word)
Read-only
0x2421
EE_Da [31:16]
Da calibration constant (16-bit, Most Significant Word)
Read-only
0x2422
EE_Db [15:0]
Db calibration constant (16-bit, Least Significant Word)
Melexis reserved
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Read-only
0x2423
EE_Db [31:16]
Db calibration constant (16-bit, Most Significant Word)
Read-only
0x2424
EE_Ea [15:0]
Ea calibration constant (16-bit, Least Significant Word)
Read-only
0x2425
EE_Ea [31:16]
Ea calibration constant (16-bit, Most Significant Word)
Read-only
0x2426
EE_Eb [15:0]
Eb calibration constant (16-bit, Least Significant Word)
Read-only
0x2427
EE_Eb [31:16]
Eb calibration constant (16-bit, Most Significant Word)
Read-only
0x2428
EE_Fa [15:0]
Fa calibration constant (16-bit, Least Significant Word)
Read-only
0x2429
EE_Fa [31:16]
Fa calibration constant (16-bit, Most Significant Word)
Read-only
0x242A
EE_Fb [15:0]
Fb calibration constant (16-bit, Least Significant Word)
Read-only
0x242B
EE_Fb [31:16]
Fb calibration constant (16-bit, Most Significant Word)
Read-only
0x242C
EE_Ga [15:0]
Ga calibration constant (16-bit, Least Significant Word)
Read-only
0x242D
EE_Ga [31:16]
Ga calibration constant (16-bit, Most Significant Word)
Read-only
0x242E
EE_Gb [15:0]
Gb calibration constant (16-bit)
Read-only
0x242F
EE_Ka [15:0]
Ka calibration constant (16-bit)
Read-only
0x2430
EE_Kb [15:0]
Kb calibration constant (16-bit)
-
-
R/W
0x2481
EE_Ha [15:0]
Ha Customer calibration constant (16 bit)
R/W
0x2482
EE_Hb [15:0]
Hb Customer calibration constant (16 bit)
-
-
R/W
0x24C0…0x24CF
-
-
R/W
0x24D4
EE_CONTROL
EEPROM Control register, measurement control
R/W
0x24D5
EE_I2C_ADDRESS
I C slave address >> 1
Example: standard address (= 0x003A) >> 1 = 0x001D
-
-
Melexis reserved
R/W
0x24E1
EE_MEAS_1
Measurement settings 1 (see section Measurement settings)
R/W
0x24E2
EE_MEAS_2
Measurement settings 2 (see section Measurement settings)
-
-
Melexis reserved
Melexis reserved
Customer data
Customer data storage area
Melexis reserved
2
Melexis reserved
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REGISTER
2
R/W
0x3000
REG_I2C_ADDRESS
I C slave address >> 1
R/W
0x3001
REG_CONTROL
Control register, measurement mode
-
-
R/W
0x3FFF
Melexis reserved
REG_STATUS
Status register: data available
RAM
Read-only
0x4000
RAM_1
Raw data 1
Read-only
0x4001
RAM_2
Raw data 2
Read-only
0x4002
RAM_3
Raw data 3
Read-only
0x4003
RAM_4
Raw data 4
Read-only
0x4004
RAM_5
Raw data 5
Read-only
0x4005
RAM_6
Raw data 6
Read-only
0x4006
RAM_7
Raw data 7
Read-only
0x4007
RAM_8
Raw data 8
Read-only
0x4008
RAM_9
Raw data 9
…
…
…
…
Read-only
0x4033
RAM_52
Raw data 52
Read-only
0x4034
RAM_53
Raw data 53
Read-only
0x4035
RAM_54
Raw data 54
Read-only
0x4036
RAM_55
Raw data 55
Read-only
0x4037
RAM_56
Raw data 56
Read-only
0x4038
RAM_57
Raw data 57
Read-only
0x4039
RAM_58
Raw data 58
Read-only
0x403A
RAM_59
Raw data 59
Read-only
0x403B
RAM_60
Raw data 60
Table 7: Memory table
Important!
The width of the EEPROM is 16 bit.
Some calibration parameters are 32 bit and split up into two 16 bit numbers in EEPROM.
The least significant 16 bits of the parameter starts on the address shown in the Memory table.
Example: To retrieve value EE_Aa (32bit) = EE_Aa_MS (at 0x2415) 1);
//it is now safe to power down the device in order load the new Slave address
//After POR the new slave address should be used for i2c communication
mlx90632_i2c_read_SA(NEW_SLAVE_ADDRESS, MLX90632_REG_CTRL, &rData);
}
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9.2. Addressed read
The addressed read command allows doing an incremental read-out, starting from any given address within the
memory space.
SCL
MSByte address
SDA
_
S 0 1 1 1 0 1 0 W A
Slave address
LSByte address
A
MSByte data
A S 0 1 1 1 0 1 0 R A
Slave address
LSByte data
A
N P
A
K
Figure 12: Addressed read
Important!
An addressed read is only valid when combining directly an addressed write and a direct read
through a repeated START condition. In case the read and write part are separated by a STOP
condition, or in case the read is not directly following the write, or in case the slave address is not
identical for both, the command will not be seen as an addressed read. As a result, the second
read will in practice act as a direct read.
As soon as incremental addressing leaves the address space, the slave will respond with all 8’hFF.
Figure 13 Addressed read - Oscilloscope Plot
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9.3. Addressed write
The addressed write command allows doing an incremental write, starting from any given address within the
memory space.
SCL
MSByte address
SDA
_
S 0 1 1 1 0 1 0 W A
LSByte address
A
MSByte data
A
LSByte data
A
A P
Slave address
Figure 14: Addressed write
Important!
The slave is sending ACK/NACK based on the fact whether it was able to write data (timing, end of
register space, access rights).
The slave will automatically increment the address of the write byte, independent if it gave an
ACK or a NACK to the master. It is up to the master to re-write the byte afterwards.
Before writing to EEPROM it is necessary to erase the specific address location in EEPROM. This is
done by first writing 0x0000. Then the new data can be written.
When the device is busy with the write operation to EEPROM, new write commands will be
ignored. A read operation will return invalid data. The fact that the device is busy is indicated via
the bit device_busy in REG_STATUS.
9.4. Global reset
This command resets all devices on the I2C bus (based on the general call address 0x00).
SCL
8'h06
SDA
_
S 0 0 0 0 0 0 0 W A
A P
Address all devices
Figure 15: Global reset
Note: After this command, a delay at least 150us is needed before the next communication with the device.
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9.5. Addressed reset
This command resets the addressed device only (based on the I2C address).
SCL
8'h30
SDA
8'h05
_
S 0 1 1 1 0 1 0 W A
A
8'h00
8'h06
A
A
A P
Slave address
Figure 16: Addressed reset
Note: After this command, a delay at least 150us is needed before the next communication with the device.
9.6. EEPROM unlock for customer access
This command unlocks the EEPROM allowing only one write operation to an EEPROM word in the customer part
of the EEPROM.
After the EEPROM write, the EEPROM access goes back to the “NoKey” access mode.
SCL
8'h30
SDA
8'h05
_
S 0 1 1 1 0 1 0 W A
A
8'h55
8'h4C
A
A
A P
Slave address
Figure 17: EEPROM unlock
9.7. Direct read
The direct read command allows an incremental read out at a default start address.
This default start address is fixed to the register location REG_STATUS (0x3FFF).
According to the I2C specification, the master will keep sending an acknowledge (A) until it want to stop. This is
indicated by sending a NAK. As a result, the slave will stop driving the SDA-bus as soon as a NAK is received by the
master.
As soon as the incremental addressing leaves the address space, the slave will respond with all 8’hFF.
SCL
MSByte of DEF. ADDR
SDA
S 0 1 1 1 0 1 0 R A
LSByte of DEF. ADDR
A
MSByte of DEF. ADDR + 1
A
LSByte of DEF. ADDR + 1
A
Slave address
...
A
MSByte of DEF. ADDR + x
A
MSByte of DEF. ADDR + x
A
N P
A
K
Figure 18: Direct read
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10. Operating Modes
The device has 2 states of operation: sleep state and active state.
Sleep state
In this state, most of the circuitry is disabled to limit the current consumption to a few uA.
Active state
In this state, the sensor is active.
Several measurement modes exist. These modes are controlled by bits mode[1:0] in register REG_CONTROL[2:1].
In continuous mode the measurements are constantly running while in step mode the state machine will execute
only one measurement which is initiated by the soc bit or a whole set of measurements initiated by the sob bit.
After finishing the measurement(s) it will go in wait state until the next measurement is initiated by the soc or sob
bit. If soc is used to initiate a measurement, the measurements are following the measurement sequence as
defined in the measurement table.
The different possible measurement modes are:
mode[1:0] = 01: Enables the sleeping step mode.
The device will be in sleep mode. On request (soc or sob bit), the device will power-on, the
state machine will perform one measurement(soc) or the full measurement table (sob), will
go into sleep and wait for the next command.
In the sleeping step mode all the measurements from the measurement table will be
performed so that all data necessary for the calculations is refreshed. The two ways of using
the device in this mode are:
SOB bit
The SOB bit initiates a full measurement table measurement. Once the measurement is
started, the SOB bit is cleared and the device_busy bit is set internally in the MLX90632.
When all the measurements from the measurement table are performed, the device_busy
bit is cleared indicating the end of measurements – the new data can be read. The flow
should be:
1. Set SOB bit
2. Wait for all the measurements from the measurement table to finish - depending on
the refresh rates (see Table 10 and Table 11)
3. Make sure that the device_busy bit is cleared
4. Read out the data
5. Calculate the temperatures
SOC bit
The SOC bit initiates a single measurement from the measurement table. The
measurements are being performed consecutively as set in the measurement table. Once
the measurement is started, the SOC bit is cleared internally in the MLX90632 and could be
set again so that the next measurement from the measurement table is started right after
the current one is done. When the current measurement is done, the new_data bit is set –
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the new data can be read and the bit should be cleared. The flow should be:
1. Set SOC bit
2. Wait for the 1 st measurement from the measurement table to finish - depending on
the refresh rate (see Table 10 and Table 11)
3. Make sure that the new_data bit is set and clear it
4. Set SOC bit
5. Wait for the 2 nd measurement from the measurement table to finish - depending on
the refresh rate (see Table 10 and Table 11)
6. Make sure that the new_data bit is set and clear it
7. If medical mode is selected proceed with step 11 (e.g. skip 8..10)
8. Set SOC bit
9. Wait for the 3 rd measurement from the measurement table to finish - depending on
the refresh rate (see Table 10 and Table 11)
10. Make sure that the new_data bit is set and clear it
11. Read out the data
12. Calculate the temperatures
mode[1:0] = 10: Enables the step mode.
The state machine will do one measurement upon request (soc bit) and will wait for the next
command. The device remains powered all the time in this mode.
mode[1:0] = 11: Device is in continuous mode.
Measurements are executed continuously. The device remains powered all time in this mode.
By default, the device is in continuous mode.
Switching between the step modes and continuous mode has only effect after the current measurement has
finished (not waiting until the end of the measurement table was reached).
There are two possible measurement types to select from:
meas_select[4:0] = 0x00: Enables the medical measurement. In order to calculate the correct
temperatures, the appropriate raw data values and formulas should be used. Refer to the medical
measurement temperature calculations
meas_select[4:0] = 0x11: Enables the extended range measurement. In order to calculate the correct
temperatures, the appropriate raw data values and formulas should be used. Refer to the extended
range measurement temperature calculations
Note: If other values are being used for meas_select, the resulting calculated temperatures will be invalid.
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11. Temperature calculation
11.1. Medical measurement
To calculate the ambient and object temperature, a set of 2 measurements is required:
Measurement 1: RAM_4, RAM_5, RAM_6;
Measurement 2: RAM_7, RAM_8, RAM_9;
One should notice this requires double the measurement time than specified (= 2 * 500ms) for the very first
calculation.
After the first calculation, TA and TO can be calculated with the next measurement.
Example:
t0:
Measurement 1
(cycle_pos = 1)
=>
no calculation of TA or TO possible
because not all parameters are known
t1:
Measurement 2
(cycle_pos = 2)
=>
calculate TA (RAM_6, RAM_9)
calculate TO (RAM_7, RAM_8, RAM_6, RAM_9)
=>
1s.
Measurement 3 (= 1)
(cycle_pos = 1)
=>
calculate TA (RAM_6, RAM_9)
calculate TO (RAM_4, RAM_5, RAM_6, RAM_9)
=>
0.5s.
Measurement 4 (= 2)
(cycle_pos = 2)
=>
calculate TA (RAM_6, RAM_9)
calculate TO (RAM_7, RAM_8, RAM_6, RAM_9)
=>
0.5s.
t2:
t3:
t4:
…
To calculate the new ambient and object temperature RAM_6 and RAM_9 have to be used.
The choice between [RAM_4 and RAM_5] or [RAM_7 and RAM_8] depends on the current measurement.
REG_STATUS[6:2] (= “cycle_pos”) returns the current position of the measurement defined in the measurement
table.
Using the current data and the data from measurement (x-1), TA and TO can be calculated every 500ms.
The complete measurement sequence can be automated by using the new_data bit in combination with
cycle_pos bits.
The sequence should look like the following:
Write new_data = 0
Check when new_data = 1
Read cycle_pos to get measurement pointer
If cycle_pos = 1
Calculate TA and TO base on RAM_4, RAM_5, RAM_6, RAM_9
If cycle_pos = 2
Calculate TA and TO base on RAM_7, RAM_8, RAM_6, RAM_9
Return to top
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11.1.1. Pre-calculations
11.1.1.1. Ambient
[
]⁄
The parameter EE_Gb is a signed 16-bit number.
11.1.1.2. Object
OR
[
]⁄
The parameter EE_Ka is a signed 16-bit number.
11.1.2. Ambient temperature
(
)
(
)
With:
Ta in degrees Celsius
P_R
= EE_P_R * 2-8
P_O
= EE_P_O * 2-8
P_G
= EE_P_G * 2-20
P_T
= EE_P_T * 2-44
The parameters EE_P_R, EE_P_O, EE_P_G and EE_P_T are signed 32-bit numbers.
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11.1.3. Object temperature
(
)
√
With:
Fa
Fb
Ga
Ha
Hb
TO0
TA0
(
(
)
(
[ ]
))
= EE_Fa * 2-46
= EE_Fb * 2-36
= EE_Ga * 2-36
= EE_Ha * 2-14
= EE_Hb * 2-10
= 25 C
= 25 C
(
)
Ea
= EE_Ea * 2-16
Eb
= EE_Eb * 2-8
Ta[K] = TADUT + 273.15 in Kelvin
TODUT = Object temperature in 25 C
= 1 = Object Emissivity parameter (not stored in EEPROM, but part of the ‘app’)
The parameters EE_Ea, EE_Eb, EE_Fa, EE_Fb, EE_Ga are signed 32-bit numbers.
The parameters EE_Gb, EE_Ka, EE_Ha and EE_Hb are signed 16-bit numbers.
Note:
One can see that to compute “To (object temperature)”, “To” already needs to be known.
“To (object temperature)” is computed in an iterative manner. In the first iteration “To” is assumed to be 25°C.
In the 2nd iteration the result of first iteration is used, and in the 3rd iteration the end result is obtained.
(See example on next page).
11.1.4. Example Medical measurement Temperature Calculation
Assumed are the following calibration parameters read from EEPROM:
DATA
(hex)
ADDR
PARAM
0x240C
EE_P_R [15:0]
0103
0x240D
EE_P_R [31:16]
005D
0x240E
EE_P_G [15:0]
FAE5
0x240F
EE_P_G [31:16]
051C
0x2410
EE_P_T [15:0]
0000
0x2411
EE_P_T [31:16]
0000
0x2412
EE_P_O [15:0]
1900
0x2413
EE_P_O [31:16]
hex to dec
Conversion to use in formula
-8
EE_P_R = 005D0103hex = 6095107dec
P_R = 6095107 * 2 = 23809.01
EE_P_G = 051CFAE5hex = 85785317dec
P_G = 85785317 * 2
EE_P_T = 00000000hex = 0dec
P_T = 0 * 2
EE_P_O = 00001900hex = 6400dec
P_O = 6400 * 2 = 25
-44
-20
= 81.81125
=0
-8
0000
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0x2424
EE_Ea [15:0]
CFAE
0x2425
EE_Ea [31:16]
0051
0x2426
EE_Eb [15:0]
0103
-16
EE_Ea = 0051CFAEhex = 5361582dec
Ea = 5361582 * 2
= 81.81125
EE_Eb = 005D0103hex = 6095107dec
Eb = 6095107 * 2 = 23809.01
EE_Fa = 03506351hex = 5559995dec
Fa = 55599953 * 2
EE_Fb = FE2571F1hex = -31100431dec
Fb = -31100431 * 2
EE_Ga = FDFFA7A5hex = -33577052dec
Ga = -33577052 * 2
-8
0x2427
EE_Eb [31:16]
005D
0x2428
EE_Fa [15:0]
6351
0x2429
EE_Fa [31:16]
0350
0x242A
EE_Fb [15:0]
71F1
0x242B
EE_Fb [31:16]
FE25
0x242C
EE_Ga [15:0]
A7A4
0x242D
EE_Ga [31:16]
FDFF
0x242E
EE_Gb [15:0]
2600
EE_Gb = 2600hex = 9728dec
Gb = 9728 * 2
0x242F
EE_Ka [15:0]
2A00
EE_Ka = 2A00hex = 10752dec
Ka = 10752 * 2
0x2481
EE_Ha [15:0]
4000
EE_Ha = 4000hex = 16384dec
Ha = 16384 * 2
0x2482
EE_Hb [15:0]
0000
EE_Hb = 0000hex = 0dec
Hb = 0 * 2
-10
-10
-46
= 7.9E-07
-36
= -0.00045
-36
= -0.00049
= 9.5
-10
= 10.5
-14
=1
=0
Table 12: Example EEPROM calibration parameters
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The returned values from the RAM (0x4000 to 0x4008):
ADDR
PARAM
DATA
(hex)
DATA
(dec)
0x4003
RAM_4
FF9B
-101
0x4004
RAM_5
FF9D
-99
0x4005
RAM_6
57E4
22500
0x4006
RAM_7
FF97
-105
0x4007
RAM_8
FF99
-103
0x4008
RAM_9
59D8
23000
Table 13: Example RAM data
11.1.4.1. Ambient temperature calculation
[
(
]⁄
]⁄
[
)
(
(
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)
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11.1.4.2. Object temperature calculation
(
)
(
)
(
)
(
)
OR
Assumed is that RAM_4 and RAM_5 are updated lastly by the device (cycle_pos = 1)
]⁄
[
[
TO0
TA0
(
)
(
]⁄
= 25 C
= 25 C
)
Ta[K] = TADUT + 273.15 = 28.3947 + 273.15 = 301.5447
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(
)
√
(
(
)
(
[ ]
))
The emissivity parameter (Ɛ) is controlled by the user and is assumed in this example equal to 1.
TODUT = 25 for the first calculation
√
(
)
(
) (
(
)
) (
(
))
(
)
The object temperature needs to be calculated 3 times in order the get the end result.
Next object temperature calculation uses previous obtained object temperature.
√
√
(
)
(
(
) (
)
(
) (
))
(
)
(
(
) (
)
(
) (
))
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(
)
(
)
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11.2. Extended range measurement
This measurement type option is implemented in order to give additional range to the medical devices.
When using the extended range measurement the following should be done:
1. Switch the device to extended range measurement mode
2. Wait for the whole measurement to finish
3. Use the following routine to read the data of interest and calculate the temperatures.
All the necessary functions are available at https://github.com/melexis/mlx90632-library
To calculate the ambient and object temperature, a set of 3 measurements is required:
Measurement 1: RAM_52, RAM_53, RAM_54;
Measurement 2: RAM_55, RAM_56, RAM_57;
Measurement 3: RAM_58, RAM_59, RAM_60;
All three measurements should be available for proper temperature calculation.
11.2.1. Pre-calculations
11.2.1.1. Ambient
[
]⁄
The parameter EE_Gb is a signed 16-bit number.
11.2.1.2. Object
OR
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[
]⁄
The parameter EE_Ka is a signed 16-bit number.
11.2.2. Ambient temperature
(
)
(
)
With:
Ta in degrees Celsius
P_R
= EE_P_R * 2-8
P_O
= EE_P_O * 2-8
P_G
= EE_P_G * 2-20
P_T
= EE_P_T * 2-44
The parameters EE_P_R, EE_P_O, EE_P_G and EE_P_T are signed 32-bit numbers.
11.2.3. Object temperature
(
)
√
With:
Fa
Fb
Ga
Ha
Hb
TO0
TA0
(
(
)
(
))
[ ]
= EE_Fa * 2-46
= EE_Fb * 2-36
= EE_Ga * 2-36
= EE_Ha * 2-14
= EE_Hb * 2-10
= 25 C
= 25 C
(
)
Ea
= EE_Ea * 2-16
Eb
= EE_Eb * 2-8
Ta[K] = TADUT + 273.15 in Kelvin
TODUT = Object temperature in 25 C
= 1 = Object Emissivity parameter (not stored in EEPROM, but part of the ‘app’)
The parameters EE_Ea, EE_Eb, EE_Fa, EE_Fb, EE_Ga are signed 32-bit numbers.
The parameters EE_Gb, EE_Ka, EE_Ha and EE_Hb are signed 16-bit numbers.
Note:
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One can see that to compute “To (object temperature)”, “To” already needs to be known.
“To (object temperature)” is computed in an iterative manner. In the first iteration “To” is assumed to be 25°C.
In the 2nd iteration the result of first iteration is used, and in the 3rd iteration the end result is obtained.
(See example on next page).
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11.2.4. Example Extended range measurement Temperature Calculation
Assumed are the following calibration parameters read from EEPROM:
ADDR
PARAM
0x240C
EE_P_R [15:0]
DATA
(hex)
hex to dec
Conversion to use in formula
0103
0x240D
EE_P_R [31:16]
005D
0x240E
EE_P_G [15:0]
FAE5
0x240F
EE_P_G [31:16]
051C
0x2410
EE_P_T [15:0]
0000
0x2411
EE_P_T [31:16]
0000
0x2412
EE_P_O [15:0]
1900
0x2413
EE_P_O [31:16]
0000
0x2424
EE_Ea [15:0]
CFAE
0x2425
EE_Ea [31:16]
0051
0x2426
EE_Eb [15:0]
0103
0x2427
EE_Eb [31:16]
005D
0x2428
EE_Fa [15:0]
6351
0x2429
EE_Fa [31:16]
0350
0x242A
EE_Fb [15:0]
71F1
0x242B
EE_Fb [31:16]
FE25
0x242C
EE_Ga [15:0]
A7A4
-8
EE_P_R = 005D0103hex = 6095107dec
P_R = 6095107 * 2 = 23809.01
EE_P_G = 051CFAE5hex = 85785317dec
P_G = 85785317 * 2
EE_P_T = 00000000hex = 0dec
P_T = 0 * 2
EE_P_O = 00001900hex = 6400dec
P_O = 6400 * 2 = 25
EE_Ea = 0051CFAEhex = 5361582dec
Ea = 5361582 * 2
EE_Eb = 005D0103hex = 6095107dec
Eb = 6095107 * 2 = 23809.01
EE_Fa = 03506351hex = 5559995dec
Fa = 55599953 * 2
EE_Fb = FE2571F1hex = -31100431dec
Fb = -31100431 * 2
EE_Ga = FDFFA7A5hex = -33577052dec
Ga = -33577052 * 2
-44
-8
FDFF
0x242E
EE_Gb [15:0]
2600
EE_Gb = 2600hex = 9728dec
Gb = 9728 * 2
0x242F
EE_Ka [15:0]
2A00
EE_Ka = 2A00hex = 10752dec
Ka = 10752 * 2
0x2481
EE_Ha [15:0]
4000
EE_Ha = 4000hex = 16384dec
Ha = 16384 * 2
0000
EE_Hb = 0000hex = 0dec
-16
= 81.81125
-8
EE_Ga [31:16]
EE_Hb [15:0]
= 81.81125
=0
0x242D
0x2482
-20
Hb = 0 * 2
-10
-10
-46
= 7.9E-07
-36
= -0.00045
-36
= -0.00049
= 9.5
-10
= 10.5
-14
=1
=0
Table 14: Example EEPROM calibration parameters
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The returned values from the RAM (0x4033 to 0x403A):
ADDR
PARAM
DATA
(hex)
DATA
(dec)
0x4033
RAM_52
FE64
-412
0x4034
RAM_53
FEAB
-341
0x4035
RAM_54
57E4
22500
0x4036
RAM_55
FEA3
-349
0x4037
RAM_56
FE6A
-406
0x4038
RAM_57
59D8
23000
0x4039
RAM_58
000B
11
0x403A
RAM_59
0009
9
Table 15: Example RAM data
11.2.4.1. Ambient temperature calculation
[
(
]⁄
]⁄
[
)
(
(
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)
)
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11.2.4.2. Object temperature calculation
(
)
[
(
)
]⁄
)
)
[
TO0
TA0
(
(
(
(
)
]⁄
= 25 C
= 25 C
)
Ta[K] = TADUT + 273.15 = 28.3947 + 273.15 = 301.5447
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(
)
√
(
(
)
(
[ ]
))
The emissivity parameter (Ɛ) is controlled by the user and is assumed in this example equal to 1.
TODUT = 25 for the first calculation
√
(
) (
(
)
) (
(
))
(
)
The object temperature needs to be calculated 3 times in order the get the end result.
Next object temperature calculation uses previous obtained object temperature.
√
√
(
(
) (
)
(
) (
))
(
(
) (
)
(
) (
))
DOC#3901090632|REVISION 11 – NOV, 2021
(
)
(
)
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12. Performance characteristics
12.1. Accuracy
The calculated ambient temperature has an accuracy of ±3˚C between -20˚C and 85˚C of ambient temperature.
Between 15˚C and 45˚C the accuracy is ±1˚C.
All accuracy specifications apply under settled isothermal conditions only.
12.1.1. Standard
Figure 19: Standard accuracy table
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12.1.2. Medical
Figure 20: Medical accuracy table
The version MLX90632SLD-DCB complies with the ASTM standard section 5.4 (Designation: E1965 – 98 (Reapproved 2009) - Standard Specification for Infrared Thermometers for Intermittent Determination of Patient
Temperature.
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12.2. Field of View (FoV)
Point heat source
Sensitivity
100%
50%
Field Of View
Angle of incidence
Rotated sensor
Figure 21: Field of View measurement principle
Parameter
50% of maximum
10% of maximum
Unit
Field Of View
50
70
° (angular degrees)
Table 16: Field Of View of the MLX90632
Figure 22: Field of View of MLX90632 (FoV = 50˚)
The 50° is measured at the 50% level of sensitivity.
For high accuracy applications, one should take care that the field of view is not obstructed by the enclosure of
the application. For this, one has to take care that no obstruction is in a cone of at least 70° wide. For medical
applications the obstacle free zone should be at least 110o wide.
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12.3. Noise
Measurement conditions for noise performance are To = Ta = 25°C.
Note:
Due to the nature of thermal infrared radiation, it is normal that the noise will decrease for high temperature and
increase for lower temperatures.
Figure 23: NETD vs. Refresh rate
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13. Mechanical Drawing
13.1. Package dimensions
Figure 24: Package dimensions for MLX90632 (FoV = 50°)
Symbol
Min
Nom
Max
DD=EE
2.9
3.0 BSC
3.1
AT
0.90
0.95
1.00
Ra
0.05
D2
2.40
2.50
2.60
E2
2.00
2.10
2.20
Lo1
0.15 Max
Kk
0.20
0.30
--
NXL
0.35
0.40
0.45
e1
0.50 BSC
NminOne_e
(5-1)*e1
Ti
0.18
0.25
0.30
Tolerance (A_CC – A_CP)
-0.15
0.15
Tolerance (A_CC – A_CD)
-0.1
0.1
Table 17: Package dimensions for MLX90632 (FoV = 50°)
*BSC Ξ basic dimension
*A_CC = Center of silicon Cap
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*A_CD = Center of Die frame
*A_CP = Center of Package
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13.2. PCB footprint
Pin1 identificator
0.30
Package outline
3.00
2.10
PTH, 8*0.2mm
0.5mm pitch
Tented or plugged
0.25
2.55
3.00
0.3
0.25
0.15
0.1
- stencil opening
- package outline
- solder mask
- copper
0.15
Footprint design
Stencil opening
0.25x0.25
Stencil design
Recommended 1)PCB finish: OSP, ENIG, ENEPIG
2)Stencil thickness max 100um
3)Solderpaste – noclean , halogen free
Figure 25: PCB footprint and stencil design for MLX90632
C1
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