MLX90641 16x12 IR array
Datasheet
1. Features and Benefits
Small size, low cost 16x12 pixels IR array
Easy to integrate
Industry standard four lead TO39 package
Factory calibrated
Noise Equivalent Temperature Difference
(NETD) 0.1K @4Hz refresh rate
I2C compatible digital interface
Programmable refresh rate 0.5Hz…64Hz
2. Application Examples
High precision non-contact temperature
measurements
Microwave ovens
Intrusion / Movement detection
Temperature sensing element for
residential, commercial and industrial
building air conditioning
Thermal Comfort sensor in automotive Air
Conditioning control system
3.3V supply voltage
Passenger classification
Current consumption ≈ 12mA
2 FOV options – 55°x35° and 110°x75°
Industrial temperature control of moving
parts
Operating temperature -40°C ÷ 125°C
Visual IR thermometers
Target temperature -40°C ÷ 300°C
Complies with RoHS regulations
Driver SW for MCU available at:
https://github.com/melexis/mlx90641library.git
3. Description
The MLX90641 is a fully calibrated 16x12 pixels
thermal IR array in an industry standard 4-lead
TO39 package with digital interface.
The MLX90641 contains 192 FIR pixels. An
ambient sensor is integrated to measure the
ambient temperature of the chip and supply
sensor to measure the VDD. The outputs of all
sensors IR, Ta and VDD are stored in internal RAM
and are accessible through I2C.
Band gap
reference and
PTAT sensor
Vdd
Regulator for
digital part
34 MHz RC
oscillator
Array
M pixels
M amplifiers
M ADC
EEPROM
Storage RAM
I2C
Vss
SDA
SCL
Figure 1 Block diagram
MLX90641 16x12 IR array
Datasheet
Contents
1. Features and Benefits ............................................................................................................................ 1
2. Application Examples............................................................................................................................. 1
3. Description ............................................................................................................................................ 1
4. Ordering Information ............................................................................................................................ 6
5. Glossary of Terms .................................................................................................................................. 7
6. Pin Definitions and Descriptions ............................................................................................................ 8
7. Absolute Maximum Ratings ................................................................................................................... 8
8. General Electrical Specifications ............................................................................................................ 9
9. False pixel correction ........................................................................................................................... 10
10. Detailed General Description............................................................................................................. 10
10.1. Pixel position ................................................................................................................................... 10
10.2. Communication protocol ............................................................................................................... 11
10.2.1. Low level ................................................................................................................................... 11
10.3. Measurement mode ....................................................................................................................... 12
10.4. Refresh rate..................................................................................................................................... 12
10.5. Measurement flow ......................................................................................................................... 13
10.6. Address map ................................................................................................................................... 15
10.6.1. Internal registers....................................................................................................................... 15
10.6.2. RAM ........................................................................................................................................... 17
EEPROM ................................................................................................................................................. 18
11. Calculating Object Temperature ........................................................................................................ 21
11.1. Restoring calibration data from EERPOM and calculations.......................................................... 21
11.1.1. Restoring the VDD sensor parameters and VDD calculations ................................................ 21
11.1.2. Restoring the Ta sensor parameters ....................................................................................... 22
11.1.3. Restoring the offset .................................................................................................................. 22
11.1.4. Restoring the Sensitivity
.................................................................................................... 23
11.1.5. Restoring the Kta(i,j) coefficient .............................................................................................. 24
11.1.6. Restoring the Kv(i,j) coefficient ................................................................................................ 24
11.1.7. Restoring the GAIN coefficient (common for all pixel) ........................................................... 25
11.1.8. Restoring the KsTa coefficient (common for all pixel) ............................................................ 25
11.1.9. Restoring corner temperatures (common for all pixel) .......................................................... 25
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11.1.10. Restoring the KsTo coefficient
(common for all pixel) .................................... 25
11.1.11. Restoring sensitivity correction coefficients for each temperature range ......................... 26
11.1.12. Restoring Emissivity ................................................................................................................ 26
11.1.13. Restoring the Sensitivity
................................................................................................. 27
11.1.14. Restoring the offset of the CP ................................................................................................ 27
11.1.15. Restoring the Kv CP coefficient .............................................................................................. 27
11.1.16. Restoring the Kta CP coefficient ............................................................................................ 27
11.1.17. Restoring the TGC coefficient ................................................................................................ 27
11.1.18. Restoring calibration resolution control settings ................................................................. 28
11.2. Temperature calculation ................................................................................................................ 28
11.2.1. Example input data ................................................................................................................... 28
11.2.2. Temperature calculation .......................................................................................................... 31
12. Performance graphs .......................................................................................................................... 42
12.1. Accuracy .......................................................................................................................................... 42
12.1.1. Pixel accuracy............................................................................................................................ 42
12.1.2. Ta accuracy ............................................................................................................................... 43
12.2. Startup time .................................................................................................................................... 44
12.2.1. First valid data........................................................................................................................... 44
12.2.2. Thermal behavior...................................................................................................................... 44
12.3. Noise performance and resolution ................................................................................................ 45
12.4. Field of view (FOV) .......................................................................................................................... 47
13. Application information ..................................................................................................................... 48
13.1. Optical considerations .................................................................................................................... 48
13.2. Electrical considerations ................................................................................................................ 48
13.3. Using the device in “image mode” ................................................................................................ 49
14. Application Comments ...................................................................................................................... 50
15. Mechanical drawings ......................................................................................................................... 51
15.1. FOV 55°............................................................................................................................................ 51
15.2. FOV 110° ......................................................................................................................................... 52
15.3. Device marking ............................................................................................................................... 53
16. Standard Information ........................................................................................................................ 54
17. ESD Precautions................................................................................................................................. 54
18. Revision History Table ....................................................................................................................... 54
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19. Contact .............................................................................................................................................. 55
20. Disclaimer .......................................................................................................................................... 55
Tables
Table 1 Ordering information .......................................................................................................................................................... 6
Table 2 Glosarry of terms ................................................................................................................................................................ 7
Table 3 Pin definition ...................................................................................................................................................................... 8
Table 4 Absolute maximum ratings ................................................................................................................................................. 8
Table 5 Electrical specification ........................................................................................................................................................ 9
Table 6 Priorities of subpage controls ............................................................................................................................................16
Table 7 Configuration parameters memory ....................................................................................................................................18
Table 8 EEPROM overview (words) .................................................................................................................................................19
Table 9 Calibration parameters memory (EEPROM - bits) ...............................................................................................................20
Table 10 Calculation example input data ........................................................................................................................................28
Table 11 Calculation example calibration data ................................................................................................................................30
Table 12 Noise performance ..........................................................................................................................................................46
Table 13 Available FOV options ......................................................................................................................................................47
Table 14 Revision history ...............................................................................................................................................................54
Figures
Figure 1 Block diagram ................................................................................................................................................................... 1
Figure 2 MLX90641 Overview and pin description ........................................................................................................................... 8
Figure 3 Pixel in the whole FOV ......................................................................................................................................................10
2
Figure 4 I C write command format (default SA=0x33 is used) ........................................................................................................11
2
Figure 5 I C read command format (default SA=0x33 is used) .........................................................................................................11
Figure 6 Refresh rate timing ...........................................................................................................................................................12
Figure 7 Recommended measurement flow ...................................................................................................................................13
Figure 8 TV mode reading pattern ..................................................................................................................................................14
Figure 9 MXL90641 memory map ...................................................................................................................................................15
Figure 10 Status register (0x8000) bits meaning .............................................................................................................................15
Figure 11 Control register 1 (0x800D) bits meaning ........................................................................................................................16
2
Figure 12 I C configuration register (0x800F) bits meaning .............................................................................................................17
Figure 13 RAM memory map (Interleaved mode - default) ..............................................................................................................17
Figure 14 EEPROM to registers mapping .........................................................................................................................................18
Figure 15 EEPROM Hamming and data bit meaning ........................................................................................................................21
Figure 16 To calculation flow .........................................................................................................................................................31
Figure 17 Temperature absolute accuracy - MLX90641BCA .............................................................................................................42
Figure 18 Temperature absolute accuracy - MLX90641BCB .............................................................................................................43
Figure 19 Different accuracy zones depending on device type (BCA on the left and BCB on the right) ..............................................43
Figure 20 MLX90641BCx noise vs refresh rate for different device types .........................................................................................45
Figure 21 MLX90641BCA noise vs pixel and refresh rate at 1Hz and 2Hz .........................................................................................45
Figure 22 MLX90641BCA noise vs pixel and refresh rate at 4Hz, 8Hz and 16Hz ................................................................................45
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Figure 23 MLX90641BCB noise vs pixel and refresh rate at 1Hz and 2Hz..........................................................................................46
Figure 24 MLX90641BCB noise vs pixel and refresh rate at 4Hz, 8Hz and 16Hz ................................................................................46
Figure 25 Field Of View measurement ............................................................................................................................................47
Figure 26 Application examples concerning the optical consideration .............................................................................................48
Figure 27 MLX90641Bxx electrical connections...............................................................................................................................48
Figure 28 Calculation flow in thermal image mode .........................................................................................................................49
Figure 29 Mechanical drawing of 55° FOV device ............................................................................................................................51
Figure 30 Mechanical drawing of 110° FOV device ..........................................................................................................................52
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4. Ordering Information
Product
Temperature
Package
Option Code
Custom
Configuration
Packing Form
Definition
MLX90641
E
SF
BCA
000
TU
16x12 IR array
MLX90641
E
SF
BCB
000
TU
16x12 IR array
MLX90641
K
SF
BCA
000
TU
16x12 IR array
MLX90641
K
SF
BCB
000
TU
16x12 IR array
Legend:
Temperature Code:
E: -40°C to 85°C
K: -40°C to 125°C
Package Code:
Option Code:
“SF” for TO39 package
xAx – TGC is disabled and may not be enabled
xCx – TGC is enabled
Option Code:
xxA – FOV = 110°x75°
xxB – FOV = 55°x35°
Custom configuration
Packing Form:
Ordering Example:
000 – standard product
“TU” - Tubes
“MLX90641KSF-BCA-000-TU”
Table 1 Ordering information
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5. Glossary of Terms
TC
POR
Temperature Coefficient (in ppm/°C)
Power On Reset
IR
Infra-Red
Ta
Ambient Temperature – the temperature of the TO39 package
IR data
Infrared data (raw data from ADC proportional to IR energy received by the sensor)
ADC
Analog To Digital Converter
TGC
Temperature Gradient Coefficient
FOV
Field Of View
nFOV
Field Of View of the N-th pixel
2
IC
Inter-Integrated Circuit communication protocol
SDA
Serial Data
SCL
Serial Clock
LSB
Least Significant Bit
MSB
Most Significant Bit
Fps
Frames per Second – data refresh rate
MD
Master Device
SD
Slave Device
ASP
Analogue Signal Processing
DSP
Digital Signal Processing
ESD
Electro Static Discharge
EMC
Electro Magnetic Compatibility
NC
Not Connected
NA
Not Applicable
Table 2 Glosarry of terms
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6. Pin Definitions and Descriptions
Pin #
Name
Description
1
SDA
I2C serial data (input / output)
2
VDD
Positive supply
3
GND
Negative supply (Ground)
4
SCL
I2C serial clock (input only)
Table 3 Pin definition
Figure 2 MLX90641 Overview and pin description
7. Absolute Maximum Ratings
Parameter
Symbol
Min.
Typ.
Max.
Unit
V
Supply Voltage (over voltage)
VDD
5
Supply Voltage (operating max voltage)
VDD
3.6
Reverse Voltage (each pin)
Operating Temperature
Storage Temperature
ESD sensitivity (AEC Q100 002)
SDA DC sink current
-0.3
V
TAMB
-40
+125
°C
TST
-40
+150
°C
4
Remark
Not in plastic tubes
kV
40
mA
Table 4 Absolute maximum ratings
Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute maximumrated conditions for extended periods may affect device reliability.
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8. General Electrical Specifications
Electrical Parameter
Symbol
Min.
Typ.
Max.
Unit
Supply Voltage
VDD
3
3.3
3.6
V
Supply Current
IDD
10
12
14
mA
VPOR_UP
2.2
2.6
V
VDD rising
2.55
V
VDD falling
POR level up analog
POR level down analog
POR hysteresis
VPOR_DOWN
VPOR_hys
50
I2C address(NOTE 3)
0x01
Input high voltage
(SDA, SCL)
VIH
Input low voltage
(SDA, SCL)
VLOW
SDA output low voltage
0x33 (default)
Condition
mV
0x7F
V
Over Ta and VDD
0.3*VDD
V
Over Ta and VDD
VOL
0.4
V
Over Ta and VDD
ISINK=3mA
SDA leakage
ISDA_leak
± 10
µA
VSDA=3.6V, Ta=150°C
SCL leakage
ISCL_leak
± 10
µA
VSCL=3.6V, Ta=150°C
SDA capacitance
CSDA
10
pF
SCL capacitance
CSCL
10
pF
Acknowledge setup time
TSUAC(MD)
0.45
µs
Acknowledge hold time
TDUAC(MD)
0.45
µs
Acknowledge setup time
TSUAC(SD)
0.45
µs
Acknowledge hold time
TDUAC(SD)
0.45
µs
1
MHz
10
times Ta = 25°C
I2C clock frequency
0.7*VDD
FI2C
0.4
Erase/write cycles
Write cell time
TWRITE
5
ms
Table 5 Electrical specification
NOTE 1: For best performance it is recommended to keep the supply voltage as accurate and stable as possible to 3.3V
± 0.05V
NOTE 2: When a data in EEPROM cell to be changed an erase (write 0x0000) must be done prior to writing the new
value. After each write at least 5ms delay is needed in order to writing process to take place.
NOTE 3: Slave address 0x00 must be avoided.
2
NOTE 4: According to I C standard the max sink current is specified to be 20mA, however due to the thermal
considerations (the dissipated power into the driver) the max current is limited to 10mA . This is the only parameter
which does not comply with the FM+ specification.
2
NOTE 5: Max EEPROM I C speed operations to be done at 400kHz.
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9. False pixel correction
The imager can have up to 1 defective pixel, with either no output or out of specification temperature reading.
2
These pixels are identified in the EEPROM table of the sensor and can be read out throu gh the I C. The defective pixel
result can be replaced by an interpolation of its neighboring pixels.
10. Detailed General Description
10.1. Pixel position
Col 1
Col 2
Col 3
Col 4
Col 5
Col 6
Col 7
Col 8
Col 10
Col 9
Col 11
Col 13
Col 12
Col 14
Col 15
Col 16
The array consists of 192 IR sensors (also called pixels). Each pixel is identified with its row and column
position as Pix(i,j) where i is its row number (from 1 to 12) and j is its column number (from 1 to 16)
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Row 8
Row 9
Row 10
Row 11
VDD
0
Row 12
SDA
GND
SCL
Reference tab
Figure 3 Pixel in the whole FOV
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10.2. Communication protocol
2
The device use I C protocol with support of FM+ mode (up to 1MHz clock frequency) and can be only slave on the bus.
2
The SDA and SCL ports are 5V tolerant and the sensor can be directly connected to a 5V I C network.
The slave address is programmable and can have up to 127 different slave addresses (SA = 0x00 must be avoided).
10.2.1. Low level
10.2.1.1. Start / Stop conditions
Each communication session is initiated by a START condition and ends with a STOP condition. A START condition is
initiated by a HIGH to LOW transition of the SDA while a STOP is generated by a LOW to HIGH transition. Both changes must
be done while the SCL is HIGH.
10.2.1.2. Device addressing
The master is addressing the slave device by sending a 7-bit slave address after the START condition. The first seven bits are
th
dedicated for the address and the 8 is Read/Write (R/W) bit. This bit indicates the direction of the transfer:
Read (HIGH) means that the master will read the data from the slave
Write (LOW) means that the master will send data to the slave
10.2.1.3. Acknowledge
th
During the 9 clock following every byte transfer the transmitter releases the SDA line. The receiver acknowledges
(ACK) receiving the byte by pulling SDA line to low or does not acknowledge (NoACK) by letting the SDA ‘HIGH’.
10.2.1.4. I2C command format
Slave address
MSByte address
LSByte address
MSByte data
LSByte data
SDA
2
I C write
S 0 1 1
0 0 1 1 W A
A
A
A
A
P
SCL
2
Figure 4 I C write command format (default SA=0x33 is used)
Slave address
Slave address
2
MSByte address
SDA
I C read
S 0 1 1
0 0 1 1 W A
LSByte address
A
MSByte data
A S 0 1 1
0 0 1 1 W A
LSByte data
A
NAK P
SCL
2
Figure 5 I C read command format (default SA=0x33 is used)
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10.3. Measurement mode
In this mode the measurements are constantly running. Depending on the selected frame rate Fps in the control
register, the data for IR pixels and Ta will be updated in the RAM each
seconds. In this mode the external microcontroller
has full access to the internal registers and memories of the device.
10.4. Refresh rate
The refresh rate is configured by “Control register 1” (0x800D) i.e. if “Refresh rate control” = 011 4Hz this would mean
that each 250ms a new data (full frame) is available in the RAM.
NOTE: It is possible to program the desired refresh rate into device EEPROM eliminating the necessity to reconfigure the
device every time it is powered on. The corresponding EEPROM cell is at address 0x240C (see Table 7)
Which subpage is updated is indicated by the “Last measured subpage” field.
It is important both subpages to be read as the necessary information for the Ta calculations is only available by combining
the data from both subpages i.e. the Ta is refreshed with refresh rate twice as low as the one set in “Refresh rate control”.
When a new data (subpage) is available a dedicated bit is set to indicate this – bit 3 “New data available in RAM” in “Status
register” (0x8000). It is up to the customer to reset the bit once the data is dumped.
Set bit “New data available in RAM”
Subpage 0
Subpage 0
Subpage 1
250ms
250ms
Subpage 1
250ms
250ms
Refresh rate control = 011b (4Hz)
Figure 6 Refresh rate timing
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10.5. Measurement flow
Following measurement flow is recommended:
Measurement Flow
0.5 Hz 4 sec
1 Hz 2 sec
2 Hz 1 sec
….
64 Hz 0.03125 sec
POR
Wait 80ms + delay determined by the refresh rate
Just once after POR
Extract calibration data from EEPROM and store in RAM
Yes
Absolute temp measurement?
No
Wait app 4 min
Sub frame “0”
Read meas data
Clear bit “New data available in RAM” - Bit3 in 0x8000
Calculate the temperature of the sub frame “0”
Image processing
decision making
Yes
Step mode ?
No
Set Start Of Measurement – Bit5 in 0x8000
Wait time determined by RR – 20%
No
Is “New data available in RAM” set
Yes
Read meas data
Sub frame “1”
Clear bit “New data available in RAM” - Bit3 in 0x8000
Calculate the temperature of the sub frame “1”
Image processing
decision making
Yes
Step mode ?
No
Set Start Of Measurement – Bit5 in 0x8000
Wait time determined by RR – 20%
Yes
Is “New data available in RAM” set
No
Figure 7 Recommended measurement flow
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Subpage 0 0x8000 = 0xXXX8
RAM
Subpage 1 0x8000 = 0xXXX9
RAM
0x0400
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
0x0400
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
0x0420
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
0x0420
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
0x0440
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
0x0440
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
0x0460
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
0x0460
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
0x0480
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
0x0480
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
0x04A0
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
0x04A0
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
0x04C0
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
0x04C0
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
0x04E0
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
0x04E0
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
0x0500
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
0x0500
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
0x0520
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
0x0520
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
0x0540
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
0x0540
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
0x0560
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
0x0560
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
0x0400
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0x0410
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
0x0440
33
34
35
36
37
38
39
40
41
42
43
44
45
46
0x0450
49
50
51
52
53
54
55
56
57
58
59
60
61
0x0480
65
66
67
68
69
70
71
72
73
74
75
76
0x0490
81
82
83
84
85
86
87
88
89
90
91
0x04C0
97
98
99
100
101
102
103
104
105
106
0x04D0
113
114
115
116
117
118
119
120
121
0x0500
129
130
131
132
133
134
135
136
137
0x0510
145
146
147
148
149
150
151
152
0x0540
161
162
163
164
165
166
167
0x0550
177
178
179
180
181
182
183
RAM
Only highlighted cells are
updated at each refresh rate
RAM
0x0420
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
0x0430
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
47
48
0x0460
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
62
63
64
0x0470
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
77
78
79
80
0x04A0
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
92
93
94
95
96
0x04B0
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
107
108
109
110
111
112
0x04E0
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
122
123
124
125
126
127
128
0x04D0
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
138
139
140
141
142
143
144
0x0520
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
153
154
155
156
157
158
159
160
0x0530
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
168
169
170
171
172
173
174
175
176
0x0560
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
184
185
186
187
188
189
190
191
192
0x0570
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
Control register 1 (0x800D) = 0981
Figure 8 TV mode reading pattern
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Datasheet
10.6. Address map
0x0000
ROM
0x03FF
0x0400
RAM
0x05BF
0x2400
EEPROM
0x273F
0x8000
Registers
(MLX reserved)
0x800C
0x800D
Registers
0x8011
0x8011
Registers
(MLX reserved)
0x8016
Figure 9 MXL90641 memory map
10.6.1. Internal registers
B12
B11
B10
B9
B8
B7
B6
B5
-
-
-
-
-
-
-
-
-
-
-
B4
B3
B2
B1
B0
Last measured subpage
controlled by MLX90641
B13
New data available in RAM
B14
Melexis reserved
B15
Enable overwrite
There are few internal register that are customer accessible through which the device performance may be
customized:
Status register - 0x8000
0
0
0
Measurement of subpage 0 has been measured
0
0
1
Measurement of subpage 1 has been measured
0
1
0
Melxis reserved
0
1
1
Melxis reserved
1
0
0
Melxis reserved
1
0
1
Melxis reserved
1
1
0
Melxis reserved
1
1
1
Melxis reserved
0
No new data is available in RAM (must be reset by the customer)
1
A new data is available in RAM
0
Data in RAM overwrite is disabled
1
Data in RAM overwrite is enabled
Melexis reserved
Figure 10 Status register (0x8000) bits meaning
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MLX90641 16x12 IR array
B7
B6
B5
B4
B3
B2
B1
B0
Enable subpages mode
B8
Melexis reserved
B9
Enable data hold
B10
Select subpage
B11
Reading pattern
B12
Refresh rate control
B13
Resolution control
B14
Melexis reserved
B15
Enable subpages repeat
Datasheet
0
-
-
-
0
Transfer the data into storage RAM at each measured frame (default)
1
Transfer the data into storage RAM only if en_overwrite = 1 (check 0x8000)
1
Select subpage determines which subpage to be measured if Enable subpages mode = "1"
0
0
Subpage 0 is selected (default)
0
0
1
Subpage 1 is selected
0
1
0
Not Applicable
0
1
1
Not Applicable
1
0
0
Not Applicable
1
0
1
Not Applicable
1
1
0
Not Applicable
1
1
1
Not Applicable
IR refresh rate = 0.5Hz
IR refresh rate = 1Hz
0
1
0
IR refresh rate = 2Hz (default)
0
1
1
IR refresh rate = 4Hz
1
0
0
IR refresh rate = 8Hz
1
0
1
IR refresh rate = 16Hz
1
1
0
IR refresh rate = 32Hz
1
1
1
IR refresh rate = 64Hz
0
0
ADC set to 16 bit resolution
0
1
ADC set to 17 bit resolution
1
0
ADC set to 18 bit resolution (default)
1
1
ADC set to 19 bit resolution
Chess pattern
Subpade mode is activated (default)
Keep this bit = "0" (default)
0
0
1
1
No subpages, only one page will be measured
1
Toggles between subpage "0" and subpage "1" if Enable subpages mode = "1" (default)
0
0
Interleaved (TV) mode (default)
0
0
0
0
0
Control register 1 - 0x800D
Melexis reserved
Figure 11 Control register 1 (0x800D) bits meaning
Enable subpage mode
(Bit 0)
Enable subpage repeat
(Bit 3)
Select subpage
(Bit 4)
Working mode
0
0
-
measure subpage 0 only
0
1
-
measure subpage 0 only
1
0
-
0101…
1
1
0
measure subpage 0 only
1
1
1
measure subpage 1 only
Table 6 Priorities of subpage controls
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MLX90641 16x12 IR array
B3
B2
B1
B0
B7
B6
B5
B4
B3
B2
B1
B0
FM+ disable
B4
I2C threshold levels
B5
SDA driver
current limit control
B6
Melexis reserved
B7
Melexis reserved
Datasheet
0
-
-
-
-
-
-
-
-
-
-
-
-
I2C configuration register - 0x800F
0
FM+ mode enabled (default)
1
FM+ mode disabled
0
VDD reffered threshold (normal mode) (default)
1
1.8V reffered threshold (1.8V mode)
0
SDA driver current limit is ON (default)
1
SDA driver current limit is OFF
Melexis reserved
Melexis reserved
2
Figure 12 I C configuration register (0x800F) bits meaning
10.6.2. RAM
Pixels 1…16 (subpage 0)
Pixels 17…32 (subpage 0)
0x041F
0x0420
Pixels 1…16 (subpage 1)
Pixels 17…32 (subpage 1)
0x043F
0x0440
Pixels 33…48 (subpage 0)
Pixels 49…64 (subpage 0)
0x045F
0x0460
Pixels 33…48 (subpage 1)
Pixels 49…64 (subpage 1)
0x047F
0x0480
…
0x0520
…
…
0x049F
…
0x053F
0x0540
Pixels 161…176 (subpage 0)
Pixels 177…192 (subpage 0)
0x055F
0x0560
Pixels 161…176 (subpage 1)
Pixels 177…192 (subpage 1)
0x057F
0x0580
0x0580=Ta_Vbe, 0x0588=CP(SP 0), 0x058A=GAIN
Melexis reserved
0x059F
0x05A0
0x05A0=Ta_PTAT, 0x05A8=CP(SP1), 0x05AA=VDDpix
Melexis reserved
0x05BF
0x0400
Figure 13 RAM memory map (Interleaved mode - default)
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Datasheet
EEPROM
The EEPROM is used to store the calibration constants and the configuration parameters of the device
EEPROM address
Access
Meaning
0x2400
Melexis
Melexis reserved
0x2401
Melexis
Melexis reserved
0x2402
Melexis
Melexis reserved
0x2403
Melexis
Configuration register
0x2404
Melexis
Melexis reserved
0x2405
Melexis
Melexis reserved
0x2406
Melexis
Melexis reserved
0x2407
Melexis
Device ID1
0x2408
Melexis
Device ID2
0x2409
Melexis
Device ID3
0x240A
Melexis
Device Options
0x240B
Melexis
Melexis reserved
0x240C
Customer
Control register_1
0x240D
Customer
Control register_2
0x240E
Customer
I2CConfReg
0x240F
Customer
Melexis reserved / I2C_Address
Table 7 Configuration parameters memory
After POR the device read dedicated EEPROM cells and transfers their content to into the control and configuration register
of the device. This way the device is configured and prepared for operation. The relation between EEPROM and register
address is shown here after (explanation of the bit meaning can be found in section 10.6.1 Internal registers):
EEPROM address
Register address
Access
Name
Data [hex]
0x240C
0x800D
Customer
Control_register_1
0901
0x240D
0x800E
Customer
Control_register_2
0000
0x240E
0x800F
Customer
I2CConfReg
0000
0x240F
0x8010
Customer
Melexis internal use (8 bit)
I2C_Address (8bit)
BE33
Figure 14 EEPROM to registers mapping
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Datasheet
Address
0x2400
0x2410
0x2420
0x2430
0x2440
0x2450
0x2460
0x2470
0x2480
0x2490
0x24A0
0x24B0
0x24C0
0x24D0
0x24E0
0x24F0
0x2500
0x2510
0x2520
0x2530
0x2540
0x2550
0x2560
0x2570
0x2580
0x2590
0x25A0
0x25B0
0x25C0
0x25D0
0x25E0
0x25F0
0x2600
0x2610
0x2620
0x2630
0x2640
0x2650
0x2660
0x2670
0x2680
0x2690
0x26A0
0x26B0
0x26C0
0x26D0
0x26E0
0x26F0
0x2700
0x2710
0x2720
0x2730
0
1
Osc Trim Ana Trim 1
Scale occ
2
3
4
5
6
7
8
9
A
B
MLX
Conf reg
Ana Trim 2
MLX
MLX
ID 1
ID 2
ID 3
MLX
MLX
Kta_avg
Kta scales
Kv_avg
Kv scales
Vdd_25
K_vdd
KsTo_2
KsTo_3
Pix os R1
MLX
row5_max row6_max
KsTa
Emissivity
OS 2 CP
Kv CP
TGC
Kt CP
Gain
KsTo scale
KsTo_1
Scale_row 1…6
PTAT_25
KsTo_4
KsTo_5
Kt_PTAT
CT6
C
D
Cont reg 1 Cont reg 2
E
F
I2C conf
I2C add
row1_max row2_max row3_max row4_max
Kv_PTAT Alpha PTAT Alpha CP
KsTo_6
CT7
KsTo_7
CP scale
OS 1 CP
CT8
KsTo_8
192 x Pixel offset - subpage 1
192 x Pixel sensitivity - α
192 x Kta, Kv (i, j)
192 x Pixel offset - subpage 2
Table 8 EEPROM overview (words)
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Datasheet
Address \ bit
0x2410
0x2411
0x2412
0x2413
0x2414
0x2415
0x2416
0x2417
0x2418
0x2419
0x241A
0x241B
0x241C
0x241D
0x241E
0x241F
0x2420
0x2421
0x2422
0x2423
0x2424
0x2425
0x2426
0x2427
0x2428
0x2429
0x242A
0x242B
0x242C
0x242D
0x242E
0x242F
0x2430
0x2431
0x2432
0x2433
0x2434
0x2435
0x2436
0x2437
0x2438
0x2439
0x243A
0x243B
0x243C
0x243D
0x243E
0x243F
0x2440
0x2441
…
0x244E
0x244F
0x2450
0x2451
…
0x24FE
0x24FF
0x2500
0x2501
…
0x250E
0x250F
0x2510
0x2511
…
0x25BE
0x25BF
0x25C0
0x25C1
…
0x25CE
0x25CF
0x25D0
0x25D1
…
0x267E
0x267F
0x2680
0x2681
…
0x268E
0x268F
0x2690
0x2691
…
0x273E
0x273F
15
14
13
12
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
Hamming code
Hamming code
…
Hamming code
Hamming code
11
10
9
8
7
6
5
4
3
2
Scale_OCC_offset_range_1
1
0
MLX
Pix_offset_part_1
Pix_offset_part_2
MLX
Kta_avg
Kta_scale_1
Kta_scale_2
Kv_avg
Kta_scale_1
Kta_scale_2
Scale_row_1
Scale_row_2
Scale_row_3
Scale_row_4
Scale_row_5
Scale_row_6
Row_1_max
Row_2_max
Row_3_max
Row_4_max
Row_5_max
Row_6_max
KsTa (fixed scale 15)
Emissivity ± 2
GAIN - part 1
GAIN - part 2
Vdd_25 (fixed scale 5)
K_Vdd (fixed scale 5)
PTAT - part 1
PTAT - part 2
Kt_PTAT (fixed scale 3)
Kv_PTAT (fixed scale 12)
Alpha_PTAT (fixed scale 11)
Alpha CP
Alpha CP scale
Offset CP - part 1
Offset CP - part 2
Kt CP scale
Kv CP scale
Cal resolution
TGC coefficient ± 4
KsTo scale
± KsTo range 1 (-40°C … -20°C)
± KsTo range 2 (-20°C … 0°C)
± KsTo range 3 (0°C … 80°C)
± KsTo range 4 (80°C … 120°C)
± KsTo range 5 (120°C … see 0x243A)
Corner temp range 6
± KsTo range 6 (see 0x243A … see 0x243C)
Corner temp range 7
± KsTo range 7 (see 0x243C … see 0x243E)
Corner temp range 8
± KsTo range 8 (see 0x243E … )
Offset pixel (1, 1) - subpage 0
Offset pixel (1, 2) - subpage 0
…
Offset pixel (1, 15) - subpage 0
Offset pixel (1, 16) - subpage 0
Offset pixel (2, 1) - subpage 0
Offset pixel (2, 2) - subpage 0
…
Offset pixel (12, 15) - subpage 0
Offset pixel (12, 16) - subpage 0
Sensitivity (1, 1)
Sensitivity (1, 2)
…
Sensitivity (1, 15)
Sensitivity (1, 16)
Sensitivity (2, 1)
Sensitivity (2, 2)
…
Sensitivity (12, 15)
Sensitivity (12, 16)
Kta (1, 1)
Kta (1, 2)
…
Kta (1, 15)
Kta (1, 16)
Kta (2, 1)
Kta (2, 1)
…
Kta (12, 15)
Kta (12, 16)
Offset pixel (1, 1) - subpage 1
Offset pixel (1, 2) - subpage 1
…
Offset pixel (1, 15) - subpage 1
Offset pixel (1, 16) - subpage 1
Offset pixel (2, 1) - subpage 1
Offset pixel (2, 2) - subpage 1
…
Offset pixel (12, 15) - subpage 1
Offset pixel (12, 16) - subpage 1
Kt CP
Kv CP
Kv (1, 1)
Kv (1, 2)
…
Kv (1, 15)
Kv (1, 16)
Kv (2, 1)
Kv (2, 1)
…
Kv (12, 15)
Kv (12, 16)
Table 9 Calibration parameters memory (EEPROM - bits)
NOTE 1: In case the pixel calibration data stored in EEPROM (Alpha, offset, Kta and Kv) is equal to 0x0000
this means that this particular pixels has failed and the calculation for To should not be trusted and avoided.
Depending on the application, the To value for such pixels can be replaced with a default value such as 273.15°C, can be equal to Ta or one calculate an average value from the adjacent pixels.
NOTE 2: The maximum number of deviating pixels is 1 (please check False pixel correction)
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Datasheet
11. Calculating Object Temperature
11.1. Restoring calibration data from EERPOM and calculations
NOTE: 1. All data in the EEPROM are coded as two’s complement (unless otherwise noted)
2. All EEPROM cells are codded using Hamming code for proper data restoring stored in the 5 most significant bits
3. The calculation bellow are considering only the “valid” data in any particular cell ignoring the Hamming code bits
i.e. as the five significant bits of each word “0” for instance if the EEPROM content is “0x9A44” we will work with “0x0244”
In the example we are restoring calibration data for pixel (6, 9)
The polynom for the Hamming code is as follows:
P0 = D0 + D1 + D3 + D4 + D6 + D8 + D10
P1 = D0 + D2 + D3 + D5 + D6 + D9 + D10
P2 = D1 + D2 + D3 + D7 + D8 + D9 + D10
P3 = D4 + D5 + D6 + D7 + D8 + D9 + D10
P4 = D0 + D1 + D2 + D3 + D4 + D5 + D6 + D7 + D8 + D9 + D10 + P0 + P1 + P2 + P3
Where P4 is the MSBit in the word while D0…D10 are the data bits.
B15
B14
B13
B12
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
P4
P3
P2
P1
P0
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Figure 15 EEPROM Hamming and data bit meaning
11.1.1. Restoring the VDD sensor parameters and VDD calculations
Following formula is used to calculate the VDD of the sensor:
[
[
If
]
]
[
]
[
]
Where:
[
]
If
[
]
If
Where
is restored in 11.1.18
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Datasheet
11.1.2. Restoring the Ta sensor parameters
Following formula is used to calculate the Ta of the sensor:
(
)
, °C
Where:
[
]
If
[
]
If
[
]
[
If
]
[
(
[
]
(
]
[
)
[
]
]
(unsigned)
)
Where:
[
]
If
[
]
If
[
]
11.1.3. Restoring the offset
There are two sets of offset data for each subpage.
(
)
(
)
(
)
(
)
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[
(
]
[
)
]
If
(
(
If
)
(
]
(
(
If
[
)
[
)
)
]
(
)
)
(
)
]
(
[
)
(unsigned)
11.1.4. Restoring the Sensitivity 𝜶(
)
Sensitivity is divided into 6 ranges (1…32, 33…64 and so on) and for each range we store a reference value as follows:
Sensitivity Max value for row 1 (pixels 1…32) is stored at EEPROM address 0x241C
Sensitivity Max value for row 2 (pixels 33…64) is stored at EEPROM address 0x241D
Sensitivity Max value for row 3 (pixels 65…96) is stored at EEPROM address 0x241E
Sensitivity Max value for row 4 (pixels 97…128) is stored at EEPROM address 0x241F
Sensitivity Max value for row 5 (pixels 129…160) is stored at EEPROM address 0x2420
Sensitivity Max value for row 6 (pixels 161…192) is stored at EEPROM address 0x2421
(
(
)
)
Where:
(
[
)
]
[
[
]
]
[
[
]
]
[
[
]
]
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[
]
[
]
[
]
[
]
[
]
[
]
11.1.5. Restoring the Kta(i,j) coefficient
(
(
)
)
Where:
[
(
]
(depending on pixel number)
)
If
(
)
[
(
)
(
)
]
If
[
]
[
(unsigned)
]
(unsigned)
11.1.6. Restoring the Kv(i,j) coefficient
(
(
)
)
Where:
(
[
)
If
]
(
(depending on pixel number)
)
[
(
)
(
)
]
If
[
]
[
(unsigned)
]
(unsigned)
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11.1.7. Restoring the GAIN coefficient (common for all pixel)
(
[
]
)
[
]
(unsigned)
11.1.8. Restoring the KsTa coefficient (common for all pixel)
[
]
If
11.1.9. Restoring corner temperatures (common for all pixel)
The information regarding corner temperatures is stored into device EEPROM and is restored as follows:
[
]
(unsigned)
[
]
(unsigned)
[
]
(unsigned)
Or we can construct the temperatures for the ranges as follows:
CT1 = -40°C (hard codded) < Range 1 > CT2 = -20°C (hard codded) < Range 2 > CT3 = 0°C (hard codded) < Range 3 > CT4 = 80°C
(hard codded) < Range 4 > CT5 = 120°C (hard codded) < Range 5 > CT6 < Range 6 > CT7 < Range 7 > CT8 < Range 8
11.1.10. Restoring the KsTo coefficient (common for all pixel)
[
]
If
[
]
If
[
]
If
[
]
If
[
If
]
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[
]
If
[
]
If
[
]
If
Where:
[
]
(unsigned)
11.1.11. Restoring sensitivity correction coefficients for each temperature range
(
(
(
)))
(
(
(
)))
(
(
))
(
(
))
(
(
))
(
(
))
(
(
))
11.1.12. Restoring Emissivity
An emissivity parameter is stored into EEPROM and can have values from -2…1.999
[
If
]
Default value stored in EEPROM is
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11.1.13. Restoring the Sensitivity 𝜶
[
]
Where:
[
]
11.1.14. Restoring the offset of the CP
[
(
]
)
[
]
(signed)
If
11.1.15. Restoring the Kv CP coefficient
[
]
(unsigned)
Where:
[
]
(signed)
If
11.1.16. Restoring the Kta CP coefficient
[
]
Where:
(unsigned)
[
]
(signed)
If
11.1.17. Restoring the TGC coefficient
Where:
[
]
If
(signed)
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11.1.18. Restoring calibration resolution control settings
For some calculation calibration resolution is needed that is why we store this parameter into EEPROM as well.
[
]
(unsigned)
11.2. Temperature calculation
11.2.1. Example input data
11.2.1.1. Example measurement data
Input data name
Input data value
Object temperature
80°C
Emissivity (ε)
0.95
Control register 1 (Resctrl)
0x0901 (2 decimal)
RAM[0x0498] (pix(6, 9) data)
0x03CC (972)
Vbe - RAM[0x0580]
0x4C54 (19540)
CP - RAM[0x0588]
0xFF97 (-105)
GAIN - RAM[0x058A]
0x2606 (9734)
PTAT - RAM[0x05A0]
0x06D8 (1752)
VDD - RAM[0x05AA]
0xCB8A (-13430)
Table 10 Calculation example input data
11.2.1.2. Calibration data
EEPROM
address
Calibration parameter name
Parameter value
+ Ham [ hex ]
Decoded value
0x2410
Scale_os_r1 - 6bits
Scale_os_r2 - 5bits
0x0000
Scale_os_r1 = 0
Scale_os_r2 = 0
0x2411
Pix_os_r1_part_1 - 11 bits
0xB7E8
-746
0x2412
Pix_os_r1_part_2 - 11 bits
0xD016
NA
0x2413
MLX
0x2414
MLX
0x2415
Kta_avg - 11 bits
0xC2FD
0.00291824
0x2416
Kta_scale_1 - 6 bits
Kta_scale_2 - 5 bits
0x1A43
Kta_scale_1 = 18
Kta_scale_2 = 3
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0x2417
Kv_avg - 11bits
0xCA9A
0.325195313
0x2418
Kv_scale_1 - 6 bits
Kv_scale_2 - 5 bits
0x5164
Kv_scale_1 = 11
Kv_scale_2 = 4
0x2419
Scale_row_1 - 6 bits
Scale_row_2 - 5 bits
0x018C
Scale_row_1 = 32
Scale_row_2 = 32
0x241A
Scale_row_3 - 6 bits
Scale_row_4 - 5 bits
0x018C
Scale_row_3 = 32
Scale_row_4 = 32
0x241B
Scale_row_5 - 6 bits
Scale_row_6 - 5 bits
0x018C
Scale_row_5 = 32
Scale_row_6 = 32
0x241C
row1_max - 11 bits
0x9CB1
2.7962960E-07
0x241D
row2_max - 11 bits
0x956C
3.2316893E-07
0x241E
row3_max - 11 bits
0xA5CC
3.4552068E-07
0x241F
row4_max - 11 bits
0x7DD1
3.4668483E-07
0x2420
row5_max - 11 bits
0x6D7F
3.2759272E-07
0x2421
row6_max - 11 bits
0x3CD4
2.8777868E-07
0x2422
KsTa, fixed scale 15
0x27B8
-0.002197266
0x2423
Emissivity - ±2, 10 bits
0x19E6
0.94921875
0x2424
GainMeasRef_word1
0xF137
9972
0x2425
GainMeasRef_word2
0x7814
NA
0x2426
Vdd_25
0x2658
-13568
0x2427
K_Vdd
0xEF9E
-3136
0x2428
PTAT_25_W1
0x917F
12280
0x2429
PTAT_25_W2
0xF018
NA
0x242A
Kt_Ptat
0xE156
42.75
0x242B
Kv_Ptat
0x4817
0.005615234
0x242C
Alpha PTAT
0x1C80
9
0x242D
Alpha cyclops
0x233E
3.0195224E-09
0x242E
Alpha cyclop scale
0xC826
38
0x242F
Offset CP W1
0xCFFC
-119
0x2430
Offset CP W2
0xA009
NA
0x2431
Kta CP scale - 5 bits
Kta CP - 6 bits
0xBB53
Kta CP scale = 13
Kta CP = -0.02319336
0x2432
Kv CP scale - 5 bits
Kv CP - 6 bits
0xF194
Kv CP scale = 6
Kv CP = 0.3125
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0x2433
Resolution control cal - 2 bits
TGC - ±4, 9 bits
0xFC00
Resolution control cal = 2
TGC = 0
0x2434
KsTo scale - 11bits
0x7814
KsTo scale = 20
0x2435
KsTo_1 - 10 bits
0xED22
KsTo_1 = -0.0007
0x2436
KsTo_2 - 10 bits
0xED22
KsTo_2 = -0.0007
0x2437
KsTo_3 - 10 bits
0xED22
KsTo_3 = -0.0007
0x2438
KsTo_4 - 10 bits
0xED22
KsTo_4 = -0.0007
0x2439
KsTo_5 - 10 bits
0xED22
KsTo_5 = -0.0007
0x243A
CT6
0x80C8
CT6 = 200
0x243B
KsTo_6 - 10 bits
0xED22
KsTo_6 = -0.0007
0x243C
CT7
0x4190
CT6 = 400
0x243D
KsTo_7 - 10 bits
0xED22
KsTo_7 = -0.0007
0x243E
CT8
0xDA58
CT6 = 600
0x243F
KsTo_8 - 10 bits
0xED22
KsTo_8 = -0.0007
Table 11 Calculation example calibration data
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11.2.2. Temperature calculation
After the parameters restore the temperature calculation is done using following calculation flow (assuming that the
EEPROM data are already extracted):
Supply voltage value calculation (common for all pixel) - 11.2.2.2
Ambient temperature calculation - 11.2.2.3
Gain compensation - 11.2.2.5.1
IR data compensation – offset, VDD and Ta - 11.2.2.5.3
IR data Emissivity compensation - 11.2.2.5.4
IR data gradient compensation - 11.2.2.7
Normalizing to sensitivity - 11.2.2.8
Calculating To for basic temperature range (0°C…80 °C) - 11.2.2.9
Image (data) processing
Figure 16 To calculation flow
For this example we calculate the temperature of pixel (12, 16) i.e. row=12 and the column=16.
Values marked with green are extracted from device EEPROM
Values marked with grey are final parameter values or are values to be used for next calculations
11.2.2.1. Resolution restore
The device is calibrated with default resolution setting = 2 (corresponding to ADC resolution set to 18bit see Fig 11) i.e.
if the one choose to change the ADC resolution setting to a different one a correction of the data must be done. First
we must restore the resolution at which the device has been calibra ted which is stored at EERPOM 0x2433.
Where:
[
]
[
(unsigned)
]
(unsigned)
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In case the ADC resolution is changed the one must multiply the
coefficient with the RAM data for VDD
only. Please note that the data for Vbe, PTAT and IR pixels (including CP) must not be changed.
11.2.2.2. Supply voltage value calculation (common for all pixel)
[
]
[
]
If
[
]
LSB
Where:
[
]
If
[
]
If
(
)
11.2.2.3. Ambient temperature calculation (common for all pixel)
(
)
, °C
Where:
[
If
[
If
]
]
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[
]
[
]
[
If
(
LSB
)
[
(
]
]
[
)
(
]
(unsigned)
)
(
)
Where:
[
] = 0x06D8 = 1752
If
[
]
If
[
]
(
)
(
)
(
(
)
)
°C
11.2.2.4. Gain parameter calculation (common for all pixels)
[
]
[
]
If
(
[
(
[
]
]
)
LSB
[
]
(unsigned)
)
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11.2.2.5. Pixel data calculations
The pixel addressing is following the pattern described in Reading pattern as shown in Fig 5:
11.2.2.5.1. Gain compensation
(
[
)
[
]
]
]
[
If
(
[
]
)
11.2.2.5.2. Offset calculation
(
)
(
)
[
(
]
(
]
)
If
(
[
)
]
(
If
[
(
[
)
]
)
)
(unsigned)
LSB
11.2.2.5.3. IR data compensation – offset, VDD and Ta
(
)
(
)
(
(
)
(
)) (
(
)
(
))
The same calculation must be done for the second subpage as well
(
)
(
(
)
If
(
)
[
)
]
(
LSB (
)
and
are the same for both subpages)
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(
)
(
)
(
(
)
(
)) (
(
)
(
))
NOTE: In the example bellow calculation are done for subpage 0 only
(
(
)
)
Where:
[
(
)
(
)
]
(depending on pixel number)
If
(
[
]
If
[
(
(
(
)
(
)
)
]
(unsigned)
[
]
[
]
(unsigned)
)
)
Where:
(
)
(
)
(depending on pixel number)
If
(
[
)
]
If
[
]
(unsigned)
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[
(
(
)
]
(unsigned)
)
(
)
(
)
(
)
(
) (
(
)) (
(
))
(
)
(
) (
(
)) (
(
))
(
)
(
(
(
)
)) (
(
)
(
))
11.2.2.5.4. IR data Emissivity compensation
[
]
If
11.2.2.6. CP data calculations
11.2.2.6.1. Compensating the GAIN of CP pixel
(
[
)
[
]
]
[
If
]
11.2.2.6.2. Compensating offset, Ta and VDD of CP pixel
(
(
(
[
]
(
)
[
)) (
(
))
]
)
If
[
]
(unsigned)
Where:
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[
]
(signed)
(signed)
If
[
]
(unsigned)
Where:
[
]
(signed)
If
(
(
) (
)) (
(
))
11.2.2.7. IR data gradient compensation
Where:
[
]
If
(
(signed)
(
)
)
11.2.2.8. Normalizing to sensitivity
(
(
)
)
The row for the pixel is calculated as follows:
(
(
((
)
[
[
(
(
)
)
)
(
((
(
)
)
)
)
( )
]
]
[
(
)
[
]
]
)
)
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[
]
[
[
[
]
]
If
(
(
)
(
(
(
) (
)
))
(
)
(
]
) (
(
) (
))
)
11.2.2.9. Calculating To for basic temperature range (0°C…80 °C)
[
]
If
Where:
[
]
(unsigned)
As the IR signal received by the sensor has two components:
1. IR signal emitted by the object
2. IR signal reflected from the object (the source of this signal is surrounding environment of the sensor)
In order to compensate correctly for the emissivity and achieve best accuracy we need to know the surrounding
temperature which is responsible for the second component of the IR signal namely the reflected part - . In case this
temperature is not available and cannot be provided it might be replaced by
.
Let’s assume
°C.
(
)
(
)
(
)
(
(
)
(
√
(
)
)
)
(
)
(
)
√
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(
)
(
)
(
)
(
)
√
(
)
√
(
√
(
)
)
(
√
)
(
(
)
(
))
11.2.2.9.1. Calculations for extended temperature ranges
In order to extent the object temperature range and get the best possible accuracy an additional calculation cycle is needed.
We can identify 8 object temperature ranges (each temperature range has its own so called Corner Temperature – CT which
is the temperature at which the range starts):
-
-
Object temperature range 1 =
Object temperature range 2 =
Object temperature range 3 =
Object temperature range 4 =
Object temperature range 5 =
Object temperature range 6 =
Object temperature range 7 =
Object temperature range 8 =
-40°C … -20°C (Corner temperature for this range is -40°C and cannot be changed)
-20°C … 0°C (Corner temperature for this range is -20°C and cannot be changed)
0°C … 80°C (Corner temperature for this range is 0°C and cannot be changed)
80°C … 120°C (Corner temperature for this range is 80°C and cannot be changed)
120°C … CT6°C(Corner temperature for this range is 120°C and cannot be changed)
CT6°C … CT7°C
CT7°C … CT8°C
CT8°C …
In order to be able to carry out temperature calculation for the ranges outside of temperature range 3 (To = 0°C…80°C)
an additional parameters are needed and must be extracted from the device EEPROM. Those parameters are:
-
So called corner temperature (CTx) i.e. the value of temperature at the beginning of the range. Please
note that the corner temperatures for range 1 is fixed to -40°C, corner temperatures for range 2 is fixed to
-20°C, corner temperatures for range 3 is fixed to 0°C, corner temperatures for range 4 is fixed to 80°C ,
corner temperatures for range 5 is fixed to 120°C while CT6, CT7 and CT8 are adjustable
Sensitivity slope for each range – KsTo x
-
(
)
calculated in 11.2.2.9
11.2.2.9.1.1. Restoring corner temperatures
The information regarding corner temperatures is stored into device EEPROM and is restored as follows:
[
]
[
]
[
]
Or we can construct the temperatures for the ranges as follows:
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CT1 = -40°C (hard codded) < Range 1 > CT2 = -20°C (hard codded) < Range 2 > CT3 = 0°C (hard codded) < Range 3 > CT4 = 80°C
(hard codded) < Range 4 > CT5 = 120°C (hard codded) < Range 5 > CT6 < Range 6 > CT7 < Range 7 > CT8 < Range 8
11.2.2.9.1.2. Restoring the sensitivity slope for each range
has been extracted in 11.1.10
[
]
If
[
]
If
[
]
If
[
]
If
[
]
If
[
]
If
[
If
]
Now we can calculate sensitivity correction coefficients for each temperature range:
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(
(
(
(
)))
(
(
(
)))
(
(
(
(
))
(
(
))
(
(
(
))
))
(
(
(
(
))
))
(
(
))
))
(
(
(
)))
))
(
(
(
(
(
(
(
)))
))
11.2.2.9.1.3. Extended To range calculation
The input parameter for this calculation is the object temperature calculated in Calculating To for basic temperature range
(0°C…80 °C) .
If
( )
< -20°C we are in range 1 and we will use the parameters (
If -20°C <
If 0°C <
If 80°C <
and
< -40°C we are in range 2 and we will use the parameters (
( )
( )
,
< 80°C we are in range 3 and we will use the parameters (
( )
,
and
,
< 120°C we are in range 4 and we will use the parameters (
)
)
and
,
)
and
)
If 120°C <
( )
< CT6°C we are in range 5 and we will use the parameters (
,
and
)
If CT6°C <
( )
< CT7°C we are in range 6 and we will use the parameters (
,
and
)
If CT7°C <
( )
< CT8°C we are in range 7 and we will use the parameters (
,
and
)
If CT8°C <
( )
(
)
we are in range 8 and we will use the parameters (
√
(
( )
,
and
)
)
(
(
( )
))
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12. Performance graphs
12.1. Accuracy
12.1.1. Pixel accuracy
All accuracy specifications apply under settled isothermal conditions only.
Furthermore, the accuracy is only valid if the object fills the FOV of the sensor completely.
Parameter definitions:
Frame accuracy is defined as average value of the all (768) pixels in the frame or for frame
̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅
( )
∑
(
can be expressed as:
)
̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅
( )
Non-uniformity is defined as the maximum deviation of each individual pixel reading vs. the absolute accuracy.
(| ( )
̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅
( )|)
Pixel absolute accuracy is defined as:
( )
To, °C
300°C
Frame accuracy ±1°C ±3.0%*|To-Ta|
Non-uniformity zone1 ±1°C ±1.5%*|To-Ta|
Non-uniformity zone2 ±2°C ±1.5%*|To-Ta|
Non-uniformity zone3 ±4°C ±1.5%*|To-Ta|
200°C
Frame accuracy ±2.5°C ±3.0%*|To-Ta|
Non-uniformity zone1 ±1°C ±1.5%*|To-Ta|
Non-uniformity zone2 ±2°C ±1.5%*|To-Ta|
Non-uniformity zone3 ±4°C ±1.5%*|To-Ta|
Frame accuracy ±4°C ±3.0%*|To-Ta|
Non-uniformity ±1°C ±1.5%*|To-Ta|
100°C
Frame accuracy ±1°C
Non-uniformity zone1 ±0.5°C
Non-uniformity zone2 ±1°C
Non-uniformity zone3 ±2°C±2%*|To-Ta|
0°C
-20°C
±5.5°C ±5% * |To-Ta|
-40°C
±3°C ±5% * |To-Ta|
0°C
±4°C ±5% * |To-Ta|
50°C
125°C
Figure 17 Temperature absolute accuracy - MLX90641BCA
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To, °C
300°C
200°C
Frame accuracy ±4°C ±3.0%*|To-Ta|
Non-uniformity ±1°C ±1.5%*|To-Ta|
Frame accuracy ±2.5°C ±3.0%*|To-Ta|
Non-uniformity zone1 ±1.5°C ±1.5%*|To-Ta|
Non-uniformity zone2 ±2.5°C ±1.5%*|To-Ta|
Frame accuracy ±1°C ±3.0%*|To-Ta|
Non-uniformity zone1 ±1°C ±2%*|To-Ta|
Non-uniformity zone2 ±2°C ±2%*|To-Ta|
100°C
0°C
±5.5°C
±3°C ±5% * |To-Ta|
-20°C
-40°C
±4°C ±5% * |To-Ta|
50°C
0°C
125°C
Figure 18 Temperature absolute accuracy - MLX90641BCB
Zone 3
Zone 3
Zone 1
Zone 3
Zone 2
Zone 1
Zone 3
Zone 2
Figure 19 Different accuracy zones depending on device type (BCA on the left and BCB on the right)
Example: If we assume that the sensor (BCA type, zone 1) is measuring a target at 80°C that would mean that there should be
no pixel with error bigger than:
( )
NOTES:
1) For best performance it is recommended to keep the supply voltage as accurate and stable as possible to 3.3V ±
0.05V
2) As a result of long term (years) drift there can be an additional measurement deviation of ± 3°C for object
temperatures around room temperature.
12.1.2. Ta accuracy
Absolute accuracy for the Ta channel (die temperature):
NOTE: Actual sensor surrounding temperature would be approximately 5°C lower
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12.2. Startup time
12.2.1. First valid data
After POR the first valid data is available after (depending on the selected refresh rate)
, ms
which is calculated as:
(Example refresh rate is 2Hz – the default value)
It is always subpage 0 to be measured first after POR then subpage 1 and so on alternating.
NOTE1: In case one changes the refresh rate on the fly (by writing new values into device register (0x800D)) the settings
will take place only after the subpage under measurement is finished.
NOTE2: Although the first subpage is ready after 500ms it is necessary to have data from both subpages in order to be
able to calculate the Ta meaning that the valid data are only possible after twice the refresh rate after POR .
Default
Set 8Hz
40ms
2Hz
Valid data
Subpage 0
Active 2Hz refresh rate
Subpage 1
Subpage 0
8Hz refresh rate start
12.2.2. Thermal behavior
Although electrically the device is set and running there is thermal stabilization time nec essary before the device can
reach the specified accuracy – up to 3 min.
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12.3. Noise performance and resolution
There are two bits in the configuration register that allow changing the resolution of the MLX90641 measurements.
Increasing the resolution decreases the quantization noise and improves the overall noise performance.
Measurement conditions for the noise are: To=Ta=25°C
NOTE: Due to the nature of the thermal infrared radiation, it is normal that the noise will decrease for high temperature and
increase for lower temperatures
Figure 20 MLX90641BCx noise vs refresh rate for different device types
Not all pixels have the same noise performance. Because of the optical performance of the integrated lens, it is normal
that the pixels in the corner of the frame are noisier in comparison with the pixels in the middle. The graphs bellow
show the distribution of the noise density versus the pixel position in the frame (pixel number)
Figure 21 MLX90641BCA noise vs pixel and refresh rate at 1Hz and 2Hz
Figure 22 MLX90641BCA noise vs pixel and refresh rate at 4Hz, 8Hz and 16Hz
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Figure 23 MLX90641BCB noise vs pixel and refresh rate at 1Hz and 2Hz
Figure 24 MLX90641BCB noise vs pixel and refresh rate at 4Hz, 8Hz and 16Hz
NETD (K)
1Hz RMS noise (temperature equivalent), all pixels
MLX90641
Average
Min
Standard deviation
BCA
0.07
0.04
0.03
BCB
0.15
0.07
0.05
Table 12 Noise performance
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12.4. Field of view (FOV)
Point heat source
Sensitivity
100%
50%
Field Of View
Angle of incidence
Rotated sensor
Figure 25 Field Of View measurement
The specified FOV is calculated for the wider direction, in this case for the 16 pixels.
FOV
MLX90641-ESF-BCA
MLX90641-ESF-BCB
X direction
Y direction
Typ
110°
55°
Typ
75°
35°
Central pointing from normal
(X & Y direction)
Max
5°
3°
Table 13 Available FOV options
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13. Application information
13.1. Optical considerations
As this is an optical device a care must be taking such that the device performs according to the specification. One such
parameter is FOV obstruction. It is paramount that the FOV in the optical path is kept clear. The external aperture is
designed such to shape the FOV of the device and is installed prior calibration process thus cam be considered as part
of the device which does not impact the performance but may be used as a reference for the so called “Optical free
zone” – see Figure 27 hereafter.
Figure 26 Application examples concerning the optical consideration
13.2. Electrical considerations
Figure 27 MLX90641Bxx electrical connections
As the MLX90641Bxx is fully I2C compatible it allows to have a system in which the MCU may be supplied with VDD=2.6V…5V
while the sensor it’s self is supplied from separate supply VDD1=3.3V (or even left with no supply i.e. VDD=0V), with the I2C
connection running at supply voltage of the MCU.
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13.3. Using the device in “image mode”
In some applications may not be necessary to calculate the temperature but rather to have just and image (for
instance in machine vision systems). In this case it is not necessary to carry out all calculations which would save
computation time or allow the one to use weaker CPU.
In order to get thermal image only following computation flow is to be used:
Supply voltage value calculation - 11.2.2.2
Ambient temperature calculation - 11.2.2.3
Gain compensation - 11.2.2.5.1
IR data compensation – offset, VDD and Ta - 11.2.2.5.3
IR data gradient compensation - 11.2.2.7
Normalizing to sensitivity - 11.2.2.8
Image (data) processing
Figure 28 Calculation flow in thermal image mode
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14. Application Comments
Significant contamination at the optical input side (sensor filter) might cause unknown additional filtering/distortion of the
optical signal and therefore result in unspecified errors.
IR sensors are inherently susceptible to errors caused by thermal gradients. There are physical reasons for these phenomena
and, in spite of the careful design of the MLX90641Bxx, it is recommended not to subject the MLX90641Bxx to heat transfer
and especially transient conditions.
The MLX90641Bxx is designed and calibrated to operate as a non-contact thermometer in settled conditions. Using the
thermometer in a very different way will result in unknown results.
Capacitive loading on an I2C can degrade the communication. Some improvement is possible with use of current sources
compared to resistors in pull-up circuitry. Further improvement is possible with specialized commercially available bus
accelerators. With the MLX90641Bxx additional improvement is possible by increasing the pull-up current (decreasing the
pull-up resistor values). Input levels for I2C compatible mode have higher overall tolerance than the I2C specification, but the
output low level is rather low even with the high-power I2C specification for pull-up currents. Another option might be to go
for a slower communication (clock speed), as the MLX90641Bxx implements Schmidt triggers on its inputs in I2C compatible
mode and is therefore not really sensitive to rise time of the bus (it is more likely the rise time to be an issue than the fall
time, as far as the I2C systems are open drain with pull-up).
Power dissipation within the package may affect performance in two ways: by heating the “ambient” sensitive element
significantly beyond the actual ambient temperature, as well as by causing gradients over the package that will inherently
cause thermal gradient over the cap
Power supply decoupling capacitor is needed as with most integrated circuits. MLX90641Bxx is a mixed-signal device with
sensors, small signal analog part, digital part and I/O circuitry. In order to keep the noise low power supply switching noise
needs to be decoupled. High noise from external circuitry can also affect noise performance of the device. In many
applications a 100nF SMD plus 10µF ceramic capacitors close to the Vdd and Vss pins would be a good choice. It should be
noted that not only the trace to the Vdd pin needs to be short, but also the one to the Vss pin. Using MLX90641Bxx with
short pins improves the effect of the power supply decoupling.
Check www.melexis.com for most recent application notes about MLX90641Bxx.
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15. Mechanical drawings
15.1. FOV 55°
Figure 29 Mechanical drawing of 55° FOV device
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15.2. FOV 110°
Figure 30 Mechanical drawing of 110° FOV device
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15.3. Device marking
The MLX90641 is laser marked with 10 symbols as follows.
1
A
A
xxxxx
xx
Laser marking
2 digits Split number
5 digits LOT number
1
A
FOV = 110°
B
FOV = 55°
A
Device without thermal gradient compensation (TGC = 0 and may not be changed)
C
Device with thermal gradient compensation (TGC = -4…+3.992)
MLX90641
Example: “1CA1052801” – Device type MLX90641BCA from lot 10528, sub LOT split 1 and Thermal Gradient
Compensation activated.
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16. Standard Information
Our products are classified and qualified regarding soldering technology, solderability and moisture sensitivity level
according to standards in place in Semiconductor industry.
For further details about test method references and for compliance verification of se lected soldering method for
product integration, Melexis recommends reviewing on our web site the General Guidelines soldering
recommendation. For all soldering technologies deviating from the one mentioned in above document (regarding peak
temperature, temperature gradient, temperature profile etc), additional classification and qualification tests have to
be agreed upon with Melexis.
For package technology embedding trim and form post-delivery capability, Melexis recommends to consult the
dedicated trim&form recommendation application note: lead trimming and forming recommendations
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/en/quality-environment
17. ESD Precautions
Electronic semiconductor products are sensitive to Electro Static Discharge (ESD).
Always observe Electro Static Discharge control procedures whenever handling semiconductor products.
18. Revision History Table
25/07/2016
Initial release
12/08/2016
Calibration data stored into EEPROM, pixel reading modes explained
13/01/2017
Added CP data extraction, example updated, accuracy table
01/02/2017
Kta(i,j) and Kv(i,j) coefficients extraction from EEPROM corrected
15/12/2017
Overall rework
12/04/2018
extra temperature ranges calculations, new approach of Emissivity compensation
08/11/2018
Driver link, Max temp = 300°C, ESD = 4kV, step mode removed, FOV added,
06/02/2019
Emissivity compensation changed, added absolute accuracy for Ta
06/12/2019
Rev 3: long term accuracy note, optical consideration, package chamfer info, note regarding max
current trough SDA driver, docserver number in the footer
Table 14 Revision history
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19. Contact
For the latest version of this document, go to our website at www.melexis.com.
For additional information, please contact our Direct Sales team and get help for your specific needs:
Europe, Africa
Telephone: +32 13 67 04 95
Email : sales_europe@melexis.com
Americas
Telephone: +1 603 223 2362
Email : sales_usa@melexis.com
Asia
Email : sales_asia@melexis.com
20. Disclaimer
The information furnished by Melexis herein (“Information”) is believed to be correct and accurate. Melexis disclaims (i) any and all liability in connection with or arising out of the
furnishing, performance or use of the technical data or use of the product(s) as described herein (“Product”) (ii) any and al l liability, including without limitation, special,
consequential or incidental damages, and (iii) any and all warranties, express, statutory, implied, or by description, includ ing warranties of fitness for particular purpose, noninfringement and merchantability. No obligation or liability shall arise or flow out of Melexis’ rendering of technical or other services.
The Information is provided "as is” and Melexis reserves the right to change the Information at any time and without notice. Therefore, before placing orders and/or prior to
designing the Product into a system, users or any third party should obtain the latest version of the relevant information to verify that the information being relied upon is current.
Users or any third party must further determine the suitability of the Product for its application, including the level of reliability required and determine whether it is fit for a
particular purpose.
The Information is proprietary and/or confidential information of Melexis and the use thereof or anything described b y the Information does not grant, explicitly or implicitly, to
any party any patent rights, licenses, or any other intellectual property rights.
This document as well as the Product(s) may be subject to export control regulations. Please be aware that export might require a prior authorization from competent authorities.
The Product(s) are intended for use in normal commercial applications. Unless otherwise agreed upon in writing, the Product(s ) are not designed, authorized or warranted to be
suitable in applications requiring extended temperature range and/or unusual environmental requirements. High reliability applications, such as medical life-support or lifesustaining equipment are specifically not recommended by Melexis.
The Product(s) may not be used for the following applications subject to export control regulations: the development, production, processing, operation, maintenance, storage,
recognition or proliferation of 1) chemical, biological or nuclear weapons, or for the development, production, maintenance or storage of missiles for such weapons: 2) civil
firearms, including spare parts or ammunition for such arms; 3) defense related products, or other material for military use or for law enforcement; 4) any applications that, alone
or in combination with other goods, substances or organisms could cause serious harm to persons or goods and that can be used as a mean s of violence in an armed conflict or any
similar violent situation.
The Products sold by Melexis are subject to the terms and conditions as specified in the Terms of Sale, which can be found at https://www.melexis.com/en/legal/terms-andconditions.
This document supersedes and replaces all prior information regarding the Product(s) and/or previous versions of this document.
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