Data Sheet
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
3901090614 Page 11 of 52 Data Sheet
Rev 008 February 28, 2013
8.3 Block description
8.3.1 Amplifier
A low noise, low offset amplifier with programmable gain is used for amplifying the IR sensor voltage.
By carefully designing the input modulator and balanced input impedance, the max offset of the system is
0.5V.
8.3.2 Supply regulator and POR
The module can operate from 3 different supplies:
VDD = 5V MLX90614Axx
VDD = 3.3V MLX90614Bxx (battery or regulated supply)
VDD = 8…16V MLX90614Axx few external components are necessary please refer to “Applications
information” section for information about adopting higher voltage supplies.
The Power On Reset (POR) is connected to Vdd supply. The on-chip POR circuit provides an active (high) level
of the POR signal when the Vdd voltage rises above approximately 0.5V and holds the entire MLX90614 in
reset until the Vdd is higher than the specified POR threshold V
POR
. During the time POR is active, the POR
signal is available as an open drain at the PWM/SDA pin. After the MLX90614 exits the POR condition, the
function programmed in EEPROM takes precedence for that pin.
8.3.3 EEPROM
A limited number of addresses in the EEPROM memory can be changed by the customer. The whole
EEPROM can be read through the SMBus interface.
EEPROM (32X16)
Name Address Write access
To
max
0x00 Yes
To
min
0x01 Yes
PWMCTRL 0x02 Yes
Ta range
0x03 Yes
Emissivity correction coefficient 0x04 Yes
Config Register1 0x05 Yes
Melexis reserved 0x06 No
… … …
Melexis reserved 0x0D No
SMBus address (LSByte only) 0x0E Yes
Melexis reserved 0x0F Yes
Melexis reserved 0x10 No
… … …
Melexis reserved 0x18 No
Melexis reserved 0x19 Yes
Melexis reserved 0x1A No
Melexis reserved 0x1B No
ID number 0x1C No
ID number 0x1D No
ID number 0x1E No
ID number 0x1F No
Table 5: EEPROM table
The addresses To
max
, To
min
and Ta range are for customer dependent object and ambient temperature
ranges. For details see section 8.5.3 below in this document
The address Emissivity contains the object emissivity (factory default 1.0 = 0xFFFF), 16 bit.
Emissivity = dec2hex[ round( 65535 x
) ]
Where dec2hex[ round( X ) ] represents decimal to hexadecimal conversion with round-off to nearest value (not
truncation). In this case the physical emissivity values are
= 0.1…1.0.
Erase (write 0) must take place before write of desired data is made.