MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
8.3 Block description
8.3.1 Amplifier
A low noise low offset amplifier with programmable gain is implemented for amplification of the IR sensor
voltage. With a carefully designed input modulator and balanced input impedance, an offset as low as 0.5µV
is achieved.
8.3.2 Supply regulator and POR
The module can operate from 2 different supplies:
VDD= 5V => MLX90614Axx
VDD=3.3V => MLX90614Bxx (battery or regulated supply)
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
MLX90614xxx in reset until the Vdd is higher than the specified POR threshold VPOR (note that this level is
different for MLX90614Axx and MLX90614Bxx). During the time POR is active, the POR signal is available as
an open drain (active high) at the PWM/SDA pin. After the MLX90614xxx 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 via SMBus interface.
EEPROM (32X16)
Name
Address
000h
001h
002h
003h
004h
005h
006h
…
Write acces
Yes
Yes
Yes
Yes
Yes
Yes
No
Tomax
Tomin
PWMCTRL
Ta range
Emissivity correction coefficient
Config Register1
Melexis reserved
…
…
Melexis reserved
00Dh
00Eh
00Fh
010h
…
No
SMBus address
Yes
Yes
No
Melexis reserved
Melexis reserved
…
…
Melexis reserved
Melexis reserved
Melexis reserved
Melexis reserved
018
No
Yes
No
No
No
No
No
No
019h
01Ah
01Bh
01Ch
01Dh
01Eh
01Fh
ID number
ID number
ID number
ID number
The addresses Tomax, Tomin and Ta range are for customer dependent object and ambient temperature
ranges. For details see point 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 ε) ]
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 ε = 0.1…1.0.
3901090614
Rev 003
Page 11 of 40
Data Sheet
03/Oct/2007
MELEXIS [ Melexis Microelectronic Systems ]
