MLX90614 family

Single and Dual Zone

Infra Red Thermometer in TO-39

3901090614

Page 11 of 40

Data Sheet

Rev 003

03/Oct/2007

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

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

Write acces

000h

Yes

001h

Yes

PWMCTRL

002h

Yes

Ta range

003h

Yes

Emissivity correction coefficient

004h

Yes

Config Register1

005h

Yes

Melexis reserved

006h

No

…

…

…

Melexis reserved

00Dh

No

SMBus address

00Eh

Yes

Melexis reserved

00Fh

Yes

Melexis reserved

010h

No

…

…

…

Melexis reserved

018

No

Melexis reserved

019h

Yes

Melexis reserved

01Ah

No

Melexis reserved

01Bh

No

ID number

01Ch

No

ID number

01Dh

No

ID number

01Eh

No

ID number

01Fh

No

ranges. For details see point 8.5.3 below in this document

The address

Emissivity contains the object em sivity (factory default 1.0 = 0xFFFF), 16 bit.

is

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