Data Sheet

MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
3901090614 Page 12 of 42 Data Sheet
Rev 004 30/Jul2008
The address PWMCTRL consists of control bits for configuring the PWM/SDA pin:
Bit 0 Select the type of
PWM mode:
1 - Single PWM, factory default for
MLX90614xAx
0 – Extended PWM, factory default
for MLX90614xBx
Bit 1 Enable/disable the
PWM:
1 - Enable PWM, disable SMBus 0 - Disable PWM (Enable SMBus),
Factory default
Bit 2 Configuration of the
pin PWM:
1 - Push-Pull, 0 – Open Drain NMOS, factory
default
Bit 3 Mode selection 1 - Thermo Relay, 0 - PWM, Factory default
Bits[8:4] Extended PWM
configuration
Number of repetitions divided by 2 of sensor 1 and 2 in Extended PWM
mode. The number of repetitions can vary from 0 to 62 times.
Bits[15:9] PWM period PWM period 1.024* ms (Single PWM) or 2.048* ms (Extended PWM)
multiplied by the number written in this place.
(128 in case the number is 0.)
* Values are for nominal HFO frequency
PWM period configuration: Period in extended PWM mode is twice the period in single PWM mode.
In single PWM mode period is T = 1.024*P [ms], where P is the number, written in bits 15..9 PWMCTRL.
Maximum period is then 131.072 ms for single and 262.144 ms for extended. These values are typical and
depend on the on-chip RC oscillator absolute value. The duty cycle must be calculated instead of working
only with the high time only in order to avoid errors from the period absolute value deviations.
The address ConfigRegister1 consists of control bits for configuring the analog and digital parts:
Bits[2:0] – Configure coefficients of IIR
digital filter:
Bit 2 Bit 1 Bit 0 a
1
b
1
0 0 0 0.5 0.5
0 0 1 0.25 0.75
0 1 0 0.167 0.833
0 1 1 0.125 0.875
1 0 0 1 0 (IIR bypassed)
1 0 1 0.8 0.2
1 1 0 0.67 0.33
1 1 1 0.57 0.43
Bit 3 – Configure the type of
ambient temperature sensor:
1 - PTC 0 – PTAT
Bits[5:4] – Configure the type of data
transmitted through PWM:
Bit 5 Bit 4 Data 1 Data 2
0 0 Ta IR 1
0 1 Ta IR 2
1 1 I I R 1 R 2
1 0 IR U 2 ndefined*
Bit 6 – Define the number of IR
sensors:
1 – 2 sensors 0 -1 sensor
Bit 7 – Define the sign Ks
(Ks=dAlpha/dTobj) :
Factory calibration, do not alter
Bits[10:8] – Configure coefficient N of
FIR digital filter:
Bit 10 Bit 9 Bit 8 N
0 0 0 8**
0 0 1 16**
0 1 0 32**
0 1 1 64**
1 0 0 128
1 0 1 256
1 1 0 512
1 1 1 1024
Bits[13:11] Gain of IR input amplifier Factory calibration, do not alter
Bits[15:14] Factory calibration, do not alter
Note: The following bits/registers should not be altered (except with special tools – contact Melexis for such
tools availability) in order to keep the factory calibration relevant:
Ke [15..0] ; Config Register1 [13..11;7;3] ; addresses 00Fh and 019h.
* not recommended for extended PWM mode
** not recommended values
Check www.melexis.com
for latest application notes with details on EEPROM settings.