MLX90616 Datasheet, PDF (21/36 Pages) Melexis Microelectronic Systems – Infra Red Thermometer in TO-39 for high temperature thermometer guns

MLX90616ESF-HCA
Infra Red Thermometer in TO-39
for high temperature thermometer guns
8.5.1 Single PWM format
In single PWM output mode only the settings for PWM1 data are used. The temperature reading can be
calculated from the signal timing as:
  T_OUT
  ^2t2
^T
T_{O _ MAX}
 T_{O _ MIN}



T_O
_
MIN
where Tmin and Tmax are the corresponding rescale coefficients in EEPROM for the selected temperature
output (Ta, object temperature range is valid for Tobj as specified in the previous table) and T is the PWM
period. Tout is T_objor T_a according to Config Register [5:4] settings.
The different time intervals t₁…t₄ have the following meaning:
t₁: Start buffer. During this time the signal is always high. t₁ = 0.125*T (T is the PWM period, refer to fig. 13).
t₂: Valid Data Output Band, 0…1/2T. PWM output data resolution is 10 bit.
t₃: Error band – information for fatal error in EEPROM (double error detected, not correctable). t₃ = 0.25 * T.
Therefore a PWM pulse train with a duty cycle of 0.875 will indicate a fatal error in EEPROM (for single PWM
format). FE means Fatal Error.
Example:
Figure 13: PWM example single mode
To__min = 0°C =>
To_min [EEPROM] = 100 * (to_min + 273.15) = 0x6AB3
To__max = +50°C =>
To_max [EEPROM] = 100 * (to_max + 273.15) = 0x7E3B
Captured PWM period is T = 1004μs
Captured high duration is t = 392 μs
Calculated duty cycle is:
D  ^t  ³⁹²  0.3904 or 39.04%
T 1004
The temperature is calculated as follows:
T_O  2*0.3904  0.125*50  0 0  2*0.2554*50  26.54C
3901090616
Rev 002
Page 21 of 36
Data Sheet
August 20, 2012