MLX90614ESF-DAA Melexis Inc, MLX90614ESF-DAA Datasheet - Page 28

• Manufacturer Part Number: MLX90614ESF-DAA
• Description: IC THERMOMETER IR 3V (MED) TO-39
• Manufacturer: Melexis Inc

Specifications of MLX90614ESF-DAA

• Function: Thermometer, Thermostat
• Topology: ADC (Sigma Delta), Voltage Regulator
• Sensor Type: Internal
• Sensing Temperature: -40°C ~ 85°C
• Output Type: PWM, SMBus™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: TO-39
• For Use With: EVB90614 - BOARD EVAL FOR MLX90614
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.8 Thermal relay
The MLX90614 can be configured to behave as a thermo relay with programmable threshold and hysteresis
on the PWM/SDA pin. The input for the comparator unit of the relay is the object temperature from sensor 1
The output of the MLX90614 is NOT a relay driver but a logical output which should be connected to a
relay driver if necessary.
The output driver is one and the same for PWM and Thermal relay.
In order to configure the MLX90614 to work as thermal relay two conditions must be met:
The PWM/SDA pin can be programmed as a push-pull or open drain NMOS (via bit PPODB in EEPROM
PWMCTRL), which can trigger an external device. The temperature threshold data is determined by
EEPROM at address 021h (Tomin) and the hysteresis at address 020h (To
The logical state of the PWM/SDA pin is as follows:
The MLX90614 preserves its normal operation when configured as a thermal relay (PWM configuration and
specification applies as a general rule also for the thermal relay) and therefore it can be read using the
SMBus (entering the SMBus mode from both PWM and thermal relay configuration is the same).
For example, the MLX90614 can generate a wake-up alert for a system upon reaching a certain temperature
and then be read as a thermometer. A reset condition (enter and exit Sleep, for example) will be needed in
order to return to the thermal relay configuration.
Example:
PWM/SDA pin will be low at object temperature below 4 C
PWM/SDA pin will be high at object temperature higher that 6 C
3901090614
Rev 006
PWM/SDA pin is high if
PWM/SDA pin is low if
Threshold = 5 C (5 + 273.15)*100 = 27815
Hysteresis = 1 C 1*100=100
o
o
Set bit TRPWMB high at address 002h in EEPROM
Enable PWM output i.e. EN_PWM is set high
“0”
Figure 20: Thermal relay : “PWM” pin versus Tobj
T
T
obj
obj
1
1
≤
≥
EEPROM 0x0000= 0x0064 (smallest possible hysteresis is 0,01 C or 0x0001)
threshold
threshold
hysteresis
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threshold
−
+
EEPROM 0x0001= 0x6CA7
hysteresis
hysteresis
hysteresis
Infra Red Thermometer in TO-39
max
Single and Dual Zone
).
“1”
T
September 30, 2010
Data Sheet