TMP12

Temperature Sensor Includes 100 Heater
Heater Provides Power IC Emulation
Accuracy 63°C typ. from 240°C to 1100°C
Operation to 1150°C
5 mV/°C Internal Scale-Factor
Resistor Programmable Temperature Setpoints
20 mA Open-Collector Setpoint Outputs
Programmable Thermal Hysteresis
Internal 2.5 V Reference
Single 5 V Operation
400 A Quiescent Current (Heater OFF)
Minimal External Components

System Airflow Sensor
Equipment Over-Temperature Sensor
Over-Temperature Protection
Power Supply Thermal Sensor
Low-Cost Fan Controller

Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . 20.3 V to 115 V
Heater Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 V
Setpoint Input Voltage. . . . . . . . . . . . .  . 20.3 V to [(V1) 10.3 V]
Reference Output Current . . . . . . . . . . . . . . . . . . . . . . . . . 2 mA
Open-Collector Output Current . . . . . . . . .. . . . . . . . . . . . 50 mA
Open-Collector Output Voltage . . . . . . . . . . . .. . . . . . . . . 115 V
Operating Temperature Range . . . . . . . . . .. 255°C to 1150°C
Dice Junction Temperature . . . . . . . . . . . . . . . . . . . . . . 1175°C
Storage Temperature Range . . . . . . . . . . . . 265°C to 1160°C
Lead Temperature(Soldering, 60 sec) . . . . . . . . . . . . . 1300°C

The TMP12 is a silicon-based airflow and temperature sensor designed to be placed in the same airstream as heat generating components that require cooling. Fan cooling may be required continuously, or during peak power demands, e.g. for a power supply, and if the cooling systems fails, system reliability and/or safety may be impaired. By monitoring temperature while emulating a power IC, the TMP12 can provide a warning of cooling system failure.

The TMP12 generates an internal voltage that is linearly proportional to Celsius (Centigrade) temperature, nominally 15 mV/°C. The linearized output is compared with voltages from an external resistive divider connected to the TMP12's 2.5 V precision reference. The divider sets up one or two reference voltages, as required by the user, providing one or two temperature setpoints. Comparator outputs are open-collector transistors able to sink over 20 mA. There is an on-board hysteresis generator provided to speed up the temperature-setpoint output transitions, this also reduces erratic output transitions in noisy environments. Hysteresis is programmed by the external resistor chain and is determined by the total current drawn from the 2.5 V reference. The TMP12 airflow sensor also incorporates a precision, low temperature coefficient 100 heater resistor that may be connected directly to an external 5 V supply.

When the heater is activated it raises the die temperature in the DIP package approximately 20°C above ambient (in still air). The purpose of the heater in the TMP12 is to emulate a power IC, such as a regulator or Pentium CPU which has a high internal dissipation.

When subjected to a fast airflow, the package and die temperatures of the power device and the TMP12 (if located in the same airstream) will be reduced by an amount proportional to the rate of airflow. The internal temperature rise of the TMP12 may be reduced by placing a resistor in series with the heater, or reducing the heater voltage.
The TMP12 is intended for single 5 V supply operation, but will operate on a 12 V supply. The heater is designed to operate from V only. Specified temperature range is from 240°C to 1125°C, operation extends to 1150°C at 5 V with reduced accuracy.

The TMP12 is available in 8-pin plastic DIP and SO packages.