Test mode and test method for a temperature tamper detection circuit

An integrated circuit temperature sensing method, composing:

• scaling a voltage across the base-emitter of a bipolar transistor of the integrated circuit and a delta voltage across the base-emitter of a bipolar transistor of the integrated circuit to lie within a voltage reference range less than a supply voltage while the sensor is exposed to a temperature within an expected operating temperature range;
• first selecting the scaled voltage across the base-emitter of the bipolar transistor of the integrated circuit if programming a high temperature threshold or selecting the scaled delta voltage across the base-emitter of the bipolar transistor of the integrated circuit if programming a low temperature threshold;
• and
• comparing the selected voltage against a reference voltage to generate an output signal.

An integrated circuit temperature sensor, comprising:

• a reference voltage generator operable in a first mode of operation to generate an incrementing reference voltage within a certain voltage range;
• a circuit operable during the first mode to scale a temperature dependent voltage signal concerning the base-emitter of a bipolar transistor of the integrated circuit and which is indicative of circuit operation outside of an acceptable temperature range to lie within the certain voltage range when the integrated circuit is exposed to a temperature that is within the acceptable temperature range;
• and
• a comparator operable to compare the scaled temperature dependent voltage signal against the incrementing reference voltage to generate an output signal and identify a certain incremented reference voltage at which the output signal changes state.

An integrated circuit temperature sensor, comprising:

• a reference voltage generator operable in a first mode of operation to generate an incrementing reference voltage signal within a certain voltage range;
• a scaling circuit operable in the first mode to scale a temperature dependent voltage signal concerning the base-emitter of a bipolar transistor of the integrated circuit to lie within the certain voltage range less than a supply voltage when the sensor is exposed to a temperature within an expected operating temperature range;
• and
• a comparator operable to compare the incrementing reference voltage signal against the scaled temperature dependent voltage signal and generate an output signal responsive thereto.

An integrated circuit temperature sensor, comprising:

• a scaling circuit operable to selectively shift a voltage reference from a first range less than a supply voltage for one mode of operation to a second range less than a supply voltage during another mode of operation such that a voltage across the base-emitter of a bipolar transistor of the integrated circuit and a delta voltage across the base-emitter of a bipolar transistor of the integrated circuit lie within the second voltage reference range during the test mode of operation when the sensor is exposed to a temperature within an expected operating temperature range;
• a multiplexer having first and second inputs coupled to receive the voltage across the base-emitter of the bipolar transistor of the integrated circuit and the delta voltage across the base-emitter of the bipolar transistor of the integrated circuit, the multiplexer selecting one of the scaled voltages at the first and second inputs for output;
• and
• a comparator operable to compare the voltage output from the multiplexer against the shifted reference voltage and generate an output signal responsive thereto.

An integrated circuit temperature sensing method, comprising:

• selectively shifting a voltage reference from a first range less than a supply voltage for one mode of operation to a second range less than a supply voltage during another mode of operation such that a voltage across the base-emitter of a bipolar transistor of the integrated circuit and a delta voltage across the base-emitter of a bipolar transistor of the integrated circuit to lie within the second voltage reference range during the another mode of operation when the sensor is exposed to a temperature within an expected operating temperature range;
• selecting one of the voltage across the base-emitter of the bipolar transistor of the integrated circuit and the delta voltage across the base-emitter of the bipolar transistor of the integrated circuit for output;
• and
• comparing the selected voltage against the shifted reference voltage to generate an output signal.

An integrated circuit temperature sensor, comprising:

• a reference voltage generator operable to generate an incrementing reference voltage within a first voltage range less than a supply voltage;
• a circuit operable to selectively shift the incrementing voltage reference from the first voltage range to a second range less than a supply voltage such that a temperature dependent voltage signal concerning the base-emitter of a bipolar transistor of the integrated circuit and which is indicative of circuit operation outside of an acceptable temperature range lies within the second voltage range when the integrated circuit is exposed to a temperature that is within the acceptable temperature range;
• and
• a comparator operable to compare the temperature dependent voltage signal against the shifted incrementing reference voltage to generate an output signal and identify a certain incremented reference voltage at which the output signal changes state.