Low voltage detector

A System-on-Chip (SoC), comprising:

• a microcontroller unit (MCU), disposed on a substrate of an integrated circuit, and powered by a power supply;
• and
• a low voltage detector, disposed on the substrate of the integrated circuit, coupled to the MCU, to a first power supply terminal of the power supply and to a second power supply terminal of the power supply, the low voltage detector including:
• a voltage generator for producing a voltage Vxm, related to a voltage at the second power supply terminal, the voltage generator including a single array of at least one self-cascode MOSFET (SCM) structure, in which the at least one SCM structure includes a first transistor coupled to a second transistor, wherein the second transistor is connected as a diode, and in which one SCM structure of the at least one SCM structure is coupled to the second power supply terminal of the power supply and to a current source for supplying a bias current to the first transistor and to the second transistor, the voltage generator having a temperature variation coefficient that is similar to the temperature variation coefficient of the power supply voltage monitor circuit;
• a power supply voltage monitor circuit, coupled to the first power supply terminal of the power supply and coupled to a current sink, for producing a voltage VSP related to a voltage at the first power supply terminal, the power supply voltage monitor circuit having a temperature variation coefficient, and wherein the power supply voltage monitor circuit does not include an array of self-cascode MOSFET (SCM) structure;
• and
• a voltage comparator, having a first comparator input coupled to the voltage generator for coupling the voltage Vxm to the first comparator input and having a second comparator input coupled to the power supply voltage monitor circuit for coupling the voltage VSP to the second comparator input, the voltage comparator for outputting a low voltage detect output signal in response to a differential voltage between Vxm and VSP, wherein the voltages Vxm, and VSP have a substantially same voltage rate of change and in a same direction with respect to temperature based on the similar temperature variation coefficient of the power supply voltage monitor circuit and the voltage generator, wherein the low voltage detect output signal changes state in response to the voltage VSP being equal to the voltage Vxm.

An integrated circuit, comprising:

• a voltage level detector, the voltage level detector including:
• a power supply voltage monitor circuit, coupled to a current sink and including a terminal for coupling to a first power supply terminal of a power supply, the power supply voltage monitor circuit having a temperature variation coefficient, for producing a voltage VSP related to a voltage at the first power supply terminal, wherein VSP has complementary to absolute temperature (CTAT) behavior with respect to the voltage at the first power supply terminal and proportional to absolute temperature (PTAT) behavior with respect to a voltage at a second power supply terminal of the power supply;
• a proportional to absolute temperature (PTAT) voltage generator, coupled to a current source and including a terminal for coupling to a second power supply terminal of the power supply, the PTAT voltage generator having a temperature variation coefficient that is similar to the temperature variation coefficient of the power supply voltage monitor circuit, for producing a voltage Vxm related to the voltage at the second power supply terminal, wherein the PTAT voltage generator includes a single array of at least one self-cascode MOSFET (SCM) structure that produces the voltage Vxm, wherein Vxm has PTAT behavior with respect to the voltage at the second power supply terminal;
• and
• a voltage comparator, having a first comparator input coupled to the PTAT voltage generator for coupling the voltage Vxm to the first comparator input and having a second comparator input coupled to the power supply voltage monitor circuit for coupling the voltage VSP to the second comparator input, the voltage comparator for outputting a voltage level detect output signal in response to a differential voltage between Vxm and VSP, wherein the voltages Vxm and VSP have a substantially same voltage rate of change and in a same direction with respect to temperature based on the similar temperature variation coefficient of the power supply voltage monitor circuit and the PTAT voltage generator, and wherein the voltage level detect output signal changes state in response to the voltage VSP being equal to the voltage Vxm.