Voltage regulator over-voltage detection system, method and apparatus
Monitoring of a core logic internal voltage regulator output is performed to detect, alarm and put an integrated circuit device into a safe mode when the voltage on the core logic exceeds a safe operating voltage value. This allows putting the integrated circuit devise into a predictable, detectable and safe mode, and to alarm the over-voltage condition to a system monitor to alert on a fault and subsequent fault disposition.
1. An integrated circuit device having an internal voltage regulator over-voltage detection circuit, said integrated circuit device comprising: an internal voltage regulator coupled to external connections for a filter capacitor and a supply voltage;
an over-voltage detection circuit having an input coupled to a regulated voltage output of the internal voltage regulator;
core logic circuits receiving operating voltage from the regulated voltage output of the internal voltage regulator; and
at least one output driver having a failsafe circuit for maintaining the at least one output driver in a safe operating condition;
wherein when the over-voltage detection circuit detects a high voltage at the regulated voltage output of the internal voltage regulator, the core logic circuits and the at least one output driver are put into a safe operating mode, and
a keeper cell controlling operation of the at least one output driver, wherein when the over-voltage detection circuit detects a high voltage at the regulated voltage output of the internal voltage regulator, the at least one output driver logic state is maintained at a last logic state thereof by the keeper cell.
2. The integrated circuit device according to claim 1 , further comprising an over-voltage alarm coupled to the over-voltage detection circuit and providing a high voltage alarm when detection of a high voltage condition occurs at the regulated voltage output of the internal voltage regulator.
3. The integrated circuit device according to claim 1 , further comprising a power disconnect switch coupled between the regulated voltage output of the internal voltage regulator and the core logic circuits, wherein the core logic circuits are disconnected from the regulated voltage output of the internal voltage regulator when the high voltage at the regulated voltage output of the internal voltage regulator is detected.
4. The integrated circuit device according to claim 3 , wherein the power disconnect switch is a power field effect transistor.
5. The integrated circuit device according to claim 1 , wherein the core logic circuits comprise a digital processor and a memory.
6. The integrated circuit device according to claim 5 , wherein the digital processor is a microcontroller.
7. The integrated circuit device according to claim 5 , wherein the digital processor is selected from the group consisting of a microprocessor, a digital signal processor (DSP), a programmable logic array (PLA) and an application specific integrated circuit (ASIC).
8. An integrated circuit device having an internal voltage regulator over-voltage detection circuit, said integrated circuit device comprising: an internal voltage regulator coupled to external connections for a filter capacitor and a supply voltage:
an over-voltage detection circuit having an input coupled to a regulated voltage output of the internal voltage regulator;
core logic circuits receiving operating voltage from the regulated voltage output of the internal voltage regulator;
at least one output driver having a failsafe circuit for maintaining the at least one output driver in a safe operating condition; and
a brown-out reset circuit coupled to the regulated voltage output of the internal voltage regulator, wherein when a voltage therefrom is less than a certain minimum operating voltage then the core logic circuits and the at least one output driver are put into the safe operating mode,
wherein when the over-voltage detection circuit detects a high voltage at the regulated voltage output of the internal voltage regulator, the core logic circuits and the at least one output driver are put into a safe operating mode, wherein the at least one output driver is held in the most recent logic level.
9. The integrated circuit device according to claim 1 , wherein the over-voltage detection circuit comprises:
a voltage comparator;
a voltage reference coupled to a negative input of the voltage comparator; and
a voltage divider coupled between the regulated voltage output of the internal voltage regulator and a positive input of the voltage comparator, wherein when the regulated voltage output of the internal voltage regulator is greater than a voltage of the voltage reference an output of the voltage comparator is at a first logic level, otherwise the output of the voltage comparator is at a second logic level.
10. The integrated circuit device according to claim 9 , wherein the voltage reference is a bandgap voltage reference.
11. The integrated circuit device according to claim 9 , wherein the first logic level is a logic high and the second logic level is a logic low.
12. The integrated circuit device according to claim 9 , wherein the first logic level is a logic low and the second logic level is a logic high.
13. A system comprising:
an integrated circuit device having an internal voltage regulator over-voltage detection circuit, said integrated circuit device comprising:
an internal voltage regulator coupled to external connections for a filter capacitor and a supply voltage;
an over-voltage detection circuit having an input coupled to a regulated voltage output of the internal voltage regulator;
core logic circuits receiving operating voltage from the regulated voltage output of the internal voltage regulator;
at least one output driver having a failsafe circuit for maintaining the at least one output driver in a safe operating condition;
wherein when the over-voltage detection circuit detects a high voltage at the regulated voltage output of the internal voltage regulator, the core logic circuits and the at least one output driver are put into a safe operating mode, wherein the at least one output driver is held in the most recent logic level;
an over-voltage alarm coupled to the over-voltage detection circuit and providing a high voltage alarm when detection of a high voltage condition occurs at the regulated voltage output of the internal voltage regulator;
an external power supply for providing the supply voltage to the internal voltage regulator; and
an external system supervisor coupled to an inhibit input of the power supply and having an input monitoring the high voltage alarm;
wherein if the high voltage alarm indicates that the high voltage condition exists at the regulated voltage output of the internal voltage regulator then the system supervisor causes the power supply to reduce the supply voltage to the internal voltage regulator.
14. The integrated circuit device according to claim 13 , wherein supply voltage is reduced to substantially zero volts.
15. The integrated circuit device according to claim 13 , further comprising a disconnect power switch between the power supply and the internal voltage regulator, wherein if the high voltage alarm indicates that the high voltage condition exists at the regulated voltage output of the internal voltage regulator then the system supervisor causes the disconnect power switch to open, thereby disconnecting the supply voltage from the internal voltage regulator.
16. A method for detecting an internal voltage regulator over-voltage condition in an integrated circuit device, said method comprising the steps of:
measuring a voltage at an external connection of an integrated circuit device coupled to an internal voltage regulator;
determining whether the measured voltage at the external connection is greater than a reference voltage; and
placing core logic and at least one output driver of the integrated circuit device into a safe mode when the measured voltage at the external connection is greater than the reference voltage and activating a respective keeper cell to keep the at least one output driver at a most recent logic level when in the safe mode.
17. The method according to claim 16 , wherein the core logic circuits comprise a digital processor and a memory.
18. The method according to claim 16 , further comprising the step of generating a high voltage alarm when a high voltage condition occurs at the external connection coupled to the internal voltage regulator.
19. The method according to claim 16 , further comprising the step of disconnecting core logic of the integrated circuit device from an output voltage of the internal voltage regulator when in the safe mode.
20. A method for detecting an internal voltage regulator over-voltage condition in an integrated circuit device comprising an internal voltage regulator, said method comprising the steps of:
providing a supply voltage to the internal voltage regulator from a power supply;
measuring a voltage at an external connection of the integrated circuit device coupled to the internal voltage regulator;
determining whether the measured voltage at the external connection is greater than a reference voltage; and
placing core logic and at least one output driver of the integrated circuit device into a safe mode when the measured voltage at the external connection is greater than the reference voltage;
generating a high voltage alarm when a high voltage condition occurs at the external connection coupled to the internal voltage regulator
disconnecting core logic of the integrated circuit device horn an output voltage of the internal voltage regulator when in the safe mode;
monitoring the high voltage alarm with a system supervisor; and
inhibiting the supply voltage from the power supply to the internal voltage regulator when the high voltage alarm indicates an occurrence of the high voltage condition.
21. The method according to claim 20 , wherein the supply voltage is inhibited to substantially zero volts.
22. The method according to claim 20 , further comprising the step of disconnecting the supply voltage from the internal voltage regulator when the high voltage alarm indicates an occurrence of the high voltage condition.
23. The system according to claim 13 , wherein the core logic circuits comprise a digital processor and a memory.