VOLTAGE REGULATION SUBSYSTEM

• US 20160048147A1
• Filed: 08/12/2014
• Published: 02/18/2016
• Est. Priority Date: 08/12/2014
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Abhishek, Kumar, Prakash, Siddi Jai, Kamal, Kushal
• Granted Patent: US 9,348,346 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05F 1/468 characterised by reference voltage circuitry, e.g. soft start, remote shutdown

Abstract

A voltage regulation subsystem for a microprocessor has both internal and external regulation modes. An internal auxiliary voltage regulator is selectively enabled to overdrive the voltage. The enablement of the auxiliary voltage regulator is contingent upon a comparison of bandgap references of the internal and external regulators used in the respective regulation modes, which boosts the supply voltage, enables circuitry supplied by the external regulator (with the assistance of auxiliary voltage regulators) to boot robustly in extreme Process-Voltage-Temperature (PVT) conditions.

Claims

1. A voltage regulation system for regulating voltage in an integrated circuit, the system comprising:

an auxiliary regulator;

a bandgap comparator; and

an interface with an external regulator,

wherein the bandgap comparator compares an external regulator bandgap voltage with an internal reference voltage and outputs a comparison signal to the auxiliary regulator,

wherein the auxiliary regulator is enabled if the comparison signal indicates that the external regulator bandgap voltage is less than the internal reference voltage and a predetermined offset, and

wherein the enabled auxiliary regulator boosts a first supply voltage in accordance with predetermined criteria, thereby ensuring that the integrated circuit exits reset.

2. The system of claim 1, wherein the bandgap comparator is enabled only when the reference voltage is determined to be stable.

3. The system of claim 2, wherein the first supply voltage is boosted using a second supply voltage, the second supply voltage being higher than the first supply voltage,

wherein the second supply voltage also is supplied to a low voltage detection (LVD) unit, said LVD unit monitoring whether the second supply voltage falls below an LVD threshold value, and

wherein the bandgap comparator is disabled when the second supply voltage falls below the LVD threshold.

4. The system of claim 3, wherein the second supply voltage provides the voltage for the external regulator, thereby ensuring that the bandgap comparator is enabled only when the bandgap voltage is stable because the voltage at the external regulator is above the LVD threshold.

5. The system of claim 1, further comprising an operational amplifier communicatively coupled to a reset generation module,

wherein the operational amplifier receives the supply voltage and compares the supply voltage to the internal reference voltage, and outputs a second comparison signal to the reset generation module indicating whether the supply voltage exceeds the internal reference voltage, and

wherein the auxiliary regulator ensures that the integrated circuit exits reset by boosting the supply voltage to exceed the internal reference voltage.

6. The system of claim 1, wherein the auxiliary regulator is enabled during a mode of the integrated circuit changes between power-on and power-off states.

7. The system of claim 1, wherein the internal reference voltage is untrimmed during electronic circuit reset, said internal reference voltage varying across an untrimmed range of voltage values.

8. The system of claim 1, wherein the auxiliary regulator is enabled during load transitions.

9. The system of claim 8, wherein the internal reference voltage is trimmed during load transitions, the internal reference voltage varying across a trimmed range of voltage values, wherein the trimmed range is narrower than an untrimmed range.

10. A method for regulating voltage in an electronic circuit, the method comprising:

receiving an external regulator bandgap from a first voltage regulator, said first voltage regulator being external to the electronic circuit;

receiving an internal reference voltage from a reference generator, said reference generator being internal to the electronic circuit;

comparing, in a bandgap comparator unit, the external regulator bandgap with the internal reference voltage;

outputting a comparison signal to an auxiliary regulator;

enabling the auxiliary regulator if the comparison signal indicates that the external regulator bandgap is less than the internal reference voltage and a predetermined offset; and

boosting, at the enabled auxiliary regulator, a supply voltage in accordance with a predetermined criterion, thereby ensuring that the electronic circuit comes out of reset.

11. The method of claim 10, wherein, prior to comparing the external regulator bandgap with the internal reference voltage, the method comprises:

determining whether the external regulator bandgap is stable; and

enabling the bandgap comparator unit only when the external regulator bandgap is stable.

12. The method of claim 11, wherein the supply voltage is boosted using a second supply voltage, said second supply voltage being higher than the supply voltage,

wherein the second supply voltage is also supplied to a low voltage detection, LVD, unit, said LVD unit monitoring whether the second supply voltage falls below an LVD threshold, and

wherein the step of determining whether the external regulator bandgap is stable comprises determining that the second supply voltage exceeds the LVD threshold.

13. The method of claim 12, wherein the second supply voltage provides the voltage for the external regulator, thereby ensuring that the bandgap comparator unit is enabled only when the bandgap is stable because the voltage at the external regulator exceeds the LVD threshold.

14. The method of claim 10, further comprising, in an operational amplifier communicatively coupled to a reset generation module:

receiving the supply voltage;

comparing said supply voltage to the internal reference voltage; and

outputting a second comparison signal to the reset generation module indicating whether the supply voltage exceeds the internal reference voltage, and

wherein the predetermined criterion for the auxiliary regulator requires the supply voltage to exceed the internal reference voltage.

15. The method of claim 10, wherein the internal reference voltage is untrimmed during electronic circuit reset, said internal reference voltage varying across an untrimmed range of voltage values.

16. The method of claim 10, further comprising enabling the auxiliary regulator during load transitions.

17. The method of claim 166, wherein the internal reference voltage is trimmed during load transitions, said internal reference voltage varying across a trimmed range of voltage values and said trimmed range being narrower than an untrimmed range.

18. A method for verifying power management in an integrated circuit design using an external design verification apparatus, wherein the integrated circuit design includes an auxiliary regulator, a bandgap comparator module and a plurality of load modules, the method comprising:

generating an estimated a current load requirement of the plurality of load modules based on a predefined current load model;

testing the integrated circuit design with the external design verification apparatus using the estimated current load requirement by executing predetermined test patterns, said test patterns including patterns corresponding to one or more of start-up, mode transition and load transition, and

during said testing;

comparing, in the bandgap comparator module, an external regulator bandgap with an internal reference voltage,

outputting a comparison signal from the bandgap comparator module to the auxiliary regulator,

enabling the auxiliary regulator if the comparison signal indicates that the external regulator bandgap is less than the internal reference voltage and a predetermined offset,

monitoring a supply voltage of the integrated circuit design, wherein the supply voltage is regulated by the enabled auxiliary regulator, the enabled auxiliary regulator boosting the supply voltage in accordance with a predetermined criterion; and

verifying that the supply voltage regulation performed by the auxiliary regulator, which is based on the estimated current load requirement, does not deviate from a predetermined operating voltage of the integrated circuit design.