Method and apparatus for power-up state initialization in a data processing system

In a data processing system having a central processing unit (CPU), a power-up state initialization system comprising:

• a power sense circuit for detecting a voltage level at a power supply terminal in said CPU, and for providing a first control signal indicating whether said voltage level is greater than a minimum voltage suitable for CMOS logic resolution;
• a counter circuit, coupled to said power sense circuit for receiving said first control signal and a plurality of internal clock pulses, and for asserting a second control signal in response thereto, and negating said second control signal when said counter circuit determines that said CPU state initialization is complete;
• an initialization logic portion coupled to said power sense circuit and said counter circuit for receiving said first control signal and said second control signal, and for providing said plurality of internal clock pulses in response thereto, said plurality of internal clock pulses being used by said system to propagate a reset condition in said CPU, said initialization logic portion stopping said internal clock pulses in response to receiving negation by said counter circuit of said second control signal, said initialization logic portion being disabled by said counter circuit when said when said number of internal clock pulses counted by said counter circuit exceeds a predetermined count value, to reduce power consumption by said system associated with state conflict in said CPU without using externally generated clock signals or a global asynchronous reset signal;
• clock generation logic for receiving said plurality of internal clock pulses and said second control signal, and for providing said plurality of multi-phase clock signals, in response thereto;
• and
• clock driver logic for receiving said plurality of multi-phase clock signal, and for providing said internal clock pulses in response thereto.

In a data processing system having a central processing unit (CPU), a power sensing circuit, clock generation logic, and reset processing logic, a method for implementing a power-up state initialization comprising:

• detecting, via a power sensing circuit, a voltage level at a power supply terminal in said CPU, and for providing a first control signal indicating whether said voltage level is greater than a minimum voltage suitable for CMOS logic resolution;
• receiving, via reset processing logic, a first control signal and a plurality of internal clock pulses generated via clock generation logic, and enabling a second control signal in response thereto, said plurality of internal clock pulses being used by said system to propagate a reset condition in said CPU;
• counting, via reset processing logic, a number of said internal clock pulses and disabling said second control signal when said number of internal clock pulses exceeds a predetermined count value;
• and
• stopping said internal clock pulses, via reset processing logic, in response to receiving said disabled second control signal to reduce power consumption by said system associated with state conflict in said CPU without using externally generated clock signals or a global asynchronous reset signal.