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US 6,720,673 B2Granted
Voltage island fencing
AssigneeInternational Business Machines Corporation
InventorsRafael Blanco, Sebastian T. Ventrone
Life of this patent
Estimating the term…
Abstract
A circuit for fencing input signals to circuits in a voltage island when switching between a normal and a standby power supply is disclosed. A voltage detector detects the switch over in power source and generates a power switch signal. The power switch signal is synchronized to a standby clock and a normal clock. The synchronized standby clock signal is delayed by a counter to allow circuit stabilization. The normal and standby clock signals are logically combined and used to fence input signals to the circuits on the voltage islands.
Claims41
An electronic device comprising:
- a voltage island switchable between a normal power supply and a standby power supply, said voltage island including circuits for receiving input signals;
- a voltage detector outputting a power sense signal in response to a fall to a first voltage value from a reference value or a rise to a second voltage value from said reference value of the voltage of said normal power supply;
- a standby clock generating a standby clock signal;
- a standby clock synchronizing circuit receiving said power sense signal and said standby clock signal, synchronizing said power sense signal to said standby clock domain and outputting a standby clock synchronized power sense signal;
- a counter receiving said standby clock synchronized power sense signal and said power sense signal, adding a delay to said standby clock synchronized power sense signal and outputting a delayed standby clock synchronized power sense signal;
- a normal clock synchronizing circuit receiving said delayed standby clock synchronized power sense signal, synchronizing said delayed standby clock synchronized power sense signal to said normal clock domain and outputting a delayed normal clock synchronized power sense signal;
- and
- a fencing logic circuit receiving said delayed normal clock synchronized power sense signal and forcing said input signals high or low synchronously with said delayed normal clock synchronized power sense signal.
5 more elements
An electronic device comprising:
- a voltage island switchable between a normal power supply and a standby power supply, said voltage island including circuits for receiving input signals;
- a voltage detector outputting a power sense signal in response to a fall to a first voltage value from a reference value or a rise to a second voltage value from said reference value of the voltage of said normal power supply;
- a standby clock generating a standby clock signal;
- a standby clock synchronizing circuit receiving said power sense signal and said standby clock signal, synchronizing said power sense signal to said standby clock domain and outputting a standby clock synchronized power sense signal;
- a counter receiving said standby clock synchronized power sense signal and said standby clock signal, adding a delay to said standby clock synchronized power sense signal and outputting a delayed standby clock synchronized power sense signal;
- and
- a fencing logic circuit receiving said delayed standby clock synchronized power sense signal and forcing said input signals high or low synchronously with said delayed standby clock synchronized power sense signal.
4 more elements
A method for fencing signals in an electronic device, comprising:
- providing a voltage island switchable between a normal power supply and a standby power supply, said voltage island including circuits for receiving input signals;
- outputting a power sense signal in response to a fall to a first voltage value from a reference value or a rise to a second voltage value from said reference value of the voltage of said normal power supply;
- generating a standby clock signal;
- synchronizing said power sense signal to said standby clock domain to create a standby clock synchronized power sense signal;
- adding a delay to said standby clock synchronized power sense signal to create a delayed standby clock synchronized power sense signal;
- synchronizing said delayed standby clock synchronized power sense signal to said normal clock domain to create a delayed normal clock synchronized power sense signal;
- and
- forcing said input signals high or low synchronously with said delayed normal clock synchronized power sense signal.
5 more elements
A method for fencing signals in an electronic device, comprising:
- providing a voltage island switchable between a normal power supply and a standby power supply, said voltage island including circuits for receiving input signals;
- outputting a power sense signal in response to a fall to a first voltage value from a reference value or a rise to a second voltage value from said reference value of the voltage of said normal power supply;
- generating a standby clock signal;
- synchronizing said power sense signal to said standby clock domain to create a standby clock synchronized power sense signal;
- adding a delay to said standby clock synchronized power sense signal to create a delayed standby clock synchronized power sense signal;
- and
- forcing said input signals high or low synchronously with said delayed standby clock synchronized power sense signal.
4 more elements
Dependencies are inferred from the claim text.