Power-up circuit for field programmable gate arrays
First Claim
1. A protection circuit for preventing a current spike in a logic module having an internal disable input during power up of a field programmable gate array, the protection circuit comprising means for providing a voltage input to the internal disable input to disable the logic module until a voltage output by a charge pump of the field programmable gate array reaches a predetermined voltage, the voltage input to the internal disable input being substantially equal to an instantaneous supply voltage being applied to the protection circuit, the means for providing comprising:
- means for providing an increasing voltage proportional to the voltage output by the charge pump to the protection circuit at a first node of the protection circuit during power up;
means for retarding the voltage increase at the first node of the protection circuit during power up;
means for providing a voltage at a second node substantially equal to the instantaneous supply voltage being applied to the protection circuit during power up; and
means for switching the voltage input to the internal disable input from a digital logic high to a digital logic low.
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Accused Products
Abstract
A protection circuit prevents a current spike in a logic module in a field programmable gate array during power up of the gate array. The protection circuit supplies a voltage onto an internal disable input of the logic module during power up until a voltage output by a charge pump reaches a predetermined voltage. The voltage on the internal disable input turns off transistor(s) in the logic module and prevents the current spike. When the voltage output by the charge pump reaches the predetermined voltage, the protection circuit no longer supplies the voltage to the logic module'"'"'s internal disable input.
58 Citations
16 Claims
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1. A protection circuit for preventing a current spike in a logic module having an internal disable input during power up of a field programmable gate array, the protection circuit comprising means for providing a voltage input to the internal disable input to disable the logic module until a voltage output by a charge pump of the field programmable gate array reaches a predetermined voltage, the voltage input to the internal disable input being substantially equal to an instantaneous supply voltage being applied to the protection circuit, the means for providing comprising:
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means for providing an increasing voltage proportional to the voltage output by the charge pump to the protection circuit at a first node of the protection circuit during power up; means for retarding the voltage increase at the first node of the protection circuit during power up; means for providing a voltage at a second node substantially equal to the instantaneous supply voltage being applied to the protection circuit during power up; and means for switching the voltage input to the internal disable input from a digital logic high to a digital logic low. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of preventing a current spike in a logic module having an internal disable input during power up of a field programmable gate array, the method comprising:
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inputting a voltage to the internal disable input to disable the logic module until a voltage output by a charge pump of the field programmable gate array reaches a predetermined voltage, wherein the voltage input to the internal disable input is substantially equal to an instantaneous voltage being applied to the logic module; providing an increasing voltage proportional to the voltage output by the charge pump to an input of a first inverter; retarding the increasing voltage at the input of the first inverter; providing a voltage at the output of the first inverter which is substantially equal to an instantaneous supply voltage being applied to the logic module during power up; and switching the voltage input to the internal disable input from a digital logic high to a digital logic low. - View Dependent Claims (8)
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9. A field programmable gate array, comprising:
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an interconnect structure comprising routing conductors; a plurality of logic modules, each of the logic modules having an input logic element, the input logic element having a plurality of inputs which when the field programmable gate array is unconfigured are not coupled to an output of any logic module, the input logic element also having an internal disable input; and a protection circuit having an output coupled to the internal disable inputs of the logic modules and supplying a first voltage signal onto the internal disable inputs during a first power up period and supplying a second voltage signal onto the internal disable inputs during a second power up period, the second power up period starting before a supply voltage VCC of the field programmable gate array reaches steady state.
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10. A field programmable gate array, comprising:
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an interconnect structure comprising routing conductors; a plurality of logic modules, each of the logic modules having an input logic element, the input logic element having a plurality of inputs which when the field programmable gate array is unconfigured are not coupled to an output of any logic module, the input logic element also having an internal disable input; a protection circuit having an output coupled to the internal disable inputs of the logic modules and supplying a first voltage signal onto the internal disable inputs during a first power up period and supplying a second voltage signal onto the internal disable inputs during a second power up period, the second power up period starting before a supply voltage VCC of the field programmable gate array reaches steady state; and a charge pump, the second power up period starting when a voltage output by the charge pump reaches a predetermined voltage.
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11. A field programmable gate array, comprising:
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an interconnect structure comprising routing conductors; a plurality of logic modules, each of the logic modules having an input logic element, the input logic element having a plurality of inputs which when the field programmable gate array is unconfigured are not coupled to an output of any logic module, the input logic element also having an internal disable input; and a protection circuit having an output coupled to the internal disable inputs of the logic modules and supplying a first voltage signal onto the internal disable inputs during a first power up period and supplying a second voltage signal onto the internal disable inputs during a second power up period, the second power up period starting before a supply voltage VCC of the field programmable gate array reaches steady state, wherein the first voltage signal has a magnitude which increases as the supply voltage VCC increases and wherein the second voltage signal is ground potential.
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12. A field programmable gate array, comprising:
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an interconnect structure comprising routing conductors; a plurality of logic modules, each of the logic modules having an input logic element, the input logic element having a plurality of inputs which when the field programmable gate array is unconfigured are not coupled to an output of any logic module, the input logic element also having an internal disable input; and a protection circuit having an output coupled to the internal disable inputs of the logic modules and supplying a first voltage signal onto the internal disable inputs during a first power up period and supplying a second voltage signal onto the internal disable inputs during a second power up period, the second power up period starting before a supply voltage VCC of the field programmable gate array reaches steady state, wherein the interconnect structure comprises antifuses. - View Dependent Claims (13, 14)
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- 15. A field programmable gate array, comprising a plurality of logic cells, an interconnect structure, a charge pump, and a protection circuit, the protection circuit outputting a first voltage signal to each of the logic cells during a power up period until a voltage output by the charge pump reaches a predetermined voltage, the protection circuit outputting a second voltage signal to each of the logic cells after the voltage output by the charge pump reaches the predetermined voltage.
Specification