Level shifter with output latch
First Claim
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1. A device comprising:
- a power input to couple to a first power voltage of a first power domain;
a power output to couple to a second power voltage of a second power domain;
an input to receive a logic signal having a first level consistent with the first power domain;
an output to provide a level-shifted logic signal output having a second level consistent with the second power domain;
a voltage detection circuit coupled to the second power domain;
a latch operable to selectively latch, in response to receiving an enable signal received from the voltage detection circuit, the level-shifted logic signal output such that, in response to a change in the enable signal from a first value to a second value, the level-shifted logic signal output that exists just prior to or at a time the enable signal changes to the second value is held at the output while the enable signal has the second value; and
the voltage detection circuit operable to;
determine whether the first power domain is powered; and
provide the enable signal based at least on the determination, wherein the first and second power domains are independent from each other.
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Abstract
A level shifter for a microcontroller shifts an input voltage in a first power domain to an output voltage level consistent with a second power domain. The level shifter is enabled to shift the voltages when both power domains are operative.
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Citations
19 Claims
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1. A device comprising:
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a power input to couple to a first power voltage of a first power domain; a power output to couple to a second power voltage of a second power domain; an input to receive a logic signal having a first level consistent with the first power domain; an output to provide a level-shifted logic signal output having a second level consistent with the second power domain; a voltage detection circuit coupled to the second power domain; a latch operable to selectively latch, in response to receiving an enable signal received from the voltage detection circuit, the level-shifted logic signal output such that, in response to a change in the enable signal from a first value to a second value, the level-shifted logic signal output that exists just prior to or at a time the enable signal changes to the second value is held at the output while the enable signal has the second value; and the voltage detection circuit operable to; determine whether the first power domain is powered; and provide the enable signal based at least on the determination, wherein the first and second power domains are independent from each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A controller comprising:
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a processor operating in a digital power domain, the processor to generate control signals and receive input signals from a touchscreen operating in an analog domain via a plurality of I/O pins; each input signal I/O pin having at least one level shifter to switch the voltage level of the input signals from the analog domain to the digital domain, each level shifter comprising; a power input to couple to a first power voltage of a first power domain; a power output to couple to a second power voltage of a second power domain independent from the first power domain; an input to receive a logic signal having a first level consistent with the first power domain; an output to provide a level-shifted logic signal output having a second level consistent with the second power domain; and a latch operable to selectively latch, in response to receiving an enable signal received from the voltage detection circuit, the level shifted logic signal output such that, in response to a change in the enable signal from a first value to a second value, the level-shifted logic signal output that exists just prior to or at a time the enable signal changes to the second value is held at the output while the enable signal has the second value. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method comprising:
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shifting input voltages from a first power domain to a second power domain via a level shifter having an input corresponding to first voltages in the first power domain and an output having an output corresponding to second voltages in the second power domain; detecting that one of the first and second power domains is off via a voltage detection circuit; latching, via an enable signal received from the voltage detection circuit, an output of the level shifter such that, in response to a change in the enable signal from a first value to a second value, the output of the level shifter that exists just prior to or at a time the enable signal changes to the second value is held at the output while the enable signal has the second value; and disabling the level shifter responsive to detecting that one of the first and second power domains is off. - View Dependent Claims (19)
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Specification