Ratiometric Sensor Output Topology And Methods
AssigneeAllegro MicroSystems, LLC
InventorsEzequiel Rubinsztain, Pablo Javier Bolsinger
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Abstract
A sensor includes an output circuit configured to generate a sensor output signal based on an input signal having a logic high or low level, as may be provided by a Schmitt trigger circuit. During normal operation, the output switches between a first percentage of the supply voltage for logic high and a second percentage of the supply voltage for logic low. To convey a failure at the output, an output signal is output as either ground or the supply voltage when a fault is detected. As such, a fault can be communicated any time the output voltage is not equal to the first percentage or the second percentage of the supply voltage.
Claims24
A circuit to generate an output signal in response to an input signal having a logic high level or a logic low level, the circuit comprising:
- a resistor divider coupled to a supply voltage and configured to produce a first reference voltage that is a first percentage of the supply voltage or a second reference voltage that is a second percentage of the supply voltage not equal to the first percentage of the supply voltage;
- an operational amplifier having a first, feedback input coupled to receive the output signal, a second input selectively coupled to receive the first reference voltage when the input signal is at a logic high level or the second reference voltage when the input signal is at a logic low level, and an output at which a difference signal indicative of a difference between the output signal and the first reference voltage or the second reference voltage is provided;
- and
- a pass element having a first terminal at which the output signal is provided, a second terminal, and a third, control terminal responsive to the difference signal to generate the output signal at a level corresponding to the first reference voltage or the second reference voltage.
A circuit to generate an output signal at an output in response to an input signal having a logic high level or a logic low level, the circuit comprising:
- a first switching element configured to be active to couple a first network to the output to provide the output signal at a first percentage of a supply voltage when the input signal is at a logic low level or to be inactive to decouple the first network from the output when the input signal is at a logic high level;
- and
- a second switching element configured to be active to couple a second network to the output to provide the output signal at a second percentage of the supply voltage that is different than the first percentage of the supply voltage when the input signal is at the logic high level or to be inactive to decouple the second network from the output when the input signal is at the logic low level.
A method of generating an output signal at an output of a circuit that receives an input signal having a logic high level or a logic low level, the method comprising:
- receiving a supply voltage;
- providing the output signal at a first level corresponding to a first percentage of the supply voltage when the input signal is a logic low level;
- providing the output signal at a second level corresponding to a second percentage of the supply voltage when the input signal is a logic high level;
- and
- providing the output signal at a third level that is different than the first level and the second level when a fault is detected.
Dependencies are inferred from the claim text.