Processor based integrated circuit with a supply voltage monitor using bandgap device without feedback
AssigneeSilicon Labs CP, Inc.
InventorKenneth W. Fernald
Life of this patent
Estimating the term…
Abstract
A voltage monitor having a bandgap reference circuit driven by a voltage to be monitored. The bandgap reference circuit produces a voltage and a second voltage that each vary with the voltage to be monitored. The magnitudes of these voltages are compared by an open loop comparator to provide a high speed output state. The output of the voltage monitor can be used to monitor a supply voltage and produce a reset signal to a processor if the supply voltage falls to a magnitude below a specified threshold.
Claims18
An integrated circuit with a voltage monitor circuit, for monitoring the supply voltage of the integrated circuit, which integrated circuit is processor based, comprising:
- a processor;
- an bandgap circuit having first and second pn junctions, said bandgap circuit driven by the supply voltage to be monitored;
- a first node associated with said first pn junction for providing a first voltage and driven by the supply voltage to be monitored, which said first voltage varies as a function of the voltage to be monitored at a first rate;
- a second node associated with said second pn junction that provides a second voltage and driven by the supply voltage to be monitored, which said second voltage varies as a function of the voltage to be monitored at a second rate different than said first rate;
- and
- a comparator circuit having a first input coupled to a voltage produced by said first node, and a second input coupled to a voltage produced by said second node to determine when said first and second voltages are within a predetermined separation and polarity, and provide as an output a reset signal to the processor.
A method of monitoring a supply voltage on an integrated circuit, which integrated circuit is processor based, comprising the steps of:
- applying to a supply input on the integrated circuit a voltage to be monitored as the supply voltage to a bandgap circuit;
- generating by the bandgap circuit a first voltage associated with current driven through a first nonlinear device and a second voltage associated with current driven through a second nonlinear device that each vary with the voltage to be monitored;
- and
- comparing with a comparator circuit the first voltage with the second voltage, and providing an output indicating a condition of the voltage to be monitored, and applying it to a processor on the integrated circuit as a reset signal.
Dependencies are inferred from the claim text.