Starter circuit, bandgap circuit and monitoring circuit

A bandgap circuit, comprising:

• a bandgap reference circuit comprising a first branch and a second branch, the first branch comprising a first node, the second branch comprising a second node such that a potential at the first node is equal to a potential at the second node in an equilibrium of the bandgap reference circuit, the bandgap reference circuit further comprising a feedback node for a feedback signal, the feedback node being coupled to the first and the second branches;
• a feedback circuit coupled to the first and the second node, the feedback circuit being adapted to compare the potentials of the first and the second nodes and adapted to provide the feedback signal to the feedback node based upon the comparison of the potentials of the first and the second nodes, wherein the feedback circuit is further adapted to provide the feedback signal based on a control signal provided to a control terminal of a feedback transistor;
• an output stage comprising a current source and an output stage transistor, the current source and the output stage transistor being directly connected in series between a terminal for a supply voltage and a terminal for a reference potential, the output stage transistor being coupled, with a control terminal, to the feedback circuit to receive the control signal, the output stage further comprising a logic circuit coupled, with an input, to a node between the output stage transistor and the current source of the output stage, the logic circuit further comprising an output, at which a status signal comprising an information indicative of the bandgap reference circuit reaching the equilibrium is obtainable.

A monitoring circuit for a bandgap circuit, comprising:

• a device having a current/voltage characteristic with a quasi-constant voltage drop for a plurality of current values above or below a threshold voltage, the device having a first terminal and a second terminal;
• a current source being directly coupled to a terminal for a supply voltage and the first terminal of the device, wherein the second terminal of the device is directly coupled to a terminal for a reference potential;
• and
• a logic circuit coupled, with an input, to the first terminal of the device and comprising an output, at which a status signal is obtainable, the status signal comprising an information indicating the presence of a sufficient voltage level at the terminal for the supply voltage to operate the bandgap circuit in a closed feedback mode of operation, the logic circuit being adapted to generate the status signal based on the potential present at the first terminal of the device.

A bandgap circuit, comprising:

• a bandgap reference circuit comprising a first branch and a second branch, the first branch comprising a first node, the second branch comprising a second node such that a potential at the first node is equal to a potential at the second node in an equilibrium of the bandgap reference circuit, the bandgap reference circuit further comprising a feedback node for a feedback signal, the feedback node being coupled to the first and the second branches;
• a feedback circuit coupled to the first and the second nodes, the feedback circuit being adapted to compare the potentials of the first and the second nodes and adapted to provide a feedback signal to the feedback node based upon the comparison of the potentials of the first and the second nodes;
• a driver circuit with an input and an output, the input being coupled to the feedback node of the feedback circuit, wherein a first status signal comprising an information indicating a presence of a situation in which the first node is coupled to the terminal for the supply voltage is obtainable at the output of the driver circuit;
• a monitoring circuit comprising a device having a diode-like current/voltage characteristic with respect to a threshold voltage, the device having a first terminal and a second terminal, a current source being directly coupled to the terminal for the supply voltage and the first terminal of the device, wherein the second terminal of the device is directly coupled to a terminal for a reference potential, and a logic circuit coupled, with an input, to the first terminal of the device and comprising an output, at which a second status signal is obtainable, the second status signal comprising an information indicating the presence of a sufficient voltage level at the terminal for the supply voltage to operate the bandgap circuit in a closed feedback mode of operation, the logic circuit being adapted to generate the second status signal based on the potential present at the first terminal of the device;
• an output stage comprising a current source and an output stage transistor, the current source and the output stage transistor being directly connected in series between the terminal for the supply voltage and the terminal for the reference potential, the output stage transistor being coupled, with a control terminal, to the feedback circuit to receive the control signal, the output stage further comprising a logic circuit coupled, with an input, to a node between the output stage transistor and the current source of the output stage, the logic circuit further comprising an output, at which a third status signal comprising an information indicative of the bandgap reference circuit reaching an equilibrium is obtainable;
• and
• an evaluation circuit adapted to receive the first, the second and the third status signals and to generate an enabling signal indicative of a situation to start a further circuit or a processor.