A first terminal receives a first DC voltage. A switch selectively couples the first terminal to a second terminal providing an output. A control circuit selectively actuates the switch in response to a comparison of the first DC voltage to a second DC voltage. A low-dropout (LDO) linear voltage regulator, connected between the first and third terminals, operates to provide the second DC voltage from the first DC voltage.

An auxiliary power supply circuit operating within a wide input voltage range has a voltage follower unit and a voltage comparison unit. The voltage follower unit has an electronic switch, a resistor, and a Zener diode. The electronic switch has a first terminal electrically connected to a voltage input terminal of the working voltage conversion circuit, a second terminal electrically connected to a voltage output terminal of the working voltage conversion circuit, and a control terminal. The resistor is electrically connected between the first terminal and the control terminal of the electronic switch. The Zener diode has a cathode electrically connected to the control terminal of the electronic switch. The voltage comparison unit has a detecting terminal electrically connected to the voltage input terminal of the working voltage conversion circuit, and an output terminal electrically connected to the control terminal of the electronic switch.

A voltage reference circuit is disclosed comprising: a supply terminal; a ground terminal; a first current source and a Zener diode connected in series between the supply and ground terminals and having a first node therebetween and configured to supply a Zener voltage at the first node; an output node configured to provide a voltage reference; and a CTAT, circuit connected between the first node and the output node; wherein the CTAT circuit comprises: two bipolar transistors, having their respective emitters connected at a second node, and configured to, in operation, have equal collector-emitter currents, the base of the first bipolar transistor being connected to the first node, the base of the second bipolar transistor being connected to a centre node of a first voltage divider; and wherein the first voltage divider is connected between the emitter of the second bipolar transistor and the output node.

A compensation circuit configured for coupling to a voltage source and a reference circuit. The voltage source is configured for supplying a supply voltage to the compensation circuit and the reference circuit. The reference circuit includes a first circuit node and a reference output electrically coupled to the first circuit node for outputting a reference signal having a constant reference amplitude. The compensation circuit includes a transient converter for converting a first transient perturbation of the supply voltage into a first compensation electrical signal proportional to said first transient perturbation, and an adder coupled to the transient converter for adding the first compensation electrical signal to an electrical signal at the first circuit node with a first polarity opposite to a disturbance polarity of a disturbance of the electrical signal in response to the first transient perturbation.

Methods and apparatus to reduce localized transistor operating temperature increases in fully integrated voltage regulator circuits are provided. Transistor self-heating effects are reduced by dispersing heat more evenly over the integrated circuit die, via use of nested voltage regulator circuits and/or use of more than one transistor in a voltage regulator circuit pass device. An electrically parallel-connected group of multiple individual integrated transistors may be laid out across cooler areas of the integrated circuit die, such as in substantially linear sets or rings of devices near the outer die perimeter. Each transistor in the group may better disperse its own heat if it is thermally segregated from other self-heating devices, as through a minimum physical layout spacing. Transistor bias voltage mismatch tolerances, load currents, and routing resistances may interrelatedly determine the number of individual transistors needed in a group.

A voltage reference circuit is disclosed comprising: a supply terminal; a ground terminal; a first current source and a Zener diode connected in series between the supply and ground terminals and having a first node therebetween and configured to supply a Zener voltage at the first node; an output node configured to provide a voltage reference; and a CTAT, circuit connected between the first node and the output node; wherein the CTAT circuit comprises: two bipolar transistors, having their respective emitters connected at a second node, and configured to, in operation, have equal collector-emitter currents, the base of the first bipolar transistor being connected to the first node, the base of the second bipolar transistor being connected to a centre node of a first voltage divider; and wherein the first voltage divider is connected between the emitter of the second bipolar transistor and the output node.

A first terminal receives a first DC voltage. A switch selectively couples the first terminal to a second terminal providing an output. A control circuit selectively actuates the switch in response to a comparison of the first DC voltage to a second DC voltage. A low-dropout (LDO) linear voltage regulator, connected between the first and third terminals, operates to provide the second DC voltage from the first DC voltage.

A first terminal receives a first DC voltage. A switch selectively couples the first terminal to a second terminal providing an output. A control circuit selectively actuates the switch in response to a comparison of the first DC voltage to a second DC voltage. A low-dropout (LDO) linear voltage regulator, connected between the first and third terminals, operates to provide the second DC voltage from the first DC voltage.

Provided is a reference voltage circuit including a Zener diode having a cathode connected to a current source via a first node, and an anode connected to a ground point; a first resistor having one end connected to the first node; a second resistor having one end connected to another end of the first resistor; a first diode having an anode connected to another end of the second resistor via a second node, and a cathode connected to the ground point; and a current control circuit configured to generate a control current corresponding to an anode voltage of the first diode so that the current source supplies a reference current corresponding to the control current to the first diode.

A cleaning system including an energy storage device receptacle, a motor controlled via a motor control circuit, a switch, and a control circuit. The energy storage device receptacle is configured to selectively receive an energy storage device. The switch is electrically connected to the energy storage device receptacle. The switch has an on position and an off position. The control circuit is electrically connected to the switch. The control circuit is configured to output power from the energy storage device to the motor control circuit when the switch is in the on position, and prohibit power from the energy storage device to the motor control circuit when the switch is in the off position.