A circuit includes a current source series-connected with a load between first and second terminals and an element coupled in parallel with the load between the first and second terminals. A value of a current in the current source is controlled based on a current flowing in the element between the first and second terminals. The value of the current in the current source is controlled proportional to power consumption in the load based on the current flowing in the element between the first and second terminals. The element is used to limit a voltage across the load while the value of the current is being controlled.

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 radiation tolerant discrete reference voltage source includes just two bipolar junction transistors, five resistors, and a Zener diode. Two of the resistors form a voltage divider that outputs a reference voltage. Values of the resistors included in the voltage divider can be selected to output a desired reference voltage level, for example, 5.00V, 4.00V, or 2.50V, which obviates a need to procure unique voltage references for those reference voltage levels and provides design flexibility. The radiation tolerant discrete reference voltage source provides improved control over radiation hardness and does not require high gain transistors. Because relatively few, inexpensive components are used, the radiation tolerant discrete reference voltage source can be produced at a low cost.

A radiation tolerant discrete reference voltage source includes just two bipolar junction transistors, five resistors, and a Zener diode. Two of the resistors form a voltage divider that outputs a reference voltage. Values of the resistors included in the voltage divider can be selected to output a desired reference voltage level, for example, 5.00V, 4.00V, or 2.50V, which obviates a need to procure unique voltage references for those reference voltage levels and provides design flexibility. The radiation tolerant discrete reference voltage source provides improved control over radiation hardness and does not require high gain transistors. Because relatively few, inexpensive components are used, the radiation tolerant discrete reference voltage source can be produced at a low cost.

A power supply unit for an aerosol inhaler includes: a case; a power supply that discharges power to a load for generating an aerosol from an aerosol generation source; a discharging terminal that connects the load to the power supply; a charging terminal that connects the power supply to an external power supply and is separated from the discharging terminal; a temperature measuring unit that measures temperature of the power supply; and a control device that controls an effective value of a first charging current to a value smaller than an effective value of a second charging current. The first charging current is supplied to the power supply when a measurement value of the temperature measuring unit is equal to or higher than a first threshold and the second charging current is supplied to the power supply when the measurement value is lower than the first threshold.

A power supply unit for an aerosol inhaler includes: a case; a power supply that discharges power to a load for generating an aerosol from an aerosol generation source; a discharging terminal that connects the load to the power supply; a charging terminal that connects the power supply to an external power supply and is separated from the discharging terminal; a temperature measuring unit that measures temperature of the power supply; and a control device that controls an effective value of a first charging current to a value smaller than an effective value of a second charging current. The first charging current is supplied to the power supply when a measurement value of the temperature measuring unit is equal to or higher than a first threshold and the second charging current is supplied to the power supply when the measurement value is lower than the first threshold.

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 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.

Reference voltage generation circuits and related methods are disclosed. An example reference voltage generation circuit includes a voltage generating circuit including an enhancement mode (E-mode) gallium nitride (GaN) transistor, the voltage generating circuit to, in response to a first clock signal having a first phase, generate a first voltage associated with the E-mode GaN transistor, and, in response to a second clock signal having a second phase different from the first phase, generate a second voltage associated with the E-mode GaN transistor, and a switching capacitor circuit coupled to the voltage generating circuit, the switching capacitor circuit to generate a reference voltage based on a difference between the first voltage and the second voltage.

Reference voltage generation circuits and related methods are disclosed. An example reference voltage generation circuit includes a voltage generating circuit including an enhancement mode (E-mode) gallium nitride (GaN) transistor, the voltage generating circuit to, in response to a first clock signal having a first phase, generate a first voltage associated with the E-mode GaN transistor, and, in response to a second clock signal having a second phase different from the first phase, generate a second voltage associated with the E-mode GaN transistor, and a switching capacitor circuit coupled to the voltage generating circuit, the switching capacitor circuit to generate a reference voltage based on a difference between the first voltage and the second voltage.