Reference voltage generating circuit and analog circuit using the same
View Patent ↗A reference voltage generating circuit includes a first power supply, a second power supply, a first variable resistance circuit having one end connected to the first power supply and configured to be capable of adjusting a resistance value of the first variable resistance circuit, a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit, a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to be capable of adjusting a resistance value of the second variable resistance circuit, a first terminal arranged between the first variable resistance circuit and the series resistance circuit, a second terminal arranged between the series resistance circuit and the second variable resistance circuit, and a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal, and output the selected voltage as a reference voltage.
1. A reference voltage generating circuit, comprising:
a first power supply;
a second power supply;
a first variable resistance circuit having one end connected to the first power supply and configured to he capable of adjusting a resistance value of the first variable resistance circuit;
a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit;
a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to he capable of adjusting a resistance value of the second variable resistance circuit;
a first terminal arranged between the first variable resistance circuit and the series resistance circuit;
a second terminal arranged between the series resistance circuit and the second variable resistance circuit; and
a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal, and output the selected voltage as a reference voltage,
wherein each of the first and second variable resistance circuits has a plurality of parallel circuits connected in series, each of the plurality of parallel circuits including a resistance and a fuse which are connected in parallel.
2. The reference voltage generating circuit according to claim 1 , wherein
the series resistance circuit has a plurality of resistances connected in series;
the reference voltage generating circuit includes a third terminal arranged between two resistances next to each other of the plurality of resistances constituting the series resistance circuit; and
the voltage selecting circuit is configured to select one of the voltage of the first terminal, a voltage of the third terminal, and the voltage of the second terminal, and output the selected voltage as the reference voltage.
3. An analog circuit, comprising:
a constant current circuit having
an output transistor configured to control an output current,
a resistance connected to the output transistor in series,
a reference voltage generating circuit configured to supply a reference voltage, and
a comparison circuit configured to compare a voltage applied to the resistance with the reference voltage from the reference voltage generating circuit and control an operation of the output transistor in accordance with a comparison result,
the reference voltage venerating circuit including:
a first power supply;
a second power supply;
a first variable resistance circuit having end connected to the first power supply and configured to be capable of adjusting a resistance value of the first variable resistance circuit;
a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit;
a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to he capable of adjusting a resistance value of the second variable resistance circuit;
a first terminal arranged between the first variable resistance circuit and the series resistance circuit;
a second terminal arranged between the series resistance circuit and the second variable resistance circuit; and
a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal and output the selected voltage as a reference voltage.
4. An analog circuit, comprising:
a constant voltage circuit having
an output transistor configured to control an output voltage,
a voltage-dividing resistance circuit configured to divide the output voltage and supply a divided voltage,
a reference voltage generating circuit configured to supply a reference voltage, and
a comparison circuit configured to compare the divided voltage from the voltage-dividing resistance circuit with the reference voltage from the reference voltage generating circuit and control an operation of the output transistor in accordance with a comparison result,
the reference voltage generating circuit including:
a first power supply;
a second power supply;
a first variable resistance circuit having one end connected to the first power supply and configured to be capable of adjusting a resistance value of the first variable resistance circuit;
a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit;
a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to be capable of adjusting a resistance value of the second variable resistance circuit;
a first terminal arranged between the first variable resistance circuit and the series resistance circuit;
a second terminal arranged between the series resistance circuit and the second variable resistance circuit; and
a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal, and output the selected voltage as a reference voltage.
5. An analog circuit, comprising:
a voltage detecting circuit having
a voltage-dividing resistance circuit configured to divide an input voltage and supply a divided voltage,
a reference voltage generating circuit configured to supply a reference voltage, and
a comparison circuit configured to compare the divided voltage from the voltage-dividing resistance circuit with the reference voltage from the reference voltage generating circuit,
the reference voltage generating circuit including:
a first power supply;
a second power supply;
a first variable resistance circuit having one end connected to the first power supply and configured to he capable of adjusting a resistance value of the first variable resistance circuit;
a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit;
a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to be capable of adjusting a resistance value of the second variable resistance circuit;
a first terminal arranged between the first variable resistance circuit and the series resistance circuit;
a second terminal arranged between the series resistance circuit and the second variable resistance circuit; and
a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal, and output the selected voltage as a reference voltage.
6. An analog circuit, comprising:
a charging circuit configured to charge a secondary battery, the charging circuit having
a charge-current detecting resistance configured to detect a charge current applied to the charge-current detecting resistance,
a current-voltage converting circuit configured to output a monitor voltage according to the charge current on the basis of voltages at both ends of the charge-current detecting resistance,
a reference voltage generating circuit configured to supply a reference voltage,
a charging transistor connected with the charge-current detecting resistance in series, and
a charge-current controlling circuit configured to compare the monitor voltage with the reference voltage from the reference voltage generating circuit and output a control signal to control an operation of the charging transistor so that a value of the monitor voltage becomes equal to that of the reference voltage,
wherein the charging transistor is configured to receive the control signal output from the charge-current controlling circuit and control the charge current to be supplied to the secondary battery in accordance with the received control signal, and
wherein the reference voltage generating circuit includes:
a first power supply;
a second power supply;
a first variable resistance circuit having one end connected to the first power supply and configured to be capable of adjusting a resistance value of the first variable resistance circuit;
a series resistance circuit having at least one resistance and one end connected to the first variable resistance circuit;
a second variable resistance circuit having one end connected to the series resistance circuit and the other end connected to the second power supply, and configured to he capable of adjusting a resistance value of the second variable resistance circuit;
a first terminal arranged between the first variable resistance circuit and the series resistance circuit;
a second terminal arranged between the series resistance circuit and the second variable resistance circuit; and
a voltage selecting circuit configured to select one of a voltage of the first terminal and a voltage of the second terminal, and output the selected voltage as a reference voltage.