Seiko Instruments Inc

Kiyoshi Yoshikawa

Atsushi Sakurai

Yoshihisa Tange

Kazuaki Sano

Toshiyuki Koike

Osamu Uehara

Takakazu Ozawa

Fumiyasu Utsunomiya

Michiyasu Deguchi

Toshiyuki Tsuzaki

Hiroyuki Masuko

Hiroki Wake

Provided is a battery state monitoring circuit including: a charge/discharge control circuit for detecting and controlling a state of a secondary battery; a temperature sensor circuit connected to an overcurrent detection terminal; an amplifier for comparing a reference voltage and a divided voltage of the overcurrent detection terminal; and a transistor that receives an output signal of the amplifier, for controlling a charge control output terminal. When a charger is connected in a state in which the secondary battery has an ultra-low voltage, a charge control FET is controlled so that a constant voltage may appear between output terminals, to thereby ensure an operating voltage of the temperature sensor circuit to enable an overheat protection function.

Battery state monitoring circuit and battery device

Provided is a sensor circuit which can amplify a sensor signal at high speed and with a high amplification factor without increasing the current consumption. The sensor circuit includes a primary amplifier for amplifying in advance a differential output signal which is a current signal of a sensor element, a secondary amplifier for amplifying the amplified differential output signal, a constant voltage generating circuit for maintaining a sensor element driving current to be constant, and a feedback circuit for feeding back a feedback signal to adjust an amplification factor. Most of the currents which pass through the primary amplifier are bias currents of the sensor element.

Sensor circuit

Provided is a voltage regulator which includes an inrush current prevention circuit so that no current is consumed after the start-up of the voltage regulator. A start-up circuit of the voltage regulator includes: a constant current circuit; a first transistor connected between the constant current circuit and a constant voltage generation circuit; a second transistor including a drain connected to a gate of the first transistor, and a gate to which a voltage based on an output voltage is input; a first depletion transistor including a gate connected to the drain of the second transistor, and a source connected to a source of the second transistor; and a third transistor including a gate connected to the gate of the second transistor, and a drain connected to the drain of the second transistor.

Voltage regulator

Provided is a battery state monitoring circuit including: a charge/discharge control circuit for detecting and controlling a state of a secondary battery; an automatic recovery circuit; a temperature sensor circuit; and a comparator for comparing a voltage of an output terminal of the automatic recovery circuit and a voltage of the secondary battery, and outputting a signal indicative of a result of the comparison to the temperature sensor circuit, to control an operation of the temperature sensor circuit. The temperature sensor circuit operates only when the output of the automatic recovery circuit is larger, that is, only when a charger is connected between external terminals.

Provided are a battery protection IC adaptable to any number of batteries connected in series without increasing a breakdown voltage thereof, and a battery device including the battery protection IC mounted thereon. A charge control signal input terminal and a discharge control signal input terminal of one battery protection IC are provided with a clamp circuit (), and hence an output driver () of another battery protection IC connected to those terminals is not applied with a voltage equal to or higher than a breakdown voltage. Accordingly, the breakdown voltage of the battery protection IC is not required to be high.

Battery protection IC and battery device

A temperature sensor performs more precise temperature measurement, even when manufacturing fluctuations are present in semiconductor elements forming a circuit for generating a temperature-dependent current. The temperature sensor includes: a temperature-dependent voltage generation circuit for generating a temperature-dependent potential that is dependent on temperature; a current generation circuit for allowing a temperature-dependent current to flow based on the temperature-dependent potential; a reference current generation circuit for generating a reference current that is independent of temperature; a capacitor that is charged alternately with the temperature-dependent current during a first charge period and the reference current during a second charge period; a pulse generation circuit for comparing a charged voltage of the capacitor with a reference voltage to generate a pulse; and a control circuit for alternately supplying the temperature-dependent current and the reference current to the capacitor. The temperature-dependent voltage generation circuit includes switches for switching connection relations between MOS transistors forming a current source circuit included in the temperature-dependent voltage generation circuit and bipolar transistors each serving as a load of the current source circuit.

Temperature sensor

Provided is a battery state monitoring circuit which is capable of preventing a discharge leak current from a battery so as to eliminate a load conventionally imposed on a user, including: a battery state detector circuit that detects a state of the battery based on a voltage of the battery; a transmitting terminal that transmits battery state information indicative of the state of the battery to an outside; a receiving terminal that receives battery state information of another battery from the outside; a transistor that is used for transmitting the battery state information, and has any one of two terminals except for a control terminal connected to the transmitting terminal; and a diode that is connected in a direction opposite to a direction of a parasitic diode disposed between the two terminals of the transistor, the diode being disposed between the transmitting terminal and one terminal of the transistor.

Battery state monitoring circuit and battery apparatus

Provided is a band gap reference voltage circuit having an improved power supply rejection ratio. Owing to a voltage supply circuit (), a power supply voltage (V) does not depend on variation of a power supply voltage (Vdd). A voltage (V&#x2212;V) which is generated across a resistor () and has a positive temperature coefficient is determined based not on the power supply voltage (Vdd) but on the power supply voltage (V), and hence the voltage (V&#x2212;V) does not depend on the variation of the power supply voltage (Vdd). As a result, the power supply rejection ratio of the band gap reference voltage circuit is improved.

Band gap reference voltage circuit

Provided is a battery protection circuit and a battery device which may be manufactured at lower cost. Before all terminals of a battery protection circuit are each connected to batteries, even when a logical circuit malfunctions by an operation of a parasitic bipolar transistor formed by P-wells due to a connection order in which the batteries are connected, the logical circuit is reset by an operation of a parasitic bipolar transistor formed by the P-wells. For this reason, a charge/discharge path of the batteries is not interrupted due to the connection order. Accordingly, no limitation is placed on the connection order.

Battery protection circuit and battery device

A charge and discharge control circuit which accommodates pulsed charge and pulsed discharge and can control charge and discharge of a secondary battery with safety, and a rechargeable power supply device having the same built therein are provided. The charge and discharge control circuit includes a delay time switching circuit for shortening a delay time of overcharge detection after charge inhibition is canceled. When overcharge is detected after the charge inhibition is canceled, the charge is inhibited in a delay time which is shorter than a normal delay time of the overcharge detection.

Charge and discharge control circuit and rechargeable power supply device

Provided is a power supply switching circuit capable of efficiently supplying a desired voltage among a plurality of voltages to a load. In the case of a P-type semiconductor substrate, N-type MOS transistors are provided between a load and an AC adapter and between the load and a battery, and hence no parasitic diode exists between the load and the AC adapter or the battery, resulting in no current path due to the parasitic diode. Thus, when the AC adapter and the battery are connected to the power supply switching circuit, the N-type MOS transistor is turned off, whereby the current path between the battery and the load is cut off completely and the N-type MOS transistor is turned on. Accordingly, the battery cannot supply a voltage to the load while only the AC adapter can supply a voltage to the load.

Power supply switching circuit

Provided are a switched capacitor amplifier capable of removing an influence of an offset voltage and a 1/f noise using a simple circuit, and a method of operating the same. According to the present invention, a switched capacitor amplifier having an operational amplifier and switched capacitors includes: a first switched capacitor one terminal of which is connected with a plus (+) input terminal of the operational amplifier and another terminal of which is applied with an input voltage; a second switched capacitor one terminal of which is connected with a minus (&#x2212;) input terminal of the operational amplifier and another terminal of which is applied with an input voltage; a third switched capacitor which is inserted between the plus (+) input terminal and a plus (+) output terminal and provided to set an amplification factor in cooperation with the first switched capacitor and store a plus (+) compensation voltage for compensating for an offset, which is applied to the plus (+) input terminal; and a fourth switched capacitor which is inserted between the minus (&#x2212;) input terminal and a minus (&#x2212;) output terminal and provided to set an amplification factor in cooperation with the second switched capacitor and store a minus (&#x2212;) compensation voltage for compensating for an offset, which is applied to the minus (&#x2212;) input terminal.

Growing community of inventors

Chiba, Japan

Kiyoshi Yoshikawa