A charging control unit decides the number of battery cells on the basis of an output voltage of a battery pack, and an output voltage of a charging circuit is determined in accordance with the decided number of battery cells. Even though supply of an external power supply is detected, when a battery connection is not detected, the power supply circuit of the charging control unit is set in a stop state. In addition, when disconnection of the battery is detected, a canceling voltage for canceling a cutoff state caused by overdischarging of the battery is output. In a power supply device for a portable terminal, a capacitor electrically charged by an output voltage of main DC/DC converter is connected as an auxiliary power supply of a backup DC/DC converter to make exchange of the auxiliary battery unnecessary.

Electric charger and power supply device for portable terminal

Provided are a battery state monitoring circuit and a battery device which are capable of inhibiting discharge without enabling an overdischarge cell balance function when an overcurrent detection circuit detects a discharge overcurrent, without the need for an additional terminal of the battery state monitoring circuit. A detection signal of the overcurrent detection circuit is input to each of a communication terminal for overdischarge signal and a communication terminal for overcharge signal included in the battery state monitoring circuit provided on a side of the overcurrent detection circuit. An overdischarge cell balance circuit outputs a cell balance signal when an overdischarge detection signal indicates an overdischarge non-detected state, an overdischarge signal indicates an overdischarge detected state, and an overcharge signal indicates an overcharge non-detected state.

Battery state monitoring circuit and battery device

A battery charge control circuit (10) senses the charge condition of cells in a battery pack (12, 14, 16, 18) using a measurement circuit (51). Upon detection of a single under-voltage cell, the charge control circuit is placed in a sleep mode. Pack sense circuit (240) senses when the battery pack is placed in a charger. If circuit (10) was in a sleep mode, it is awakened. If any cell is measured over-voltage, the status is checked versus the other cells. If all the cells are over-voltage, the battery is considered balanced. If one or more cells are not over-voltage, a control circuit (32) activates a discharge transistor (212, 214, 216, 218), discharging the cell within a hysteresis voltage below the over-voltage limit. Charge balancing of cells is continued until the cells are within a programmable hysteresis voltage of each other.

Circuit and method for battery charge control

A logic gate is constructed of an insulated gate field effect transistor (MIS transistor) having a thin gate insulation film. An operation power supply line to the logic gate is provided with an MIS transistor having a thick gate insulation film for switching the supply and stop of an operation power source voltage. A voltage of the gate of the power source switching transistor is made changing in an amplitude greater than an amplitude of an input and an output signal to the logic gate. Current consumption in a semiconductor device configured of MIS transistor of a thin gate insulation film can be reduced and an power source voltage thereof can be stabilized.

Low power consumption MIS semiconductor device

Provided is a battery device for controlling charge/discharge of a secondary battery by a single bidirectionally conductive field effect transistor, a charge/discharge control circuit with which a leakage current of the bidirectionally conductive field effect transistor is reduced to perform stable operation. The charge/discharge control circuit includes: a switch circuit for controlling a gate of the bidirectionally conductive field effect transistor based on an output of a control circuit for controlling the charge/discharge of the secondary battery; and two MOS transistors for preventing back-flow of a charge current and a discharge current. The first MOS transistor has a drain and a back gate which are connected to each other, and a source connected to a drain of the bidirectionally conductive field effect transistor. The second MOS transistor has a drain and a back gate which are connected to each other, and a source connected to a source of the bidirectionally conductive field effect transistor.

Charge and discharge control circuit and battery device

A charge/discharge control circuit is provided for an electric power source apparatus in which a service life is prolonged. A voltage dividing circuit, an overcharge voltage detection circuit, an overdischarge voltage detection circuit and a control circuit are connected in parallel to a secondary cell which is an electric power source, wherein the control circuit detects a condition of the secondary cell from the overcharge/overdischarge voltage detection circuits and outputs a signal Vs for controlling a power supply to an external equipment and a charge by an external power source and controls a switching element provided in series with the voltage dividing circuit and reduces a current which flows through the voltage dividing circuit.

Charge/discharge control circuit and chargeable electric power source apparatus

PROBLEM TO BE SOLVED: To stop discharge before a switching circuit generates heat and breaks down, by performing discharge control receiving the signals of a circuit which detects two kinds or more of different voltages of overcurrent detecting terminals, and exhibiting a discharge stopping function by an appropriate delay time, against two kinds or more of different load currents. SOLUTION: The reference voltage 111 of a reference voltage circuit 105 is set higher than the reference voltage 112 of a reference voltage circuit 106, and the delay time of a delay circuit 109 is set shorter than that of a delay circuit 110. By performing setting this way, a switching circuit 103 is turned off after the delay time preset by the delay circuit 110, when an overcurrent flows and the voltage of a current sensing resistor 104 is kept higher than the reference voltage 112 and lower than the reference voltage 111. Accordingly, it becomes possible to turn the switching circuit off by a shorter delay time than the switching circuit generates heat and breaks down, even if something abnormal happens and an excessive current flows. COPYRIGHT: (C)1998,JPO

Charge/discharge control circuit.

A charge/discharge control circuit cuts off a current path to stop charging of an abnormal secondary cell when the voltage of the secondary cell is less than the threshold voltage of a MOS transistor. The charge/discharge control circuit includes a charge and discharge control circuit for monitoring the voltage of a secondary cell and outputting a signal for controlling the charging and discharging of the secondary cell, a switch circuit for receiving the output signal of the charge and discharge control circuit to stop the charging of the secondary cell in an overcharged or overdischarged state, and a low voltage detecting circuit for receiving the output signal of the charge and discharge control circuit, detecting whether the voltage of the secondary cell is below a predetermined voltage, which is below the overdischarge voltage and which is equal to the threshold voltage of a MOS transistor, and for controlling the switch circuit to prevent charging of the secondary cell if the voltage thereof is below the predetermined voltage.

Charge and discharge control circuit having low voltage detecting means for preventing charging of an abnormal cell

PROBLEM TO BE SOLVED: To make it impossible to charge a battery which is overdischarged and is in an abnormal condition and thereby prevent the destruction or other problems of the battery by not allowing charging current to flow by turning a switching circuit off when a secondary battery becomes a threshold voltage of a MOS transistor or below and a charger is connected at that time. SOLUTION: When the voltage of a secondary battery 101 in an overdischarged condition becomes a threshold voltage of a P-channel MOS transistor 504 or below due to self discharge or other causes, a charge and discharge controlling circuit 102 outputs an overdischarge signal, in other words, sends a Low signal to an output terminal 112A and a High signal to a low voltage detecting circuit 107. Then, the low voltage detecting circuit 107 outputs a Low signal to an output terminal 112B regardless of the output of the charge and discharge controlling circuit 102 to turn the voltage between the gate and the source of a FET-B111 in a switching circuit 103 to zero volt and thereby turn the FET-B111 off. Even if a charger 108 is connected under this condition, the FET-B111 is in an off state and a parasitic diode is reversely connected and therefore charging current is not allowed to flow into the secondary battery 101. COPYRIGHT: (C)1998,JPO

Takayuki Takashina

Papers

Charge/discharge control circuit and chargeable electric power source apparatus

Charge/discharge control circuit.

Charge and discharge control circuit having low voltage detecting means for preventing charging of an abnormal cell

Charging type power supply device

Overcharge/overdischarge detecting circuit having current detecting means with latch function and chargeable electric power source apparatus