Abstract: There is provided a power supply capable of reducing switching elements. In a power supply, an AC/DC adapter 121 supplies electric power to a load 125 and a battery charger 122. The battery charger comprises a high side FET 102 and a low side FET 103 which operate according to a synchronous rectification method, and charges batteries 108 and 109. When a commercial power supply fails, a power outage detection circuit provided in the battery charger detects the power outage, and outputs a power outage signal. The battery charger which has received the power outage signal sets the high side FET to be ON KEEP. A discharge current from the battery flows via a discharge path 119. This enables a reduction in the number of FETs in comparison with other power supplies.

Abstract: There is provided a power supply capable of reducing switching elements. In a power supply, an AC/DC adapter 121 supplies electric power to a load 125 and a battery charger 122. The battery charger comprises a high side FET 102 and a low side FET 103 which operate according to a synchronous rectification method, and charges batteries 108 and 109. When a commercial power supply fails, a power outage detection circuit provided in the battery charger detects the power outage, and outputs a power outage signal. The battery charger which has received the power outage signal sets the high side FET to be ON KEEP. A discharge current from the battery flows via a discharge path 119. This enables a reduction in the number of FETs in comparison with other power supplies.

Abstract: Disclosed is an electric power supplying unit for use in an electronic apparatus and includes an external AC adapter externally connected to the body of the electronic apparatus for receiving an external AC power source. An internal AC adapter is accommodated into the body of the electronic apparatus for receiving an external AC power source. An AC power source input detection circuit is provided within the internal AC adapter for detecting whether the external AC power source is input to the internal AC adapter. The power supply unit further includes power source switching circuit responsive to the detection output of the AC power source input detection circuit for switching the power supply to the electronic apparatus from the output of the external AC adapter to the output of the internal AC adapter.

Abstract: Two batteries can be selectively coupled to a computer, each through a separate pair of serially coupled transistors. Each of the four transistors is shunted by a diode, and each transistor can be individually controlled by a control circuit. To couple one of the batteries to the computer, the control circuit activates one pair of transistors, such that the battery current flows through the transistors and not through the diodes, thereby avoiding any power loss that would occur in the diodes. When switching from one battery to the other, the control circuit enters an intermediate mode in which one transistor in each of the two pairs of transistors is switched OFF, such that both batteries are momentarily "OR" coupled to the computer through two of the diodes, thereby preventing a momentary loss of power during the switching operation. A door covers both batteries such that neither battery can be removed except when the door is open.

Abstract: An invention to effect charging for a battery pack at the suitable time irrespective of the kind of an installed battery pack. A battery pack detects voltage, electric current, and temperature of an accommodated battery main body. When it is determined that charging for the battery main body is required, the battery pack outputs a charge request signal. Further, when it is determined that the battery main body has been brought into a full-charged state, the battery pack stops outputting of the charge request signal. When the charge request signal is inputted from the battery pack, the charge controller causes a direct current voltage supplied from an AC/DC adapter to be supplied for the battery pack, so as to start charging the battery main body of the battery pack. Further, when the continued inputting of the charge request signal is stopped, and the charging for the battery main body is stopped.

Abstract: A communication apparatus includes a Dual Tone Multi-Frequency (DTMF) noise signal detector for detecting a first DTMF noise signal caused by the apparatus and a second DTMF signal detector for detecting a DTMF signal transmitted from another apparatus. If self-induced DTMF noise is sensed, the second DTMF signal detector is disabled. As a result, the communication apparatus is able to distinguish the DTMF noise signal caused by said apparatus from the DTMF signal transmitted from another apparatus.