Electric charger and power supply device for portable terminal
First Claim
1. An electric charger, comprising:
- a charging circuit outputting a charging voltage in correspondence with the number of battery cells incorporated in a battery in a supply state of an external power supply;
a charging control unit which, upon detection of connection of said battery functioning normally, said battery is charged by turning on a switch unit provided in a connection path extending from the charging circuit to the battery; and
a cutoff releasing circuit which, upon detection of connection of said battery in a cutoff state caused by overdischarge, outputs a releasing voltage for releasing the cutoff state set by over-discharge of the battery,wherein the cutoff releasing circuit comprises;
a first FET switch connecting a drain to the output of the charging circuit;
a second FET switch which has a source connected to the source of the first FET switch and a drain connected to the battery and which is ON/OFF-controlled by the charging control unit, anda switch control circuit which, upon connection of said battery in a cutoff state caused by over-discharging, turns on the first FET switch in accordance with a battery abnormal signal outputted from the battery, thereby applying a charge voltage for releasing the cutoff state to the battery via a parasitic diode of the second FET switch in an OFF state.
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Accused Products
Abstract
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.
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Citations
3 Claims
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1. An electric charger, comprising:
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a charging circuit outputting a charging voltage in correspondence with the number of battery cells incorporated in a battery in a supply state of an external power supply; a charging control unit which, upon detection of connection of said battery functioning normally, said battery is charged by turning on a switch unit provided in a connection path extending from the charging circuit to the battery; and a cutoff releasing circuit which, upon detection of connection of said battery in a cutoff state caused by overdischarge, outputs a releasing voltage for releasing the cutoff state set by over-discharge of the battery, wherein the cutoff releasing circuit comprises; a first FET switch connecting a drain to the output of the charging circuit; a second FET switch which has a source connected to the source of the first FET switch and a drain connected to the battery and which is ON/OFF-controlled by the charging control unit, and a switch control circuit which, upon connection of said battery in a cutoff state caused by over-discharging, turns on the first FET switch in accordance with a battery abnormal signal outputted from the battery, thereby applying a charge voltage for releasing the cutoff state to the battery via a parasitic diode of the second FET switch in an OFF state. - View Dependent Claims (2, 3)
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Specification