Battery charging circuit for electronic apparatus

Claim 1

A charging circuit for charging a battery from an external power supply and supplying power to a load comprising: first charging means provided for interrupting the supply of power from said external power supply to the load to rapidly charge a secondary battery from said external power supply in a rapid charge mode; second charging means provided for enabling the supply of power to said load from said external power supply to charge said secondary battery in a trickle charge mode; and control means for selectively activating said first charging means or said second charging means, said control means including, a constant voltage circuit for developing a constant voltage, a reference voltage circuit for generating two kinds of reference signals, a mode switch for selectively switching between said first charging means and said second charging means, a gate coupled to said load, and a control circuit responsive to the switching of said mode switch for controlling said reference voltage circuit and said gate.

Claim 4

A device for supplying power from a primary power source to an external load comprising: a constant voltage circuit connected to said primary power source and producing a regulated power voltage output; a secondary battery voltage source connected across said regulated power voltage output; mode selection means for selecting between a trickle charge mode and a rapid charge mode; first detection and control means, enabled when said rapid charge mode is selected by said mode selection means, for detecting whether the charging current to be applied to said secondary battery voltage source is below a normal level and for reducing the voltage applied to said secondary battery voltage source in response thereto to disable rapid charging; and second detection and control means, operatively connected to said mode selection means, for disconnecting said external load from said device when said rapid charge mode is selected and for monitoring the voltage across said secondary battery voltage source, when in said trickle charge mode, to determine if said secondary battery voltage source is overly discharged and disconnecting said external load from said device when said secondary battery voltage source is overly discharged.

Claim 5

A device for supplying power from a primary power source to an external load comprising: a constant voltage circuit connected to said primary power source and producing a regulated power voltage output; a secondary battery voltage source connected across said regulated power voltage output; mode selection means for selecting between a trickle charge mode and a rapid charge mode; first detection and control means, enabled when said rapid charge mode is selected by said mode selection means, for detecting whether the charging current to be applied to said secondary battery voltage source is below a normal level and for reducing the voltage applied to said secondary battery voltage source in response thereto to disable rapid charging; and second detection and control means, operatively connected to said mode selection means, for disconnecting said external load from said device when said rapid charge mode is selected and for monitoring the voltage across said secondary battery voltage source, when in said trickle charge mode, to determine if said secondary battery voltage source is overly discharged and disconnecting said external load from said device when said secondary battery voltage source is overly discharged.