Single-stage AC-to-DC switching converter that directly charges a battery requiring a multi-state charging profile

A secondary side battery charger controller integrated circuit, comprising:

• a first current sense terminal;
• a second current sense terminal;
• a battery voltage sense terminal;
• a battery temperature detection signal input terminal;
• a control output signal terminal;
• an amplifier that outputs a first voltage that is proportional to a voltage between the first and second current sense terminals;
• a first reference voltage selector circuit that outputs a second voltage, wherein the second voltage is a selected one of a plurality of reference voltages;
• a first comparator circuit that compares the first voltage to the second voltage and that outputs a first digital signal;
• a second reference voltage selector circuit that outputs a third voltage, wherein the third voltage is a selected one of a plurality of reference voltages;
• a second comparator circuit that determines whether a voltage on the battery voltage sense terminal is above the third voltage, and that outputs a second digital signal;
• a control signal generating circuit that receives a selected one of the first and second digital signals and that generates a control signal, and wherein the control signal is output from the secondary side battery charger controller integrated circuit via the control signal output terminal;
• and
• a digital state machine circuit that controls the first reference voltage selector circuit and that controls the second reference voltage selector circuit, wherein a plurality of digital state machines is preprogrammed into the digital state machine circuit, but wherein only one of the digital state machines is selected and implemented at a given time.

A battery charger device for charging a rechargeable battery, the battery charger device comprising:

• an output terminal adapted to be coupled to a battery assembly, wherein the rechargeable battery is a part of the battery assembly;
• a pair of AC supply voltage input terminals;
• a single-stage AC-to-DC switching converter circuit that receives a 110 volt AC RMS supply voltage from the pair of AC supply voltage input terminals and that supplies a charging current through the output terminal and to the battery, wherein the single-stage AC-to-DC converter comprises:
• a primary side circuit that comprises a pulse width modulator (PWM) integrated circuit and a primary winding of a transformer;
• and
• a secondary side circuit that comprises a secondary winding of the transformer, a current sense resistor, a transistor, and a battery charger controller integrated circuit, wherein the battery charger controller integrated circuit controls the transistor, wherein the battery charger controller integrated circuit detects a voltage on the output terminal and detects a current supplied to the rechargeable battery via the output terminal and sends a control signal to the PWM integrated circuit of the primary side circuit such that the rechargeable battery is charged in accordance with a multi-state battery charging profile, wherein the multi-state battery charging profile includes a constant current (CC) charging state and a constant voltage (CV) charging state, and wherein a charging current supplied to the battery flows from the secondary winding, through the current sense resistor, through the transistor, through the output terminal, and into the battery.