Battery charger system having a charge pump power stage

A method comprising:

• receiving, by a battery charger, a voltage or a current from an adapter, wherein the battery charger includes:
• a first transistor having a first current terminal, a second current terminal, and a first control terminal;
• a second transistor having a third current terminal, a fourth current terminal, and a second control terminal, the third current terminal coupled to the second current terminal;
• a third transistor having a fifth current terminal, a sixth current terminal, and a third control terminal, the fifth current terminal coupled to the fourth current terminal;
• a fourth transistor having a seventh current terminal, an eighth current terminal, and a fourth control terminal, the fourth control terminal coupled to the second control terminal and the seventh current terminal coupled to the sixth current terminal;
• and
• a fifth transistor having a ninth current terminal, a tenth current terminal, and a fifth control terminal, the ninth current terminal coupled to the eighth current terminal and the fifth control terminal coupled to the third control terminal;
• and
• a capacitor having a first capacitor terminal and a second capacitor terminal, wherein the first capacitor terminal is coupled to the fourth current terminal and the second capacitor terminal is coupled to the eighth current terminal;
• charging, by the battery charger, the capacitor during a first time period, while charging a battery, wherein the capacitor is in series with the battery during the first time period;
• and
• during a second time period, discharging, by the battery charger, the capacitor while charging the battery, wherein the capacitor is in parallel with the battery during the second time period, the second time period after the first time period.

A system comprising:

• an adapter configured to produce power;
• a bus coupled to the adapter;
• and
• a battery charger coupled to the adapter over the bus, the battery charger configured to:
• during a first time period, charge a capacitor while charging a battery using the power, wherein the capacitor is in series with the battery during the first time period;
• and
• during a second time period, discharge the capacitor while charging the battery using the power, wherein the capacitor is in parallel with the battery during the second time period;
• wherein the battery charger includes:
• a first transistor having a first current terminal, a second current terminal, and a first control terminal;
• a second transistor having a third current terminal, a fourth current terminal, and a second control terminal, the third current terminal coupled to the second current terminal;
• a third transistor having a fifth current terminal, a sixth current terminal, and a third control terminal, the fifth current terminal coupled to the fourth current terminal;
• a fourth transistor having a seventh current terminal, an eighth current terminal, and a fourth control terminal, the fourth control terminal coupled to the second control terminal and the seventh current terminal coupled to the sixth current terminal;
• and
• a fifth transistor having a ninth current terminal, a tenth current terminal, and a fifth control terminal, the ninth current terminal coupled to the eighth current terminal and the fifth control terminal coupled to the third control terminal;
• and
• a capacitor having a first capacitor terminal and a second capacitor terminal, wherein the first capacitor terminal is coupled to the fourth current terminal and the second capacitor terminal is coupled to the eighth current terminal.