Power management topologies
A wake up circuit according to one embodiment includes a comparison circuit and an output decision circuit. The comparison circuit may be adapted to receive a first signal representative of a charging current level provided to a battery via a path and a second signal representative of a predetermined wake up current level and to provide a comparison output signal in response to the first and second signal. The output decision circuit may be adapted to receive at least the comparison output signal and a selector signal from a selector circuit, the output decision circuit providing one of the comparison output signal and the selector signal to a switch to control a state of the switch, the switch coupled to the path.
1. A wake up circuit comprising:
a comparison circuit configured to receive a first signal representative of a charging current level provided to a battery via a path and a second programmable signal representative of a predetermined wake up current level and to provide a comparison output signal in response to said first and second signals; and
an output decision circuit configured to receive at least said comparison output signal and a selector signal from a selector circuit, said output decision circuit is configured to provide one of said comparison output signal or said selector signal to a switch to control the charging current level provided to said battery by controlling the state of said switch-coupled to said path;
wherein said comparison output signal comprises an analog signal, said switch responsive to said analog signal to enter an intermediate conduction state to provide a current level to said battery representative of said predetermined wake up current level; and wherein said selector signal comprises a first state and a second state, said switch is responsive to said first state to enter a full conduction state and responsive to said second state to turn off said switch.
2. The wake up circuit of claim 1 , wherein said analog signal comprises a voltage signal, said switch comprising a field effect transistor having a gate terminal receiving said voltage signal.
3. The wake up circuit of claim 1 , wherein said output decision circuit is further configured to receive at least one additional input signal in addition to said comparison output signal and said selector signal, said at least one additional input signal being an enabling signal, said output decision circuit responsive to said enabling signal to provide said comparison output signal to said switch if said enabling signal is in a first state.
4. The wake up circuit of claim 1 , wherein said output decision circuit is further configured to receive at least one additional input signal in addition to said comparison output signal and said selector signal, said at least one additional input signal being a battery voltage signal, said output decision circuit responsive to said battery voltage signal to provide said selector output signal to said switch if said battery voltage signal is representative of a voltage level of said battery greater than a threshold voltage level.
5. The wake up circuit of claim 1 , wherein said output decision circuit is further configured to receive at least one additional input signal in addition to said comparison output signal and said selector signal, said at least one additional input signal being a maximum wake up charge time signal, said output decision circuit responsive to said maximum wake up charge time signal to provide said selector output signal to said switch if said maximum wake up charge signal is representative of a continuous time of said output decision circuit providing said comparison output signal exceeding a maximum time interval.
6. The wake up circuit of claim 1 , wherein said comparison circuit comprises an enor amplifier, said error amplifier is further configured to receive said first signal and said second signal and providing said comparison output signal.
7. A method comprising:
generating a first signal representative of a charging current level provided to a battery via a path and a second programmable signal representative of a predetermined wake up current level;
comparing said first signal to said second signal;
generating an analog comparison output signal in response to said first and second signals;
generating a selector signal having a first state and a second state; and
controlling the conduction state of a battery charging switch using said analog comparison output signal or said selector signal to control a charging current level provided to a battery;
wherein if said analog comparison output signal is used to control said battery charging switch, said switch is responsive to said analog comparison output signal to enter an intermediate conduction state to provide a current level to said battery representative of said predetermined wake up current level; and wherein if said selector signal is used to control said battery charging switch, said switch is responsive to said first state to enter a full conduction state and responsive to said second state to turn off said switch.
8. The method of claim 7 , wherein said first signal comprises a voltage signal, said switch comprising a field effect transistor having a gate terminal receiving said voltage signal.