Control circuit
A control circuit ( 101 ) is configured for use with a load in the form of hardware ( 102 ) of a laptop computer ( 103 ). Circuit ( 101 ) includes input terminals ( 105, 106 ) for electrically connecting with respective terminals ( 107, 108 ) of a battery pack ( 109 ). The battery pack ( 109 ) supplies a battery current and has a predetermined maximum operational current. Circuit ( 101 ) also includes output terminals ( 111, 112 ) for electrically connecting in parallel hardware ( 102 ) and a supercapacitor ( 113 ). A controller ( 115 ) is disposed between the input and the output terminals for allowing the battery to transfer energy to hardware ( 102 ) and supercapacitor ( 113 ) while maintaining the battery current at less than the predetermined maximum operational current.
1. A control circuit for a load, the circuit including:
input terminals for electrically connecting with respective terminals of a battery that has a predetermined maximum operational current whereby the battery supplies a battery current;
output terminals for electrically connecting in parallel the load and a supercapacitor; and
a controller being disposed between the input and the output terminals for allowing the battery to transfer energy to the load and the supercapacitor while maintaining the battery current at less than the predetermined maximum operational current wherein the load draws a load current that varies with time, where the load current is the sum of the battery current and the current provided by the supercapacitor; and
wherein the load current is greater than or equal to zero and the controller maintains the battery current at greater or equal to zero.
2. A circuit according to claim 1 wherein the controller also prevents the supercapacitor from providing energy to the battery.
3. A circuit according to claim 1 that is a power-up protection circuit for a portable computing device.
4. A circuit according to claim 1 wherein the predetermined maximum operational current is an average over a given interval.
5. A circuit according to claim 1 wherein the predetermined maximum operational current is an instantaneous current.
6. A circuit according to claim 1 wherein the battery includes a plurality of battery cells.
7. A circuit according to claim 1 wherein the battery includes a protection circuit for electrically disconnecting the battery terminals from the input terminals in response to the predetermined maximum operational current being exceeded.
8. A circuit according to claim 1 wherein the controller is responsive to the battery current for varying a resistance between the input and the output terminals.
9. A circuit according to claim 8 wherein the controller includes one or more solid-state devices for varying the resistance.
10. A circuit according to claim 9 wherein at least one of the solid-state devices is a MOSFET.
11. A circuit according to claim 9 wherein the load has a start up sequence and the at least one of the solid-state devices operates in a linear mode during that sequence.
12. A circuit according to claim 1 wherein the battery has a battery voltage and the supercapacitor has a supercapacitor voltage and wherein when the battery current is greater than zero the supercapacitor voltage is substantially equal to or less than the battery voltage.
13. A circuit according to claim 12 wherein the battery voltage is greater than approximately 2.7 Volts and less than approximately 24 Volts.