Method and system for rationing charge or energy provided to a portable device
View Patent ↗A charging method and system for rationing charge or energy supplied by a host to a portable device. The system includes a power switch connected to a current sensing module that detects instantaneous current drawn by the portable device. A current register connected to the current sensing module stores the instantaneous current value. A timing module generates timing information. A cumulative charge value obtained by multiplying the instantaneous current value with the timing information is stored in a charge register. Further, a cumulative energy value may be obtained by multiplying the cumulative charge value with a detected voltage value. A threshold database stores a threshold value, and a rationing module connected to the host and the charge register continuously compares the cumulative charge value and/or the cumulative energy value with the threshold charge value. A control signal is generated when the threshold charge value is exceeded.
1. A system for rationing a cumulative charge or a cumulative energy, the system comprising:
a host coupled with a charging system,
a power supply and a connector operable to be connected with a portable device comprising a battery, wherein the host system is operable to charge the battery of the portable device when the portable device is connected with the charging system through the connector, wherein the host, charging system, the power supply and the connector are part of another portable device and the power supply is a host battery of the another portable device, wherein the charging system comprises:
a power switch coupled with the power supply and the connector;
a current sensing module, connected to the power switch, for detecting an instantaneous current drawn by the portable device during a charging process;
a converter, at the output of the current sensing module, for converting the instantaneous current into a digital current value representing the instantaneous current drawn by the portable device;
a current register connected to the current sensing module for storing the digital current value representing the instantaneous current drawn by the portable device;
a timing module generating elapsed time information;
a charge register storing a cumulative charge value, the cumulative charge value representing a cumulative current drawn by the portable device during the charging process, and obtained by multiplying the digital current value representing the instantaneous current drawn by the portable device with the elapsed time information;
a threshold database storing a threshold value representing a total charge or total energy to be drawn by the portable device, wherein the threshold database obtains a threshold value from the host via a data communication bus and wherein the threshold value is calculated by the host based on an available charging capacity of the host battery and the operating mode of the host; and
a rationing module configured for:
continuously comparing a cumulative value with the threshold value representing the total charge or total energy to be drawn by the portable device, wherein the cumulative value is the cumulative charge value or is calculated based on the cumulative charge value; and
generating a control signal when the cumulative value exceeds the threshold value.
2. The system of claim 1 further comprising a first multiplier, connected to the output of the current register for multiplying the digital current value with the elapsed time information.
3. The system of claim 2 , wherein the current sensing module includes a current sensing resistor converting the instantaneous current into a corresponding voltage signal.
4. The system of claim 3 further comprising:
a voltage multiplexer, connected to the output of the power switch and the current sensing module, for multiplexing the corresponding voltage signal and an instantaneous voltage;
a voltage register for storing a digital voltage value; and
an energy register for storing a cumulative energy value obtained by multiplying the cumulative charge value with the digital voltage value.
5. The system of claim 4 further comprising a second multiplier connected to the output of the first multiplier and the voltage register, for generating the cumulative energy value.
6. The system of claim 4 further comprising a switch connected to the input of the current register and the voltage register.
7. The system of claim 4 , wherein the cumulative value is at least one of the cumulative charge value or the cumulative energy value.
8. The system of claim 1 , wherein the control signal is at least one of a disable signal or an alert signal.
9. The system of claim 1 , wherein the current sensing module and the rationing module are implemented in discrete circuitry.
10. The system of claim 1 , wherein the current sensing module and the rationing module are components on a single semiconductor chip.
11. A method for rationing a cumulative charge or energy supplied from a host to a portable device over a universal serial bus (USB) port, the method comprising:
coupling a portable device comprising a battery with a host system, wherein the host system comprises a host and a charging system operable to charge the battery of the portable device from a power supply of the host system wherein the power supply is a host battery;
sensing an instantaneous current drawn by the portable device from the power supply of the host;
converting the instantaneous current into a digital current value representing the instantaneous current drawn by the portable device during a charging process;
storing the digital current value representing the instantaneous current drawn by the portable device;
determining an elapsed time from beginning of charging to current time;
multiplying the digital current value representing the instantaneous current drawn by the portable device with the elapsed time to obtain a cumulative charge value representing a cumulative current drawn by the portable device during the charging process;
storing the cumulative charge value representing the cumulative current drawn by the portable device during the charging process;
storing a threshold value representing a total charge or total energy to be drawn by the portable device, wherein the threshold value has been received from the host and wherein the threshold value is calculated by the host based at least on an available charging capacity of the host battery and the operating mode of the host system;
comparing a cumulative value with the threshold value representing the total charge or total energy to be drawn by the portable device, wherein the cumulative value is the cumulative charge value or is calculated based on the cumulative charge value; and
generating a control signal if the cumulative value exceeds the threshold value.
12. The method of claim 11 further comprising updating the cumulative charge value at predetermined intervals.
13. The method of claim 11 further comprising:
converting the instantaneous current into a corresponding voltage signal; and
converting the corresponding voltage signal into the digital current value.
14. The method of claim 13 further comprising:
detecting an instantaneous voltage supplied to the portable device;
converting the instantaneous voltage into a digital voltage value storing the digital voltage value;
multiplying the digital voltage value with the cumulative charge value, in real time, to determine a cumulative energy value; and
continuously updating the cumulative energy value.
15. The method of claim 14 wherein comparing the cumulative value with the threshold value comprises comparing at least one of the cumulative energy value or the cumulative charge value with the threshold value.
16. The method of claim 15 further comprising multiplexing the corresponding voltage signal and the instantaneous voltage.
17. The method of claim 11 further comprising at least one of disabling a power switch supplying current to the portable device; disabling the power switch supplying current to the portable device and alerting the host; or alerting the host.
18. The system of claim 8 , wherein the disable signal terminates charging of the portable device battery.
19. The system of claim 18 , wherein the another portable device is a notebook computer.
20. The method of claim 11 , wherein the host system is in a sleep mode and said control signal is used to wake up the host system.
21. The method of claim 20 , wherein the another portable device is a notebook computer.
22. The method according to claim 20 , wherein the host system withdraws the threshold value upon receiving the control signal if it determines that an external power supply is connected with the host system to charge the host battery.
23. The system according to claim 1 , wherein different threshold values are assigned just before going into sleep mode.
24. The system according to claim 1 , wherein operating modes includes a full power mode, an idle mode, and a sleep mode.
25. The system according to claim 1 , wherein the operating modes further includes a hibernating mode, a transition to sleep mode, and a shutdown mode.
26. The system according to claim 1 , wherein the threshold value is determined depending on a host usage pattern.
27. The method according to claim 11 , wherein different threshold values are assigned just before going into sleep mode.
28. The method according to claim 11 , wherein operating modes includes a full power mode, an idle mode, and a sleep mode.
29. The method according to claim 11 , wherein the operating modes further includes a hibernating mode, a transition to sleep mode, and a shutdown mode.
30. The method according to claim 11 , wherein the threshold value is determined depending on a host usage pattern.