| 摘要 |
This invention includes an electronic device that has both electrical contacts for coupling to local, application specific circuitry and contacts for supplying power to another electronic device. The electronic devices may be coupled in series, so as to eliminate the need for bulky, unsightly cables or wires. Since the devices may be coupled in series ad infinitum, the possibility exists that the series combination of devices may draw more power than either a power source can provide or sensitive internal circuitry, like fuses for example, can handle. As such, each electronic device includes a current limiting circuit having a current sense circuit and a switch coupled serially between the input and the output that powers the next electronic device. When the current drawn from the input to the output supplying power for the downstream devices exceeds a predetermined threshold, the switch deactivates the upstream chargers local circuitry. Once the downstream devices have completed their desired activities, the current drawn by the downstream devices will be reduced. When this occurs, the current sense circuits of the upstream devices will detect that the total current drawn has fallen below the predetermined threshold and will once again reactivate their local circuitry. In one embodiment, the electronic devices are desktop battery chargers. By disabling upstream battery chargers while downstream battery chargers complete their charging cycle, the current limiting devices in the upstream battery chargers ensure that fuses disposed within the upstream battery chargers do not blow. A blown fuse in an upstream charger could result in the entire series combination losing power. By including the current limiting circuit of the invention, a user may couple as many series devices together as they want without fear of blowing fuses in the upstream devices.
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