WIRELESS WATCH CHARGING STAND AND STANDBY CIRCUIT
A charging stand placeable on a charging surface has a receiver circuit in a base configured to receive power from a wireless charging device through a receiving coil in the base. A support of the charging stand has a transmitting coil configured to transmit power to a chargeable device mounted on the support, and a power transfer circuit receives an induced current from the receiving coil in the base and provides a charging current to the transmitting coil. An energy storage device is configured to receive the induced current or a rectified current. A transmitter circuit is configured to provide the charging current to the transmitting coil. A sensor is configured to detect whether the chargeable device is mounted on the support, and a controller may be configured to power-down the power transfer circuit when chargeable device is not mounted on the support.
1 . A charging stand, comprising:
a base that has a receiver circuit configured to receive power from a wireless charging device through a receiving coil provided in the base;
a support that that has a transmitting coil configured to transmit power to a chargeable device mounted on the support; and
a power transfer circuit configured to receive an induced current from the receiving coil of the base and to provide a charging current to the transmitting coil of the support.
2 . The charging stand of claim 1 , wherein the power transfer circuit comprises an impedance matching network that couples the receiving coil to the transmitting coil in the support.
3 . The charging stand of claim 1 , further comprising:
an energy storage device configured to receive the induced current or a rectified current derived from the induced current; and
a transmitter circuit configured to use the rectified current or a current output by the energy storage device to provide the charging current to the transmitting coil.
4 . The charging stand of claim 3 , wherein the energy storage device comprises a battery.
5 . The charging stand of claim 3 , wherein the energy storage device comprises a capacitive storage device.
6 . The charging stand of claim 3 , wherein the receiver circuit the transmitter circuit are operated in accordance with a common wireless charging protocol.
7 . The charging stand of claim 3 , wherein the receiver circuit is operated in accordance with a first wireless charging protocol and the transmitter circuit is operated in accordance with a second wireless charging protocol, wherein the first wireless charging protocol is different from the second wireless charging protocol.
8 . The charging stand of claim 3 , further comprising:
a sensor configured to detect whether the chargeable device is mounted on the support; and
a controller coupled to the sensor and configured to:
power-down one or more circuits of the power transfer circuit when the sensor indicates that the chargeable device is not mounted on the support; and
power-up the one or more circuits of the power transfer circuit when the sensor indicates that the chargeable device is mounted on the support.
9 . The charging stand of claim 8 , further comprising:
a switch configured to couple the energy storage device to a transmitter circuit when the one or more circuits of the charging stand are powered-up,
wherein the transmitter circuit is configured to provide the charging current to the transmitting coil.
10 . The charging stand of claim 1 , wherein the chargeable device comprises a watch, and wherein the support is configured to align the transmitting coil parallel to a back surface of the watch when the chargeable device is mounted on the support.
11 . A power transfer method comprising:
configuring a receiver circuit in a base of a charging stand to receive power from a wireless charging device through a receiving coil provided in the base;
configuring a transmitting coil in a support of the charging stand to transmit power to a chargeable device mounted on the support; and
configuring a power transfer circuit to receive an induced current from the receiving coil of the base and to provide a charging current to the transmitting coil of the support.
12 . The power transfer method of claim 11 , wherein the power transfer circuit comprises an impedance matching network that couples the receiving coil to the transmitting coil in the support.
13 . The power transfer method of claim 11 , further comprising:
configuring an energy storage device to receive the induced current or a rectified current derived from the induced current; and
configuring a transmitter circuit to use the rectified current or a current output by the energy storage device to provide the charging current to the transmitting coil.
14 . The power transfer method of claim 13 , wherein the energy storage device comprises a battery.
15 . The power transfer method of claim 13 , wherein the energy storage device comprises a capacitive storage device.
16 . The power transfer method of claim 13 , wherein the receiver circuit the transmitter circuit are operated in accordance with a common wireless charging protocol.
17 . The power transfer method of claim 13 , wherein the receiver circuit is operated in accordance with a first wireless charging protocol and the transmitter circuit is operated in accordance with a second wireless charging protocol, wherein the first wireless charging protocol is different from the second wireless charging protocol.
18 . The power transfer method of claim 13 , further comprising:
configuring a sensor to detect whether the chargeable device is mounted on the support; and
powering-down one or more circuits of the power transfer circuit when the sensor indicates that the chargeable device is not mounted on the support; and
powering-up the one or more circuits of the power transfer circuit when the sensor indicates that the chargeable device is mounted on the support.
19 . The power transfer method of claim 18 , further comprising:
configuring a switch to couple the energy storage device to a transmitter circuit when the one or more circuits of the charging stand are powered-up,
wherein the transmitter circuit is configured to provide the charging current to the transmitting coil.
20 . The power transfer method of claim 11 , wherein the chargeable device comprises a watch, and wherein the support is configured to align the transmitting coil parallel to a back surface of the watch when the chargeable device is mounted on the support.