# US 2019/0356167 A1 · Wireless power multiple receive coil self-startup circuit for low battery condition

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- Number: US 2019/0356167 A1
- Document ID: US20190356167A1
- Status: Published application
- Kind: A1
- Application number: 16/369,523
- Filed: 2019-03-29
- Published: 2019-11-21
- Earliest claimed: 2018-03-30
- Assignees: Integrated Device Technology, Inc.
- Applicants: Integrated Device Technology, Inc.
- Inventors: Nicholaus Wayne SMITH; Tao QI; Jiangjian HUANG; Chan Young JEONG; Gustavo James MEHAS
- Web page: https://patentgrep.com/patent/US20190356167A1

## CPC

- H04B 5/79: for data transfer in combination with power transfer
- H01F 38/14: Inductive couplings
- H02J 7/90: Regulation of charging or discharging current or voltage
- H02J 50/12: of the resonant type
- H04B 5/26: using coils
- H02J 2207/20: Charging or discharging characterised by the power electronics converter
- H04B: TRANSMISSION
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY

## Abstract

A wireless power circuit is presented that includes a transmit coil coupled to a first node; a receive coil coupled to the first node; a switch circuit coupled to the transmit coil and the receive coil opposite the first node, the switch switching the transmit coil to a second node in a transmit mode and switching the receive coil to the second node in a receive mode; a controller coupled to the first node and the second node, the controller coupled to provide signals to the switch circuit; and a self-start circuit coupled to the receive coil (or Tx coil) that automatically selects one of the coils to be used, the self-start circuit providing power to the switch circuit to hold the switch circuit in the receive mode (or predefined coil to be selected by default).

## Claims

### Claim 1

A wireless power circuit, comprising:
a transmit coil coupled to a first node;
a receive coil coupled to the first node;
a switch circuit coupled to the transmit coil and the receive coil opposite the first node, the switch switching the transmit coil to a second node in a transmit mode and switching the receive coil to the second node in a receive mode;
a controller coupled to the first node and the second node, the controller coupled to provide signals to the switch circuit; and
a self-start circuit coupled to the receive coil, the self-start circuit providing power to the switch circuit to hold the switch circuit in the receive mode.

### Claim 2 (depends on 1)

The wireless power circuit of claim 1, the switch circuit includes a transistor coupled between the receive coil and the second node, the transistor configured to conduct in the receive mode and not to conduct in the transmit mode.

### Claim 3 (depends on 2)

The wireless power circuit of claim 2, wherein the transistor is powered to conduct by the self-start circuit.

### Claim 4 (depends on 2)

The wireless power circuit of claim 2, wherein the transistor includes one or more FET transistors.

### Claim 5 (depends on 1)

The wireless power circuit of claim 1, wherein the self-start circuit includes a first diode coupled to the receive coil to receive power and a second diode coupled in series with the first diode, the self-start circuit providing power from a node between the first diode and the second diode.

### Claim 6

A method of operating a device, comprising:
switching to couple a receive coil to a receive circuit with a switch;
receiving power into the switch if a power source is available; and
providing power from a self-start circuit coupled to the receive coil if the power source is unavailable.

### Claim 7 (depends on 6)

The method of claim 6, wherein the switch includes a transistor coupled between the receive coil and the second node, the transistor configured to conduct in the receive mode and not to conduct in the transmit mode.

### Claim 8 (depends on 7)

The method of claim 7, wherein the transistor is powered to conduct by the self-start circuit.

### Claim 9 (depends on 7)

The method of claim 7, wherein the transistor is an FET transistor.

### Claim 10 (depends on 6)

The method of claim 6, wherein the self-start circuit includes a first diode coupled to the receive coil to receive power and a second diode coupled in series with the first diode, the self-start circuit providing power from a node between the first diode and the second diode.