System for limiting inrush current in a battery endpoint
Described is a system that includes a solid-state switch in series with a battery and a controller. The system also includes a capacitor coupled between a source and a gate of the solid-state switch and a resistor coupled between the gate of the solid-state switch and ground. The solid-state switch gradually transitions from an open state to a closed state over a time constant of the capacitor and the resistor upon application of power from the battery to the solid-state switch. The system further includes a first switching device that controls the application of power from the battery to the solid-state switch. Additionally, the system includes a second switching device that provides a discharge path of the capacitor upon completion of a task by the controller.
1. A resource metering system, comprising:
a resource metrology module;
a transmitter configured to send data packets associated with the resource metrology module to a head-end system or other resource metering systems;
a battery configured to provide power to the transmitter;
an inrush current limiter comprising:
a solid-state switch in series with the battery and the transmitter;
a capacitor coupled between a source and a gate of the solid-state switch;
a first switching device configured to control application of the power from the battery to the solid-state switch;
a second switching device configured to provide a discharge path of the capacitor upon completion of a task by the transmitter; and
a resistor coupled between the gate of the solid-state switch and ground, wherein the solid-state switch is configured to gradually transition from an open state to a closed state over a time constant of the capacitor and the resistor upon application of power from the battery to the solid-state switch, and wherein the closed state of the solid-state switch enables transmission of the power from the battery to the transmitter; and
a controller configured to receive the power from the battery and to control the transmitter, wherein the solid-state switch is configured to maintain a voltage of the power received by the controller above a power-on-reset threshold voltage of the controller, and wherein the controller provides a control signal to control the first switching device and the second switching device.
2. The system of claim 1 , wherein the solid-state switch comprises an enhancement mode p-type metal-oxide semiconductor.
3. The system of claim 1 , wherein the first switching device is controlled by the controller to open to stop application of the power from the battery to the solid-state switch when the second switching device closes to discharge the capacitor.
4. The system of claim 1 , wherein the task completed by the transmitter comprises transmitting a data packet.
5. The system of claim 1 , wherein the first switching device comprises a normally open complementary metal-oxide-semiconductor (CMOS) transistor and the second switching device comprises a normally closed CMOS transistor.
6. The system of claim 1 , wherein the battery comprises a manganese dioxide lithium battery.
7. The system of claim 1 , further comprising:
a switched-mode power supply configured to receive the power from the inrush current limiter and to control a voltage of the power provided to the transmitter to a predetermined voltage value.
8. A method, comprising:
receiving an input power from an input power source at (i) a solid-state switch of an inrush current limiting device and (ii) a resistor-capacitor circuit of the inrush current limiting device, wherein the inrush current limiting device is in a resistive mode configured to prevent transmission of an output power from the inrush current limiting device to a transceiver of a resource metering device;
gradually transitioning the solid-state switch from the resistive mode to a conductive mode over a resistor-capacitor time constant of the resistor-capacitor circuit while maintaining a voltage of the input power above a power-on-reset voltage threshold of a microprocessor controlling the transceiver of the resource metering device; and
closing a discharging switch to discharge a capacitor of the resistor-capacitor circuit upon completion of a packet transmission by the transceiver.
9. The method of claim 8 , further comprising:
opening a battery applicator switch positioned in series between the battery and the solid-state switch upon closing the discharging switch.
10. The method of claim 8 , wherein the resistor-capacitor circuit of the inrush current limiting device is tuned by changing a resistance of a resistor of the resistor-capacitor circuit or changing a capacitance of a capacitor of the resistor-capacitor circuit based on a predicted timing of a current spike of a switched-mode power supply positioned in series between the inrush current limiting device and the transceiver.
11. The method of claim 8 , wherein the resistor-capacitor time constant is tuned based on a timing of a communication protocol used during the packet transmission by the transceiver.
12. The method of claim 8 , further comprising:
transitioning the solid-state switch from the conductive mode to the resistive mode upon closing the discharging switch.
13. The method of claim 8 , wherein the capacitor is fully discharged before receiving the input power from the input power source at the solid-state switch during a subsequent data transmission cycle.
14. A system, comprising:
a resource metrology module;
a controller configured to control components of the resource metrology module, wherein the controller comprises a power-on-reset voltage threshold;
a battery configured to provide power to the controller;
a solid-state switch in series with the battery and the controller;
a capacitor coupled between a source and a gate of the solid-state switch;
a resistor coupled between the gate of the solid-state switch and ground, wherein the solid-state switch gradually transitions from an open state to a closed state over a time constant of the capacitor and the resistor upon application of power from the battery to the solid-state switch, and wherein a voltage of the power from the battery to the solid-state switch is maintained above the power-on-reset voltage threshold while the solid-state switch transitions from the open state to the closed state;
a first switching device configured to control the application of power from the battery to the solid-state switch; and
a second switching device configured to provide a discharge path of the capacitor upon completion of a task by the controller.
15. The system of claim 14 , wherein the task by the controller comprises controlling a transmitter to transmit a data packet.
16. The system of claim 14 , wherein the first switching device is controlled to open by the controller when the second switching device closes to discharge the capacitor.