Power management device
A power management device is adapted to reduce power consumption, particularly in battery-powered applications such as within a node in a utility network (e.g., in a gas, water, or other utility application). In one example, a low-current voltage regulator provides power to a processor during low-power “sleep” states. A high-current voltage regulator provides power to the processor, metrology devices and/or a radio during “awake” states. A buck-boost device may provide power to a transmitter during radio frequency (RF) transmissions. A max device may determine a greater of voltages output by a battery and the buck-boost device, and use the higher to power the high-current voltage regulator. The power management device may include a state machine, which may include several states and operations to perform within each state. In one state, the processor enters a sleep state prior to recovery of battery voltage after a transmission state.
1. A power management device, comprising:
a first voltage regulator to provide regulated power to at least one device external to the power management device;
a second voltage regulator to provide regulated power to the at least one device external to the power management device, wherein the second voltage regulator is configured to provide greater current levels than the first voltage regulator;
a controller to switch between operation of the first voltage regulator and the second voltage regulator; and
a switch to tie a power output lead to a potential that prevents floating when the power output lead is not providing power.
2. The power management device of claim 1 , additionally comprising:
a buck-boost device to provide a programmable output voltage; and
a max device to determine whether voltage from a battery or voltage provided by the buck-boost device is higher and to select the higher of the voltage of the battery and the voltage from the buck-boost device to supply the second voltage regulator.
3. A utility meter comprising the power management device of claim 1 , wherein the controller is configured to:
switch to the first voltage regulator to provide power for sleep functions; and
switch to the second voltage regulator to provide power for metrology functions.
4. A utility meter comprising the power management device of claim 1 , the utility meter comprising:
a transmitter;
a buck-boost device, configured to:
receive power from a battery; and
power the transmitter;
a processor configured to:
manage operation of the transmitter; and
enter a sleep mode after a transmission is sent by the transmitter and before recovery of the battery; and
a max device to turn off the buck-boost device upon recovery of the battery after the transmission.
5. A utility meter comprising the power management device of claim 1 , the utility meter comprising a state machine including states comprising:
an awake period during which the controller is configured to switch from operation of the first voltage regulator to the second voltage regulator;
a radio transmission period during which a transmitter is powered by a buck-boost device;
a processor sleep period during which a battery recovers and the buck-boost device is operational; and
a sleep-with-minimal-current-use period during which the buck-boost device is turned off.
6. A utility meter comprising the power management device of claim 1 , the utility meter comprising a state machine to perform state changes responsive to conditions comprising:
a drop in battery voltage during which power is provided to the second voltage regulator using a buck-boost device; and
an initiation of a sleep period during which a power output lead is switched to prevent floating and current leaks.
7. A utility meter comprising the power management device of claim 1 , the utility meter comprising a state machine to perform state changes responsive to conditions, the conditions comprising a low voltage situation and cancelling a transmission.
8. A utility meter, comprising:
a metrology device to obtain metrology information;
a transmitter to transmit the metrology information;
a processor to operate the metrology device and/or the transmitter;
a battery to provide power;
a buck-boost device to receive the power from the battery and to provide power to the transmitter;
a power management device, comprising a state machine and states comprising:
a sleep period as the battery recovers in which the processor is put to sleep; and
a sleep period with minimal current use in which the buck-boost device is turned off;
a first voltage regulator to provide regulated power to devices within the utility meter;
a second voltage regulator to provide regulated power to devices within the utility meter, wherein the second voltage regulator is configured to provide greater current levels than the first voltage regulator at a similar voltage and wherein only one of the first voltage regulator or the second voltage regulator is operational at a time; and
a max device to:
determine whether voltage of the battery or voltage of the buck-boost device is higher; and
select the battery or the buck-boost device to supply power to the second voltage regulator based on the determination.
9. The utility meter of claim 8 , wherein the buck-boost device is turned off at least in part in response to a comparison of an output voltage of the battery and an output voltage of the buck-boost device, wherein the comparison is made by the max device.
10. The utility meter of claim 8 , wherein the states additionally comprise an awake period during which a low-current-providing voltage regulator is turned off and a high-current providing voltage regulator is turned on.
11. The utility meter of claim 8 , wherein the states additionally comprise a radio transmission period during which the transmitter is powered using the buck-boost device.
12. The utility meter of claim 8 , wherein the power management device is configured to:
switch to the first voltage regulator to provide power for sleep functions; and
switch to the second voltage regulator to provide power for metrology functions.
13. A utility meter, comprising:
a metrology device to obtain metrology information;
a transmitter to transmit the metrology information;
a battery to provide power;
a buck-boost device, configured to:
receive power from the battery; and
power the transmitter;
a processor to manage operation of the transmitter and to enter a sleep mode after a transmission sent by the transmitter and before recovery of the battery;
a max device to turn off the buck-boost device upon recovery of the battery after the transmission; and
one or more switches to prevent floating of power output leads not providing power.
14. The utility meter of claim 13 , the utility meter comprising a state machine and states comprising:
an awake period during which the controller is configured to switch from operation of a first voltage regulator to a second voltage regulator;
a radio transmission period during which a transmitter is powered by a buck-boost device;
a processor sleep period during which a battery recovers and the buck-boost device is operational; and
a sleep-with-minimal-current-use period during which the buck-boost device is turned off.
15. The utility meter of claim 13 , the utility meter comprising a state machine and states comprising:
switch to a first voltage regulator to provide power for sleep functions; and
switch to a second voltage regulator to provide power for metrology functions.
16. The utility meter of claim 13 , additionally comprising a state machine to perform state changes responsive to conditions comprising:
a drop in battery voltage and providing power to the second voltage regulator using the buck-boost; and
an initiation of a sleep period and switching a power output lead to prevent floating and current leaks.
17. A power management device, comprising:
a first voltage regulator to provide regulated power to at least one device external to the power management device;
a second voltage regulator to provide regulated power to the at least one device external to the power management device, wherein the second voltage regulator is configured to provide greater current levels than the first voltage regulator;
a controller to switch between operation of the first voltage regulator and the second voltage regulator;
a buck-boost device to provide a programmable output voltage; and
a max device to determine whether voltage from a battery or voltage provided by the buck-boost device is higher and the select the higher of the voltage of the battery and the voltage from the buck-boost device to supply the second voltage regulator.