Peak current reduction in a cordless telephone handset
AssigneeMotorola, Inc.
InventorHugh S. Montgomery, Jr.
Life of this patent
Estimating the term…
Abstract
A method and apparatus reduces the peak current drawn from a DC-to-DC voltage converter (126) in a battery powered communication device such as a radiotelephone handset (104). The radiotelephone handset (104) enters high current operating conditions during transmit time slots (208, 210) and receive time slots (212, 214) defined by a TDMA protocol. During the receive time slots (212, 214) and the transmit time slots (208, 210), operating power is removed from a portion of the communication device, such as the display (120), to reduce the peak current drawn from the voltage converter (126). Excessive current drain from the battery (124) and rapid battery discharge are thereby eliminated.
Claims14
A method for reducing a peak current in a voltage converter during communications in a communication device, the method comprising the steps of:
- providing operating power from a power source through a voltage converter to the communication device, the voltage converter having an efficiency which varies with current provided to the communication device;
- selectively providing operating power through a first switch in response to a first control signal from a controller to a transmit circuit during transmit time intervals for transmitting from the communication device;
- concurrently removing operating power through a second switch in response to a second control signal from the controller from a display of the communication device to limit a current from the voltage converter to less than a maximum level during the transmit time intervals to reduce the peak current to maintain the voltage converter in an operating region of maximum efficiency;
- and
- maintaining power to the voltage converter and the controller.
A communication device, comprising:
- a transmit circuit for transmitting during transmit time intervals, and a receive circuit for receiving during receive time intervals;
- a power source for providing operating power;
- a voltage converter for passing power from the power source to the communication device, the voltage converter having an efficiency which varies with current provided to the communication device;
- a controller for selectively removing operating power from a display of the communication device during at least one of the transmit and receive time intervals to reduce peak current through the voltage converter below a maximum level so as to maximize efficiency of the voltage converter, the power source, voltage converter and controller being continually powered;
- a first switch coupled to the controller, the first switch for selectively decoupling the transmit circuit from the power source in response to a first control signal from the controller;
- and
- a second switch coupled to the controller, the second switch for selectively decoupling the display from the power source in response to a second control signal from the controller.
A radiotelephone handset configured for communication with a remote transceiver according to a time division multiple access communication protocol, the radiotelephone handset comprising:
- a power source for providing operating power;
- a voltage converter with an efficiency which varies with current provided to the radiotelephone handset from the power source;
- a transmit circuit coupled to the power source through the voltage converter for receiving operating power, the transmit circuit transmitting to the remote transceiver during transmit time slots defined by the time division multiple access communication protocol;
- a receive circuit coupled to the power source through the voltage converter for receiving operating power, the receive circuit receiving from the remote transceiver during receive time slots defined by the time division multiple access communication protocol;
- a controller for selectively removing operating power from a display of the radiotelephone handset during at least one of the transmit time slots and the receive time slots for reducing peak current so as to operate the voltage converter at maximum efficiency, the power source, voltage converter and controller being continually powered;
- a first switch coupled to the controller, the first switch for selectively decoupling the transmit circuit from the power source in response to a first control signal from the controller;
- and
- a second switch coupled to the controller, the second switch for selectively decoupling the display from the sower source in response to a second control signal from the controller.
Dependencies are inferred from the claim text.