Ultra low power wake-up circuit

A method of selectively enabling a power supply of a portable electronic medical device to supply power to a controller of the portable electronic medical device, said method comprising:

• sensing the activation of an input of the device by a user of said device;
• initially providing a power supply enable signal from a sensing circuit of the device to a load switch of the device in response to the sensed activation of the input by the user, wherein the load switch is responsive to the power supply enable signal to provide power from the power supply to the controller;
• latching the enabled power supply, said latching comprising continuing to provide the power supply enable signal to the load switch from a latch circuit of the device such that the power supply continues providing power to the controller during operation of the device;
• and
• disabling the latch circuit via the controller when operation of the device has ended such that the power supply discontinues providing power to the controller.

An apparatus for selectively enabling power comprising:

• a power supply;
• a portable electronic medical device having a controller and an input activated by a user, said controller selectively powered by the power supply;
• a load switch responsive to a power supply enable signal for selectively supplying power to the controller from the power supply;
• a sensing circuit for sensing activation of the input by the user and for initially providing the power supply enable signal to the load switch in response to the sensed activation of the input by the user such that the power supply initially provides power to the controller;
• and
• said controller being responsive to the sensed activation of the input by the user for providing a latch signal to the sensing circuit, said latch signal causing the sensing circuit to continue providing the power supply enable signal during operation of the device, and wherein said controller discontinues the latch signal after operation of the device has ended such that the power supply discontinues providing power to the controller.

A portable electronic thermometer comprising:

• a power supply;
• a controller selectively powered by the power supply;
• an input for activation by a user;
• a load switch responsive to a power supply enable signal for selectively supplying power to the controller;
• a sensing circuit for sensing activation of the input by the user and for initially providing the power supply enable signal to the load switch in response to the sensed activation of the input by the user such that the power supply supplies power to the controller;
• and
• a latch circuit for continuing to provide the power supply enable signal to the load switch thereby causing the power supply to continue to provide power to the controller, wherein the latch circuit provides the power supply enable signal to the load switch while the latch circuit is enabled by the controller and the latch circuit discontinues providing the power supply enable signal when disabled by the controller, and wherein the controller is responsive to the sensed activation of the input by the user for enabling the latch circuit and for disabling the latch circuit.

A portable electronic thermometer comprising:

• a power supply;
• a controller selectively powered by the power supply;
• an input for activation by a user;
• a load switch responsive to a power supply enable signal for selectively supplying power to the controller from the power supply;
• a sensing circuit for sensing activation of the input by the user and for initially providing the power supply enable signal to the load switch in response to the sensed activation of the input by the user such that the power supply initially provides power to the controller;
• and
• said controller being responsive to the sensed activation of the input by the user for providing a latch signal to the sensing circuit, said latch signal causing the sensing circuit to continue providing the power supply enable signal during operation of the device, and wherein said controller discontinues the latch signal after operation of the device has ended such that the power supply discontinues providing power to the controller.