Wake up system for electronic component supported on a vehicle

A power control assembly limits the amount of leakage current absorbed by a device (30) supported on a vehicle when the device is in a sleep mode. The described example includes a switch (40) between a vehicle power source (54) and a power supply (50, 52) for the peripheral device. A locking portion (44) controls operation of the switch (40) so that selected portions of the device (30) are isolated from the vehicle power source (34) when the device (30) is in a sleep mode. A wake up signal received by a communication bus transceiver (32) activates the switch locking portion (44), which in turn allows the isolating switch (40) to be electrically closed and kept in the closed condition until the controller (54) of the device determines that the device should enter the sleep mode.

BACKGROUND OF THE INVENTION

This invention generally relates to controls for electronic devices that need to be awakened out of a sleep mode where wake up time is limited. More particularly, this invention relates to a unique switching strategy within a wake up system for such electronic devices.

Modern day vehicles include a variety of electronic components. The power consumption of all of these components can prove to be too much and designers are constantly facing the challenge of reducing power consumption while, at the same time, providing the same or enhanced options on a vehicle. One way of managing power consumption is to have various peripheral devices enter a sleep mode when the device is not in use.

There are a variety of strategies for causing such devices to enter a sleep mode and for waking up the devices as needed. Typical arrangements include a linear voltage regulator, which introduces expense. Cost-savings are a critical concern in automotive applications. Another difficulty with conventional approaches is that they are not universally applicable and cannot meet some of the more stringent requirements regarding parasitic leakage current and limited wake up times. This difficulty is particularly present in devices where an energy reserve is part of a power supply to boost a battery voltage to a higher voltage level for powering the electronics of a particular device.

In one example, the parasitic leakage current when a device is in sleep mode must be less than or equal to 500 micro amps. It is desirable to provide an arrangement that satisfies the low leakage current requirements, is versatile enough to be useful with a variety of devices, facilitates a fast wake up response and is cost effective to implement. This invention addresses those needs while avoiding the shortcomings of prior arrangements.

SUMMARY OF THE INVENTION

In general terms, this invention is an assembly for controlling power consumption of at least one device supported on a vehicle that has a communication bus over which signals are transmitted to or from the device.

The inventive assembly includes a controller that controls operation of the device. A power supply portion derives power from a vehicle power source, such as a battery, and provides power to the controller. A switch is placed between the power supply portion and the vehicle power source. The switch selectively opens the connection between the power supply portion and the vehicle power source when the device is in a sleep mode and closes the connection when the device is in an active mode. A transceiver receives a wake up signal provided on the communication bus. A switch locking portion responds to the wake up signal received by the transceiver to lock the switch into the closed position. The switch locking portion maintains the switch in the closed position until the controller provides an indication that the device is to enter the sleep mode.

A significant advantage to the incentive approach is that it does not require a regulated voltage.

In one example, the switch locking portion comprises a plurality of transistors, arranged to lock the switch into a conducting state while the device is in the active mode. The controller provides a signal that unlocks the switch when the controller determines that the device should enter into the sleep mode.

In one example implementation of this invention, the switch locking device comprises a mono-flop that moves from a non-conducting state, which holds the switch open, to a conducting state, which closes the switch. Once in the conducting state, the mono-flop is unable to exit that state until it is reset by the controller determining that the device should enter the sleep mode.

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As schematically shown inFIG. 1, a communication network20facilitates communications between a main control22, for example over a communication bus24with a plurality of peripheral devices26,28and30. The illustrated arrangement can be particularly useful on a vehicle, for example, where the peripheral devices include items such as an airbag controller that enter a sleep mode to conserve energy. The main control22in one example provides a wake up signal on the bus24to wake up the devices26,28and30as needed.

The communication bus24in one example is a CAN communication bus as known. The plurality of peripheral devices receive and transmit signals that are propagated along the communication bus24in a known manner. The inventive arrangement is particularly well suited for controlling an amount of leakage current absorbed by the peripheral devices when they are in a sleep mode and for waking up the devices using a wake up signal promulgated along the communication bus24.

As can be appreciated fromFIG. 2, an example one of the peripheral devices30is schematically illustrated with only selected portions of that device being shown in the drawing. The main control22provides signals along the communication bus24that are processed through a transceiver32. In the illustrated example, the transceiver32comprises a conventional CAN transceiver as known in the art.

A vehicle power source34such as a car battery provides a supply of energy to the device30through a rectifier36. A switch40selectively separates the power source34from selected ones of the components within the device30when the device is in a sleep mode.

A switch control42operates the switch40to electrically open or close the switch to provide a selective coupling between the power source34and other components within the device30. The switch control42is powered based upon the operation of a switch locking portion44that is responsive to a signal on an input45from the transceiver32indicating that a wake up signal was received from the bus line24. The switch locking portion44provides an output signal at46to the control42. The power to the switch control42is derived from the vehicle power source34. The same power source34powers the switch locking portion44along an input48.

The switch locking portion44receives an input signal at45from the transceiver32. The transceiver32preferably responds to a wake up signal on the communication bus24by transmitting the signal at45. In one example, the wake up signal comprises a 7 volt signal on the communication bus24. The 7 volt signal, as known, is used for a wake up signal because it has a higher voltage than standard communication or control signals provided along the communication bus24. The switch locking portion44enables the switch control42to change the switch40from a non-conductive state to a conducting state. Once activated, the control42closes the switch40, which couples the power supply portion of the device30to the power source34. The locking portion ensures that the control42keeps the switch40closed until the device30should enter the sleep mode once again.

The illustrated example includes an energy reserve portion50and a power supply portion52, each of which comprise components as known in the art. The energy reserve portion50facilitates boosting the battery voltage of the energy source34to a higher voltage. In some examples the boosted voltage may be 23 or 33 volts, for example whereas the battery voltage is typically between 8 and 16 volts.

The power supply portion52provides the primary power to the device controller54. When the controller54determines that the device30should enter the sleep mode, a reset signal is provided to the switch locking portion44along the output56, which causes the switch locking portion44to effectively cut off the control42from the vehicle power source34, which results in the switch40being opened.

FIG. 3schematically illustrates one example implementation of a switch locking portion44designed according to this invention. In the illustrated example, the switch locking portion44includes a plurality of transistors arranged so that a wake up signal received by the transceiver32causes the switch locking portion44to change to a conductive state allowing the control42to receive battery power to close the switch40. In the illustrated example, the transistors60,62and64are arranged, as can be appreciated from the illustration, in a manner so that the falling edge of a signal from the transceiver32at45results in the transistor62locking into a conductive state. Once the locking portion is locked, the power output at46is available to the control42, which in turn closes the switch40. The control42continues to maintain the switch40in a closed position as long as the transistor62is conducting between the input48(i.e., the power source34) and the output46.

In the illustrated example, the base of the transistor60is held such that the transistor60is nonconducting when the device30is in the sleep mode. In the illustrated example, the transistor60and64are part of the same component and are interrelated such that when one is nonconducting, the other is nonconducting. When the transceiver32provides an output responsive to a wake up signal on the communication bus24, the falling edge of that output enables the transistor60and the transistor64to be conducting. Once the transistors60and64are conducting, the base of the transistor62is effectively coupled through resistors to the vehicle power source34. At this point, the transistor62is conducting and the voltage of the vehicle power source34is available at46to the switch control42.

In this condition, the transistor64is unable to stop conducting. Accordingly, it matters not whether the transistor60opens or closes once the transistor62is conducting. As such, the switch locking portion44is unable to independently switch itself out of a conductive state once the transistor62is conducting and effectively providing power to the switch control42.

Because the switch locking portion44changes from a non-conductive state to a conductive state and cannot change itself out of the conducting state, the illustrated example can be referred to as a mono-flop. The use of such a mono-flop locking portion ensures power supply to the switch control42maintains the switch40in a conductive state as long as the device30is to be active.

Once the controller54determines that the device30should enter the sleep mode, it provides a reset signal at56to the base of a transistor70. As the controller54in the illustrated example pulls down the base of the transistor70, that pulls the base of transistor64to ground, which grounds the base of the transistor62. This cuts off the power source34from the control42, which in turn results in the control42opening the switch40. An example situation where the controller54determines that the device should enter the sleep mode is when a specific function required of the device has been completed or when a wake up signal is received followed by no further signals within a specified period.

The illustrations show one example implementation of this invention. Various modifications and other so-called mono-flop devices can be used to control the operation of a switch such as the switch40to provide power to the device30when it is in an active mode. The illustrated example is particularly advantageous because the leakage current is approximately 200 micro amps when the device is in the sleep mode and no regulated voltage is required.

The illustrated example includes an ignition logic level portion80that is supplemental to the switch locking portion44so that the device30can be woken up by a signal as known other than a wake up signal received from the communication bus24.