1. Field of the Invention
Embodiments of the present invention generally relate to power interruption and more specifically to power interruption protection methods and apparatuses for power interruption protection in handheld devices.
2. Description of the Related Art
Some devices lose power momentarily. A momentary power loss can cause memory loss. The momentary power loss can be due to a number of factors. For example, momentary power loss can be caused by dropping a device and/or when a power adapter is plugged into the device there is a power fluctuation(s), that result in no (or insufficient) power to the device. As a result of the momentary power loss, valuable information can be lost.
Prior solutions utilize either a backup battery and/or multiple power sources to prevent momentary power loss. However, these solutions can add to the cost and size of the device.
There is a need to prevent momentary power loss with minimal increase to the overall cost and size of the device.
Embodiments disclosed herein generally relate to power interruption protection module, system and method. The power interruption protection module, comprising a charging module for storing a boosted display voltage, a detecting module for identifying at least one of a drop or an increase of a functioning system voltage, wherein at least one of the drop or the increase is beyond a threshold, and a regulating module for receiving a signal from the detecting module, wherein the signal determines at least one of the drop or the increase beyond the threshold, and wherein the regulating module allows or stops the flow of the stored boosted display voltage of the charging module according to the signal of the detecting module.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
a depicts an embodiment of a high level block diagram of a power interruption protection system;
b depicts an embodiment of a block diagram of a power interruption protection module;
c depicts an embodiment of a detailed block diagram of a power interruption protection system;
The present invention generally relates to power interruption protection method and apparatus for power interruption protection. The method and apparatus may be utilized in a handheld device. A handheld device may be a camera, a camcorder, a calculator, a personal digital assistance (PDA), a phone, and the like. The power interruption protection utilizes boosted display voltage rail to charge at least one capacitor to a higher voltage than the system voltage to detect when a system voltage falls below a threshold. Thus, the purpose of the power interruption protection system is to detect a fall in the system voltage and to transfer a suitable charge to the system voltage when the system voltage falls below such threshold.
a depicts an embodiment of a high level block diagram of a power interruption protection system 100. The power interruption protection system 100 includes a display power system 10, a booster module 12, a power interruption protection module 14 and a functionality system 16. The display power system 10 is utilized to power a display utilized for displaying various graphics or functionality performed by a system. For example, a display on a calculator is utilized to display user's inputs, functions and calculation outputs. Usually, the display power system 10 is separate from the power system supporting the whole calculator. The voltage output of the display power system 10 is boosted by the booster module 12 to generate a boosted display voltage VLCD (shown in
The power interruption protection module 14 provides power protection to the functionality system 16. The power interruption protection module 14 stores voltage from the display power system 12. When the power interruption protection module 14 recognizes that the functionality system 16 voltage has dropped below a threshold, the power interruption protection module 14 utilizes the boosted display voltage stored from the display power system 12 in the power interruption protection module 14 to provide more voltage to the functionality system 16. Power interruption protection module 14 may step-down the voltage stored in order to provide the functionality system 16 the appropriate voltage.
The functionality system 16 is any system that utilizes a voltage to successfully power ON and to perform the required functionality. For example, the functionality system 16 may be incorporated to perform the functions of a camera, a camcorder, a calculator, a personal digital assistance (PDA), a phone, and the like. If the functionality system 16 loses power, the power interruption protection system 100 prevents the rebooting of the device in the middle of an operation.
b depicts an embodiment of a detailed block diagram of a power interruption protection module 14. The power interruption protection module 14 is coupled to a booster module 18. The booster module 18 may be internal or external to the power interruption protection module 14 or may be incorporated into the display power system 10, shown in
The booster module 12 receives voltage from the display power system 10, both shown in
c depicts an embodiment of a detailed block diagram of a power interruption protection system 100. The power interruption protection system 100 may be incorporated into a portable battery operated device, such as, a camera, a camcorder, a calculator, a remote control, and the like. The power interruption protection system 100 may be adapted to utilize batteries 102, such as, multiple AAA batteries, as a power source and, in various embodiments, is also adapted to receive power from an alternate power source via AC adapter 104.
A power switch/multiplexer 106 receive power from the batteries 102 and/or AC via the AC adapter 104. The power switch 106 determines which power source to accept power from and provides main power to a main power rail (VSYS) in the power interruption protection system 100. VSYS is transmitted towards the power supply module 108 and acts as the main system voltage. The power supply module 108 includes boost regulators 110 and buck regulators/low drop out (LDO) regulators 112 for adjusting the main system voltage VSYS.
Boost regulators 110 receive VSYS and provide high voltage (relative to VSYS), through a boosted display voltage rail, to system components. For example, one boosted display voltage rail VLCD 116, for example, 18 v, is depicted in
Buck regulators/LDO's 112 receive VSYS and provide system voltage rails via rails 111, 113 and 115 to the system processing components 122. The system voltage rails are lower voltage than VSYS (e.g., rail 111 provides voltage at about 3.3 v, rail 113 provides voltage at about 1.8 v, and rail 115 provides voltage at about 1.2 v).
The system processing components 122 include a central processing unit (CPU) 122 for controlling circuitry and memory 126 for storing data and control programs and the like. The CPU 122 may comprise one or more conventionally available microprocessors. The microprocessor may be an application specific integrated circuit (ASIC). The memory 126 is any computer readable memory and may comprise random access memory, read only memory, removable disk memory, flash memory, and various combinations of these types of memory. The memory 126 is sometimes referred to main memory and may, in part, be used as cache memory or buffer memory.
Power from the current limiting and reverse current protection module 118 allows voltage rail VLCD 116 to charge a high energy storage component 124, while limiting current by limiting the load on voltage rail VLCD 116. During the time that VSYS is below a voltage threshold, the voltage rail VLCD 116 may prevent the high voltage energy storage component 124 from supplying its stored charge to the LCD module sub-system 120.
When a device, incorporating power interruption protection system 100, momentarily loses power, the low voltage detection and energy transfer control module 130 detects the voltage loss in the main system voltage (VSYS) and enables an energy transfer component 128 to transfer energy from the high voltage energy storage component 124 to VSYS. In various embodiments, software can monitor the low voltage detect circuit, such as, using the microprocessor 124. The software may monitor the battery level, which may utilize a hardware interface. Hence, if the processor detects that the battery level or VSYS level is too low, then the processor may enable a general purpose input/output (GPIO) signal that enables the high voltage energy storage component 124 to dump its charge into the system voltage, shut down non-critical components to preserve power, and/or maintain user data and system integrity until a controlled shutdown of the system.
The first schematic embodiment 200 may be divided into three groups, which are a charging module 18 (
In this embodiment, the boosted display voltage VLCD 202 is coupled to on one side the transistor 204 and to the booster module 12, shown in
The transistor 218 is coupled to the VDD 212 and transistor 214, wherein the transistor 218 is OFF when VSYS 228 is equal or above a threshold and is ON when VSYS 228 is below or equal to a threshold. One side of the resistor 220 is coupled to the VDD 212 and transistor 218. The second side of the resistor 220 is coupled to the resistor 222 and to the transistor 218 and the capacitor 224. The resistor 222 is coupled from one side to the resistor 220 and the other side to the capacitor 224 and the capacitor 226. One side of the capacitor 224 is coupled to the transistor 218 and the resistor 220 and the other side is coupled to the resistor 222 and the capacitor 226. The capacitor 226 is coupled to VSYS 228, resistor 222 and capacitor 224 and is grounded to ground 210 on the other side.
For illustrative purposes values suitable for some of the elements depicted in
In the circuit 200, VLCD 202 is about 15 volts to about 25 volts (e.g., 18 volts); and the operating range of VSYS 228 is about 6.0 volts to about 3.6 volts. In short, when VSYS falls below 3.6 volts the transistor 214 is enabled and the capacitor 208 dumps its stored voltage to VSYS 228.
When the device, i.e. a calculator, is powered ON, the LCD is ON and the boosted display voltage VLCD 202, from the booster module 12 (shown in
Through transistor 204 and resistor 206, VLCD 202 charges the capacitor 208. Resistor 206 is used to minimize the initial current demand (i.e., a current limiter) on VLCD 202 (to prevent VLCD from being directly connected to VSYS) and stores the charge in capacitor 208. In addition, the resistor 206 determines the rate at which capacitor 208 charges.
Under good battery contact conditions, VSYS is kept high enough (i.e., VSYS is close enough to VDD, such as, VSYS about 4.9 v to about 3.6 v, to avoid discharging capacitor 208 since both transistor 218 and transistor 214 are turned OFF. VDD 212 is a 5 v rail derived from VSYS. In the event of a momentary loss in battery contact, such as, VSYS falls below 3.6 v, transistors 218 turns ON and enables transistor 214, such as, transistor 214 is turned ON, to allow capacitor 208 to provide its stored charge to VSYS 228.
Resistors 220 and 222 act as a voltage divider where resistor values for resistors 220 and 222 are selected to keep transistor 218 OFF until the difference between VDD and VSYS is great enough, for example, VSYS is below 3.3 v, to turn transistor 218 ON. The combination of resistors 220 and 222, capacitor 224, and transistor 218 acts as VSYS low voltage detector.
Even if the batteries are removed from the device VSYS does not immediately become 0 v because a regulator (not shown) is still providing voltage to VDD and the difference between VDD and VSYS will be great enough to turn transistor 218 ON. Because of the charge stored in bulk capacitor 226, VSYS will drop before it becomes 0 v. In this embodiment, when VSYS falls below 3.3. v, transistor 218 turns ON and enables transistor 214 (i.e., turns transistor 214 ON) for the transfer of charge stored in capacitor 208 to VSYS though transistor 214.
In circuit 200, when transistor 214 turns ON, the voltage at VSYS 228 increases and causes transistors 214 and 218 to turn OFF. Transistor 214 turns OFF because transistor 214 is a voltage follower. Because transistor 214 is a voltage follower, the voltage at the emitter (VE) of transistor 214 can never be higher than VB−VBE. In one embodiment, once VE gets to 4.3 v, for example, 5 v-0.7 v, transistor 214 turns OFF. This prevents capacitor 208 from overcharging VSYS and exceeding 5 v, minus the drop across transistor 218. As a result, capacitor 208 and bulk capacitor 226 may cycle the voltage between them, thus, extending the time the power interruption protection system utilizes the voltage stored in the capacitor 208 and bulk capacitor 226.
However, if the difference between VDD and VSYS is large enough, such as, VSYS below 3.3 v, transistor 218 turns ON again to enable transistor 214. When transistor 214 is enabled, capacitor 206 provides more of its stored charge to VSYS 228 through transistor 214. The process of transistor 218 turning ON and enabling transistor 214 is repeated until connection to the battery is reestablished. When the device is OFF, the current demand for maintaining the calculator is relatively small and bulk capacitor 226 may be sufficient to maintain VSYS.
The second schematic embodiment 300 includes a charging module 18 (shown in
The boosted display voltage VLCD 302 is coupled to the resistor 304 from one side and the booster module 12 (
The capacitor 328 is grounded to ground 308 on the second side. The second side of the resistor 324 is coupled to the voltage detector 320 and the low battery indicator 322. The voltage detector 320 is also coupled to the VSYS 318.
For illustrative purposes, values suitable for some of the elements are depicted in
When the device is ON, capacitor 306 stores charge until the capacitor 306 is fully charged or until the system voltage falls below a threshold. When there is an indication that there is a low battery signal, transistors 310 and 314 are turned ON permitting VSYS 326 to be supplied voltage from the stored charge in capacitor 306.
Transistor 310 is a voltage follower and operates similarly to the voltage follower 214 described above and depicted in
As transistor 314 turns ON, voltage at a node connecting transistor 310 to resistor 316 is sufficiently lower than VDD to turn ON transistor 310. Resistor 316 works in conjunction with resistor 324 (a voltage divider configuration) to ensure that transistors 310 and 314 are OFF when the LOWBAT signal is low and ON when the LOWBAT signal is high. Transistor 310 is a voltage follower that, when ON, allows capacitor 306 to discharge through transistors 310 and 314 to VSYS 326. When the voltage detector 320 determines that VSYS 318 is equal or above a threshold, voltage detector 320 transmits a signal indicative of the high voltage at VSYS 318 to turn OFF transistor 314.
In various embodiments, a pin on a microprocessor can be connected to law bat signal 322. When the voltage detector 320 detects low battery signal, the microprocessor may initiate a controlled shutdown, turning OFF certain processor functions (e.g., functions which use relatively higher power) or turning on other component to turn on the transistor 314.
Electronic circuit 400 includes transistors 408, 410, and 420; resistor 422; capacitors 412, 424, 426, and 428; ground 414; system voltage 416 (VSYS 416); DISPOFF 402; a diode 404 (e.g. Schottky); and a boost voltage VSS 418. For illustrative purposes the boosted display voltage is derived from the voltage supplied to a display (VSS).
In this embodiment, two side of the transistor 420 are coupled to VSS 418. The third side of the transistor 420 is coupled to the resistor 422. The other side of the resistor 422 is coupled to the transistor 408 and 410 and capacitors 424, 426 and 428. The other sides of the capacitors 424, 426, and 428 are coupled to each other. The second side of the transistor 408 is coupled to the diode 404. The second side of the diode 404 is coupled to the DISPOFF 402. The third side of the transistor 410 is coupled to the third side of the transistor 408. The third side of the transistor 410 is coupled to the VSYS 416 and the first side of the capacitor 412. The second side of the capacitor 412 is grounded to ground 414.
For illustrative purposes, values suitable for some of the elements depicted in
Resistor 422 operates similarly to resistor 206, described in
When a device, having the circuitry of schematic 400, is ON the device display is also ON. A boosted display voltage rail (e.g., about 18 volts) supplies voltage to VSS 418 and is available when the device is ON. DISPOFF is also available when the device is ON and is maintained at about 3.3 volts. While the device is ON, current used for the device is higher than when the device is in the OFF state. Thus, when the device is ON, it will use the stored charge on the system voltage VSYS 418 faster than when the device is OFF. When the device is OFF, charge stored in the bulk capacitor 328 is usually sufficient to provide its stored charge to VSYS to power the system components.
However, when the device is ON and a momentary loss of contact with the battery occurs, the charge stored in bulk capacitor 412 is usually insufficient to maintain VSYS until reconnection with the battery occurs. To maintain sufficient charge on VSYS during a loss of contact with the battery, when the device is ON, requires increasing the amount of bulk capacitance connected directly to VSYS, which is done by either increasing the capacitance of bulk capacitor 412 and/or adding capacitors to bulk capacitor 412. However, as indicated above, increasing bulk capacitor 412 adds to the overall cost and size of the system.
In contrast, circuitry 400 utilizes capacitors 424, 426, and 428 which can be low cost bulk capacitors that charge up to about the maximum voltage (e.g., about 18 volts) provided by the boosted display voltage rail VSS 418, when the display is ON. As explained above, resistor 422 is a current limiting resistor and determines the rate at which capacitors 424, 426, and 428 are charged.
The DISPOFF 402 signal is high when the display is ON and is used to enable the circuit 400. DISPOFF 402 is set at the 3.3V rail. In the event of a power fluctuation of VSYS below the threshold (i.e., when VSYS falls below 2 volts), the voltage difference between the base and emitter of transistor 408 cause transistors 408 and 410 turn ON allowing VSYS to be maintained by the capacitors 424, 426, and 428. As VSYS drops, there may be enough voltage at DISPOFF 402 to keep DISPOFF high enough, such that there is a potential difference between DISPOFF 402 and VSYS 416 in the positive direction.
Diode 406, transistor 408 and transistor 410 act as a voltage follower system. The addition of diode 406 and transistor 408 requires a higher voltage difference to turn on transistor 410 than a voltage follower without diode 406 and transistor 408 (e.g., the voltage follower depicted in
If the change is a drop, the method proceeds to step 512, wherein the voltage charged in the high voltage capacitor is allowed to flow to the functionality system. From step 512, the method 500 proceeds to step 516, wherein the method 500 checks if the high voltage capacitor is drained. If the high voltage capacitor is not drained of voltage, the method 500 returns to step 508. If the high voltage capacitor is drained the method 500 ends at step 518.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims benefit of U.S. provisional patent application Ser. No. 60/969,571, filed Aug. 31, 2007, which is herein incorporated by reference.
Number | Date | Country | |
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60969571 | Aug 2007 | US |