WO2006102928A1

WO2006102928A1 - Mobile device and a method for power management

Info

Publication number: WO2006102928A1
Application number: PCT/EP2005/004652
Authority: WO
Inventors: Bertrand Clou; Laurent Bordes; Marianne Maleyran
Original assignee: Freescale Semiconductor, Inc.
Priority date: 2005-04-01
Filing date: 2005-04-01
Publication date: 2006-10-05

Abstract

A method (200) for power management , the method includes supplying (240) power to at least one component of a mobile device. The method is characterized by autonomously detecting (210) power sources capabilities selecting a (220) power source in response to the detected capabilities and to at least one power source selection rule; and applying (230) a power regulation operation on the power to be supplied to at least one component of the mobile device. A mobile device (100) having power management capabilities, the mobile device includes at least one component (190) that is powered by a supply voltage. The mobile device is characterized by including a power management circuit (190) that is adapted to: (i) autonomously detect power sources capabilities, (ii) select a power source in response to the detected capabilities and to at least one power source selection rule; and (iii) perform at least one regulation operation on the power to be supplied to the at one component (190) of the mobile device.

Description

MOBILE DEVICE AND A METHOD FOR POWER MANAGEMENT

FIELD OF THE INVENTION

The present invention relates to a mobile device and a method for managing power, especially in a multiple power source environment.

BACKGROUND OF THE INVENTION

Modern mobile devices such as but not limited to a cellular phone, a personal data accessory and the like are powered by various power sources. External power sources, such as chargers are used to charge internal power sources such as a main battery.

The charger is usually connected to the mobile device via a dedicated connector.

Recently, mobile devices are also equipped with standard USB connectors that can be used to charge also the main battery. A new requirement for all mobile applications is the ability to operate from a dead battery.

Usually, mobile devices include a backup or secondary battery to allow support memory hold functions while for instance user is swapping the main battery. A general constraint for all mobile applications using these four different power sources (Main battery, wall charger, USB charger and backup battery) is to optimize life time of the main battery and increase memory hold time.

Usually, external power sources are treated separately leading to several system supplies which are powering via regulator or analog multiplexer, all the different functions of the power management device and other possible mobile functions. The several system on chip supplies used to power the different functions (ADC, Charger, Real time clock, ...) lead to first duplicate few basic blocks that are required by these complex functions: voltage and current reference, oscillator or power on reset; second to add level shifters which are mandatory for a system using multiple on chip supplies. Because of this usual power management method each function could only work while the dedicated external power resource was available. FIG. 1 illustrates a prior art power management circuit and its environment. The power management circuit can be connected to a USB charger 20 and a wall charger 22. It is also connected to a battery 24 (also referred to as main battery) and a button cell (also referred to as secondary battery or backup battery) 26. Various components, such as memory units and real time clock system 30, are connected to the main battery 24 or to the secondary battery 26 through a selector 28. The selector 28 connects to the memory unit and the real time clock system 30 the power source that provides the higher voltage. This arrangement shortens the life of the secondary battery, as the secondary battery can be forced to supply power to the various components, even if other power sources can supply power to these components. The USB charger 20 is connected to the mobile device 100' via a USB voltage regulator 40. The latter is connected to various components (denoted 50) such as a USB transceiver, a USB charging support unit, current reference circuit, clock reference circuit, and a trimmer voltage circuit.

The wall charger 22 is connected to the power management circuit via a charger clamp circuit 42. The latter is connected to various components (denoted 52) such as a charger control unit, current reference circuit, clock reference circuit, and a trimmer voltage circuit .

The main battery voltage is regulated by a main battery voltage regulator 44 to provide a voltage referred to as Vcore. Vcore is decoupled thanks to the capacitor 34 and is used as a supply voltage in the control part of power management components. These multiple components (denoted 54) include an SPI/ control logic, and various core elements of the mobile device. The voltage supplied by the main battery 24 is usually termed core voltage Vcore.

This supply flow also propose a poor voltage regulated power supply (no decoupling cap and resistive path) to this Real time clock and memory hold system (30)

There is a need to provide an efficient power management scheme.

SUMMARY OF THE PRESENT INVENTION A mobile device and a method for power management, as described in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

FIG. 1 illustrates a prior art power management circuit and its environment; FIG. 2 illustrates a mobile device, according to an embodiment of the invention;

FIG. 3 illustrates a power management circuit, according to an embodiment of the invention; - A -

FIG. 4 illustrates a power management circuit, according to another embodiment of the invention;

FIG. 5 illustrates in greater detail the power management circuit, according to an embodiment of the invention;

FIG. 6 illustrates in greater detail the power management circuit, according to an embodiment of the invention; and

FIG. 7 is a flow chart of a power management method, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The following figures illustrate exemplary embodiments of the invention. They are not intended to limit the scope of the invention but rather assist in understanding some of the embodiments of the invention. It is further noted that all the figures are out of scale .

According to an embodiment of the invention a method for power management is provided. The method is adapted to operate with multiple power sources. The method includes: autonomously detecting power sources capabilities; selecting a power source in response to the detected capabilities and to at least one power source selection rule; applying a high performances power regulation operation on the power which is selected and supplying power to various on chip functions of an audio & power management integrated circuit and potentially to other functions of a mobile device. Conveniently, the method provides a unique core supply that allows to greatly simplify a system on chip. Conveniently, the power management circuit is adapted to receive a large range of supply voltage and provides a max rating self adaptive design.

Conveniently, the provision of a unique Vcore allows to use maximum low voltage components.

According to an embodiment of the invention a device having power management capabilities is provided. The device includes a power management circuitry that is capable of operating as soon as one of multiple external power sources is available and can provide a unique output voltage. The power management circuit is adapted to: (i) autonomously detect power sources capabilities, (ii) select a power source in response to the detected capabilities and to at least one power source selection rule; and (iii) perform regulation operation to provide a unique regulated voltage to a power management and audio/video integrated circuit and potentially to other functions of the mobile device.

Conveniently, the power management circuit simplifies greatly the structure of a system on chip.

FIG. 2 illustrates a mobile device 100 according to an embodiment of the invention.

Mobile devices usually include multiple integrated circuits. Each integrated circuit includes multiple circuitry such as power management circuitry, base band circuitry, radio frequency circuitry, audio and video circuitry and the like. The allocation of circuitry per integrated circuit can change.

According to an embodiment of the invention the power management circuits and the audio/video circuitry were included within a first integrated circuit 90. The radio frequency circuitry and the base band circuitry were arranged in other integrated circuits referred to as base band and RF circuitry 60.

The base band and RF circuitry 60 are connected to various components such as but not limited to: one or more memory units 61 that can include a DRAM and/or a flash memory unit, display 64, SIM card 63, keypad 62 and antenna 65.

Integrated circuit 90 includes a power management circuit 190 and additional components (collectively denoted 90'), such as: audio out module 91, audio in module 92, audio buses module 93, USB and serial data (RS-232) interface 94, peripheral module 95, main battery and charger module 96, switchers module 97, regulator module 98, analog to digital converter module 99, stereo digital to analog converter module 81, CODEC module 82, audio mixing module 85, secondary battery, clock and timing module 83 and system control module 84. At least some of these components receive a regulated Vcore 260 from the power management circuit 190. The integrated circuit 90 is connected to various components of the mobile device 100 such as backlight sources 71, LED matrix 72, microphone 74, speaker 75, headphone 76, and the like. The integrated circuit is also connected via various interfaces and connectors to USB charger 20 and to wall charger 22.

FIG. 3 illustrates integrated circuit 90, according to an embodiment of the invention.

Power management circuit 190 is connected to four internal and external power sources: USB charger 20, wall charger 22, main battery 24 and secondary battery 26. The output of the power management circuit 190 is connected to a capacitor 34 as well as to other components of the mobile device 100. Conveniently, the power management circuit 190 is connected to a USB charger via USB and serial data (RS- 232) interface 94. The power management circuit 190 is connected to a main battery and to the wall charger 22 via the main battery and charger module 96. The power management circuit 190 is connected to the backup battery via secondary battery, clock and timing module 83.

The power management circuit 190 includes a power source capabilities detection unit 120, a power source selection unit 130 and a regulator circuit 140. The regulation circuit 140 has multiple inputs and a single output. The power source capability detection circuit 120 autonomously detects power sources capabilities to supply power. If a power source is connected to the mobile device and can provide a voltage that is above a certain voltage threshold, the power management will send an indication to the power source selection unit 130.

The power source selection unit 130 receives signals representative of the detected capabilities of the multiple power source and applies one or more power source selection rule in order to select one power source. The power source detection rule can be responsive to the amount of current and/or voltage amplitude supplied by the power source, to the status of the mobile device, and the like. At least one rule can be aimed to prolong the life of the main battery 24 or of the life of the secondary battery 26 by prioritizing external power sources .

The multi input single output regulation circuit 140 performs various switching operations, according to control signals from the power source selection unit 130, performs a power regulation operation on the voltage of the selected power source and provides a regulated voltage Vcore 260 as an output signal of the power management circuit 190.

According to an embodiment of the invention the power regulation is performed at a component that is connected to the power management circuit 190 and not by the power management circuit 190.

According to yet another embodiment of the invention the regulation circuit 190 also protects non-selected power sources from leakage currents. FIG. 4 illustrates integrated circuit 90 according to another embodiment of the invention. The power management circuit 190 of mobile device 100 is connected to three power sources: the USB charger 20, the wall charger 22 and the main battery 24. The secondary battery 26 is connected to the output of the power management circuit 190.

In this configuration the secondary battery 26 replaces the capacitor 34 and can be constantly charged by Vcore 260. It provides power to some of the mobile device components only if other power sources fail.

According to an embodiment of the invention the power management circuit 190 supplies power to a backup tank or a secondary battery (150) of the mobile device. This allows to save a dedicated voltage regulator decoupling capacitor (34) and also to get an automatic memory hold tank for the mobile device. This simplifies the design of the mobile device.

FIG. 5 illustrates in greater detail the power management circuit 190, according to an embodiment of the invention.

The power source capabilities detection unit 120 is connected to the USB charger 20, the wall charger 22, the main battery 24 and to the secondary battery 26. It also receives an indication (on/off signal 129) whether the mobile device 100 is shut down or not. This is represented by IC_turn_on switch 29.

Conveniently, even when the mobile device 100 is turned off there is at least one circuit that is not shut down. This circuit can be the power regulation circuit 190 that selects the power source to be utilized during an power up sequence.

The power source capabilities detection unit 120 has a multiple comparators. A USB charger comparator (denoted A4 230) compares a voltage Vudiv 235 that is derived from a USB charger voltage (Vusb) 320 to a reference voltage Vuref 236. This comparison determines if the USB charger 20 is connected to the mobile device and if it is active. The output of the USB charger comparator A4 230 provides a U_detect signal 123.

A wall charger comparator (denoted Al 203) compares voltage Vcdiv 210 that is derived from the wall charger voltage (Vc) 322 to a reference voltage Vcref 211 to determine if the wall charger 22 is connected to the mobile device and if it is active. The output of the wall charger comparator Al 302 provides a C_detect signal 126.

A battery comparator (denoted A7 270) compares voltages (Vmain 324, Vs 326) provided by main battery 24 and the secondary battery 26 to determine which battery provides the higher voltage and provides a B_detect signal 128.

According to another embodiment of the invention the power source capability detection unit 120 can determine the voltage level (and/or the current intensity) of the power sources in various manners such as by comparing supplied voltages to multiple reference levels. According to yet another embodiment of the invention the power source capability detection unit 120 can compare the power supplied by the main battery and/or the secondary battery to appropriate reference voltages. This comparison can be in addition to or instead of the comparison between the two batteries.

The power source selection unit 130 receives the U_detect signal 123, the C_detect signal 126, the B_detect signal 128 and the on/off signal 129. It applies one or more rule and in response to the detection signals selects one power source.

Conveniently, at least one rules is aimed to optimize the life time of the main and secondary batteries by considering the overall performances of the mobile device in the different user modes. For instance in call mode

(ON mode) the preferred power source is the main battery to ensure better audio transmission quality

Tables 1 illustrates an exemplary selection rule. When the on/off signal 129 is high the integrated circuit is "ON". The B_detect signal 128 is high if the main battery 24 is selected. The symbol "X" indicates that the value of a certain signal is not relevant.

TABLE 1

Conveniently, the power source selection unit 130 outputs four selection signals: USB charger selection signal (U_select) 131, wall selection signal (C_select) 132, main battery selection signal (M_select) 133 and secondary battery selection signal (S_select) 134.

Each of these selection signal is controls a switch circuit 141, 142, 143 and 144. Once a certain voltage supply is selected the corresponding switch circuit is connected to an error amplifier (illustrates as error amplifiers unit 450) and to the output of the power management circuit 190.

Each switch circuit 141, 142, 143 and 144 includes a switch 141', 142', 143' and 144' and a PMOS transistor 141", 142", 143" and 144". The gate of each PMOS is connected to the output of an error amplifiers unit 450 via the appropriate switch. The source of each PMOS is connected to a corresponding power source. The drain of each PMOS is connected to the output of the power management circuit 190. The PMOS transistors are connected in order to prevent leakage current.

FIG. 6 illustrates in greater detail the power management circuit 190, according to an embodiment of the invention. Vc 322 is provided to a C_reference circuit 204, to a pair of voltage divider resistors Rl 201 and R2 202, to a wall charger comparator Al 203, to a control input of error amplifier A2 205 and to a source of PMOS 142". A first input of the wall charger comparator Al 203 is connected between Rl and R2 such as to receive Vcdiv 210, whereas Vcdiv= (Vc*R2) / (Rl + R2) . Al 203 compares Vcdiv 210 to a reference voltage Vcref 211. Vcref 211 is provided by C reference circuit 204. C__reference circuit 204 provides Vcref of about 1.15v when Vc 322 exceeds 2v. C_reference circuit 204 also provides a reference current Icref 212 of about lμA. Icref is provided to a control input of error amplifier A2 205.

Error amplifier A2 205 compares between Vfb 200 and between Vcref 211. Vfb 200 substantially equals Vref*Rll/ (RIl + R12) . The output of the error amplifier A2 205 is selectively connected, via switch 142' , to the gate of PMOS 142".

The drain of PMOS 142" is connected to the drains of PMOS transistors 141", 143" and 144". These drains are connected to RlO 251. Switch 142" is controlled by C_select signal 132. Vu 320 is provided to a Dereference circuit 234, to a pair of voltage divider resistors R3 223 and R4 234, to a USB charger comparator A4 230, to a control input of error amplifier A5 231 and to a source of PMOS 141". A first input of the USB charger comparator A4 230 is connected between R3 and R4 such as to receive Vudiv 235, whereas Vudiv= (Vu*R4) / (R3 + R4). A4 230 compares Vudiv 235 to a reference voltage Vuref 236. Vuref 236 is provided by U_reference circuit 234.

U_reference circuit 234 provides Vuref of about 1.15v when Vu 320 exceeds 2v. U_reference circuit 234 also provides a reference current Iuref 237 of about lμA. Iuref 237 is provided to a control input of error amplifier A5 231. Error amplifier A5 231 compares between Vfb 200 and between Vuref 236. The output of the error amplifier a5 231 is selectively connected, via switch 141', to the gate of PMOS 141".

Vm 324 is provided to a m_reference circuit 221, to a control input of error amplifier A3 225 and to a source of PMOS 143". M_reference circuit 221 provides Vmref 220 of about 1.15v when Vm 324 exceeds 1.7v. M_reference circuit 234 also provides a reference current Imref 222 of about 0.4μA. Imref 222 is provided to a control input of error amplifier A3 225. Error amplifier A3 225 compares between Vfb 200 and between Vmref 220. The output of the error amplifier A3 225 is selectively connected, via switch 143', to the gate of PMOS 143".

Vs 326 is provided to a S_reference circuit 244, to a control input of error amplifier A6 241 and to a source of PMOS 144". S_reference circuit 244 provides Vsref 243 of about 1.15v when Vs 326 exceeds 2v. S_reference circuit 244 also provides a reference current Isref 242 of about O.lμA. Isref 242 is provided to a control input of error amplifier A6 241. Error amplifier A6 241 compares between Vfb 200 and between Vsref 243. The output of the error amplifier A6 241 is selectively connected, via switch 144', to the gate of PMOS 144". RlO 251 and RIl 252 are coupled to a source of NMOS transistor 255. The PMOS 255 is controlled by S_select signal 134. Thus, if a power source other than the secondary battery 26 is selected then RIl is grounded. The reference circuits 204, 234, 221 and 244 has a bias circuit that has a low-impedance point that rises up to a very stable reference voltage, when the power source is active.

FIG. 7 is a flow chart of method 400 for power management, according to an embodiment of the invention. Method 400 starts by stage 410 of autonomously detecting power sources capabilities. Conveniently, the power sources includes internal and external power sources. Conveniently the power sources include a USB charger. Conveniently, the amount of power sources exceeds three.

Stage 410 is followed by stage 420 of selecting a power source in response to the detected capabilities and to at least one power source selection rule.

Conveniently, at least one power source selection rule is responsive to the status of the mobile device. The status can reflect is the mobile device is open or closed.

Conveniently, the selecting includes performing switching operations and protecting non-selected power sources from leakage currents.

Stage 420 is followed by stage 430 of applying at least one power control operation on the power to be supplied to at least one component of the mobile device. Conveniently the at least one power control operation includes power regulation.

Stage 430 is followed by stage 440 of supplying power to at least one component of a mobile device.

Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed.

Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims.

Claims

WE CLAIM

1. A method (400) for power management, the method comprises: supplying (440) power to at least one component of a mobile device; characterized by autonomously detecting (410) power sources capabilities; selecting a (420) power source in response to the detected capabilities and to at least one power source selection rule; and applying (430) a power regulation operation on the power to be supplied to at least one component of the mobile device.

2. The method (400) according to any of the preceding claims wherein the amount of power supplies exceeds three .

3. The method (400) according to any of the preceding claims wherein the at least one power source selection rule is responsive to the status of the mobile device.

4. The method (400) according to any of the preceding claims wherein the selecting (420) comprises performing switching operations and protecting non-selected power sources from leakage currents.

5. The method (400) according to any of the preceding claims wherein the stage of supplying (440) comprises providing a power controlled voltage to a capacitor (34) that is coupled in parallel to at least one component of the mobile device.

6. The method (400) according to any of the preceding claims wherein the stage of supplying (440) comprises supplying power to a secondary battery (26) of the mobile device.

7. The method (400) according to any of the preceding claims wherein one of the power sources is a secondary battery of the mobile device.

8. A mobile device (100) having power management capabilities, the mobile device comprises at least one component (90') that is powered by a supply voltage; characterized by comprising a power management circuit (190) adapted to: (i) autonomously detect power sources capabilities, (ii) select a power source in response to the detected capabilities and to at least one power source selection rule; and(iii) perform at least one regulation operation on the power to be supplied to the at one component (90') of the mobile device.

9. The mobile device (100) according to claim 8 wherein the power sources comprise a USB charger.

10. The mobile device (100) according to any claim of claims 8-9 wherein the amount of power supplies exceeds three.

11. The mobile device (100) according to any claim out of claims 8-10 wherein the at least one power source selection rule is responsive to the status of the mobile device .

12. The mobile device (100) according to any claim out of claims 8-11 wherein the power management circuit (190) comprises a power source capabilities detection unit (120) .

13. The mobile device (100) according to any claim out of claims 8-12 wherein the power management circuit (190) comprises a power source selection unit (130).

14. The mobile device (100) according to any claim out of claims 8-13 wherein the power management circuit (190) comprises a regulator circuit (140) for regulating the voltage supplied to at least one component of the mobile device.

15. The mobile device (100) according to any claim out of claims 8-14 wherein one of the power sources is a secondary battery (26) .

16. The mobile device (100) according to any claim out of claims 8-15 wherein a secondary battery (26) of the mobile device is powered by the power management circuit (190) .

17. A power management circuit (190) comprising: a power source capabilities detection unit (120) adapted to autonomously detect power sources capabilities; a power source selection unit (130), coupled between the power source capabilities detection unit and a regulation unit (140), adapted to select a power source in response to the detected capabilities and to at least one power source selection rule; and a regulation unit (140) adapted to perform at least one regulation operation on an output voltage of the power management circuit (190) .

18. The power management circuit (190) according to claim 17 wherein the power sources comprise a USB charger.

19. The power management circuit (190) according to any claim of claims 17-18 wherein the amount of power supplies exceeds three.

20. The power management circuit (190) according to any claim out of claims 17-19 wherein the at least one power source selection rule is responsive to the status of the mobile device.