GB2349757A - A watchdog circuit for a mobile phone battery charging system - Google Patents
A watchdog circuit for a mobile phone battery charging system Download PDFInfo
- Publication number
- GB2349757A GB2349757A GB9906365A GB9906365A GB2349757A GB 2349757 A GB2349757 A GB 2349757A GB 9906365 A GB9906365 A GB 9906365A GB 9906365 A GB9906365 A GB 9906365A GB 2349757 A GB2349757 A GB 2349757A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit
- watchdog circuit
- current sink
- mobile phone
- capacitor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/0703—Error or fault processing not based on redundancy, i.e. by taking additional measures to deal with the error or fault not making use of redundancy in operation, in hardware, or in data representation
- G06F11/0751—Error or fault detection not based on redundancy
- G06F11/0754—Error or fault detection not based on redundancy by exceeding limits
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00302—Overcharge protection
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/3827—Portable transceivers
- H04B1/3883—Arrangements for mounting batteries or battery chargers
Landscapes
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- Quality & Reliability (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Protection Of Static Devices (AREA)
- Coupling Device And Connection With Printed Circuit (AREA)
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
- Combinations Of Printed Boards (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Pulse Circuits (AREA)
- Electronic Switches (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
A watchdog circuit ensures that that the charging control circuit of a mobile phone is set to a safe state in the event of a fault occurring. An alternating output (S) from the CPU of the phone causes periodic discharge of a capacitor (C185) through a current sink (TR28-B) and maintains a low voltage on the emitter of a transistor (TR28A). With the low voltage maintained at its emitter the transistor remains switched on and charging continues. Loss of the alternating voltage (S) removes the periodic current sink from the capacitor (C185) which charges to a high voltage and by switching off the transistor (TR28A) terminates charging of the phone.
Description
Watchdog circuit
This invention relates to watchdog circuits and in particular it relates to watchdog circuits operating a fail safe condition.
Mobile phones and many other portable devices rely for their operation on battery power from batteries which need regularly to be re-charged. When a battery in use with a mobile phone becomes discharged, the battery in use can be exchanged with a spare battery. Spare batteries can be maintained at a fully charged state. It is very often the case, however, that the battery in use with the mobile phone is recharged whilst remaining within the phone. Means for controlling the current supplied by an external charger to re-charge its battery are usually included in a mobile phone.
The circuitry for controlling the current supplied by an external charger is controlled by the CPU of the phone. A fault condition can occur which results in the phone turning on the charge current to the battery and then failing to turn it off when the battery becomes fully charged. Under these conditions the battery within the phone can become overcharged such that it swells in size and produces noxious fumes.
Watchdog circuits are known from the prior art and reference is made to
WO 97/24652 assigned to Advanced Micro Devices Inc. and WO 98/43164 assigned to Robert Bosch GmbH for technological background.
It is an object of the present invention to provide a watchdog circuit for effective operation of a fail safe condition in which the circuit is composed of a minimum number of components.
According to the invention there is provided a watchdog circuit maintaining an output voltage level in a safe condition and altering said output voltage in response to a fault condition for control of an external circuit where the level of the output voltage depends upon the state of charge of a capacitor and in which, in a safe condition, periodic discharge of said capacitor through a current sink is effected by switching of said current sink by an alternating voltage.
The external circuit referred to here is external in the sense that it does not form part of the watchdog circuit but may be co-located with the watchdog circuit.
One example of the invention will now be described with reference to the figures in which like reference letters and numerals identify identical elements and wherein: figure 1 is a block diagram of the charging control circuit in a mobile phone, figure 2 is a circuit diagram of a watchdog circuit.
With reference to figure 1 a mobile phone is shown generally at 1 and an external charger unit is shown at 2. When charging is to proceed, a signal R from the microprocessor, CPU 6 is an input to the enable circuit 5. Whilst the signal R is present as an input to enable circuit 5, the switch 4 remains closed and charger 5 is connected to battery 3. A further signal S from CPU 6 is passed to the watchdog circuit 7. As long as the correct signal S is received by the watchdog circuit 7, then the watchdog circuit 7 has no effect on the operation of enable circuit 5 and charging continues.
With reference to figure 2, a circuit diagram is shown of the watchdog circuit 7 and the enable circuit 5 of figure 1. The output T connects to the gate of an
FET which operates as a switch as indicated by block 4 of figure 1. The charging current to the battery is controlled by the FET of block 4. In order to turn the FET on and enable the charging current to flow into the battery, a high level voltage R is applied to terminal 111. The voltage input to terminal 111 is derived from an output port of the CPU 6. A high level on terminal 111 causes transistor TR28-A to turn on and the FET of block 4 to turn on also.
When the FET is on, the charge current is allowed to flow into the battery for charging to proceed.
The circuitry provided for the watchdog function comprises transistor TR28-B resistors R182, R155, R154 and capacitors C185, C184. With no input applied to terminal 112, TR28-B will remain switched off and will act as an open circuit. Whilst TR28-B is switched off the capacitor C185 will charge through R182 toward half of the voltage level R applied to terminal 111. The voltage R/2 will then be applied to the emitter of TR28-A, keeping TR28-A turned off and consequently keeping the FET of block 4 turned off.
An output S from the CPU6 will, under normal conditions, be applied to terminal 112. The output S is a 300KHz square wave, AC coupled via C 184 to the base of TR28-B. The square wave signal applied to the base of TR28
B periodically turns TR28-B on. Each time TR28-B is turned on it acts as a current sink and begins to discharge capacitor C185. The regular discharge of capacitor C185 maintains a low voltage across the capacitor and at the emitter of TR28-A, such that TR28-A remains on. With TR28-A switched on the
FET of block 4 remains on and charging proceeds.
If a failure occurs and there is no output S from the CPU 6 to terminal 112 then C185 will charge up via R182, causing TR28-A and consequently the
FET to turn off so that charging is stopped.
By this means the safety of the phone is improved over the prior art and in the event of software crash or a hardware problem, the phone cannot continue to overcharge of a battery.
As the signal from the CPU 6 is AC coupled via C184, an alternating signal is needed for the watchdog circuit to maintain a satisfactory output to the enabling circuit. An additional safety feature is therefore provided as the processor CPU 6 has to be actively running code to generate the required alternating waveform. If the processor has stopped due to a broken connector in the supply to the clock for example, the charger cannot be left turned on.
The circuit may be used for other purposes, such as to generate a system reset in the event of a software crash, or for monitoring a safety critical control circuit to ensure setting to a safe state in the event of a software error.
Claims (5)
- Claims 1. A watchdog circuit maintaining an output voltage level in a safe condition and altering said output voltage in response to a fault condition for control of an external circuit where the level of the output voltage depends upon the state of charge of a capacitor and in which, in a safe condition, periodic discharge of said capacitor through a current sink is effected by switching of said current sink by an alternating voltage.
- 2. A watchdog circuit as in claim 1 in which the output voltage is maintained at a low level in a safe condition and altered to a high level in a fault condition.
- 3. A watchdog circuit as in claim 1 or 2 in which the external circuit controlled by the output of the watchdog circuit is a charging control circuit within a mobile phone.
- 4. A watchdog circuit as in claims 1 to 3 in which the alternating voltage switching the current sink is a square wave output from a microprocessor.
- 5. A watchdog circuit as in any preceding claim in which the current sink is a transistor.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9906365A GB2349757B (en) | 1999-03-20 | 1999-03-20 | Watchdog circuit |
JP2000006530A JP2000278108A (en) | 1999-03-20 | 2000-01-14 | Watchdog circuit and charging controller |
JP2000073708A JP2000307285A (en) | 1999-03-20 | 2000-03-16 | Intermediate frame for circuit board |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9906365A GB2349757B (en) | 1999-03-20 | 1999-03-20 | Watchdog circuit |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9906365D0 GB9906365D0 (en) | 1999-05-12 |
GB2349757A true GB2349757A (en) | 2000-11-08 |
GB2349757B GB2349757B (en) | 2003-07-16 |
Family
ID=10849968
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9906365A Expired - Fee Related GB2349757B (en) | 1999-03-20 | 1999-03-20 | Watchdog circuit |
Country Status (2)
Country | Link |
---|---|
JP (2) | JP2000278108A (en) |
GB (1) | GB2349757B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2717418A3 (en) * | 2002-04-03 | 2017-02-15 | Black & Decker, Inc. | Battery charger with protection circuitry |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101360288B (en) * | 2007-08-03 | 2012-09-12 | 宇龙计算机通信科技(深圳)有限公司 | Bi-mode mobile phone and battery protection circuit thereof |
JP2009130181A (en) * | 2007-11-26 | 2009-06-11 | Necディスプレイソリューションズ株式会社 | Electronic circuit board, and method and structure for shielding electronic circuit board |
JP5313635B2 (en) * | 2008-11-10 | 2013-10-09 | 株式会社マキタ | Electric tool charging system, electric tool battery pack, and electric tool charger |
JP6298648B2 (en) * | 2014-02-17 | 2018-03-20 | 矢崎総業株式会社 | Backup signal generation circuit for load control |
EP3585137A4 (en) * | 2017-03-09 | 2020-03-25 | Huawei Technologies Co., Ltd. | Motherboard and terminal for use with consumer electronic products |
CN108155788A (en) * | 2017-12-07 | 2018-06-12 | 中国航空工业集团公司西安航空计算技术研究所 | A kind of adjustable energy supply startup control circuit of voltage threshold |
CN108711689B (en) * | 2018-04-24 | 2020-03-24 | 番禺得意精密电子工业有限公司 | Electrical connector |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4403302A (en) * | 1980-10-30 | 1983-09-06 | Essex Group Inc. | Automatic resetting of control system for loss of time reference |
GB2120428A (en) * | 1982-05-19 | 1983-11-30 | Nissan Motor | Monitoring apparatus for control system with microcomputer |
US4600987A (en) * | 1982-12-08 | 1986-07-15 | Pitney Bowes Inc. | Monitoring circuit for an electronic postage meter |
WO1988004074A1 (en) * | 1986-11-26 | 1988-06-02 | Robert Bosch Gmbh | Circuit for monitoring a pulse train |
US4893348A (en) * | 1987-09-09 | 1990-01-09 | Mitsubishi Denki Kabushiki Kaisha | Power source control device in car telephone mobile station system |
-
1999
- 1999-03-20 GB GB9906365A patent/GB2349757B/en not_active Expired - Fee Related
-
2000
- 2000-01-14 JP JP2000006530A patent/JP2000278108A/en active Pending
- 2000-03-16 JP JP2000073708A patent/JP2000307285A/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4403302A (en) * | 1980-10-30 | 1983-09-06 | Essex Group Inc. | Automatic resetting of control system for loss of time reference |
GB2120428A (en) * | 1982-05-19 | 1983-11-30 | Nissan Motor | Monitoring apparatus for control system with microcomputer |
US4600987A (en) * | 1982-12-08 | 1986-07-15 | Pitney Bowes Inc. | Monitoring circuit for an electronic postage meter |
WO1988004074A1 (en) * | 1986-11-26 | 1988-06-02 | Robert Bosch Gmbh | Circuit for monitoring a pulse train |
US4893348A (en) * | 1987-09-09 | 1990-01-09 | Mitsubishi Denki Kabushiki Kaisha | Power source control device in car telephone mobile station system |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2717418A3 (en) * | 2002-04-03 | 2017-02-15 | Black & Decker, Inc. | Battery charger with protection circuitry |
Also Published As
Publication number | Publication date |
---|---|
GB9906365D0 (en) | 1999-05-12 |
JP2000278108A (en) | 2000-10-06 |
JP2000307285A (en) | 2000-11-02 |
GB2349757B (en) | 2003-07-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
KR100341133B1 (en) | Charge/discharge control circuit ad charging type power-supply | |
JP3305257B2 (en) | Charge / discharge control circuit, rechargeable power supply device and control method therefor | |
JP4398432B2 (en) | Charge / discharge control circuit and rechargeable power supply | |
US6507173B1 (en) | Single chip power management unit apparatus and method | |
JP3383607B2 (en) | Battery condition monitoring circuit, battery device, and electronic device | |
JP2009529850A (en) | Power surge filtering in protection against overcurrent and short circuit | |
JPH0767263A (en) | Overdischarge preventive circuit for secondary battery | |
US5959437A (en) | Charge and discharge control circuit | |
KR20080113230A (en) | Gate driver for a battery pack | |
US9774194B2 (en) | Charge and discharge control circuit and battery device | |
JP3190597B2 (en) | Charge / discharge control circuit and rechargeable power supply | |
JP2002238173A (en) | Charging/discharging control circuit and chargeable power supply | |
CN112117800A (en) | Battery protection circuit, battery pack and electronic device | |
US6111388A (en) | Charge and discharge control circuit | |
GB2349757A (en) | A watchdog circuit for a mobile phone battery charging system | |
US6388491B1 (en) | Delay circuit | |
JP2001145271A (en) | Secondary battery protection method and circuit | |
US20010011882A1 (en) | Lithium ion battery unit adapted to be charged by an alkaline charger | |
KR19990083257A (en) | Charging and discharging control circuit and charging type power supply device | |
JPWO2020110542A1 (en) | Battery pack and electrical equipment system | |
KR20210097950A (en) | Apparatus and method for controlling power supply of battery management system using Pulse Width Modulation signal | |
KR100308530B1 (en) | Battery charge / discharge control circuit | |
KR102316487B1 (en) | The battery protection circuit for preventing malfunction of the secondary IC | |
CN110048472B (en) | Standby power supply operation method of controller | |
WO2015063968A1 (en) | Battery pack, electronic device system, and electronic device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20060320 |