CN101685319A - Real-time clock circuit - Google Patents
Real-time clock circuit Download PDFInfo
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- CN101685319A CN101685319A CN200810200329A CN200810200329A CN101685319A CN 101685319 A CN101685319 A CN 101685319A CN 200810200329 A CN200810200329 A CN 200810200329A CN 200810200329 A CN200810200329 A CN 200810200329A CN 101685319 A CN101685319 A CN 101685319A
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Abstract
The invention relates to a real-time clock circuit, comprising a clock chip, a first diode, a second diode and a first super capacitor, wherein, the clock chip is provided with a main power source pinV<DD>, a battery pin V<BAT>, a grounding pin V<SS>, a serial clock input pin SCL, a serial data input/output pin SDA, a square wave/output driver pin SQW/OUT and crystal pins X1 and X2; the first diode and the second diode are connected in series, the anode of the first diode is connected with an exterior main power V<CC>, the cathode of the second diode is connected with the main power pin V<DD>of the clock chip; and the anode of the first super capacitor is connected with the cathode of the first diode, and the cathode thereof is grounded. The real-time clock circuit of the invention has high accuracy and high reliability, can be used for multi-rate meters, IC card water meters, IC card gas meters, mobile phones, portable instruments, fax machines, battery power products and televisions.
Description
Technical field
The present invention relates to a kind of clock circuit, particularly a kind of real time clock circuit.
Background technology
Real time clock circuit RTC generally includes primary power, reserve battery and clock chip, and clock chip generally all has power supply power supply input end and powered battery input end, and clock chip is battery-powered when system cut-off.Clock chip has two states: accessed state and non-Access status.Generally speaking, when being powered by power supply, clock chip allows processor that it is normally visited; When battery-powered, reduce to minimum for making battery current, and avoid data destroyed, system can forbid communicating by letter between clock chip and the ppu.
Summary of the invention
The object of the present invention is to provide a kind of real time clock circuit, degree of accuracy height, good reliability.
In order to achieve the above object, technical scheme provided by the invention is, a kind of real time clock circuit comprises clock chip, first diode, second diode and first farad capacitor, and described clock chip is provided with primary power pin V
DD, battery pin V
BATWith grounding pin V
SS
Described first diode is connected with second diode, the positive pole of described first diode and outside primary power cource V
CCConnect the primary power pin V of the negative pole of described second diode and clock chip
DDConnect; Described battery pin V
BATWith primary power pin V
DDConnect;
The positive pole of described first farad capacitor connects the negative pole of first diode, and its negative pole is connected with ground, described grounding pin V
SSBe connected with ground.
Above-mentioned real time clock circuit wherein, also includes second farad capacitor, first electric capacity and second electric capacity;
Described clock chip also is provided with serial clock input pin SCL, serial data I/O pin SDA, square wave/output driver pin SQW/OUT and crystal pins X
1, X
2
Described serial clock input pin SCL and serial data I/O pin SDA connect respectively resistance and outside primary power cource V
CCConnect;
Described crystal pins X
1Connect successively and be connected with ground behind second farad capacitor, first electric capacity; Between the positive pole of described second farad capacitor and ground, be connected one second electric capacity;
Described crystal pins X
2Be connected with the negative pole of second farad capacitor.
Above-mentioned real time clock circuit, wherein, by described primary power pin V
DDWith grounding pin V
SSInput 5v direct supply V
CC
Above-mentioned real time clock circuit, wherein, described battery pin V
BATInsert a 3v battery.
Above-mentioned real time clock circuit, wherein, described crystal pins X
1, X
2Be respectively the link of standard 32.768KHz quartz crystal.
Above-mentioned real time clock circuit, wherein, the electric capacity of described first farad capacitor is 0.33 farad.
Above-mentioned real time clock circuit, wherein, described clock chip comprises oscillator and allocator module, square wave output module, energy supply control module, serial bus interface IP, control logic module, address register, clock register and user register;
Described oscillator is connected with clock register with the square wave output module respectively with allocator module, draws crystal pins X by oscillator and allocator module
1With crystal pins X
2
Described square wave output module is connected with control logic module, draws square wave/output driver pin SQW/OUT by the square wave output module;
Described energy supply control module is connected with each module and each storer respectively, for each module, each storer provide voltage, draws primary power pin V by energy supply control module
DD, battery pin V
BATWith grounding pin V
SS
Described serial bus interface IP is connected with address register with control logic module respectively, draws serial clock input pin SCL and serial data I/O pin SDA by serial bus interface IP;
Described address register also is connected with user register.
Above-mentioned real time clock circuit, wherein, described user register is the 56 byte non volatile register of preparing and carrying with battery.
The present invention makes it compared with prior art owing to adopt technique scheme, has the following advantages and good effect:
1, real time clock circuit of the present invention is because its crystal pins X
1With crystal pins X
2Employing standard 32.768KHz quartz crystal, and crystal pins X
1With crystal pins X
2The fine setting load capacitance with mating well between the oscillatory circuit load capacitance, so clock accuracy height of real time clock circuit of the present invention.
2, real time clock circuit of the present invention is because at its primary power pin V
DDWith grounding pin V
SSBetween insert a farad capacitor, can when complete machine cuts off the power supply, continue power supply, so improve the reliability of real time clock circuit.
3, therefore real time clock circuit of the present invention has improved the reliability of real time clock circuit because the user register of its clock chip is the 56 byte non volatile register of preparing and carrying with battery.
Description of drawings
Fig. 1 is the structural representation of real time clock circuit of the present invention.
Fig. 2 is the structural representation of the clock chip of real time clock circuit of the present invention.
Embodiment
Specify more excellent embodiment of the present invention below in conjunction with accompanying drawing.
Referring to Fig. 1, a kind of real time clock circuit comprises clock chip 1, the first diode 21, second diode 22 and first farad capacitor 31.
Described clock chip 1 is provided with 8 pins, is respectively primary power input pin V
DD, battery input pin V
BAT, grounding pin V
SS, serial clock input pin SCL, serial data I/O pin SDA, square wave/output driver pin SQW/OUT, crystal pins X
1With crystal pins X
2
Described first diode 21 is connected with second diode 22, the positive pole of described first diode 21 and outside primary power cource V
CCConnect the primary power input pin V of the negative pole of described second diode 22 and clock chip 1
DDConnect; Described battery input pin V
BATWith primary power input pin V
DDConnect.
The positive pole of described first farad capacitor 31 connects the negative pole of first diode 21, and its negative pole is connected with ground, described grounding pin V
SSBe connected with the negative pole (promptly) of first farad capacitor 31.
Described serial clock input pin SCL and serial data I/O pin SDA connect respectively resistance and outside primary power cource V
CCConnect.
Described crystal pins X
1Connect successively second farad capacitor 32, first electric capacity, 41 backs is connected with ground; Between the positive pole of described second farad capacitor 32 and ground, be connected one second electric capacity 42.
Described crystal pins X
2Be connected with the negative pole of second farad capacitor 32.
Described crystal pins X
1, X
2Be respectively the link of standard 32.768KHz quartz crystal, the specified crystal load electric capacity (CL) of internal oscillator circuit is 12.5pF.
Referring to Fig. 2, the inner structure of clock chip 1.
Described clock chip 1 comprises oscillator and allocator module 11, square wave output module 12, energy supply control module 13, serial bus interface IP 14, control logic module 15, address register 16, clock register 17 and user register 18.
Described oscillator is connected with clock register 17 with square wave output module 12 respectively with allocator module 11, draws crystal pins X by oscillator and allocator module 11
1With crystal pins X
2
Described square wave output module 12 is connected with control logic module 15, draws square wave/output driver pin SQW/OUT by square wave output module 12.
Described energy supply control module 13 is connected with each module and each storer respectively, for each module, each storer provide voltage, draws primary power pin V by energy supply control module 13
DD, battery pin V
BATWith grounding pin V
SS
Described serial bus interface IP 14 is connected with address register 16 with control logic module 15 respectively, draws serial clock input pin SCL and serial data I/O pin SDA by serial bus interface IP 14.
Described address register 16 also is connected with user register 18.
Described user register 18 is for preparing and carrying 56 byte non volatile register with battery.
By described primary power pin V
DDWith grounding pin V
SSInput 5v direct supply V
CC, described battery pin V
BATInsert a 3v battery, as standard 3v lithium battery.Nominal write protection switch voltage is set to 125 * V by internal circuit
BAT, under this voltage, can not visit clock register 17 and user register 18, but clocking capability is not subjected to the influence of low input; Work as V
CCDrop to and be lower than V
BATThe time, clock register 17 and user register 18 switch to by V
BATThe external power source of end; Work as V
CCGreater than V
BATDuring+0.2V, real time clock circuit of the present invention will switch to by V from battery-powered
CCPower supply; Work as V
CCGreater than 1.25 * V
BATThe time, device can be discerned the input data.
Real time clock circuit of the present invention is supported I
2The C bus is transmitted agreement.The device that sends data on the bus is a forwarder, and the device that receives data is a receiver, and the device of control information is a main device, in check device is from device, and the main device control bus produces serial clock, the control bus passage, and produce starting START and stop the STOP condition.Real time clock circuit of the present invention is at I
2On the C bus as one from device work.
Real time clock circuit of the present invention can be worked under two kinds of patterns:
1, from receiver mode (WriteMode): real time clock circuit of the present invention receives serial data and clock by serial clock input pin SCL and serial data I/O pin SDA.After receiving each byte, just send a response bits, and start START and stop the end at the whole story that STOP is a serial transfer.Receiving behind address and direction position, hardware automatically performs Address Recognition.After main device produced starting START condition, first byte that receives was an address byte, and this address byte packet contains 7 address: 1101000, follow indicating bit (R/～(be write operation this moment, and this position is 0) W) afterwards.After receiving and translating address information, real time clock circuit of the present invention is just exported response bits on sda line.In real time clock circuit of the present invention identification behind address+write the position, main device will send a register address to real time clock circuit of the present invention, on real time clock circuit of the present invention, register pointer is set with this, afterwards, main device will begin to send data byte (real time clock circuit of the present invention all will return a response bits after having accepted each byte), after all data byte for transmission were finished, main device will produce one to be stopped the STOP condition and interrupts writing of data.
2, from transmitter mode (reading mode): to the reception and the processing of first byte, with the same from receiver mode.Yet in this pattern, it is invalid that indicating bit will be indicated the transport address.When the serial clock input was arranged on the SCL, serial data went up transmission by stopping at SDA, and the starting START condition and the STOP condition that stops to be used to discern the end at the whole story of serial transmission.First byte that receives after the starting START condition that is produced by main device is the address, comprises one 7 address: 1101000, follow indicating bit (R/～(be read operation this moment, and this position is 1) W) afterwards.After receiving and translating address information, device will be imported one and reply on sda line.Then, will to begin to transmit with the specified register address of register pointer be initial data to real time clock circuit of the present invention.If do not write register pointer before the reading mode initialization, first address of then reading is last that is stored in the register pointer.In the time will stopping read operation, real time clock circuit of the present invention must receive one " not replying ".
Real time clock circuit of the present invention has a built-in voltage decision circuitry, has the power supply power-fail of detection function, when power supply power-fail, can automatically switch to battery-powered.
Described first farad capacitor 31 is as standby power supply power supply, under the normal condition by outside primary power cource V
CCPower supply is charged to first farad capacitor 31 simultaneously, and complete machine outage back is powered by first farad capacitor 31.The electric capacity of described first farad capacitor 31 is 0.33 farad.
Real time clock circuit degree of accuracy height of the present invention, good reliability can be used for multi-rate meter, IC-card water meter, IC-card gas meter, mobile phone, portable instrument, facsimile recorder, battery supply product and televisor.
Claims (8)
1, a kind of real time clock circuit comprises clock chip (1), and described clock chip (1) is provided with primary power pin V
DD, battery pin V
BATWith grounding pin V
SS, it is characterized in that, also comprise first diode (21), second diode (22) and first farad capacitor (31);
Described first diode (21) is connected with second diode (22), the positive pole of described first diode (21) and outside primary power cource V
CCConnect the primary power pin V of the negative pole of described second diode (22) and clock chip (1)
DDConnect; Described battery pin V
BATWith primary power pin V
DDConnect;
The positive pole of described first farad capacitor (31) connects the negative pole of first diode (21), and its negative pole is connected with ground, described grounding pin V
SSBe connected with ground.
2, real time clock circuit as claimed in claim 1 is characterized in that, also includes second farad capacitor (32), first electric capacity (41) and second electric capacity (42);
Described clock chip (1) also is provided with serial clock input pin SCL, serial data I/O pin SDA, square wave/output driver pin SQW/OUT and crystal pins X
1, X
2
Described serial clock input pin SCL and serial data I/O pin SDA connect respectively resistance and outside primary power cource V
CCConnect;
Described crystal pins X
1Second farad capacitor (32), first electric capacity (41) back of connecting successively is connected with ground; Between the positive pole of described second farad capacitor (32) and ground, be connected one second electric capacity (42);
Described crystal pins X
2Be connected with the negative pole of second farad capacitor (32).
3, real time clock circuit as claimed in claim 1 is characterized in that, by described primary power pin V
DDWith grounding pin V
SSInput 5v direct supply V
CC
4, real time clock circuit as claimed in claim 1 is characterized in that, described battery pin V
BATInsert a 3v battery.
5, real time clock circuit as claimed in claim 2 is characterized in that, described crystal pins X
1, X
2Be respectively the link of standard 32.768KHz quartz crystal.
6, real time clock circuit as claimed in claim 1 is characterized in that, the electric capacity of described first farad capacitor (31) is 0.33 farad.
7, real time clock circuit as claimed in claim 1, it is characterized in that described clock chip (1) comprises oscillator and allocator module (11), square wave output module (12), energy supply control module (13), serial bus interface IP (14), control logic module (15), address register (16), clock register (17) and user register (18);
Described oscillator is connected with clock register (17) with square wave output module (12) respectively with allocator module (11), draws crystal pins X by oscillator and allocator module (11)
1With crystal pins X
2
Described square wave output module (12) is connected with control logic module (15), draws square wave/output driver pin SQW/OUT by square wave output module (12);
Described energy supply control module (13) is connected with each module and each storer respectively, for each module, each storer provide voltage, draws primary power pin V by energy supply control module (13)
DD, battery pin V
BATWith grounding pin V
SS
Described serial bus interface IP (14) is connected with address register (16) with control logic module (15) respectively, draws serial clock input pin SCL and serial data I/O pin SDA by serial bus interface IP (14);
Described address register (16) also is connected with user register (18).
8, real time clock circuit as claimed in claim 7 is characterized in that, described user register (18) is for preparing and carrying 56 byte non volatile register with battery.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810200329A CN101685319A (en) | 2008-09-24 | 2008-09-24 | Real-time clock circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810200329A CN101685319A (en) | 2008-09-24 | 2008-09-24 | Real-time clock circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101685319A true CN101685319A (en) | 2010-03-31 |
Family
ID=42048504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200810200329A Pending CN101685319A (en) | 2008-09-24 | 2008-09-24 | Real-time clock circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101685319A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102508514A (en) * | 2011-10-27 | 2012-06-20 | 无锡东集电子有限责任公司 | Realization method of real-time clock self clocking |
| CN103226376A (en) * | 2013-04-14 | 2013-07-31 | 嵊州市华丰电子有限公司 | High-precision real-time clock chip |
| CN110457248A (en) * | 2019-08-07 | 2019-11-15 | 深圳市兴威帆电子技术有限公司 | A method of improving the reliability of real-time timepiece chip serial data transmission |
-
2008
- 2008-09-24 CN CN200810200329A patent/CN101685319A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102508514A (en) * | 2011-10-27 | 2012-06-20 | 无锡东集电子有限责任公司 | Realization method of real-time clock self clocking |
| CN102508514B (en) * | 2011-10-27 | 2014-09-17 | 无锡东集电子有限责任公司 | Realization method of real-time clock self clocking |
| CN103226376A (en) * | 2013-04-14 | 2013-07-31 | 嵊州市华丰电子有限公司 | High-precision real-time clock chip |
| CN103226376B (en) * | 2013-04-14 | 2015-12-09 | 嵊州市华丰电子有限公司 | A kind of High-precision real-time clock chip |
| CN110457248A (en) * | 2019-08-07 | 2019-11-15 | 深圳市兴威帆电子技术有限公司 | A method of improving the reliability of real-time timepiece chip serial data transmission |
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Effective date of abandoning: 20100331 |
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