JP2008256574A - Electronic device with built-in real-time clock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic device with a built-in real-time clock that supplies power from a back up capacitor to the real-time clock even when the power supply is shielded by power failure or the like, and prevents clock information from being lost. <P>SOLUTION: A main power supply pad that is connected with a main power supply of a real-time clock IC and feeds power to an internal circuit is disposed, and a pad for back up conducted to a branch line from a chip internal power feed line is disposed independently from this main power supply pad. A ceramic capacitor as a backup power supply is connected to the pad for back up. Connection may be performed by wire bonding via an electrode or with an adhesive. The electronic device is constructed by molding or being built in a ceramic package. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device with a built-in real-time clock, and more particularly to an electronic device with a built-in real-time clock that drives a real-time clock with a secondary battery after a main power supply is cut off.

  The real-time clock is provided as an electronic device that provides a clock function to a motherboard of an electronic device such as a computer. As one form of the real-time clock, there is one that is operated by being supplied with power from a built-in secondary battery (battery) even when the main power is turned off. Of course, while the main power switch is turned on, the power is supplied from the external power source or the built-in primary power source which is the main power source.

  The real-time clock is provided as an electronic device that provides a clock function to a motherboard of an electronic device such as a computer. As one form of the real-time clock, there is one that is operated by being supplied with power from a built-in secondary battery (battery) even when the main power is turned off. Of course, while the main power switch is turned on, the power is supplied from the external power source or the built-in primary power source which is the main power source.

FIG. 10 shows a circuit configuration of a conventional real-time clock. As shown in the figure, the real-time clock IC 1 includes an oscillation circuit 3 to which a piezoelectric vibrator 2 is connected, and a clock circuit 4 that performs clock processing using an oscillation signal of the oscillation circuit 3. It is driven by an external power source supplied through the power pad 5 and is configured to exhibit a clock function by outputting clock information such as date and time information from the clock circuit 4. The real-time clock IC 1 has a backup secondary battery 6 connected in parallel to the power supply circuit so that the operation can be continued even when the power supply from the external power supply is cut off, and the external power supply is cut off. In this case, power is supplied from the secondary battery 6 to the real-time clock IC 1 through the power pad (Patent Document 1).
JP 2002-162485 A

The current consumption of the real-time clock decreases year by year due to technological progress, and the current leaking between the wiring from the backup secondary battery to the real-time clock power supply terminal cannot be ignored. Furthermore, in order to reduce costs, backup secondary batteries are required to have a small capacity, and losses due to leakage between wirings must be minimized.
In order to solve this, in the conventional example, a real time clock and a secondary battery are integrated.

However, when the configuration of this conventional example is applied to a real-time clock provided with a piezoelectric vibrator, the oscillation frequency of the piezoelectric vibrator may change due to heat generated by the secondary battery, and the accuracy of the real-time clock may be reduced. In order to prevent this, it is necessary to provide a means for heat insulation between the secondary battery and the piezoelectric vibrator and a means for dissipating the heat generated by the secondary battery, which is not suitable for miniaturization, thickness reduction, and cost reduction.
In addition, since the secondary battery is vulnerable to heat, there is a problem that the entire product cannot be heat-treated (annealed).

  The present invention provides an electronic device with a built-in real-time clock configured to supply power to a real-time clock without loss from a backup capacitor even when the power is cut off due to a power failure or the like, so that clock information is not lost. Objective.

  In order to achieve the above object, the present invention provides an electronic device with a built-in real-time clock in which a piezoelectric vibrator, a real-time clock IC, and a backup capacitor are housed in a package, wherein the real-time clock IC includes a main power supply pad, A backup pad, and the main power pad is connected to a power supply line that supplies power to a circuit in the real-time clock IC, and the backup pad is a branch branched from the power supply line in the real-time clock IC. The backup capacitor is connected to the line, and the backup capacitor is connected to the backup pad of the real-time clock IC.

  In the electronic device with a built-in real-time clock configured as described above, since the branch line connected to the backup pad is connected to the power supply line in the real-time lock IC, the wiring between the backup capacitor and the real-time clock IC is the shortest. Thus, current loss due to leakage can be minimized.

  A power supply switching charging circuit may be provided at a branch portion branched from the power supply line. This power supply switching charging circuit can be composed of a backflow prevention diode. Further, a booster circuit can be interposed in the branch line.

  By providing the power supply switching charging circuit, the backup capacitor is charged from the external power supply, and when the external power supply is cut off, the backup power supply is not supplied to the outside of the real-time lock IC through the main power supply pad. Therefore, the backup time can be extended. Further, by interposing the booster circuit, the charging voltage from the main power supply to the backup capacitor can be increased, and the backup time can be further extended.

  The electronic device with a built-in real-time clock according to the present invention is provided with a backup pad connected to a branch line branched from a power supply line that supplies power to a circuit in the real-time clock IC. Is mounted on the package, and a backup capacitor is connected to the backup pad.

  In the electronic device with a built-in real-time clock configured as described above, since the branch line connected to the backup pad is connected to the power supply line in the real-time lock IC, the wiring between the backup capacitor and the real-time clock IC is the shortest. Thus, the device can minimize current loss due to leakage.

The backup capacitor is connected to an electrode pattern formed on a package, the backup pad is connected to an electrode pattern formed on the package, or the backup capacitor and the backup pad are connected by wire bonding. it can.
The backup capacitor is preferably composed of a ceramic capacitor.

  Since the electronic device with a built-in real-time clock can be mounted close to the real-time clock IC via the package-side electrode pattern, the capacitor capacity can be increased, and the current loss due to the proximity arrangement can be reduced. Can be small. In particular, a higher current loss suppression effect can be obtained by wire bonding connection. Further, by using a ceramic capacitor, heat resistance is provided, and there is no fear of power supply deterioration due to heat treatment during packaging.

  Furthermore, the electronic device with a built-in real-time clock according to the present invention includes a real-time clock IC provided with a backup pad connected to a branch line branched from a power supply line inside the chip, and a ground pattern formed on the package and the ground pattern. A backup capacitor is connected between the backup pads.

  In the electronic device with a built-in real-time clock configured as described above, the real-time clock IC can be mounted close to the ground pattern of the package to reduce current loss.

  Alternatively, the real-time clock IC is provided with a backup pad conducted to a branch line branched from a power supply line inside the chip and a ground pad, and this is mounted on a package, and a backup capacitor is provided between the backup pad and the ground pad. It may be a configuration characterized by molding after connecting.

  In the electronic device with a built-in real-time clock configured as described above, the real-time clock IC is mounted close to the package ground pattern and then molded, so that the effect of suppressing the current loss can be maintained for a long time.

  Furthermore, the real-time clock IC is provided with a backup pad conducted to the branch line branched from the internal power supply line and a ground pad, and the real-time clock IC is mounted on the electrode pattern formed in the package via the pad. A backup capacitor may be connected between the electrode pattern connected to the backup pad and the electrode pattern connected to the ground pad.

  In the electronic device with a built-in real-time clock configured as described above, a backup capacitor is connected between the electrode patterns to which the backup pad and the ground pad of the real-time clock IC are connected. Can be achieved.

  In addition, the real-time clock IC is provided with a backup pad connected to the branch line branched from the internal power supply line and a ground pad, and the real-time clock IC is mounted on the package and backed up to the electrode pattern formed in the package. A capacitor may be connected, and the electrode pattern, the backup pad, and the ground pad may be connected by wire bonding.

  In the electronic device with a built-in real-time clock configured as described above, a backup capacitor is arranged outside the real-time clock IC to increase the capacity, thereby extending the life of the power supply, and at least one pad is connected by wire bonding. The effect of reducing current loss can be increased.

  As described above, according to the present invention, when the backup power is supplied to the real-time clock IC, the wiring between the capacitor serving as the backup power and the real-time clock is minimized, and current loss due to leakage can be minimized. Yes. Further, the leakage current can be reduced by directly bonding the capacitor and the IC. Further, only the real-time clock can be supplied with power, and the backup time can be extended. In addition, the backup capacitor has the same effect as the bypass capacitor, and can stabilize the power supply.

The best mode for carrying out an electronic device with a built-in real-time clock according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a real-time clock according to the embodiment. The real-time clock 10 according to this embodiment is configured by forming a real-time clock circuit such as an oscillation circuit 14 or a clock circuit 16 inside a semiconductor element, and an excitation electrode of a crystal resonator 18 is connected to the oscillation circuit 14. Clock information is output from the clock information output terminal 19. The real-time lock IC is provided with a main power supply pad 20 connected to an external power supply or an internal primary power supply. The real time clock IC 10 is driven by supplying power through the main power supply pad 20.

  The real-time clock IC 10 having such a basic configuration is provided with a backup pad 22 independently of the main power supply pad 20. The backup pad 22 is connected to the branch line 26 from the main power supply pad 20 to the power supply line 24 for the in-chip circuit. A backup capacitor 28 serving as a backup power supply is connected to the backup pad 22 so that power can be supplied from the backup capacitor 28 to the on-chip circuit when the power supply from the main power supply is cut off. In order to switch the power supply path from the main power supply pad 20 side to the backup pad 22 side when the power supply from the main power supply is cut off, a power supply switching charging circuit 30 is provided at a branch portion of the power supply line 24 and the branch line 26. . In this circuit, a diode 32 for preventing a backflow of current to the main power supply pad 20 is attached to the main power supply pad 20 from the branch point. Usually, a drive current is supplied from the main power supply to the in-chip circuit and simultaneously to the backup capacitor 28. When charging is performed and power supply from the main power supply is cut off, the circuit in the chip is supplied with power while preventing backflow.

  In the real-time clock IC configured in this way, the branch line 26 connected to the backup pad 22 is connected to the power supply line 24 in the real-time clock IC, so that the wiring between the backup capacitor 28 and the real-time clock IC 10 is connected. Is minimized, and current loss due to leakage can be minimized. Further, since the backup power is supplied via the dedicated backup pad 22, the power can be supplied only to the real-time clock IC 10, and the backup time can be prolonged. Further, the backup capacitor 28 has the same effect as the bypass capacitor, thereby contributing to the stabilization of the power supply.

  In addition to the above configuration, a booster circuit 34 may be provided in the branch line 26 in the chip. As a result, the charging voltage from the main power supply to the backup capacitor 28 can be increased, and the backup time can be made longer than in the case of the above embodiment.

  FIG. 2 shows an outline of an electronic device 40A with a built-in real time clock according to the present invention. In this embodiment, the real-time clock IC 10 described above is built in a ceramic package. The ceramic package 42 is divided into two chambers, and a tuning fork type crystal resonator 18A is mounted in one chamber. A real time clock IC 40A is inserted in the other chamber side, and the IC side pad and the terminal electrode in the package are connected by wire bonding. In this embodiment, a ground pad 44 is provided for the real-time clock IC 10 together with a backup pad 22 conducted to a branch line branched from a power supply line inside the chip, and a ground pattern 46 is provided on the ceramic package 42 side. Form it. A backup capacitor 28 is connected to the backup pad 22, and a ceramic capacitor is preferably used as the backup capacitor 28. One terminal of the backup capacitor 28 is directly connected to the package-side ground pattern 46 by a conductive adhesive, and the other terminal of the backup capacitor 28 is connected to the backup pad 22 by wire bonding 48. The other pads of the real-time clock IC 10 are also constructed by connecting the electrode terminals on the package side by wire bonding.

  In the real-time clock built-in electronic device 40A according to such a configuration, the backup capacitor 28 as a secondary battery can be built in the ceramic package 42. In particular, the heat treatment is performed at the time of packaging, but the use of a ceramic capacitor having high heat resistance for the backup capacitor 28 allows the built-in without causing deterioration of the power supply, so that the contribution to miniaturization is very high. Yes. In addition, since the backup capacitor 28 is disposed close to the real-time clock IC 10 and connected using wire bonding, the effect of suppressing leakage current is very good.

  FIG. 3 shows an electronic device 40B with a built-in real time clock according to the second embodiment. An example of the configuration of the device formed as the mold package is shown. The real-time clock IC 10 is laminated on the crystal unit 18 and the whole is covered with a resin mold 50. The real-time clock IC 10 is provided with a backup pad 22 conducted to a branch line branched from a power supply line inside the chip, and a ground pad 44 is provided adjacently. The backup capacitor 28 is disposed in the vicinity of the pads 22 and 44, connected by wire bonding 48, and then resin molded.

  Even in such an embodiment, particularly by using a ceramic capacitor as a backup power source, it is not affected by heat during molding and is not affected by the surrounding humidity environment, so that the leakage current increases. It is prevented.

  FIG. 4 shows an electronic device 40C with a built-in real time clock according to the third embodiment. The real-time clock IC 10 is integrated with the crystal unit 18 via the stage 52 and is entirely covered with a resin mold 50. Also in this example, the real-time clock IC 10 is provided with the backup pad 22 connected to the branch line branched from the power supply line inside the chip and the ground pad 44 adjacently provided. A backup capacitor 28 is arranged in the vicinity of the pads 22 and 44, connected by wire bonding 48, and then a device is constructed by resin molding.

  Even in such an embodiment, by using a ceramic capacitor as a backup power source, it is not affected by heat during molding and is not affected by the surrounding humidity environment, so that the leakage current may increase. What is prevented is the same as in the second embodiment.

  5 to 6 show a plan view and a vertical plan view of the main part of an electronic device 40D with a built-in real-time clock according to the fourth embodiment. In this embodiment, the real-time clock IC 10 is FCB mounted on a pair of electrode patterns 56 formed on the substrate 54 via a metal ball 58. One of the electrode patterns 56 is connected to the backup pad 20 of the real-time clock IC 10 and the other is connected to the ground pad 44. Then, the backup capacitor 28 is connected and mounted on the electrode pattern 56 on the pair of substrates 54 using a conductive material. Of course, the backup pad 22 of the real-time clock IC 10 is naturally conducted to a branch line branched from the power supply line inside the chip.

  Also in the electronic device 40D according to the fourth embodiment, the backup capacitor 28 is disposed in the vicinity of the real-time clock IC 10 and is connected to the backup pad 22 using the electrode pattern 56. The wiring between the clock ICs 10 becomes the shortest, and the current loss due to leakage can be suppressed to the minimum.

  7 to 8 are a plan view and a longitudinal sectional view of a main part of an electronic device 40E with a built-in real time clock according to the fifth embodiment. The backup pad 22 and the ground pad 44 of the real-time clock IC 10 mounted on the substrate 54 face the upper surface, and an electrode pattern 56 including a ground pattern 60 is formed on the substrate 54. A backup capacitor 28 is mounted on the ground pattern 60 and the electrode pattern 56, and the electrode patterns 56 and 60 and the pads 22 and 44 on the real-time clock IC 10 side are electrically connected by wire bonding 48. The wire bonding may be routed from the pads 22 and 44 on the real-time clock IC 10 side. However, as shown in FIG. 9, so-called reverse bonding is performed by drawing from the electrode patterns 56 and 60 side to the IC pads 22 and 44 side. Also good. Reverse bonding increases the thin-wall effect.

  Also in the fifth embodiment, the wiring between the real-time clock IC 10 and the backup capacitor 28 can be shortened, and the effect of reducing leakage current is high.

  As described above, in the electronic device with a built-in real-time clock according to the present invention, a backup pad independent from the main power supply pad connected to the branch line branched from the main power supply line of the IC is provided, and a backup capacitor, preferably Since the ceramic capacitor is connected, charging from the main power supply and backup power supply when the main power supply is shut off can be done through the backup pad, reducing loss due to leakage current and making the backup power supply a real-time clock circuit. It is possible to supply only to the backup time. By resin molding the backup capacitor as a ceramic capacitor, an electronic device mounted on a plastic package or a small device can be achieved even when mounted on a ceramic package. In addition, the use of ceramic capacitors can withstand the heat during packaging and requires no special attention. By using the electronic device mounted on the ceramic package, there is an advantage that the wiring leakage current does not increase without being affected by the surrounding humidity environment.

It is a circuit block diagram of the real-time clock IC which concerns on embodiment. It is a plane lineblock diagram of a 1st embodiment of an electronic device with a built-in real time clock. It is a plane block diagram of 2nd Embodiment of an electronic device with a built-in real-time clock. It is a plane block diagram of 3rd Embodiment of the electronic device with a built-in real time clock. It is a plane block diagram of 4th Embodiment of an electronic device with a built-in real-time clock. It is a longitudinal cross-section block diagram of FIG. It is a principal part top view block diagram of 5th Embodiment of an electronic device with a built-in real-time clock. It is a longitudinal cross-sectional view block diagram of FIG. It is a block diagram which shows the modification of FIG. It is a conventional real-time clock circuit and its peripheral circuit diagram.

Explanation of symbols

10... Real-time clock IC, 14... Oscillation circuit, 16... Clock circuit, 18 ..... Crystal oscillator, 19 ....... Clock information output terminal, 20. ... backup pad, 24 ......... feeder line, 26 ......... branch line, 28 ......... backup capacitor, 30 ......... power supply switching charging circuit, 32 ......... diode, 34 ...... booster circuit, 40A, 40B, 40C, 40D, 40E ......... Real time clock built-in electronic device, 42 ......... Ceramic package, 44 ......... Ground pad, 46 ......... Ground pattern, 48 ......... Wire bonding, 50 ......... Resin mold , 52... Stage 54... Substrate 56... Electrode pattern 58... Metal ball 60.

Claims (12)

An electronic device with a built-in real-time clock in which a piezoelectric vibrator, a real-time clock IC, and a backup capacitor are housed in a package,
The real-time clock IC has a main power pad and a backup pad, the main power pad is connected to a power supply line that supplies power to the circuits in the real-time clock IC, and the backup pad is the real-time clock IC. Are connected to a branch line branched from the power supply line,
The electronic device with a built-in real-time clock, wherein the backup capacitor is connected to the backup pad of the real-time clock IC.   2. The electronic device with a built-in real-time clock according to claim 1, wherein a power supply switching charging circuit is provided at a branch portion where the branch line branches from the power supply line.   3. The electronic device with a built-in real-time clock according to claim 2, wherein the power supply switching charging circuit comprises a backflow prevention diode.   2. The electronic device with a built-in real-time clock according to claim 1, wherein a booster circuit is interposed in the branch line.   The real-time clock IC is provided with a backup pad connected to a branch line branched from a power supply line that supplies power to the circuits in the real-time clock IC, and the real-time clock IC is mounted on the package and backed up to the backup pad. An electronic device with a built-in real-time clock characterized by connecting a capacitor.   6. The electronic device with a built-in real-time clock according to claim 5, wherein the backup capacitor is connected to an electrode pattern formed on a package, and the backup pad is connected to an electrode pattern formed on the package.   6. The electronic device with a built-in real-time clock according to claim 5, wherein the connection between the backup capacitor and the backup pad is performed by wire bonding.   6. The electronic device with a built-in real-time clock according to claim 5, wherein the backup capacitor is a ceramic capacitor.   A real-time clock IC provided with a backup pad conducted to a branch line branched from a power supply line inside the chip is mounted on the package, and a backup capacitor is connected between the ground pattern formed on the package or the substrate and the backup pad. An electronic device with a built-in real-time clock.   The real-time clock IC is provided with a backup pad connected to a branch line branched from a power supply line inside the chip and a ground pad, and a molding is performed by connecting a backup capacitor between the backup pad and the ground pad. Real-time clock built-in electronic device.   The real-time clock IC is provided with a back-up pad connected to the branch line branched from the internal power supply line and a ground pad, and the real-time clock IC is mounted on the electrode pattern formed on the package or the substrate via the pad, An electronic device with a built-in real-time clock, wherein a backup capacitor is connected between an electrode pattern connected to the backup pad and an electrode pattern connected to a ground pad.   The real-time clock IC is provided with a backup pad connected to the branch line branched from the internal power supply line and a ground pad. The real-time clock IC is mounted on the package, and a backup capacitor is mounted on the electrode pattern formed on the package or the substrate. An electronic device with a built-in real-time clock, wherein the electrode pattern, the backup pad, and the ground pad are connected by wire bonding.

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