JPS61210844A - Power source feeder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a power supply device used in small electronic equipment.

[Prior art]

Conventionally, power supply devices used for small electronic devices use two batteries, a main battery and a sub battery, with different voltage values, so that when the voltage drops due to the main battery being exhausted, this is reported, and the sub battery A method has been proposed in which power is supplied to the drive circuit of a small electronic device until the main battery is replaced.

For example, as shown in FIG. 2, voltage is supplied to the IC 5 from the main battery 1 via the diode 3.

At this time, the voltage of the main battery 1 is set to a higher voltage than the voltage of the sub battery 2, so the sub battery 2 is connected to the diode 4.
In this state, power cannot be supplied to the IC5 via the IC5.

Here, when the voltage of main battery 1 becomes lower than the voltage of sub battery 2 due to power consumption of IC5, the voltage of sub battery 2 becomes lower than IC5.
With this method, the drive circuit of the small electronic device can be driven without stopping its function.

[Problems with conventional technology]

In conventional power supply devices such as those mentioned above, when the main battery is exhausted, the sub battery is replaced, so the main battery can be replaced without causing the small electronic device to stop functioning, but it requires a battery with a different voltage. At the same time, since the voltage of the main battery that is normally consumed is considerably higher than the operating lower limit voltage of the IC and electronic circuit, power is wasted when controlling the drive circuit.

Furthermore, it is possible to use one battery and detect and notify a voltage drop using a voltage detection circuit.

Variations in the electrical characteristics of resistors, transistors, etc. used in the detection circuit greatly affect voltage detection.

It is difficult to stably detect a voltage drop in the main battery 1.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional art, it is an object of the present invention to provide a power supply device capable of operating a memory bus or quadruple circuit without using batteries of different voltages and without wasting power consumption.

[Key points of the invention]

In order to achieve the above object, the present invention constantly supplies an operating voltage to a load circuit by a first power supply means, and when the supply voltage of the first power supply means is determined to be below a predetermined voltage by a detection means, The second power supply means supplies power to a part of the load circuit, such as a memory section.

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a circuit block diagram of an electronic timepiece in which the power supply device of the present invention is installed. In the figure, the oscillator 6 for clock functions such as time, date, and day of the week, and timing signals required for circuit operation is 32.
A high frequency signal of 768 Mllz is supplied to the frequency divider 7, and an IHz signal frequency-divided by the frequency divider 7 by 9 is output to the clock circuit 8. The 111z signal is converted by the clock circuit 8 into a time signal such as hour 2 minutes 2 seconds, date, and day of the week signals, and is outputted to the LCD (liquid crystal) display section 10 via the display control section 9, and the time is displayed on the LCD display section 10.

Displays the date and day of the week.

On the other hand, RAM20 contains various data (number 9 names.

(telephone number, schedule, etc.) is configured to be memorized, and data input and output are performed via the switch unit 1 from the outside.
1 is operated via the control section 12, and the input and output signals of the data are displayed on the LCD display section 10 via the display control section 9.

All of the above functions except for the LCD display section 10 are provided within the LS 113.

Next, to explain the power supply system that supplies power to this LSI 13, the negative side of the sub-battery 15 (output voltage 1.5V) is connected to one input of the power supply circuit 14,
The negative side of the main battery (output voltage 1.5V) 16 is connected to the other input of the power supply circuit 14, and the main battery 15. The bottom side of the sub-battery 16 is connected to the LS 113 as a common reference (earth) electrode. In addition, the negative side of the main battery 16 is connected to the RAM 20 of the LSI 13.
connected directly to the circuit except Also, main battery 1
6 is a smoothing capacitor 1 for the output voltage of the main battery 16.
7 are connected in parallel, and the power supply circuit 14
The output of is connected to RAM20.

FIG. 3 is a specific circuit diagram of the power supply circuit 14 described above, and the IN input of the detection circuit 18 is connected to the output voltage of the main battery (
-1.5V) is input, and the output voltage (-1.5V) of the sub-battery 15 is input to the REF input of the detection circuit 18. The output voltage of the sub battery 15 is set to 5 within the detection circuit 18.
On the other hand, the main battery output voltage (-1,5V) is not divided in the detection circuit 18 and is used as a comparison value. Ru.

Further, the output of the detection circuit 18 is output to an inverter 19, and the output of the inverter 19 is output to a MOS transistor 23 and an inverter 21. Furthermore, the inverter 21
The output of is output to the MOS transistor 22, and this MO
S) transistor 22 and MO3) transistor 23
The outputs of are connected together and supplied to the output terminal.

Describing the circuit operation of the power supply device of the present invention having the above configuration, when the main battery 16 is still low in consumption, the IN input voltage of the detection circuit 18 is high (1.25V or more), so the detection circuit 18 is The output is a low signal (denoted as “0” below)
This becomes a signal and "0" is output to the inverter 19. The signal output to the inverter 19 is inverted and becomes a high signal (hereinafter referred to as "1") and is output to the inverter 21 and the gate of the MO3I transistor 23. The signal output to the inverter 21 is inverted again and becomes 'O' and output to the gate of the MOS transistor 22.

Therefore, the gate of transistor 22 (MOS) is +1QII
is input, there is no conduction between the drain and source of the MO3I-Randisk, and the voltage of the sub-battery 15 does not appear at the output of the power supply circuit 14.

Since 1'' is input to the gate of the MOS transistor 23, conduction occurs between the drain and source of the MOS transistor 23, and the voltage of the main battery appears at the output of the power supply circuit 14.

Next, when the main battery 16 is exhausted and the power of the main battery 16 decreases to 1.25V or less, the output of the detection circuit 18 becomes "1" and is output to the inverter 19. The signal output to the inverter 19 is inverted by the inverter 19 and I
IQll becomes inverter 21 and MOS transistor 2
Output to gate 3. Therefore, at this time, contrary to the circuit operation described above, the MO3I-transistor 23 is turned off, and the MO3I-transistor 23 is turned off.
The S transistor 22 is turned on and power is not supplied from the main battery 16, but power is supplied from the sub battery 15.

Therefore, when the main battery 16 is new and has little consumption, the output voltage of the main battery 16 is applied to the output of the power supply circuit 14, and the voltage is applied to the RAM 20 and 5113, and at this time, the sub battery 15 , only a small current flows through the power supply circuit, and the voltage drop of the sub-battery 15 is almost negligible. On the other hand, main battery 1
6 is exhausted, the sub-battery 15 is connected to the RAM 20 by the above-described function of the power supply circuit 14.

The voltage (-1.5V) of the sub-battery 15 is supplied to the RAM 20. At this time, except for the RAM 20, power is supplied to the LSI 13 only from the main battery 16.

Operation stops due to battery voltage drop due to battery exhaustion,
Although the display on the LCD display section 10 also stops, the RAM 20 is supplied with voltage by the sub-battery 15 and continues to operate normally, and the data stored in the RAM 20 is retained.

Here, when the main battery 16 is replaced with a new one, the power supply circuit 14 is activated and the power supply within the LSI 25 including the RAM 20 is switched to being supplied from the main battery 16 again. Therefore, the LSI 13 starts operating again and displays the time, day of the week, etc. on the LCD display section 10.

FIG. 4 is a circuit block diagram showing another embodiment of the present invention. In this figure, the explanation of the structure of the same parts as in FIG. 1 will be omitted. That is, the clock function such as the time 1 date and day of the week provided in the LSI 25 and the data input/output operation of the RAM 34 are the same as in FIG. The power supply circuit 24 includes a main battery 27. Sub battery 28. A capacitor 26 is connected to the LSI from the power supply circuit 24.
VCH power supply and VO on 25. Two power supplies are connected. However, at this time, the main battery 27 and the sub-battery 28 are composed of lithium batteries, and both output voltages are 3V. Power ■. . is normally 3■, and is connected to the display control section 35 of the LSI 25 and the illumination lamp 37 of the LCD display section 36. Further, the power supply circuit 24 is connected to the display control unit 35 and the sub-battery 2
The BS signal when switched to 8 is output, and the voltage drop of the main battery 27 is notified to the LCD display section 36 via the 9 display control section 35. Further, the illumination lamp 37 is turned on by operating a switch 38, and a signal for detecting this is input to the control section 30 in the LSI 25 via the signal line, and the control section 30 From BU, B
The two signals U are output to the power supply circuit 24. B.U.

The single signal is a signal that controls the output voltage VCH of the power supply circuit 24.

Further, FIG. 5 is a specific circuit diagram of the above-mentioned power supply circuit 24, and in the figure, the detection circuit 39 internally divides the reference voltage input into 5/6 as in the above-mentioned FIG. It is operated by converting it to 5V.

Therefore, when the main battery 27 is new and has little consumption, the MOS transistor 42 is on and the MOS transistor 43 is off, so that the voltage V o □ is equal to 3 V of the main battery 27 .

At this time, the BS signal is outputting "1". Also.

■ oD is voltage, harbor (hereinafter indicated by V and H) 44
Since it is connected to the eave, the output of V and H44 is -1.5V
become. Next, the output of V, H44 is the MOS transistor 4
6 and the BU double signal illumination lamp 37 input to the gate of the MOS transistor 46 is not lit.
O'', the outputs of V and H44 are input to the voltage regulator (hereinafter referred to as V and R) 48.

On the other hand, the voltage ■ is also applied to the MOS transistor 47 without passing through V and H44. . is connected, but since the BU multiplier signal input to the gate of the MOS transistor 47 is "0", the MOS transistor 47 is off, and the power supply ■ is turned off. 0 is output to V, R48. Then, the output of V and R48 is input to the capacitor 49, where it is smoothed and the voltage V (
Output as H.

Next, when the voltage drop due to depletion of the main battery 27 becomes 2.5V or less, the output of the detection circuit 39 is inverted in the same way as described above.
Since the MOS transistor 42 is turned off and the MOS transistor 43 is turned on, the voltage becomes ■. . sub battery 2
8-3V is output. At this time, the BS signal outputs "0" and sends a signal to the display control section 35 shown in FIG. 4 to notify the LCD display section 36 of the voltage drop of the main battery 27. but.

Voltage ■. . There is no operational change in the power supply circuit from VCH to VCH.

Further, when the illumination lamp 37 is turned on by the switch 38, the control unit 30 outputs the BU and BU times the signals as described above, and the gate of the IMOS transistor 46 receives "O".
However, "1" is input to the gate of the MOS transistor 47, and the MOS transistor 47 is turned on and the MOS transistor 46 is turned off. Therefore, the voltage of the sub battery is V,
Applied to R48.

In addition, if the battery is replaced in the same manner as in the previous embodiment, the RAM
There is no need to stop 34 data retention 2 meter functions.

As can be seen from the above explanation of the operation, this embodiment uses two batteries of the same voltage, with a main battery of 16.27 degrees and a sub battery of 15 degrees.
．． 28, compare the voltage drop of the main battery 16.27 with the reference voltage of the sub battery 15.28, and when the voltage of the main battery 16.27 drops below the reference voltage, it is determined that the voltage of the sub battery 15 has not dropped. .28 and therefore does not use a voltage higher than necessary, there is no needless power consumption. Furthermore, according to another embodiment of the present invention, not only the data in the RAM 20.34 can be held, but also the sub battery 15.
28 is a method to continue supplying power, and the lighting lamp 37
It operates in the same way even when the voltage drops when the lighting lamp 37 is turned on, and furthermore, the power supply for the timer function and the RAM 34''- is via V, H44, V, and R4B, so that when the lighting lamp 37 is turned on, Voltage drop or main battery 27.
The supply voltage is stabilized against a drop in the voltage of the sub-battery 28.

It goes without saying that the embodiments of the present invention can be used not only for the above-mentioned electronic watches, but also for small-sized electronic computers, electronic game devices, cameras, and the like.

〔Effect of the invention〕

As explained in detail above, according to the present invention, it is possible to switch from the main battery to the sub battery when the battery voltage drops below a predetermined voltage using two batteries with the same voltage, so one circuit □ lower limit operation You can use batteries with a voltage close to that of
Since there is no unnecessary power consumption and commonly used lithium batteries, silver oxide batteries, etc. can be used, batteries are easy to obtain. Furthermore, since it is possible to detect a voltage drop in the main battery based on the voltage of the sub-battery, a stable circuit with high detection accuracy can be created, allowing for efficient power supply.

Furthermore, it is also possible to reliably maintain records in a memory circuit such as a RAM within the LSI.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an electronic timepiece including a power supply device according to an embodiment of the present invention. Figure 2 is a circuit diagram of a conventional power supply device. FIG. 3 is a circuit diagram of a power supply device according to an embodiment of the present invention. FIG. 4 is a circuit block diagram of an electronic timepiece including a power supply device according to another embodiment of the present invention. FIG. 5 is a circuit diagram of a power supply device according to another embodiment of the present invention. 13.25...LSI. 15.28...Sub battery. 16.27...Main battery. 14.24...Power supply circuit. 18.39...Detection circuit. 20.34...RAM. 37...Illumination lamp. 35...Display control unit.

Claims (3)

[Claims] (1) a first power supply means for supplying an operating voltage to the load circuit; and a voltage detection means for detecting that the voltage supplied by the first power supply means has reached a predetermined voltage; A power supply device comprising: second power supply means for supplying an operating voltage to at least a part of the circuits in the load circuit based on the result detected by the voltage detection means. (2) The power supply device according to claim 1, wherein the voltage detection means uses the output voltage of the second power supply means as a reference voltage. (3) The first and second power supply means are lithium batteries, and the load circuit is supplied with a voltage obtained by stepping down the output voltage of the first and second power supply means as an operating voltage. A power supply device according to claim 1, characterized in that: