JPS5836228Y2 - DC power supply increasing voltage circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention is intended to minimize the load current of the battery and obtain a long battery life, especially when boosting the voltage of a dry battery to obtain a constant voltage for a control circuit.

In recent years, the number of cordless appliances powered by dry batteries has increased due to their simplicity, and even kitchen utensils such as gas staplers are now being equipped with temperature detection functions using batteries.

Outdoor radios, televisions, etc. use a large number of batteries and have a high degree of battery consumption, so they need to be replaced in a short period of time, but since they are leisure equipment, there is no particular problem.

However, in the kitchen utensils and the like, both the large number of dry batteries used and the short battery life create a sense of waste, which is a big problem.

Therefore, in order to obtain the necessary voltage with a small number of devices, it is necessary to boost the voltage and use it, but in the past, the current consumption was large and satisfactory performance could not be obtained.

An example of a conventional step-up voltage circuit is shown in FIG.

1 is the dry battery voltage, and the open collector type comparator 10 performs self-oscillation together with the peripheral circuit.

First, the oscillation operation will be explained.

The capacitor 3 is charged via the resistor 2, and at the moment its potential becomes higher than the reference potential determined at the midpoint of the resistors 4 and 7, the comparator 10 is turned on, and the charge on the capacitor 3 is transferred via the resistor 8 and the diode 9. and start discharging.

At this time, the resistor 5 and diode 6 are connected in parallel to the resistor 7 through the negative line of the power supply circuit (not shown) of the comparator 10, so that the reference potential is lowered.

When the potential of the capacitor 3 falls below the reference potential, the comparator 10 is turned off, and the above state is repeated to perform self-oscillation.

When the comparator 10 is OFF, the base current of the transistor 12 is supplied through the resistor 13.11, so that the transistor 12 stores energy in the ONL and inductance 14.

When the comparator 10 is ON, the base current is cut off, so the transistor 12 is OFF L, and energy is transferred from the inductance 14 to the capacitor 16 via the diode 15 and boosts the voltage.

For example, the time the transistor 12 is on and the time it is off
When the on-time periods are equal, the voltage is twice the power supply voltage, and the voltage is controlled by the ratio of ON and OFF times.

Furthermore, the voltage of the capacitor 16 is made constant by a resistor 17 and a Zener diode 19, and the voltage of the capacitor 16 is made constant by a resistor 17 and a Zener diode 19.
8.

Note that the power source of the comparator 10 is taken from Vo to ensure stable operation.

Assuming that the battery voltage is Vt, the current is Vt, and the rising voltage is Vo, L and V when the battery voltage is changed.

An example of the characteristics is shown in Fig. 2.

In this characteristic example, when ■1 is the lowest 4■, V. 8■ is generated, and the IL is 3MA in the oscillation circuit section and 1MA in the constant voltage circuit section.
Designed to flow mA.

A voltage of 4■ corresponds to when four dry batteries are used in series and the voltage of ■ is consumed to 1■.

In this way, if each battery is designed so that the above voltage and current can be obtained even if it becomes 1■ when the battery is new and the voltage is 1.75V, Vo will be 8■, and ■, will be 4
It increases by more than mA, leading to wasteful consumption and shortening battery life.

FIG. 3 shows an example of the circuit of the present invention.

Components with the same numbers as in FIG. 1 are the same parts and have the same functions, and their explanation will be omitted.

The difference from FIG. 1 is that the power source of the constant voltage section is fed back to the reference potential of the oscillation circuit via a resistor 20.

In other words, this can be summarized as follows.

A charging/discharging circuit for a first capacitor 3 connected in parallel to a DC power source (dry battery 1), a reference potential circuit formed by dividing a resistor by 4° into 7, and a capacitor potential of the capacitor charging/discharging circuit and the reference potential. By changing the comparator 10 to be compared and the reference potential to the side where the output of the comparator 10 is further stabilized in accordance with the inversion of the output of the comparator 10, and reversing the charging and discharging of the capacitor charging and discharging circuit. a circuit for self-oscillating the comparator 10, an inductance 14 and a switching section (transistor 12) that switches in accordance with the output of the comparator 10 are connected in series in parallel with the DC power supply 1; A series circuit of a diode 15 and a second capacitor 16 is connected in parallel with the switching section 12 to generate a boost voltage across the second capacitor 16, and a constant voltage circuit (Zener diode) is connected in parallel with the second capacitor 16. 19)
The constant voltage power supply of the constant voltage circuit 19 feeds back the reference potential of the reference potential circuit through a resistor 20 to suppress the rate at which the reference potential increases in accordance with the voltage increase of the DC power supply. It is.

This action suppresses the reference potential from rising along with ■1 when ■1 is high, and on the other hand, the charging speed of the capacitor 3 becomes faster, so the OFF time of the comparator 10 becomes shorter than the ON time, and the voltage increases. suppress.

Therefore, even if ■1 changes, V.

Therefore, the changes in the current to the comparator 10 and the current to the constant voltage section are extremely small, and the battery life is greatly extended.

An example of its characteristics is shown in FIG.

Even if ■1 changes by 4 to 7■, the change in Vo is suppressed to about 1■.

Therefore, the change in H is also extremely small, about 1 mA.

■according to the increase of 1■.

The reason why L decreases even though L increases is because the current decrease in the switching section due to the duty ratio change is greater than the current increase in the constant voltage section.

As described above, by adding just one resistor to the conventional circuit, wasteful consumption of the battery can be significantly reduced, making it possible to extend the battery replacement life.

[Brief explanation of drawings]

Figure 1 is a conventional step-up voltage circuit diagram, and Figure 2 is a conventional battery voltage ■1 and step-up voltage ■. , a characteristic diagram of the battery load current It, FIG. 3 is a voltage increasing/regulating circuit diagram according to an embodiment of the present invention, and FIG. 4 is a characteristic diagram of the battery voltage V1, increasing voltage VO, and battery load current H according to the present invention. be. 1...DC power supply, 2...Resistor, 3...
...Container, 4...Resistor, 5...
...Resistance, 6...Diode, 7,8...
...Resistance, 9...Diode, 10...
...Comparator, 12...Transistor, 1
4... Inductance, 15... Diode, 16... Capacitor, 18...
...Load, 20...Resistance (for feedback).

Claims (1)

[Scope of utility model registration request] a first capacitor charging/discharging circuit connected in parallel to a DC power source; a reference potential circuit formed by resistor division; a comparator for comparing both ends of the capacitor of the capacitor charging/discharging circuit with the reference potential; and the comparison. a circuit that performs self-oscillation of the comparator by changing the reference potential to a side where the output of the comparator becomes more stable in response to the reversal of the output of the comparator, and reversing the charging and discharging of the capacitor charging and discharging circuit; A switching section that switches according to an inductance and the output of the comparator is connected in series in parallel with the DC power supply, and a series circuit of a diode and a second capacitor is further connected in parallel with the switching section. While generating a rising voltage across the capacitor No. 2,
A constant voltage circuit is provided in parallel with the second capacitor, and the constant voltage power supply of the constant voltage circuit feeds back the reference potential of the reference potential circuit through a resistor, so that the reference potential increases in accordance with the voltage rise of the DC power supply. A DC power supply step-up/regulate voltage circuit configured to suppress the rate of increase.