JPH09297625A - Battery save circuit - Google Patents

Abstract

(57) Abstract: A battery save circuit 11 capable of turning on and off a bandgap reference type voltage generating circuit 13 of an IC 14 by an external signal and reducing power consumption in the IC 14 when the battery is off. The power supply voltage Vcc can be applied to the bandgap reference type voltage generation circuit 13 without any voltage loss. An impedance means R16 is connected between an emitter and a base of a current mirror circuit 13b of a bandgap reference type voltage generation circuit 13, and a current is turned on by a signal from the outside in a path through which a current flows to the impedance means R16. A switching means Q13 for operating the mirror circuit 13 and operating the bandgap reference type voltage generation circuit 13 is inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can control ON / OFF of a battery save circuit, mainly an internal power supply circuit in an IC for communication or the like, by a signal from the outside.
The present invention relates to a battery save circuit that reduces power consumption to 0 when the internal power supply circuit is off.

[0002]

2. Description of the Related Art As shown in FIG. 3, a communication ICc used in a communication device such as a pager, PHS or cordless phone uses a bandgap reference type voltage generating circuit as an internal power supply circuit a. The output voltage of the voltage generating circuit is sent to each part in the IC as a reference voltage or a power supply voltage, for example.

As a method of turning off the internal power supply circuit a that has been activated once, a method of stopping the application of the power supply voltage from the battery to the communication ICc or a not-shown NPN transistor is provided in the ICc as an off element. A method has conventionally been adopted in which the supply of the power supply voltage Vcc to the internal power supply circuit a is stopped by operating this.

By the way, in the conventional method of stopping the supply of the power supply voltage Vcc to the internal power supply circuit a by cutting off the power supply voltage to the communication ICc, when the microcomputer is used, an external component b is used. There is a problem that the number of mobile communication devices will increase, which is a factor that prevents the downsizing and price reduction required for portable communication devices.

In addition, a method of providing an NPN transistor for turning off the power supply voltage in the communication ICc and turning on the NPN transistor to stop the supply of the power supply voltage to the internal power supply circuit a includes turning off the internal power supply circuit a. Even at times, there is a problem that the NPN transistor for turning off the power supply voltage continues to be turned on. Since this naturally entails power consumption at the time of off, it becomes a factor that prevents the demand for longer battery life for portable communication devices.

Therefore, a new battery save circuit has been developed in which the internal power supply circuit can be turned on / off by an external signal in the ICc and the power consumption in the ICc at the time of turning off can be reduced to 0. The battery save circuit according to
Proposed by No. 98109.

4 (A) and 4 (B) are for explaining the battery save circuit, FIG. 4 (A) is a circuit diagram of the battery save circuit, and FIG. 4 (B) is a schematic configuration of a communication device using the same. It is a circuit block diagram shown.

In the drawings, 1 is a battery save circuit, 2 is an internal power supply circuit, 3 is a bandgap reference type voltage generation circuit which is a main part of the internal power supply circuit 2, 4
Is a communication IC incorporating these, and 5 is a microcomputer for controlling the IC 4.

Next, the configuration of the battery save circuit 1 will be described.

The battery save circuit 1 includes a series constant voltage circuit 6 forming a power supply voltage transmission circuit, a transistor Q8 as a switching means inserted in a path for supplying a power supply voltage Vcc to the series constant voltage circuit 6, and a resistor R7. R8 and.

Q4 is a PN for controlling the serial constant voltage circuit 6
In the P-type transistor, the emitter is connected to the power supply terminal (Vcc) and the collector is connected to the output terminal (Vout). This output terminal is connected to the power supply terminal of the bandgap reference type voltage generating circuit 3 of the switching means 2.

The Q5 has a PNP whose emitter is connected to the power supply terminal (Vcc) and whose collector is connected to one end of the resistor R5.
The base of the transistor is connected to the output point of a bias circuit including resistors R1 and R2, and a predetermined current is stably supplied to the resistor R5 to generate a predetermined reference voltage at the resistor R5. The other end of the resistor R5 has the switching means Q
8 collectors connected.

Q1 is a PNP transistor for detecting the output voltage Vout of the battery save circuit 1, the emitter of which is the output terminal (Vou) of the battery save circuit 1.
The base collectors connected to t) and short-circuited to each other are connected to the collector of the switching means Q8 via the resistor R3.

Q6 is an NPN transistor whose base is connected to the connection point between the transistor Q1 and the resistor R3, and Q6.
Reference numeral 7 is an NPN transistor whose base is connected to the connection point between the transistor Q5 and the resistor R5, and the emitter of both is connected to the collector of the switching means Q8 via the resistor R4. The transistors Q6 and Q7 are the reference voltage (that is, the potential at the connection point between the transistor Q5 and the resistor R5) and a voltage obtained by shifting the output voltage Vout by Vf of the transistor Q1 (that is, the transistor Q1 and the resistor R1). The potential of the connection point) is compared to form a differential amplifier for differential amplification.

Q2 and Q3 are PNP transistors which are current-mirror connected to each other and form a load on the transistors Q6 and Q7. The base of the control transistor Q4 is connected to the connection point between the transistors Q3 and Q7.

The switching means Q8 is an NPN transistor, the collector is connected to the ground side terminal of the constant voltage circuit 6, the emitter is grounded, and the base is a resistor R.
It is connected to the switching signal input terminal via 6. The input terminal is a terminal to which a power supply switching signal (SW) from the microcomputer 5 is input.
R7 is a resistor connected between the base of the transistor Q8 and the ground.

Next, the operation of the battery save circuit 1 will be described.

When a switching signal is input from the microcomputer and the transistor Q8 becomes high, the transistor Q8 turns on and the constant voltage circuit 6 becomes operable. Then, the control transistor Q4
Since a path passing through the transistor Q7, the resistor R4, and the transistor Q8 is formed in the transistor, a base current flows to turn on the transistor Q4, and the power supply voltage Vcc from the battery input to the battery save circuit 1 is output to the output terminal Vo.
It is transmitted to the bandgap reference type voltage generation circuit 3 of the internal power supply circuit 2 through ut.

In such a battery save circuit 1, when the switching signal (SW) from the microcomputer 5 becomes low, the transistor Q8 turns off. Then, the path through which the base current flows to the control transistor Q4 is cut off by the transistor Q8, the control transistor Q4 is cut off, and the power supply voltage Vcc is transmitted to the bandgap reference type voltage generation circuit 3 of the internal power supply circuit 2. Not done.

Moreover, since the constant voltage circuit 6 and the ground are cut off by the transistor Q8, no current flows in the constant voltage circuit 6 and the power consumption becomes zero. Of course, since the transistor Q8 itself is also turned off, no current flows through it, and no current is supplied to the resistors R6 and R7. Therefore, the battery save circuit 1
The power consumption at is completely zero.

Therefore, the power consumption of the communication IC 4 when the communication device using the battery save circuit 1 is off is reduced to 0.
Can be It can be said that it is excellent in that respect.

[0022]

However, in the battery save circuit shown in FIG. 4, the power supply voltage from the battery drops due to the voltage drop due to the control transistor Q4.
The lowered power supply voltage is applied to the bandgap reference type voltage generation circuit 3 of the internal power supply circuit 2, and there is a problem that the minimum power supply voltage required for the operation of the bandgap reference type voltage generation circuit 3 becomes high. this is,
The voltage of the battery is as low as 3V, for example, and it is a serious problem that cannot be overlooked particularly for those used for portable devices such as PHS and cordless phones.

That is, the battery save circuit shown in FIG. 4 is basically composed of a series type constant voltage circuit 6, and has a power supply voltage input terminal (Vcc) and an output terminal (Vou).
A control transistor Q4 is interposed between t) and t). Therefore, this causes a voltage drop of the emitter-collector voltage V _CEQ4 of the transistor Q4. This value is set to, for example, about 0.3 to 0.4 V to avoid saturation (about 0.2 V in the case of saturation), and therefore 0.3
Voltage lower than the power supply voltage Vcc by about 0.4V [Vcc-
V _CEQ4 (= 0.3 to 0.4 V)] is applied to the bandgap reference type voltage generating circuit 3.

Therefore, assuming that the power supply voltage Vcc of the battery is 3V, the output voltage Vo of the battery save circuit 1
ut is only 2.7 to 2.6V. On the other hand, the bandgap reference type voltage generation circuit 3 is generally 1.3
An output voltage of up to 1.4 V (2 Vf) is generated, and a voltage higher by about 1.3 to 1.4 V (2 Vf) or more is required as a power supply voltage. Therefore, when the power supply voltage Vcc is about 3V, the bandgap reference type voltage generating circuit 3 operates normally, but the voltage Vcc is reduced due to the exhaustion of the battery.
If cc is reduced only slightly, normal operation of the bandgap reference type voltage generation circuit 3 cannot be expected.

The present invention has been made in order to solve such a problem, and it is provided in the IC, and an internal power supply circuit in the IC can be turned on / off by a signal from the outside, and at the time of turning off the IC. It is an object of the present invention to enable a power supply voltage of a battery to be directly applied to a bandgap reference type voltage generation circuit without a voltage loss in a battery save circuit capable of reducing power consumption to 0.

[0026]

In the battery save circuit of the present invention, impedance means is connected between the emitter and base of a current mirror circuit of a bandgap reference type voltage generating circuit, and an external current is passed through the impedance means. A switching means which is turned on by a signal from to activate the current mirror circuit and activates the bandgap reference type voltage generating circuit.

Therefore, according to the battery save circuit of the present invention, when the switching means is off, not only the switching means itself consumes electric power but also no current flows through the impedance means. No voltage can be generated between the emitter and base of the current mirror circuit of the generating circuit. Therefore, no current flows in the current mirror circuit, and the bandgap reference type voltage generation circuit keeps the operation stopped state with no power consumption.

Since no element that causes a voltage drop is interposed in the path for transmitting the power supply voltage to the bandgap reference type voltage generating circuit, there is no fear of reducing the power supply voltage by the battery save circuit, and the battery voltage is completely reduced. It is possible to supply the voltage to the bandgap reference type voltage generating circuit as its power supply voltage without the need to do so.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 shows the first embodiment of the battery save circuit of the present invention.
3 is a circuit diagram showing an embodiment of FIG. In the drawing, 14
Is a communication IC, 11 is a battery save circuit in the communication IC 14, and 13 is a bandgap reference type voltage generation circuit which constitutes an internal power supply circuit for supplying a power supply voltage or a reference voltage to each part in the communication IC 14. It is composed of a section 13a and a current mirror circuit 13b for transmitting a power supply voltage (supplying a current) to the section 13a.

First, the battery save circuit 11 will be described. Q13 is a transistor whose base is grounded,
It turns on when it receives a signal from the outside (for example, a control microcomputer not shown in FIG. 1) via the resistor R13. R14 is a resistor connected between the base of the transistor Q13 and the ground.

Q11 and Q12 are a pair of differential transistors whose emitters are connected to each other and are also connected to the collector of the transistor Q13 via a resistor R15. One of the transistors, Q11, has a collector connected to a resistor R16.
Is connected to the power supply voltage (Vcc) terminal via. The other transistor Q12 has a collector whose power supply voltage (Vc
c) a current mirror circuit 13b of the bandgap reference type voltage generation circuit 13 connected to the terminal and having a base
Is connected to one connection point a of the main portion 13a.

R11 is a resistor whose one end is connected to the power supply voltage (Vcc) terminal, and the other end is connected to the collector of the transistor Q13 via the resistor R12.
The connection point with 1 is connected to the base of the transistor Q11.

Next, the band gap reference type voltage generating circuit 13 will be described. The emitters of Q15 and Q16 are connected to the power supply voltage (Vcc) terminal, and their bases are connected to each other to form a current mirror circuit 13b.
A resistor (impedance means in the claims) R16 is connected between the emitter and the base of the P-transistor, and when a current flows through the resistor R16, the base voltage is biased by the terminal voltage of the resistor R16 to generate a bandgap reference voltage. A pair of equal currents Io and Io are supplied to the main portion 13a of the generation circuit 13. The main part 13a of the bandgap reference type voltage generation circuit 13 is the same as a general part, so its explanation is omitted.

Next, the circuit operation will be described.

First, when a control signal is input,
When the base current flows through the transistor Q13, it turns on. Then, a current flows through the bias circuit including the resistors R11 and R13, the transistor Q11 is turned on, and a current flows through the resistor R16. Then, the current mirror circuit 13b is turned on to supply the currents Io and Io to the main portion 13a of the bandgap reference type voltage generating circuit 13, and as a result, the output voltage 1.3 to 1.4V is output from the main portion 13a. appear. This output voltage is IC
It is sent to each part inside as a power supply voltage or as a reference voltage. At the same time, the transistor Q12 also turns on.

Transistors Q11 and Q12 have a differential amplifier.
And the base of transistor Q12 is connected
The potential of the continuation point a is connected to the base of the transistor Q11.
To the potential of the connection point b between the resistors R11 and R12
Feedback is applied so that they are equal, and stable operation is performed.
Be in a state. That is, the potential at the connection point a is higher than the potential at the connection point b.
Becomes higher, the current of transistor Q12 increases and
The current of the transistor Q11 decreases and the voltage drop of the resistor R16
Decrease. Therefore, the transistors Q15 and Q16
The ground bias becomes shallower and the collector-emitter voltage
Pressure V_CEQ15 , V _CEQ16 Goes up. As a result, the connection point a
The level goes down. Conversely, the connection point a has a lower potential than b.
Then, increase the level of the connection point a by the above differential amplifier.
To take a return. Therefore, the connection point a is always a differential
Pump so that the potential becomes equal to that of connection point b.
Position controlled, bandgap reference type
The voltage generation circuit 13 operates stably. Resistor R15 is the difference
Specifies the gain of the dynamic amplifier.

By the way, when the control signal is not input, that is, when the signal becomes low, the transistor Q13
Turns off. Then, no current can flow in the transistors Q11 and Q12. That is, the transistors Q11 and Q12
Turns off. As a result, no current can flow through the resistor R16. Then, the current mirror circuit 13
Both the transistors Q15 and Q16 forming the transistor b are in a state of receiving no voltage between the base and the emitter, and are turned off. As a result, the currents Io and Io are not supplied to the main portion 13a of the bandgap reference type voltage generation circuit 13, and the bandgap reference type voltage generation circuit 13 is in an operation stop state in a state where no power is consumed. . Then, the circuits of the reception system and the transmission system in the IC 14 are completely turned off.

Further, the battery save circuit 11 turns off the transistor Q13 so that the transistors Q11 and Q are turned on.
Not only 12 is turned off, but also no current flows through the resistors R11 and R12 that base-bias the transistor Q11, so that no power is consumed.

Therefore, the battery save circuit 11 can turn on / off the bandgap reference type voltage generating circuit 13 by a control signal from the outside, and the power consumption amount when the bandgap reference type voltage generating circuit 13 is off. Can be zero. Therefore, useless consumption of the battery can be avoided, and the life of the battery can be extended.

The battery save circuit 11 is shown in FIG.
A series type constant voltage circuit is not used like the applied battery save circuit 1 shown in FIG. 1, and a circuit element that causes a voltage drop is provided in the path for transmitting the power supply voltage Vcc to the bandgap reference type voltage generation circuit 13. Not not.
Therefore, the power supply voltage Vcc from the battery can be applied to the bandgap reference type voltage generation circuit 13 without any reduction. That is, it is possible to eliminate the voltage loss of the emitter-collector voltage V _CEQ4 due to the control transistor Q4 of the conventional battery save circuit 1, and tolerate the drop in the battery voltage that occurs when using a portable device such as a cordless fan. The range can be widened accordingly.

FIG. 2 shows one specific example of the receiving or transmitting circuit in which the bandgap reference type voltage generating circuit 13 is turned off and the operation is stopped when the output voltage becomes 0V and the power consumption becomes completely zero. It is a circuit diagram.

This circuit is not a novel circuit, and since it does not have the essence of the present invention, it will not be described in detail, but it will be briefly described.

When an output of the reference voltage is generated from the bandgap reference type voltage generating circuit 13, the transistor Qa is turned on accordingly, and as a result, the transistor Qb is turned on. Then, the transistor Qc,
Qd turns on, the input main signal Vin is amplified, and becomes the output signal Vout.

However, when the band-gap reference type voltage generating circuit 13 becomes a state in which the reference voltage is not generated by the battery save circuit 11 not shown in FIG. 2, the transistor Qa is turned off and the transistor Qb is turned on.
Is turned off, and as a result, the transistors Qc and Qd are turned off. Then, no current can flow in the amplifier circuit for amplifying the input main signal Vin, and the operation is stopped in the state where the consumption current is 0. Therefore, the power consumption in the IC can be reduced to zero.

[0046]

According to the battery save circuit of the present invention,
When the switching means is off, the switching means itself consumes no electric power, and no current flows through the impedance means. Therefore, the emitter / mirror of the current mirror circuit of the bandgap reference type voltage generating circuit is
No voltage can be generated between the bases. Therefore, no current flows in the current mirror circuit, and the bandgap reference type voltage generation circuit maintains the operation stopped state with zero power consumption.

Since there is no intervening means for causing a voltage drop in the path for transmitting the power supply voltage to the bandgap reference type voltage generating circuit, there is no fear of reducing the power supply voltage by the battery save circuit.
It becomes possible to apply the voltage to the bandgap reference type voltage generating circuit as its power supply voltage without lowering the battery voltage at all.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a battery save circuit of the present invention.

FIG. 2 shows a specific example of a transmission or reception circuit in which a band gap reference type voltage generation circuit receives an output voltage as a reference voltage by the battery save circuit shown in FIG. 1 and power consumption becomes 0 when the voltage becomes 0V. It is a circuit diagram.

FIG. 3 is a circuit block diagram showing a schematic configuration of a conventional example of a communication device.

4 (A) and (B) are for explaining a battery saving circuit which has been developed and applied, (A) is a circuit diagram of the battery saving circuit, and (B) is for using the battery saving circuit. FIG. 3 is a circuit block diagram showing a schematic configuration of an existing device (communication device).

[Explanation of symbols]

11 ... Battery save circuit, 13 ... Bandgap reference type voltage generation circuit, 13a ... Main part, 13b ... Current mirror circuit for transmitting power supply voltage to main part, Q13 ... Switching means, R16 ...
.Impedance means

Claims (1)

[Claims] 1. An impedance means connected between an emitter and a base of a current mirror circuit for transmitting a power supply voltage from a battery to a main part of a bandgap reference type voltage generating circuit, and a path for flowing a current through the impedance means. Is inserted into
A battery save circuit comprising: switching means which is turned on by a signal from the outside to operate the current mirror circuit and bring the bandgap reference type voltage generating circuit into an operating state.