JPS62248015A - Stabilizing constant-voltage circuit - Google Patents

Abstract

PURPOSE:To reduce the current consumption by connecting a current limiting circuit in parallel to a comparator current source, releasing the battery saving, and thereafter, increasing a current only for a prescribed time and shortening the rise time. CONSTITUTION:A comparator circuit consists of transistors Q1-Q4 and a resistance R1 being a comparator current source, and a stabilizing constant-voltage circuit is constituted of a two-stage constitution with an emitter ground amplifier consisting of a transistor Q5 and a resistance R2. Also, to the resistance R1 of the output source of the comparator circuit, a current control circuit consisting of an npn transistor Q6 to whose base a control signal CONT is inputted is connected in parallel. In this state, by varying a current IEE by the signal CONT, a current is increased only for a prescribed time after the battery saving has been released, a capacitive load is charged quickly and an output voltage is raised in a short time, and thereafter, the current is decreased. In this way, the power consumption can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a stabilized constant voltage circuit, and in particular has a capacitive load, a PNP (PNP) runnostar as an output transistor,
The present invention relates to a stabilizing constant voltage circuit suitable for a semiconductor integrated circuit installed in a selective call receiver operating at a low voltage.

[Conventional technology]

In recent years, selective call receivers equipped with semiconductor integrated circuits equipped with this type of stabilizing voltage regulator have become smaller and smaller.
Lower prices and lower current consumption are extremely important issues. In particular, it is necessary to operate for a long period of time with a single battery, and in order to reduce the current consumption, it is possible to perform reception operations intermittently by periodically disconnecting and disconnecting one power source. ing.

(This is hereinafter referred to as pantry saving).

By performing this battery saving, the current consumption is reduced, but for this purpose, it is necessary to stably raise and supply the output voltage of the stabilizing voltage regulator circuit in a short time. Furthermore, since a large capacitive load is often attached to the output of the stabilizing voltage regulator, it becomes a major hindrance to raising the output voltage in a short time.

Conventional stabilizing voltage regulator circuits of this type use a PNP transistor in the output stage in order to start up the capacitive load in a short time.

1. Individual transistors were used to obtain a high current amplification factor (hFE) without being mounted on a semiconductor integrated circuit (IC).

1), Ver Moical PNP (V-PNP)
) It was installed in the IC as a runnostar.

3. It was a lateral PNP (L-PNP) transistor. However, this occurs due to the low hFE of the L-PNP transistor, which allows a large current to flow through the differential pair current source of the comparator included in the stabilizing constant voltage circuit. The output L-PNP corresponds to an increase in the base current of the transistor.

[Problem that the invention seeks to solve]

In the above-mentioned conventional stabilizing constant voltage circuit, miniaturization is an important problem in the case of 2-select call receiving machine, and the use of external transistors is a major obstacle to miniaturization.

In the second case, the use of V-PNP transistors increases the number of steps in the manufacturing process for integrated circuits, lowers the yield, and increases the cost of ICs, which hinders price reductions. That's a problem.

In the case of 3 above, there is no problem regarding miniaturization and cost reduction.

However, L-PNP compared to the case of 1 and 2.

Because hFE is low, in order to start up the capacitive load in a short time, it is necessary to increase the current flowing through the comparator differential pair of the stabilizing voltage regulator circuit by the amount of the increase in base current considered as described above. This has the disadvantage that current consumption increases. The above drawbacks will be explained using FIG. 2.

As shown in FIG. 2, the conventional circuit has a two-stage configuration including a comparator circuit consisting of +Q1 to Q4 and R, and a common emitter amplifier consisting of +QssR2. Here 1
．． is a constant current source.

■2 due to the reference voltage Vi created by the reference voltage circuit 1
becomes vz=v1, and the output voltage ■o is Vo = R2I
It is expressed as f +V2 --(1). R2 to I
The output voltage is arbitrarily set by trimming inside the C.

When the power is turned on in this circuit, the output voltage V.

The rise time of is determined by the charging characteristics of capacitor CI. The charging time is given by the following formula.

Here, vl=0.85■, vBF, □=0.65v, R
1=500Ω.

CI=47μF r Vo=1-05 V r %Bp
Np) ” 25, t=5ms, ■EE=400
It becomes μA.

Let us consider the bias offset of the comparator differential pair due to the load. This is because the bias offset that occurs here appears directly in the output voltage V.

In order to suppress the output voltage fluctuation to ±10 rnV, load current IL = 1 mA and no load. =Icl=engineering. If it's 2, it's Tonashie. . =
2I, = 100μ8 degrees. In the conventional circuit, in order to improve the charging characteristics at startup, it was necessary to constantly flow as much as 300 μA of current after canceling battery saving.

[Means for solving problems]

According to the present invention, the present invention includes a comparator circuit consisting of a differential pair and a comparator differential pair, and an amplifier connected to the output terminal of the comparator circuit. A stabilized constant voltage circuit characterized by having a channel control circuit is obtained.

〔Example〕

Next, one embodiment of the present invention will be described in detail with reference to FIG.

FIG. 1 shows a circuit diagram of an embodiment of the present invention.

Comparator circuit consisting of Ql-Q4 and R1 and Q51
A stabilizing constant voltage circuit consists of a two-stage configuration of a common emitter amplifier consisting of R2, and the collector is connected to Ql of the comparator circuit, the resistor R3 connected to the emitter of Q2, and the other end, and the control signal C0NT is input to the base. It has a current control circuit consisting of an NPN transistor Q6. Here, it is assumed that the control signal C0NT is a signal that remains at a high potential for 30 mS after battery saving is canceled.

First, battery saving is canceled and the reference voltage rises. At the same time, the control signal becomes high potential and Q6 is turned on.

The electric current EF flowing in this state is V here in the margin below. E(SAT) is the saturation voltage of transistor Q6.

By choosing an appropriate value for R3, 5 ■ only while the C0NT signal is at high potential. The positive and negative rise times are all equal to those of conventional circuits, and current consumption can be reduced.

Specific figures are shown below.

From formulas (2) and (5), CI''=47 AF + vo=1.05 V t
hpE(pNp) ”” 25 +VCE(SAT)=
50 mV I VBg t = o, 65 V r R
3=500Ω.

When V1 = 0.85 V and Rt = 2 kΩ, I g E = 400 μA + t = 5 rnS
Furthermore, by increasing the current consumption to 400 μA only at startup and normally operating at 100 μA, the current consumption can be reduced by 300 μA.

Next, another embodiment will be explained using FIG. 3 and FIG. 4.

FIG. 3 is similar to FIG. 1. The differential pair current source resistor R1 is replaced with a transistor Q6, and a transistor Q7 for current control during startup is provided in parallel with the transistor Q6. Transistor Q7 is transistor Qa, Q
A constant current source consisting of a resistor R4 causes the device to enter the operating state when the control signal C0NT is at a low level. increase.

When the control signal C0NT is at a high level, Q7 is determined only by the current of the activated transistor Q6.

As mentioned above, the control signal causes the operation 1. By changing E, the current is increased only when the shield pantries saving is canceled, thereby shortening the start-up time. This eliminates the need for a large current to flow through EE all the time, reducing current consumption.

In Figure 4, the differential pair current source resistor R1 in Figure 1 is replaced with a series connection of R1 and R5, and the collector-emitter of a switching trannoctor Qll for current control is connected to both ends of R1. . Since Qll is turned on when the control signal is at a high level, R1 can be ignored and IEEE is determined by R5.

When the control signal C0NT is at a low level, the impedance between the emitter and collector of tQst becomes high, so that the current EE is determined by R1+R5.

〔Effect of the invention〕

As explained above, the present invention increases the current only for a certain period of time after pantry saving is canceled by inserting a current control circuit in parallel with the current source of the comparator, rapidly charging the capacitive load, and increasing the output voltage in a short time. By increasing the current and then decreasing the current, it is effective to reduce the current consumption.

In particular, selective calling receivers are becoming smaller and cheaper.

In ICs that are mounted in devices that require low current consumption, the output transistor is built into the IC and the increase in current consumption can be significantly suppressed by using L-PNP to shorten startup time. can be.

The effect is a dog.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the stabilizing voltage regulator circuit of the present invention, FIG. 2 is a circuit diagram of an example of a conventional circuit, and FIGS. 3 and 4 are circuit diagrams of other embodiments of the present invention. It is. Ql"Qtt...transistor r R1"" R5.
··resistance. C,... Capacitor, 1... Reference voltage circuit. Figure 1 Figure 2

Claims (4)

[Claims] (1) A comparator circuit comprising a differential pair and a comparator current source, an amplifier connected to an output terminal of the comparator circuit, and a current control circuit connected to the comparator current source. Stabilized constant voltage circuit. (2) The stability according to claim (1), comprising a series circuit of a resistor and a transistor connected in parallel with a current source resistor serving as a comparator current source, and a current control circuit connected to the base of the transistor. Constant voltage circuit. (3) A patent that includes a current control resistor connected in series with a current source resistor serving as a comparator current source, and a transistor whose collector and emitter are connected to both ends of the current control resistor and whose base is the current control terminal. Claim No. (1)
Stabilizing constant voltage circuit as described in section. (4) Stabilization according to claim (1), which has a first current source, a second current source in parallel with the current source, and a control circuit that connects and connects the second current source. Constant voltage circuit.