JP2005025595A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage stabilizing circuit for realizing low current consumption without consuming the control currents of the output driver of a voltage regulator in a regulator. <P>SOLUTION: This semiconductor device is configured of a reference voltage generating circuit 11, a differential amplifier circuit 12 constituted of an MOS transistor and a voltage regulator including output driver transistors M10 and Q8 and resistances R1 and R2. The output driver transistors are constituted of an NPN by-polar transistor Q8 for outputting currents to an output terminal and a PchMOS transistor M10 for controlling the base voltage of the NPN by-polar transistor Q8. The source of the PchMOS transistor M10 is connected to an input voltage terminal, and the drain is connected to the base of the NPN by-polar transistor Q8, and the collector of the NPN by-polar transistor Q8 is connected to the input voltage terminal, and the emitter is connected to the output voltage terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device including a voltage stabilization circuit, and more particularly to a semiconductor device including a voltage stabilization circuit including a combination of an NPN bipolar transistor and a PchMOS transistor as an output driver.
[0002]
[Prior art]
A voltage regulator that is a voltage stabilization circuit includes, for example, a reference voltage generation circuit unit that generates a reference voltage Vref that is a bandgap reference, and a voltage regulator unit that includes a differential amplifier circuit and an output driver. All of these are integrated in a one-chip semiconductor device.
In the output driver portion of a conventional voltage regulator, a pair of a PNP bipolar transistor and an NchMOS transistor for controlling the base voltage is generally used as an output driver. However, the base current of the PNP bipolar transistor is drawn into the semiconductor device and is wasted in the semiconductor.
[0003]
As a conventional proposal that uses a bipolar transistor and a CMOS transistor as an output driver of a voltage regulator circuit, for example, see “Bipolar” described in Japanese Patent No. 3190943 (Japanese Patent Laid-Open No. 3-132812) (see Patent Document 1). / CMOS regulator circuit ”. This is a bandgap circuit section (reference voltage generation circuit section) and a CMOS gate control voltage used as the gate bias voltage of the NchMOS transistor to produce a well controlled current with respect to temperature, power supply voltage and process corner variations And a conversion circuit unit that provides The conversion circuit unit includes a current mirror part, a current source part, and an output part.
[0004]
The current mirror part is formed of a pair of Pch MOS transistors, and the current of one transistor flows to the NPN bipolar transistor and the emitter resistor of the current source part, and the current of the other transistor is the same current as a mirror as a diode and Nch MOS. It flows to the transistor. As the output driver, an NPN bipolar transistor is used, and its base is connected between the other PchMOS transistor and the diode of the current mirror portion.
As described above, although the NPN bipolar transistor is used as the output driver in the above proposal, it is doubtful whether the current consumption is reduced, and the entire configuration of the voltage regulator is also a special form.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-132812 (Patent No. 3190943)
[0006]
[Problems to be solved by the invention]
A voltage regulator using a bipolar transistor typified by a three-terminal regulator as an output driver has been widely used because it can take a large output current and obtain a constant voltage. In that case, a PNP bipolar transistor has been used as the driver transistor in order to reduce the input / output voltage difference. For example, when the input voltage is 4V, the output voltage is 3.3V, and the input / output voltage difference is 0.7V, a voltage regulator using a PNP bipolar transistor as an output driver operates sufficiently.
[0007]
When the driver transistor is a PNP bipolar transistor, the control input signal is a current, and the control current flows into the regulator ground and is consumed in the regulator. Therefore, there is a problem that the internal current consumption of the IC increases as the output current increases.
Thus, although the output driver is constituted by a voltage-driven MOS transistor, it has been found that in this case, a PchMOS transistor having a low driving capability must be used, and a target output current cannot be obtained.
Therefore, a regulator having both of these characteristics is desired.
[0008]
(the purpose)
Accordingly, an object of the present invention is to provide a semiconductor device including a voltage stabilizing circuit capable of reducing current consumption without consuming control current of an output driver of a voltage regulator in the regulator.
[0009]
[Means for Solving the Problems]
The semiconductor device of the present invention is (1) a semiconductor device configured with a voltage regulator including a reference voltage generation circuit, a differential amplifier circuit configured with a MOS transistor, an output driver transistor, and a resistor, and the output driver The transistor is characterized by comprising an NPN bipolar transistor that outputs a current to an output terminal and a PchMOS transistor that controls the base voltage of the NPN bipolar transistor.
[0010]
In (1), the source of the PchMOS transistor is connected to the input voltage terminal, the drain is connected to the base of the NPN bipolar transistor, the collector of the NPN bipolar transistor is connected to the input voltage terminal, and the emitter is connected to the output voltage terminal. It is characterized by being.
In (1) and (2), the configuration up to the PchMOS transistor among the output driver transistors is made into an IC, and either or both of the NPN bipolar transistor and the voltage dividing resistors 1 and 2 are externally connected. Also features.
Further, in the above (1) and (2), a constant current circuit is connected between the drain of the PchMOS transistor for controlling the base voltage of the NPN bipolar transistor and the ground.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 3 is a block diagram of the voltage regulator according to the embodiment of the present invention.
In FIG. 3, V2 is a power supply voltage, 11 is a reference voltage generating circuit, 12 is a differential amplifier circuit, M10 is a PchMOS transistor controlled by the output of the differential amplifier circuit 12, and Q8 is an NPN bipolar controlled by a PchMOS transistor M10. It is a transistor. R1 and R2 are output resistors, and the divided voltage from the intermediate point of the resistors R1 and R2 is fed back to the non-inverting input terminal of the differential amplifier circuit 12.
[0012]
As described above, in this embodiment, the NPN bipolar transistor Q8 is used as an output driver, and when the output is performed at a voltage lower than the input voltage by the Vbe voltage (base-emitter voltage), the circuit operates normally. Operate. For example, if the difference between the input voltage and the output voltage (input / output voltage difference) is about 1V, the circuit operates normally.
Further, since the control current (base current) of the NPN bipolar transistor is supplied by the PchMOS transistor M10, even if a large output current flows, the sum of the base current and the collector current becomes the output current, so that a large consumption current does not occur. .
Up to this point, the configuration including all the circuits in FIG. 3 has been described as an example. However, the PchMOS transistor M10 is integrated into an IC, and either or both of the NPN bipolar transistor and the resistors R1 and R2 are used. It can also be applied to products that are externally attached.
As an application example of the basic circuit of FIG. 3, it is also possible to configure a circuit in which a constant current circuit is inserted between the drain of the Pch MOS transistor M10 and the ground. This will be described in detail later with reference to FIG.
[0013]
FIG. 1 is a circuit diagram describing details of the configuration of FIG.
Reference numeral 11 in FIG. 1 denotes a reference voltage generation circuit, which is composed of, for example, Nch MOS transistors M8 and M9. The differential amplifier circuit includes a PchMOS transistors M1, M2, and NchMOS transistor M4, M5, composed of the constant current circuit _{I 1.} Also provided are an output driver PchMOS transistor M10 controlled by the output of the differential amplifier circuit and an NPN bipolar transistor Q8 whose base voltage is controlled by the PchMOS transistor M10.
[0014]
The NPN bipolar transistor Q8 supplies an output current to the load connected to the output terminal and also supplies a current to the resistors RHR1 and RHR2 connected to the ground. A feedback voltage is supplied from the middle point of the resistors RHR1 and RHR2 to the gate of the Nch MOS transistor M5 through the non-inverting input terminal of the differential amplifier circuit.
As shown in FIG. 1, the source of the PchMOS transistor M10 is connected to the input voltage terminal, the drain is connected to the base of the NPN bipolar transistor Q8, the emitter load of the emitter of the NPN bipolar transistor Q8, and the collector to the input voltage terminal. , Each connected.
[0015]
FIG. 2 is a circuit diagram showing an application example of FIG. 3. The constant current circuit I ₁ connected to the output of the differential amplifier circuit 12 improves the over-transient response characteristic of the regulator and is stable when the output current is small. The advantage is that the operation can be obtained.
In Figure 2, the constant current circuit _{I 2} is connected between the drain and ground PchMOS transistor M10 of the circuit configuration of FIG.
To explain the purpose of connecting the constant current circuit I _2, the load current becomes small when a large resistance value of the resistor RHR1, RHR2 load, also reduced the base current of the NPN bipolar transistor Q8 accordingly. In order to supply the current stably, by connecting the constant current circuit _{I 2} between the drain and ground PchMOS transistor M10, PchMOS transistor M10 becomes possible to control stably.
[0016]
FIG. 4 is a characteristic diagram showing the relationship between output current and current consumption in the present invention.
The horizontal axis is the output current, and the vertical axis is the current consumption.
As shown by the characteristic D in FIG. 4, the voltage regulator of the present invention uses the NPN bipolar transistor Q8 as an output driver and the PchMOS transistor M10 for controlling the output driver. It turns out that it does not increase. That is, the current consumption always maintains a constant value of 5 μA.
[0017]
【The invention's effect】
As described above, according to the present invention, in the voltage regulator, the NPN bipolar transistor is used as the output driver and the control current is supplied by the PchMOS transistor, so that the base current becomes the output current and the current consumption can be reduced. It becomes.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a voltage regulator according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing an application example of FIG. 1;
FIG. 3 is a circuit diagram showing an IC part and an external part of FIGS.
FIG. 4 is a characteristic diagram showing the relationship between output current and current consumption of a voltage regulator in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Reference voltage generation circuit, 12 ... Differential amplifier circuit, 13 ... Load,
I ₁ , I ₂ ... constant current circuit, V2 ... power supply voltage,
M10: PchMOS transistor,
Q8 ... NPN bipolar transistor, R1, R2 ... output resistor,
M1, M2, M4, M5... MOS transistors constituting a differential amplifier circuit,
RHR1, RHR2 ... Output resistors.

Claims (4)

A reference voltage generation circuit; a differential amplifier circuit that receives an output of the reference voltage generation circuit and is configured by a MOS transistor; an output driver transistor that is controlled by an output of the differential amplifier circuit; and the output driver transistor In a semiconductor device composed of a voltage regulator including a resistor through which current flows,
A semiconductor device comprising: an NPN bipolar transistor that outputs current to an output terminal; and a PchMOS transistor that controls a base voltage of the NPN bipolar transistor as the output driver transistor. The semiconductor device according to claim 1,
The source of the PchMOS transistor is connected to the input voltage terminal, the drain is connected to the base of the NPN bipolar transistor, the collector of the NPN bipolar transistor is connected to the input voltage terminal, and the emitter is connected to the output voltage terminal. Semiconductor device. The semiconductor device according to claim 1 or 2,
A semiconductor device characterized in that the configuration up to the Pch MOS transistor among the output driver transistors is made into an IC, and either or both of the NPN bipolar transistor and the output voltage dividing resistor are externally attached. The semiconductor device according to claim 1 or 2,
A semiconductor device, wherein a constant current circuit is connected between a drain of a PchMOS transistor for controlling a base voltage of the NPN bipolar transistor and a ground.

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