JPH03257607A - Constant voltage current circuit - Google Patents

Abstract

PURPOSE:To control both the constant-current and constant-voltage temperature characteristics a by canceling the constant current temperature characteristic of a base/emitter voltage in the first transistor by utilizing the base/emitter voltage of the 4th transistor equipped with the temperature characteristic in a reverse direction to the first transistor. CONSTITUTION:A current flows into a second transistor 4 with the value obtained by dividing the value, which is the constant voltage generated by a band gap type constant voltage circuit 30 subtracted by the base/emitter voltage of a first transistor 13, by the resistance value 24 of the first resistor. Therefore, the above mentioned current multiplied by the value obtained by adding '1' to the ratio between the emitter areas between second and third transistors 4 and 5 flows from the first potential of the circuit 30. On the other hand, a current also flows from the first potential with a value dividing the base/emitter voltage of the second transistor 4 with the value of a second resis tor 25. Thus, the both temperature characteristics of the constant voltage and the constant current can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a constant voltage constant current circuit, and particularly to compensating the temperature characteristics of the constant current portion thereof.

[Conventional technology]

Conventionally, the above-mentioned constant voltage current circuit includes one as shown in FIG. This is provided, for example, in a semiconductor integrated circuit, and includes a power terminal (100) and an output terminal (3).
00), a band gap type constant voltage circuit (30)
Or is provided. Note that (200) is a 2-ground terminal. This band gap type constant voltage circuit (30) has N
PN transistors (1), (2), (3), PNP transistors (10), (11), (12), and resistor (2)
0), (21), (22), and (23). Here, the emitter area ratio of NPN) run transistors (1) and (2) is N, the resistance ratio of resistors (20) and (21) is R+, and the resistance ratio of resistors (21) and (22) is 82. ,
NPN) - If the base-emitter voltage of the transistor (3) is VBEff, there is a constant voltage V between the power supply terminal (100) and the output terminal (300) as shown in equation (1).
IIEF occurs.

VRcr= VaE:+”R2”V7”In(N+”R
+)"" (1) However, vT is the thermal voltage kT/Q, K is Boltzmann's constant, T is the absolute temperature, and q is the charge of the electron.

In addition, in this constant voltage current circuit, in order to make the current value flowing from the power supply terminal (100) a constant value, the constant voltage VPIEF shown in equation (1) is used to connect the resistor (24) with a resistance value R24. and the base-emitter voltage VIIEr3 of the transistor (13), PNP
P) - Collector current IC+3 of Lancistor (13) is Ic+3=(VRl:r-Ve!++)/R2< ・”
(2). This collector current 1el 3,
NPNI transistor connected to current mirror (
When the emitter area ratio of transistors (4) and (5) is N2, the current flowing from the power supply terminal (100) m s is the output terminal. (If the impedance is 30(1) or higher, 1*tr= (N2+1)"(V*Er-VB2+
:+)/R2<”(3).

Considering the constant voltage characteristic 'VREF in this constant voltage current circuit, the first term on the right side of equation (1) is
It is determined by the temperature characteristics of the base-emitter voltage VllF:3, and generally has negative temperature characteristics. The second term on the right side determines the temperature coefficient by the resistance ratios R1 and R2 and the emitter area ratio N, and the temperature coefficient is always a positive value. Therefore, by varying the values of the resistance ratios R1 and R2 and the emitter area ratio N, the negative temperature characteristic in the first term on the right side can be canceled out.

The temperature characteristics of the constant current IREF are as follows: When the temperature characteristics of the constant voltage VFIEF are set to O as described above, the voltage between the base and emitter of the transistor (13) is
is determined by the temperature characteristics of resistor R24.

(Problem to be solved by the invention) Since the conventional constant voltage current circuit is configured as described above, the temperature characteristics of the constant voltage VREF are determined by the resistance ratios RI and R2.
The temperature characteristics of the constant current IR□ are determined by the integrated circuit manufacturing process depending on the base-emitter voltage VIIE I:I of the PNP transistor (13) and the temperature characteristics of the resistor R24. Therefore, there was a problem in that the temperature characteristics of constant current IREF could only be controlled at the design stage.

An object of the present invention is to provide a constant voltage current circuit that solves the above problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides first and second
a bandgap constant voltage circuit provided between the potentials of the emitter and the emitter connected to the first potential via the first resistor;
A first PNP transistor whose base is connected to a second potential, an emitter connected to a third potential, or a second NPN transistor whose collector is connected to the collector of the first transistor, and an emitter connected to a third potential. or a third NPN transistor whose collector is connected to the second potential and whose base is connected to the base of the second transistor; and a second resistor connected between the base and the emitter of the second transistor. , a fourth NPN transistor whose collector is connected to the second potential or whose emitter is connected to the base of the first transistor, and whose base is connected to the collector of the first transistor;
It is equipped with.

(Function) According to the present invention, similarly to the conventional device described above, the value obtained by subtracting the base-emitter voltage of the first transistor from the constant voltage by the bandgap type constant voltage circuit is determined by the resistance of the first resistor. A current equal to the value divided by the current value flows through the second transistor. As a result, a current equal to the value obtained by multiplying the above current by a value obtained by adding 1 to the emitter area ratio of the second transistor and the third transistor flows from the first potential. On the other hand, a current having a value obtained by dividing the base-emitter voltage of the second transistor by the value of the second resistor also flows from the first potential.

〔Example〕

In this embodiment, in the conventional constant voltage current circuit shown in FIG. 2, a new resistor (
25) and an NPN)-transistor (6) is added.

That is, in the circuit of FIG. 2, the collector of the NPN transistor (4) was directly connected to the base, whereas in this embodiment, the above connection was removed and the collector of the NPN transistor (4) was directly connected to the collector of the NPN transistor (4).
) is connected to the base of an NPN)-runsistor (6), the collector of this NPN l-runsistor (6) is connected to the output terminal (300), and the emitter of the same transistor (6) is connected to the NPN)-runsistor (4). ) is connected to the base. Furthermore, the resistor (25) is connected to the transistor (
4) is connected between the base and emitter.

In this constant voltage current circuit, as in the conventional circuit shown in Fig. 2, the constant voltage V□ between the power supply terminal (100) and the output terminal (300) is the value shown by equation (1). Become.

Further, a current I flows from the output terminal (100). F is
If the impedance of the output terminal (300) is high, by adding a new transistor (6) and resistor (25), VBE4/R2S is added to the value shown in equation (3), and IFIEF = (N2 “l)” (VREF-VBEI3
)/R24"VBE4/R25...(4). However, VBE4 is NPN) - Runsistor (4)
The base-emitter voltage of R2S is the resistance value of the resistor (25). Transistors (4) and (5) or transistor (6) that functions as a current mirror circuit.
This is because the base and emitter of the transistor (4) are connected through the tie-out between the base and emitter of the transistor (4).

The temperature characteristic of the constant voltage VREF in this constant voltage current circuit can be set to O as in the conventional circuit shown in FIG. The temperature characteristics of constant current IREF are determined by the temperature characteristics of the first term and the second term on the right side of equation (4), assuming that the temperature characteristics of constant voltage are 0, and the temperature characteristics of the first term are , is determined by the base-emitter voltage VBE I3 of the PNP transistor (13) and the temperature characteristics of the resistor (24). Generally, this has a positive temperature characteristic because the base-emitter voltage VBE I3 of the PNP transistor (13) and the resistance value R24 of the resistor (24) have positive temperature characteristics. On the other hand, the temperature characteristics of the second term are the base-emitter voltage VBE4 of the NPN)-Lancistor (4), which has negative temperature characteristics, and the resistance value of the resistor (24), which has positive temperature characteristics. Since it is a quotient of R21, it has negative temperature characteristics. Therefore, by varying the resistance value R25 of the resistor (25), the temperature characteristics of the second term can be controlled and the temperature characteristics of the first term can be canceled.

[Effects of the Invention] As described above, according to the present invention, in the conventional constant voltage current circuit, the temperature characteristics of the base-emitter voltage of the first transistor (in the embodiment, the PNP transistor (13)) By using the base-emitter voltage of the fourth transistor (for example, a PNP transistor (6)), which has a temperature characteristic in the opposite direction to that of the first transistor (13), It is configured as follows. Moreover, the constant voltage temperature characteristic can be set to 0 as in the conventional one. Therefore, it is possible to control the temperature characteristics of both constant voltage and constant current at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of a constant voltage and current circuit according to the present invention, and FIG. 2 is a circuit diagram of a conventional constant voltage and current circuit. (4)...second transistor, (5)...third transistor, (6)...fourth transistor, (24)...first resistor, (25)...
Second resistor, (30)...Band gap type constant voltage circuit, (100)...Power terminal (first potential)
, (200)...Output terminal (second potential)
, (:1OO)...Grounding terminal (third potential).

Claims (1)

[Claims] (1) A bandgap constant voltage circuit provided between first and second potentials, and a PN whose emitter is connected to the first potential via a first resistor and whose base is connected to the second potential.
a first transistor with an emitter at a third potential;
NPN whose collector is connected to the collector of the transistor
a third NPN transistor having an emitter connected to a third potential, a collector connected to the second potential, and a base connected to the base of the second transistor;
a second voltage connected between the base of the transistor and the third potential;
and a fourth NPN transistor, the collector of which is connected to a second potential, the emitter of which is connected to the base of the second transistor, and the base of which is connected to the collector of the first transistor.