SU1628053A1 - D c voltage stabilizer - Google Patents

Abstract

The invention relates to electrical engineering and / can be used as a source of reference DC and thermodependent voltages. The purpose of the invention is to improve the accuracy and expansion of functionality. The introduction of an additional resistor in the circuit of three transistors, three resistors and a differential amplifier, connected between the emitters of two transistors, allows to obtain not only the main, but also thermal voltage. The introduction of the fourth transistor and the fifth resistor allows to obtain a highly stable voltage in the device relative to the common bus, and the introduction of the fifth transistor and the sixth resistor to obtain an additional thermal-dependent current. 2 hp f-ly, 3 ill. C 9 (L

Description

The invention relates to electrical engineering and may be used in electronic devices as a source of reference constant and thermo-dependent voltages.

The purpose of the invention is to improve the accuracy and enhance the functionality of the stabilizer.

Figure 1-3 presents the concepts of the proposed stabilizer.

The DC voltage regulator contains three transistors 1-3, the first two of which form a matched pair, three resistors 4-6 and a differential amplifier 7, with the emitter of the first transistor

1 is connected to the common bus, its collector and base are connected to the base of the second transistor 2 and through the first resistor 4 to the power bus, to which the collector of the second transistor 2 is connected to the common bus through the second resistor 5.

The DC voltage regulator also contains an additional resistor 8, one output of which is connected to the emitter of the third transistor 3 and an additional output of the thermo-dependent voltage Ur, and the other output connected to the emitter of the second transistor 2, the collector of which is connected to the inverter inlet OE B

00

about

SP

00

the house of the differential amplifier 7, the non-inverting input of which is connected to the bases of the first and second transistors 1 and 2, and the output is the main output (Uj) of the device and connected to the base of the third transistor 3, the collector of which is connected to the base and collector of the fourth 9 and base n In addition, 10 transistors that form a matched pair with conductance opposite to that of transistors 1–3.

At the same time, the emitters of transistors 9 and 10 are connected via the fifth and sixth resistors 11 and 12, respectively, to the power supply line of the power supply 13. The connection point of the collectors of the third transistor 3 and the collector of the fourth transistor 9 is an additional output of the reference voltage U2, stabilized with respect to the power supply bus, and the collector of the fifth transistor 10 is the output of a thermospecific current.

The DC voltage stabilizer works as follows.

When the power is turned on, the differential amplifier 7 creates such a voltage on the base of the transistor 3 that the potential at the midpoint of the resistive divider to which the emitter of the transistor 2 is connected becomes such that the voltages on the collectors of these transistors are equal (within the accuracy of the bias of the differential amplifier).

This happens in the case when the voltage drops across resistors 4 and 5 when the collector currents 14 and T.Ј flow through them of the first and second transistors are equal

I 4- R4- It R-g

or k r.f

1g

For collector currents of transistors can be written

h i99: e. i 1.2, ...

where issiv transition saturation current

emitter - base of the 1st transistor; U, B- - voltage drop

i-ro emitter junction

(ABOUT

transistor;

CT

 - - temperature potential;

mt q

K is the Boltzmann constant;

1628053

T - absolute temperature; q is the electron charge. For a matched pair of transistors

5% S Issa. m ° I U

C b 3t

(2)

where U U., B, - 1bb2.

Obviously, Ue is equal to the voltage drop across the resistor 6. By appropriately selecting the resistances of the resistors 4-6, you can get the emitter current of the transistor 3

 uh, 1a and u

2

 I

Uh

(3)

Taking into account (1), (2) and (3), we obtain R5

 .. ""

R-f. r

4V. R or I --- In -.

Thus, if you choose the value of the resistor 5 is large enough (Rg.R6), the transistor 3 with a sufficiently large gain

(1z 1e5-1tb then the transistor 3 can be considered as a current generator of size 1G А-Т,

/ КIn R «r / R G.D6 (A q, I

By selecting the appropriate value of the resistor 8, it is possible to achieve that the voltage U at the output of the differential amplifier 7 is stable.

For this, it is necessary that its value be close to the numerical value of the width of the forbidden band in silicon. In known stabilizers, to generate such a voltage,

voltage is added the emitter is the base of the transistor 3, which has a negative and almost constant temperature coefficient during the flow of direct current through it

 -2.39 mV / ° C, with a voltage having a positive temperature coefficient equal to it. In the case described, transistor 3 does not flow a constant current, but directly proportional to the absolute temperature. However, in this case, the temperature coefficient otf is also practically constant. Show it. Physical meanings; it is derivative

what's the temperature. Known that ive t i

CT

L5S

or, iB - (Inl - lnI5S),

where I is the collector current of the transistor;

- saturation current

eat derivative

-dni - q

1Sh55)

CT

  t

dl

I dT

d (ln I55} dT

We write this formula for when I. (T) const);

Ј-

(I

and

Ebo

 1W ") CT d lnlss q df

IT

For the case when

Al

And, we get

h dl const) and jU

TO,

1n1) +

“T- | lnIrK A CT djlniss} q A q dT

then

s

0 T- “l- Ј (1n 1- + 1).

Let us assume that at a certain temperature T0, for example, room temperature (T 293 ° K), 1T IQ. Then it is possible to record IT / JO t / t and in the temperature range (-55 ° C - 125 ° C) the ratio 1T / 1B varies within 0.744-1.35 and the value 1n1t / 1o (-0.3-0.31 ).

Since K / q is 0.086 mV / ° C, in the case of a collector current of the transistor, directly proportional to the absolute temperature, 0 (t is almost constant and is equal to:

OtT 2.4710.02 (mV / & C).

Thus, in order for the output of the differential amplifier 7 to produce a stable voltage equal to the sum of the voltages 11 eBe and the voltage drops across the resistors 6 and 8, it is necessary that the temperature coefficient of this voltage be 2.47 mV / ° WITH. For this, the total voltage drop across resistors 6 and 8 should be: U-j-T = 2.47 (mV) (for example, for a temperature of 293 ° K, this value is 724 mV).

At the same time, the voltage Uj is stabilized at 1.22 V.

0

Similarly, the same voltage, but relative to another power source voltage, stabilizes at the collector of transistor 3 and is equal to the sum of the base-emitter voltage of transistor 9 (negative temperature coefficient) and voltage drop across resistor 11 caused by the same temperature proportional current of 1T (positive temperature coefficient). The value of resistor 11 should be equal to the sum of resistors 6 and 8.

The collector of the transistor 10 is a current source at a linear proportional temperature, since this transistor, together with the resistor 12, forms a current mirror circuit with the transistor 9 and the resistor 10.

Claims (2)

Invention Formula one . A DC voltage regulator containing three transistors, the first two of which form a matched pair, three resistors and a differential amplifier, the emitter of the first transistor connected to the common bus, its collector and base connected to the base of the second transistor and through the first resistor a power bus to which a collector of the second transistor is connected via a second resistor, the emitter of which is connected to a common bus through a third resistor, in order to increase accuracy and expansion. functionality, it introduces an additional resistor, one pin of which is connected to the emitter of the third transistor and is a thermo-dependent voltage output, and the other pin is connected to the emitter of the second transistor, the collector of which is connected to the inverting input of the differential amplifier, the non-inverting input of which is connected to the bases of the first and the second transistor, and the output is used as the output of the main voltage and is connected to the base of the third transistor, the collector of which is connected to the bus no. 2. Stabilizer. According to claim 1, that is, so that, in order to expand its functionality, a fifth resistor is introduced into it 0 five five 0 five 2