SU1128236A1 - Voltage stabilizer having protection - Google Patents

Abstract

VOLTAGE AND PROTECTION STABILIZER, containing a series of adjustments transistor, the base of which is connected to the output of a feedback amplifier, inputs connected to an output voltage divider and a source of reference voltage and. an output terminal, a voltage divider connected between the emitter of the regulating transistor and a common busbar, a shunt transistor connected by a collector to the regulator base I A, a transistor and increasing the protection efficiency by providing a constant protection threshold when adjusting the output voltage down to zero and reducing the short-circuit current. Comparison and developmental operational amplifiers, an offset voltage divider and an auxiliary source of voltage are introduced into the bias block of the protection unit, the output of the compared opamp is connected to the base of the shunt transistor bias, which is connected via a separate operational amplifier to the series and according to the connected adjustable reference voltage source auxiliary voltage source,. The connection point of which is connected to the output terminal.

Description

The invention relates to electrical engineering, in particular, to DC voltage regulators. It is known a voltage regulator sanpJTH device containing an element and a current circuit, connected in series along the control circuit, and a current, a protection transistor, the emitter of which is connected to one of the current sensor outputs, and the base is connected to the midpoint of a voltage divider consisting of two resistances ClJ The disadvantage of this device is the dependence of the protection response current on the output voltage, as well as the high short-circuit current. The closest to the technical essence of the invention is a stabilized voltage circuit with protection, soda, a bruised serial control transistor, ba, which is connected to the output of the feedback amplifier, the inputs of the output voltage connected to the divider, and the voltage source overload, consisting of a current sensor connected between the emitter of the regulating transistor and the output terminal, a voltage divider connected between the emitter of the regulating transistor and the common busbar shunt a transistor connected by a collector to the regulating transistor base, and an emitter to the output terminal, and an offset threshold offset node 23. The disadvantage of the known stabilizer is the narrow range of output voltage variation, in which the protection response current remains constant, and . з. The purpose of the invention is to increase the effectiveness of protection by providing a constant threshold for triggering, protection when adjusting the output voltage down to zero and reducing the short-circuit current. The goal is achieved by the fact that in a voltage regulator with a protection containing a series regulating transistor, a feedback amplifier whose output is connected to the base of the regulating transistor, and the inputs are respectively connected to the output voltage divider and the source of the reference voltage, an overload protection unit consisting of a current sensor connected between the emitter of the regulating transistor and the output terminal, a voltage divider connected to the emitter of the regulating transistor and a common busbar The nf1 transistor connected by the collector to the base: the regulating transistor, and the emitter connects the output terminal of the offset bias node to the protection, the last one has a comparing and decoupling op-amp amplifiers, a bias voltage divider and an auxiliary voltage source, and the shunt transistor base, and the inputs are connected to the middle outputs of the voltage divider of the protection unit and the bias voltage divider, which is connected via The switching operational amplifier is sequentially connected to the adjustable voltage source of the stabilizer voltage and an auxiliary voltage source, the junction point of which is connected to the output terminal. FIG. 1 is an electrical circuit diagram of a voltage regulator with protection; FIG. 2 - load characteristics in relative terms. The stabilizer contains a series regulating transistor 1, a feedback amplifier 2, the code of which is connected to the base of the regulating transistor 1, an output voltage divider 3 connected by a midpoint to one of the inputs of the feedback amplifier 2, and a voltage source connected to another the input of the feedback amplifier 2, an overload protection unit, consisting of a current sensor 5 connected between the emitter of the control transistor 1 and the output terminal of the stabilizer, a voltage divider 6 connected between Itter regulating transistor 1 and the common bus stabilizer shunt transistor 7, a collector connected to the base of the regulating transistor 1 and the emitter - to the output terminal of the stabilizer assembly unit sosto- bias protection. IT from the comparing operational amplifier 8, connected by its output to the base of the shunt transistor 7, one of the inputs of the amplifier 8 is connected to the midpoint of the voltage divider 6, which expands the operational amplifier 9 and the auxiliary source 10 of the reference voltage. The midpoint divider 11 of the bias voltage is connected to the second input of the amplifier 8. The connection point of sources 4 and 10 of the reference voltage is connected to the output terminal.

The stabilizer works as follows. In normal operation mode, until the load current exceeds a predetermined threshold value, the overload protection unit does not affect the operation of the stabilizer, the shunt transistor 7 is closed by the voltage of the amplifier 8. As the load current increases, the voltage drop across the sensor increases 5, the voltage on the voltage divider 6 accordingly increases. When a voltage divider 6 arrives at one of the inputs of a comparison of operational amplifier 8, the voltage at its other input is formed from the values of the voltage of the source 4 of the reference voltage and the auxiliary source 10 of the reference voltage by means of an uncoupling operating voltage. amplifier 9 and bias voltage divider 11; The output voltage of the comparison opamp 8 changes its sign, opens the shunt transistor 7, which begins to have a shunt effect on the control control transistor 1.

The stabilizer switches to the operation mode determined by the operation of the protection unit.

The work condition is generally written as

 and, n -M ek - n5). .

II

where and is the comparison voltage on one of the inputs of the amplifier 8j K (j is the division factor of the voltage divider 6.

The voltage U is formed from the voltage of the source 4 of the reference voltage Uflni of the auxiliary source 10 of the reference voltage U ,, - Thus, the magnitude of the voltage U is generally equal to

-. .

where K and K- are the corresponding transfer coefficients. The change in voltage of the source 4 of the reference voltage is related to the change in the output voltage of the stabilizer by the ratio

% x, l2.

where kj is the division factor of the divider

4 output Voltages, and xxpenses the dependence on output voltages in the trigger condition of the protection unit

.Vz-HVs.i eMxrs.M-;

Therefore, the condition of compensation is the following ratio

In such a case, the protection triggering condition is

.H "5 (K) ::

Thus, the tripping current is independent of the output voltage and is equal to

| and cf

. (

for the limiting case of protection (short-circuit mode) current,

:: (t 2

From the above ratios it can be seen that

. kz icp. .

The protection unit provides for a change in load resistance up to a short circuit. a decrease in the output voltage and current, and when the emergency load is removed due to the presence of a short-circuit current. - return the circuit to its original state.

A positive effect in the proposed stabilizer is achieved by changing the circuit of the displacement block of the protection unit, which makes it possible to form the load characteristics of the stabilizer with a constant current response in the entire range of output voltage variation down to zero and not having limitations on the short-circuit current.

Ukft

FiC

Claims (2)

PROTECTED VOLTAGE STABILIZER, comprising a serial control transistor, the base of which is connected to the output of a feedback amplifier, inputs connected to an output voltage divider and a reference voltage source, an overload protection unit, consisting of a current sensor connected between the regulator transistor emitter and the output terminal, a divider voltage connected between the emitter of the control transistor and the common bus, the shunt transistor connected by the collector to the base of the control transi of the torus, and by the emitter to the output terminal of the offset threshold shift node, the protection is that in order to increase the protection efficiency by ensuring a constant protection threshold when adjusting the output voltage to zero and reduce short-circuit current a comparing and decoupling operational amplifiers, a bias voltage divider and an auxiliary reference voltage source are introduced into the bias unit of the protection unit, the output of the comparing op-amp is connected to the base of the shunt transistor, and the inputs are connected to the middle terminals of the voltage divider of the protection unit and the bias voltage divider, which is connected through decoupling operational amplifier to series and according to the connected adjustable voltage source of the stabilizer and auxiliary - the source of the reference voltage. whose connection point is connected to the output pin. the emitter of the regulating transistor and the output terminal, a voltage divider connected between the emitter of the regulating transistor and the common bus, a shunt transistor connected by the collector to the base of the regulating transistor, and the emitter to the output terminal of the bias node of the protection threshold, the latter includes comparing and decoupling operational amplifiers, a bias voltage divider and an auxiliary reference voltage source, the output of the comparative operational amplifier being connected to the shunt base guide transistor, and the inputs are connected to the average output of the divider the voltage: Nia protection unit and a divider of a bias voltage that is coupled through an isolating operational amplifier to the series and the compounds according to the regulated source of reference voltage regulator and an auxiliary source of reference voltage, a connection point which is connected to the output terminal. In FIG. 1, an electric circuit of voltage stabilizer 30 with protection * is shown; FIG. 2 - load characteristics in relative terms. The stabilizer contains a serial control transistor 1, a feedback amplifier 2, the output of which is connected to the base of the control transistor 1, an output voltage divider 3 connected by a midpoint to one of the inputs of the feedback amplifier 2, a reference voltage source 4 connected to another input of the feedback amplifier 2 connection, overload protection unit, consisting of a current sensor 5 connected between the emitter of the regulating transistor 1 and the output terminal ·, a stabilizer, divide the voltage 6 connected between the emitter rub the regulating transistor 1 and the common bus of the stabilizer, the shunt transistor 7 connected by a collector to the base of the regulating transistor 1, and the emitter to the output terminal of the stabilizer. The offset unit of the protection block is 'ith from the comparing operational amplifier 8, connected by its output to the base of the shunt transis10 ¹ 1128236