SU1553964A1 - Dc voltage regulator with protection from current overloads - Google Patents

Abstract

The invention relates to electrical engineering and can be used in power supply devices for technical means of electronics, automation and radio engineering. The goal is to increase the effectiveness of protection against current overloads and improve performance. A DC voltage regulator with current overload protection consists of a regulating transistor 1 connected in series with a current sensor 2 into the power bus, a feedback node 3, the output of which is connected to the base of the regulating transistor 1 and to the collector of the transistor of the key stage 4, c the base of which is connected to the output of the comparator 5, the voltage divider of the output voltage 6, the bias voltage source and the voltage divider 7 of the protection signal. In case of overload due to an increase in the voltage on the inverting input of the comparator 5, the latter overturns and is held in this state by the sum of the voltages of the bias source and from the divider 7. The voltage from the output of the comparator, which has a positive polarity, turns off the device. When the overload is removed, the comparator and the stabilizer generally return to their original state. 1 il.

Description

The invention relates to electrical engineering and can be used in power supply devices for technical means of automation, electronics and radio engineering.

The purpose of the invention is to increase the effectiveness of protection.

The drawing shows an electrical circuit of a voltage regulator with protection.

The stabilizer contains a regulating element 1 connected in series with the current sensor 2 to the power bus, a feedback node 3 connected in parallel to the output terminals, the output of which is connected to the control circuit of the regulating element 1 and to the output of the key element 4 on the transistor whose emitter is connected to the common bus and the control circuit of the key element 4 is connected to the output of the comparator 5, the voltage divider 6, one output of which is connected to the power bus between the output of the regulating element and the one of the current sensor 2 terminals and the other output of the voltage divider is connected to the common bus, the divider 7 is the protection signal voltage,

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connected between the common bus and the output of the comparator 5, the divider 7 output through a parallel connected capacitor 8 and the resistor 9 is connected to the non-inverting input of the compensator 5 and through the resistor 10 to the output of the voltage divider 6, and the inverting input of the comparator 5 through the resistor 11 is connected to another The output of sensor 2 to-jq ka, a chain of series-connected resistors 12 and diode 13, connected between the non-ventilation input of comparator 5 and terminal 14 to tune the bias source E cm, is temperature-stable.

The stabilizer works as follows.

In normal operation, up to a maximum of 20 mV | nta of the increase in the load current is given a threshold value, the transistor 4 of the key element is closed by the output voltage of the comparator 5 and the protection node does not affect the operation 25 of the regulating element 1 and the stabilizer as a whole.

This condition of the stabilizer circuit corresponds to the condition: the sum of the voltages at the non-inverting input of the comparator 5, which has the components of the voltage source of the bias voltage Esm from the output divider of the comparator output bis.5, is less than the voltage on the inverting input 4 of the comparator. As the load current increases, the voltage drop across the resistor of the current sensor 2 increases. Accordingly, the voltage at the non-inverting input of the comparator 5 increases. When the voltage of this voltage reaches the voltage at the inverting input of the comparator 5 (stabilizer output), the comparator tilts in those. the voltage at its output, g changes the sign — becomes positive. This opens the transistor 4, which bypasses the control / transition of the regulating element 1. The voltage at the output of the stabilizer decreases sharply, and its steady value is determined by the mode of operation of the protection node elements. The overturning process of comparator 5 occurs. Forced due to the presence of a capacitor 8 in the positive feedback circuit of comparator b. In the off state, the stabilizer is deducted mainly by voltage and power.

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displacement point E & m and part of the output voltage of comparator 5 taken from divider 1. The sum of these voltages should be greater than the residual voltage of the off stabilizer.

When the overload is removed, the voltage at the output of the stabilizer increases and, at a certain value of the load resistance, the voltage at the inverting input of the comparator 5 becomes greater than at its non-inverting input. In this case, the comparator is forcedly returned to the initial state, including the stabilizer in the operating mode.

Claims (1)

Thus, the proposed stabilizer in comparison with the known one has a higher efficiency of the device for protection against current overloads, providing automatic activation of the stabilizer in the working state after eliminating the overload or affecting the stabilizer of signals of various pulsed or other types of interference. The stabilizer operates stably over the entire range of variation. the magnitude of the load current ranges from zero to the tripping current of the protection. Invention Formula A DC voltage regulator with overcurrent protection, containing a regulating element connected in series to the power bus, a feedback node connected in parallel with the output terminals, the output of which is connected to the control circuit of the regulating element, and a protection node consisting of a sensor current, capacitor, voltage divider, comparator, the output of which is connected to the control input of the key element on the transistor, the collector of which is connected to the control input of the regulating element, and the emitter - the common bus, the inverting input of the comparator through the first resistor is connected to one of the current sensor pins, the non-inverting input of the comparator through the second resistor is connected to the output of the voltage divider and to one of the pins of the third resistor and diode connected in series, , in order to increase the effectiveness of protection, a divider is inserted in the protection node the voltage of the protection signal connected between the comparator output and the common bus and a fourth resistor connected in parallel with the capacitor, the resistor and the capacitor being connected between the middle output of the protection signal divider and the non-inverting input of the comparator, and another output of the chain from the series A third resistor and a diode are connected to an input terminal for connecting a bias source, another current sensor terminal connected in series with the regulating element is connected to the output of the regulating element and to one of the terminals of a voltage divider whose other terminal is connected to the common bus. 04 about