SU1629980A1 - Trabsistor switch with overload protection - Google Patents

Abstract

The invention relates to a pulse technique and can be used in various switching devices where protection of a power key element against overload currents is required. The purpose of the invention is to simplify, increase speed and reliability. The device contains a key element 1, a control transistor 2, resistors 3-7, a capacitor 8. This goal is achieved through new significant connections between the elements, as well as by combining the control and protection functions of element 1 against overload in one transistor 2. 1 silt

Description

union of soviet

SOCIALIOTIC

REPUBLIN, _a SU, ·. 1629980 A1 (51) 5 8 .03 ^{to 17/08} __________________________

STATE COMMITTEE ON INVENTIONS AND OPENINGS

AT GNNT SS SR

DESCRIPTION OF THE INVENTION

N AUTHOR'S CERTIFICATE

ALL-UNIONED 8 * "8THE WAYS EKWHIQTEHA (21) 44291.90 / 21 (22) 05.24.88 (46) 02.23.91. Bull. No. 7 (72) V.F. Braginsky, N.I. Fadeev and M.N. Zaikin (53) 621.314.572 (088.8) (56) USSR Copyright Certificate

G 1173545, class H 03 K 17/60, 1983.

^: Application of Germany No. 3409057, CL-G 05 F 1 / 57'3, 1985.

(54) TRANSISTOR KEY WITH OVERLOAD PROTECTION (57) The invention relates to a pulse technique and can be used in various switching devices where protection of the power key element from overload currents is required. The purpose of the invention is to simplify, increase speed and reliability. The device contains a key element 1, a control transistor 2, resistors 3-7, a capacitor 8. The goal is achieved due to new significant connections between the elements, as well as by combining the control and protection functions of element 1 from overload in one transistor

2. 1 ill.

The invention relates to pulse technology and can be used in various switching devices where protection of the power key element from overload currents is required.

The purpose of the invention is to simplify, increase speed and reliability. .10

The drawing shows a schematic diagram of a transistor switch.

The transistor switch contains a key element 1, a control transistor 2, five resistors 3-7, a capacitor 15, a control bus 9, a power bus 10, an output bus 11, a common bus 1 2.

The first output of element 1 is connected to the bus 11 and through resistor 6 to the base of transistor 2 20, the collector of which is connected to the input of element 1 and through resistor 5 to bus 10. The emitter of transistor 2, the second output of element 1 and the first output of resistor 3 25 connected to the bus 12, the base of the transistor 2 is connected to the first terminal of the resistor 4, the second terminal of which is connected to the second terminal of the resistor 3 and the first terminals of the resistor 7 and 3Q of the capacitor 8, the second terminals of which are connected to the bus 9.

The transistor switch operates as follows.

In the initial state, a high voltage level is applied to the control bus 9, while the transistor 2 is in the open state, and the key element 1 is in the closed state, which determines the high voltage level on the output bus 11. A part of the base transistor current flows through the resistor 6. 2. The capacitor 8 is charged to a voltage whose value is determined by the resistances of 45 resistors 3, 4 and 7.

Upon receipt of a low voltage level on the control bus 9, the potential of the second output of the capacitor 8 becomes negative relative to the common bus 12, and at the output of the voltage divider formed by the resistors 4 and 6, a voltage level appears that closes the transistor 2 for the time required for the $ end of the transient in the key circuits and the load and determined by the discharge time of the capacitor 8. When the transistor 2 is closed, the key element 1 goes into the open state, which determines the low voltage level on output bus .11. In this case, the voltage level at the output of the voltage divider formed by the resistor 6 and resistors 3, 4, and 7 is insufficient to open the transistor 2, so the transistor switch remains in a stable open state.

Upon receipt of a high voltage level on the control bus 9, the transistor 2 opens and the key element 1 closes, while the boost action of the capacitor 8, the presence of a positive feedback circuit formed by a voltage divider consisting of resistors 4 and 6, as well as the direct connection of the input of the key element 1 to the collector of the control transistor 2 reduces the duration of the shutdown front of the key element 1, thereby increasing the speed of the transistor switch.

When an overload current occurs in the power circuit and there is a low voltage level on the control bus 9, the key element 1 enters the active mode of operation, while the voltage on the output bus 11 and, therefore, the voltage at the output of the voltage divider formed by resistors 4 and 6 quickly increase . When the latter reaches the opening level of the transistor 2, an avalanche-like process of closing the transistor switch occurs. Moreover, due to the absence of inertial elements in the specified voltage divider, the transistor switch closes without delay.

The proposed transistor switch is more reliable than the known one, since it contains fewer radioelements, which is made possible by combining the functions of the protective and control transistors with the functions of the control transistor 2 of the device; the thermal mode of operation of the key element 1 is facilitated by reducing the dissipated pulsed power in emergency mode, which is made possible by the separation of the functions for turning on the key element 1 when starting the transistor switch and opening the transistor 2 in emergency mode between two!

there are chains in the device, where the circuit consisting of a capacitor 8 and resistors 3, 4 and 7 performs the function of starting a transistor switch, and the circuit consisting of resistors 4 and 6 performs the function of opening a control transistor 2 and, therefore, closing a key element 1 in emergency mode. In this case, the closing of the key element 1 occurs without delay, since the last chain does not contain inertial elements. In addition, the proposed transistor switch has a higher speed due to a decrease in the duration of the shutdown front of the key element 1, which was made possible by the inclusion of a boost capacitor 8 in the base circuit of the control transistor 2, the direct connection of the key element 1 input to the collector of the control transistor 2, and the presence of a positive circuit feedback consisting of ^- resistors 4 and 6.

Claims (1)

SUMMARY OF THE INVENTION Transistor switch with overload protection содержащий containing a key element6, a control transistor, a capacitor and five resistors, the first ”output of the key element is connected to the output bus, the second output to the common 5 by a bus to which the emitter of the control transistor and the first output of the first resistor are connected, the base of the control transistor is connected to the first tg terminal of the second resistor, and the collector is connected through the third resistor to the power bus, characterized in that, in order to simplify, increase the speed and reliability, the input of the key element is connected to the collector of the control transistor, the fourth resistor is connected between the first output of the key element and the base of the control transistor, the second output of the second resistor is connected with the second terminal of the first resistor, the first terminal of the fifth resistor and the first terminal of the capacitor, the second terminal of which is connected 25 nen with the second output of the fifth resistor and with the control bus.