SU1483441A1 - Thermal protection unit of integrated voltage stabilizer - Google Patents

Abstract

The invention relates to electrical engineering and may find application in integrated semiconductor constant voltage stabilizers and in other devices where thermal overloads are possible. The purpose of the invention is to increase efficiency and reliability by reducing the current consumption and simplifying the circuit. The goal is achieved by a circuit design combining a reference current source having a negative temperature drift of the reference current, and a device that has thermal hysteresis (the shutdown temperature and the subsequent switching on of the integral stabilizer differ from 30 to 50 ° C). Such a construction of the device makes it possible to significantly reduce the probability of failure of the integral stabilizer during the long existence of thermal overload. 1 il.

Description

The invention relates to electrical engineering and can be used in semiconductor integrated constant voltage stabilizers and other electronic devices in which thermal overloads are possible.

The purpose of the invention is to increase efficiency and reliability by reducing the current consumption and simplifying the node circuit.

The drawing shows a circuit diagram of the device.

The thermal protection unit of the integral voltage regulator contains the first 1, second 2, third 3, fourth 4, fifth 5, sixth 6, seventh 7, eighth 8 and ninth 9 transistors, first 10, second 11, third 12 and fourth 13 resistors . The emitters of transistors 1 and 2 are connected to the input terminal 14, and the bases of transistors 1 and 2 are connected to the emitter of transistor 6. The collector of transistor 1 is connected to the base of transistor bis by a collector of transistor 3, the emitter of which is connected via resistor 10 to common bus 15. First 16 collector the transistor 2 is connected to the collector and the base of the transistor 7, to which the base of the transistor 3 is also connected. The base of the transistor 4 is connected to the emitter of the transistor 7 and through a resistor 11 is connected to the collector of the transistor 4 and the base of the transistor 9. Second 17 collector t anzistora 2 is connected to the emitter of the transistor 8 whose base is connected to the collector of the third transistor 9 and the collector 18

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transistor 2. The collector of transistor 8 is connected to the base of transistor 5 and connected in series through resistors 12 and 13 connected to a common bus 15 to which the first emitter 19 of transistor 4, the collector of transistor 6 and emitters of transistor 9 and 5 are also connected connected to the connection point of resistors 12 and 13. The collector of transistor 5 is connected to the control input of the regulating element 21. The transistor 22 performs the function of a current source in the control circuit of the regulating element 21.

The device works as follows.

The static mode of the reference current source (items 1-5, 9-13) is determined by the value of resistor 10

Ion / I 10,

where / ", is the value of the reference current; and eee is the voltage drop of the emitter-base of the transistor 4.

In this case, the reference current / on has a negative temperature drift.

The collector current 18 of transistor 2 has a negative temperature drift, and the collector current of transistor 9 has a positive temperature drift. The collector current / s of transistor 9 is defined by the following relationship:

(

OE 20 ™ t

/.

dT

 ) BA „I, about CTU P1

where / IB-collector current 16 transistor 2; 5e2o - emitter area 20 of transistor 4; S39 is the emitter area of the transistor 9; temperature potential.

Differential expression for temperature and taking into account that / K, where K. is the ratio of the collector area of transistor 1 to the collector area of 16 transistor 2, get

dl, / 9 (Tx),, ACL

where LEO is the value of the silicon band gap;

d) 3.5–4 is a parameter depending on the properties of the semiconductor material; ) - the current value of the collector of the transistor 9 at a certain reference temperature.

Thus, if the condition is satisfied, the collector current of the transistor 9 has a positive temperature drift. The thermal protection node triggers at a temperature at which the collector current value of transistor 9 slightly exceeds the collector current value 18 of transistor 2. This causes a current in the collector circuit of transistor 4, the voltage drop across resistors 12 and 13 sharply increases, which leads to the transition of the transistor 5 in the saturation mode. Transistor 5 shunts

five

0

five

0

five

0

five

the control input of the regulating element 21, turning off the voltage regulator.

In normal operation (the crystal temperature is less than the response temperature of the protection node), the elements 5, 8 and 9 are in the cut-off mode and do not affect the operation of the stabilizer.

The difference in the temperatures of the shutdown and the subsequent switching on of the stabilizer (thermal hysteresis) is formed as follows.

The emitters 19 and 20 of transistor 4 have a different area, and S32o. V-S 9in where. This allows in the normal operation of the stabilizer to distribute the emitter currents of transistor 4 in proportion to the areas of the corresponding emitters 19 and 20. Thus, until the protection node triggers, almost the entire collector current of transistor 4 flows through the emitter 20, which has a large area. After the protection node trips, the voltage drop across resistor 13 causes the collector current of transistor 4 to redistribute between emitters 19 and 20. The emitter current 20 decreases sharply, and the emitter current 19 increases, therefore, the voltage drop of emitter 19 - base of transistor 4 increases. This leads to a proportional increase in the voltage applied to the emitter-base junction of transistor 9 and, as a result, to a shift in the switching-on temperature of the integral stabilizer towards lower temperatures. The temperature difference between the switching off and the subsequent switching on of the stabilizer is determined by the ratio of the areas of the emitters 19 and 20 of the transistor 4. Thus, when the temperature range in which the stabilizer is in the off state, is 35-40 ° C.

Thus, the proposed unit of thermal protection allows to significantly increase the reliability of integrated voltage stabilizers of medium and high power and reduce their current consumption, and also has a rather simple circuit design.

Claims (1)

Invention Formula The thermal protection unit of the integrated voltage regulator, containing nine transistors and four resistors, the bases of the first and second transistors are combined, and their emitters are connected to the input terminal, the collector of the first transistor is connected to the collector of the third transistor, the emitter of which is connected to the first through a resistor the common bus, which is also connected to the first emitter of the fourth transistor, the emitter of the pth transistor and the collector of the sixth transistor, the first collector of the second transistor is connected to the base seven transistor, the second collector of the second transistor is connected to the emitter of the eighth transistor, the base of which is connected to the collector of the ninth transistor, the base of the fourth transistor is connected through the second resistor to its collector and the base of the ninth transistor, the collector of the eighth transistor is connected to the base of the fifth transistor and through series-connected third and fourth resistors are connected to the common bus, and the collector of the fifth transistor is a control output of the node, characterized in that, in order to increase efficiency reliability by reducing current consumption and simplification of the circuit, the base of the third transistor is connected to the base and collector of the seventh transistor, the emitter of which is connected to the base of the fourth transistor, which is two-emitter, while the second emitter is connected to the connection point of the third and fourth resistors, the third collector of the second transistor is connected to the collector nine of the transistor, the emitter of which is connected to the common bus, the base of the first i: the second transistor is connected to the ematch of the sixth transistor, and the base of the sixth transistor is connected to the collector of the first transistor.