CN211266767U

CN211266767U - Power generation circuit with self-recovery overvoltage and overtemperature protection functions

Info

Publication number: CN211266767U
Application number: CN201922261175.9U
Authority: CN
Inventors: 韩益锋; 张维; 吴文桃; 祁昊; 徐蒙蒙
Original assignee: Etman Lighting Electronics Changzhou Co ltd
Current assignee: Etman Lighting Electronics Changzhou Co ltd
Priority date: 2019-12-16
Filing date: 2019-12-16
Publication date: 2020-08-14
Anticipated expiration: 2029-12-16

Abstract

The utility model discloses a power generation circuit of area self-resuming excessive pressure and excess temperature protect function, including diode D1, error amplifier AMP, adjusting tube T1 and resistance R1, input signal Vin is connected to diode D1's positive pole, diode D1's negative pole connecting resistance R1 and resistance R2, adjusting tube T1's drain electrode is connected to resistance R1's the other end, adjusting tube T1's grid connecting resistance Rc, electric capacity Cc and triode T2's collecting electrode, triode T2's base connecting resistance R2's the other end and resistance R3, adjusting tube T1's source connection diode D2's positive pole, the utility model discloses a power generation circuit structure of area self-resuming excessive pressure and excess temperature protect function is compact, and output voltage can the accurate configuration to have the excessive pressure protect function that can self-resume and the excess temperature protect function that can self-resume.

Description

Power generation circuit with self-recovery overvoltage and overtemperature protection functions

Technical Field

The utility model relates to a power technical field specifically is a take self recovery excessive pressure and excess temperature protect function's power generation circuit.

Background

With the development of the internet of things (IoT), the power supply requirements for each node of the internet of things are miniaturization and low cost while meeting the requirements of voltage and current, and therefore, a power generation circuit with simple circuit, comprehensive functions, and stable and reliable operation needs to be developed to supply power to other modules.

A conventional power generation circuit is shown in fig. 1 and 2. The difference between the two circuits is that fig. 1 is implemented by using a power MOS transistor T1, and fig. 2 is implemented by using a power transistor T2.

In the circuit of fig. 1, Vin is an input voltage, Vout is an output voltage, a power MOS transistor T1 is a tuning transistor, a zener diode Z1 is a voltage regulator, a power resistor R1 is a current limiting resistor for outputting current, a resistor R2 is a current limiting resistor for the voltage regulator Z1, and a capacitor C1 is an output capacitor for reducing ripples of an output power supply.

The input voltage Vin is greater than the output voltage Vout, the regulated voltage of the Zener diode Z1 is Vz, and the threshold voltage of the MOS transistor T1 is Vth. The initial state Vout approaches 0, the zener generates a regulated voltage Vz, and the condition Vz > Vgs is satisfied, where Vgs is the gate-source voltage of the MOS transistor, and the MOS transistor T1 is turned on. When the output stability of the circuit is reached, the output voltage Vout = Vz-Vth, at which time the MOS transistor T1 is turned off. When the circuit is in stable operation, if the voltage of Vout is reduced, the MOS transistor T1 is turned on to charge the output terminal, and until Vout is close to Vout = Vz-Vth, T1 tends to turn off.

The circuit shown in fig. 2 is similar to that shown in fig. 1 and is implemented using a power transistor T1 of a power transistor NPN. In steady state, the output voltage Vout = Vz-Vbe. Normally, the transistor T1 has a Vbe around 0.7V if a silicon manufacturing process is used.

The circuit shown in fig. 1 and fig. 2 is the basic principle of the LDO circuit, the minimum voltage drop of the input and the output depends on the characteristics of the power tube, and the output voltage Vout is determined by the regulated voltage of the zener Z1.

The traditional power generation circuit has the advantages of simple circuit and low cost. The disadvantage is that the circuit has a poor accuracy of the output voltage. To solve the above problems, more circuit functions are integrated.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a take self recovery excessive pressure and excess temperature protect function's power generation circuit to solve the problem that provides among the above-mentioned background art.

In order to achieve the above object, the utility model provides a following technical scheme:

a power generation circuit with self-recovery overvoltage and overtemperature protection functions comprises a diode D1, an error amplifier AMP, a regulating tube T1 and a resistor R1, wherein the anode of the diode D1 is connected with an input signal Vin, the cathode of a diode D1 is connected with a resistor R1 and a resistor R2, the other end of the resistor R1 is connected with the drain of a regulating tube T1, the gate of the regulating tube T1 is connected with a resistor Rc, a capacitor Cc and the collector of a triode T2, the base of the triode T2 is connected with the other end of a resistor R2 and a resistor R3, the source of a regulating tube T1 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with a resistor Rf1, a capacitor C1 and an output end Vout, the other end of the Rf1 is connected with a resistor Rf2 and the inverting input end of the error amplifier AMP, the non-inverting input end of the error amplifier AMP is connected with a reference voltage, the output end of the error amplifier, The other terminal of capacitor Cc, the other terminal of resistor Rf2, and ground.

As a further aspect of the present invention: the regulating tube T1 may use a power MOS or a power transistor.

As a further aspect of the present invention: the triode V2 is an NPN triode.

As a further aspect of the present invention: the resistor Rc and the capacitor Cc constitute a frequency compensation circuit.

As a further aspect of the present invention: the resistor R2 and the resistor R3 have the same temperature coefficient.

Compared with the prior art, the beneficial effects of the utility model are that: the utility model discloses take self-resuming excessive pressure and excess temperature protect function's power to produce circuit structure compactness, output voltage can the accurate configuration to have the excessive pressure protect function that can self-resume and the excess temperature protect function that can self-resume.

Drawings

Fig. 1 is a power supply circuit diagram based on power MOS.

Fig. 2 is a power supply circuit diagram based on a power transistor.

Fig. 3 is a circuit diagram of a power supply generation circuit with over-temperature protection.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 3, embodiment 1: in an embodiment of the present invention, a power generating circuit with self-recovery overvoltage and over-temperature protection function includes a diode D1, an error amplifier AMP, a regulating tube T1 and a resistor R1, the anode of the diode D1 is connected to an input signal Vin, the cathode of the diode D1 is connected to a resistor R1 and a resistor R2, the other end of the resistor R1 is connected to the drain of the regulating tube T1, the gate of the regulating tube T1 is connected to a resistor Rc, a capacitor Cc and the collector of a transistor T2, the base of the transistor T2 is connected to the other end of the resistor R2 and a resistor R3, the source of the regulating tube T1 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the resistor Rf1, the capacitor C1 and an output terminal Vout, the other end of the resistor Rf1 is connected to the resistor Rf2 and the inverting input terminal of the error amplifier AMP, the non-inverting input terminal of the error amplifier AMP, the emitter of the transistor T2 is connected to the other end of the resistor R3, the other end of the capacitor Cc, the other end of the resistor Rf2, and ground.

In the initial state Vin, Vout is 0, the feedback voltage Vf is 0, the output of the error amplifier AMP is high, the MOS transistor T1 is turned on, Vin charges the capacitor C1 and the load through D1, R1, T1, and D2, and the voltage Vout rises.

When the output voltage Vout rises, Vf also rises. Vf is connected to the inverting input terminal of the error amplifier AMP. When the Vf voltage is smaller than the Vref voltage, the output of the error amplifier AMP is at a high level, the regulating transistor T1 continues to charge, and Vout rises. The regulating tube T1 is turned off until the output voltage Vout stabilizes. If the output voltage Vout is too high, the voltage value of Vf is lower than the voltage value of Vref, at this time, the output of the error amplifier AMP is low, the regulating tube T1 is turned off, and Vout is decreased by the influence of the load discharge.

In a steady state, the voltage value of the output sampling voltage Vf is:

when Vf = Vref, then

。

Therefore, the output voltage Vout at this time is determined by the value of Vref and the feedback resistances Rf1 and Rf 2. From the above theoretical analysis, the steady-state value of the output voltage Vout is independent of the tuning tube T1, and the output value is not affected by the T1 parameter. The regulating tube T1 may use a power MOS or a power transistor.

In addition, the Vref can use a Zener diode as a voltage regulator to reduce the cost, and a reference voltage source can also be adopted. When Vref employs a reference voltage source, the characteristic of the reference voltage source is that the output voltage is independent of supply voltage and temperature. Therefore, when Vref employs a reference voltage source, the output voltage Vout is also independent of temperature.

The frequency compensation circuit is composed of Rc and Cc, forming a first order low pass filter with a 3dB bandwidth.

By adjusting the values of Rc and Cc, the loop parameters of the power supply circuit can be changed, thereby achieving a balance of stability and fast regulation response.

Other types of filters may be used in the frequency compensation circuit to obtain loop characteristics more suitable for the application.

The diode D2, which prevents reverse conduction, functions to ensure that current can only flow from the input Vin to the output Vout, making use of the unidirectional conductivity of the diode to ensure that the branch conducts in one direction. The function of the diode is that when the input Vin is normally or abnormally closed, the input voltage Vin will be rapidly reduced, and the output part Vout has the existence of C1, which may result in that the falling speed of Vout will be slower, which may result in that Vin < Vout, and at this time, if the diode D2 is not provided, a reverse voltage and a current from Vout to Vin may be generated, which may result in that the device breaks down and damages the circuit.

The rectifier D1 is used to make the power circuit support Vin not only as dc input, but also as ac input. If Vin is a dc input, rectifier D1 may be omitted.

The overvoltage and temperature protection circuit of the power generation circuit consists of a resistor R2, a resistor R3 and an NPN triode T2. The transistor T2 functions as a switching tube in the circuit, and operates in an off state and a saturation state. If the D1 rectifier is neglected, the divided voltage values of R2 and R3 are

。

The turn-on voltage of the transistor T2 is Vbe, and if the transistor is made of silicon, the Vbe voltage value is around 0.7V at normal temperature. If the triode is a germanium tube, the voltage is near 0.3V. The principle analysis was performed here using a silicon tube.

Under normal conditions, the resistance of R3 is much smaller than that of R2, i.e., Vb is normally set to be less than Vbe, transistor T2 is in the off state, and the power circuit operates normally.

Overvoltage protection function of the circuit: when the input voltage is too high, namely Vin is very high, Vb is greater than Vbe, the triode T2 is conducted, the grid voltage of the MOS transistor T1 is pulled low, the MOS transistor T1 is closed, the path between the input and the output is closed, the input too high voltage cannot be guided to the output Vout end, and therefore the subsequent circuit is protected. When the input voltage is normal, Vb is smaller than Vbe, the triode T2 is closed, the power generation circuit works normally, and the overvoltage protection function can be recovered.

The over-temperature protection function of the circuit: the over-temperature protection function of the circuit can be realized without adopting an additional circuit or a device, and the over-temperature protection is self-recoverable. The principle is as follows:

the resistor has the characteristic of positive temperature coefficient, and the resistance value of the resistor can be expressed by adopting the temperature coefficient of a first-order approximate resistor

Wherein RT0 is the resistance of the resistor at normal temperature T0, TCR is the temperature coefficient of the resistor, T is the working temperature of the resistor, and RT is the resistance of the resistor at temperature T.

Example 2: based on example 1, if the resistors R2 and R3 are made by the same process and material, then R2 and R3 have the same or similar temperature coefficients, and at the temperature T, the resistance value can be expressed as.

R2：

R3：

Thus, at temperature T, Vb is expressed as:

Vb:

through the above analysis, the voltage value of Vb is not affected by temperature, i.e., the voltage value of Vb is independent of temperature.

According to semiconductor theory, the triode input Vbe is a PN forward biased diode, the forward conducting voltage Vbe of the diode is a negative temperature coefficient, namely the voltage value of the Vbe is reduced along with the rise of temperature.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A power generation circuit with self-recovery overvoltage and overtemperature protection functions comprises a diode D1, an error amplifier AMP, a regulating tube T1 and a resistor R1, and is characterized in that the anode of the diode D1 is connected with an input signal Vin, the cathode of the diode D1 is connected with the resistor R1 and a resistor R2, the other end of the resistor R1 is connected with the drain of the regulating tube T1, the gate of the regulating tube T1 is connected with the resistor Rc, a capacitor Cc and the collector of a triode T2, the base of the triode T2 is connected with the other end of the resistor R2 and a resistor R3, the source of the regulating tube T1 is connected with the anode of the diode D2, the cathode of the diode D2 is connected with the resistor Rf1, the capacitor C1 and an output end Vout, the other end of the resistor Rf1 is connected with the resistor Rf2 and the inverting input end of the error amplifier AMP, the non-inverting input end of the error amplifier, the emitter of the transistor T2 is connected to the other end of the resistor R3, the other end of the capacitor Cc, the other end of the resistor Rf2, and ground.

2. The power generation circuit with self-recovery over-voltage and over-temperature protection function of claim 1, wherein the regulating transistor T1 can be a power MOS or a power transistor.

3. The power generation circuit with self-recovery over-voltage and over-temperature protection function of claim 1, wherein the transistor V2 is an NPN transistor.

4. The power generation circuit with self-recovery overvoltage and overtemperature protection function of claim 3, wherein the resistor Rc and the capacitor Cc form a frequency compensation circuit.

5. The power generation circuit with self-recovery over-voltage and over-temperature protection function of claim 1, wherein the resistor R2 and the resistor R3 have the same temperature coefficient.