CN215300611U

CN215300611U - Photoelectric coupler aging circuit

Info

Publication number: CN215300611U
Application number: CN202121678781.1U
Authority: CN
Inventors: 代骞; 王智; 吴双彪; 杨军; 钱军军; 杨辉; 任真伟
Original assignee: China Zhenhua Group Yongguang Electronics Coltd
Current assignee: China Zhenhua Group Yongguang Electronics Coltd
Priority date: 2021-07-23
Filing date: 2021-07-23
Publication date: 2021-12-24
Anticipated expiration: 2031-07-23

Abstract

A photoelectric coupler aging circuit comprises an input end power supply V1, an output end power supply V2, an output end sampling circuit, an aged optical coupler, a current limiting protection circuit, a one-way conduction circuit, an aging display circuit and a fault warning circuit. One end of the output end sampling circuit is connected with the positive electrode of the V2, the other end of the output end sampling circuit is connected to the positive electrode end of the optocoupler output unit through the aging display circuit, and the negative electrode end of the optocoupler output unit is connected with the high-level output end of the current-limiting protection circuit; the positive electrode of the V1 is respectively connected to the current-limiting protection circuit and the positive electrode end of the optical coupler input unit; the negative end of the optical coupler input unit is connected with the negative end of the optical coupler output unit through a one-way conduction circuit; the fault display circuit is connected in parallel with the high level output end and the low level output end of the current-limiting protection circuit. The problems that the existing optical coupler burn-in circuit is unstable in burn-in power and unreliable in burn-in quality are solved. The aging device is suitable for aging the photoelectric coupler with high reliability and high quality consistency.

Description

Photoelectric coupler aging circuit

Technical Field

The utility model relates to a components and parts burn-in technical field particularly, relates to a photoelectric coupler burn-in circuit.

Background

In the occasion that needs physical isolation on electricity, photoelectric coupler (optical coupler for short) transmission signal is commonly used, and its transmission process is: the input end converts the electric signal into an optical signal, and the output end receives the optical signal and converts the optical signal into the electric signal; the input end of the photoelectric conversion module is physically isolated from the output end, and the input end is usually an electro-optical conversion module, such as a Light Emitting Diode (LED), a Laser Diode (LD) and the like; the output end is a photoelectric conversion module, such as a phototriode, a light receiving diode PD and the like.

At present, the aging screening of the optical coupler is divided into two steps of input end aging and output end aging. When the output end is aged and screened, a specified forward current I needs to be applied to a light emitting diode in the optical coupler_FWhile applying a prescribed V to the phototriode at the output terminal_CETo make it reach rated power (P)_CM) And (5) aging.

Fig. 1 shows a circuit used for aging an output end of an optical coupler (OC1) in the prior art, and the working principle of the circuit is as follows: regulating output voltage V2 to specified V_CEVoltage values (typically between 0.6 and 0.75 times the breakdown voltage); ros is output end sampling resistor, and the voltage at two ends of the resistor is I_CCurrent at R_OSThe resulting voltage drop; i is controlled by regulating V1 voltage and input sampling resistor Ris_FMake the output end I_CCurrent and V_CEThe product of the voltages reaches P_CMThereby achieving the purpose of aging.

Since the optical coupler is producedThe problem of certain individual consistency and batch repeatability exists in the process, the CTR of the same optical coupler fluctuates under different work conditions, such as temperature fluctuation and other reasons, so that the power P is caused_CGenerating a change; the optical couplers of the same batch and the same type have individual difference on the parameter of CTR, if each optical coupler is specifically connected, some CTR is larger, some CTR is smaller, and the difference value is different from tens of percent to hundreds of percent.

Due to the fact that the problem that the power of the output end aging is unstable exists, in the actual aging process, the problems that a phototriode at the output end is short-circuited and broken, series resistors Ros in an aging circuit are damaged and the like occur.

Therefore, in the prior art, the aging power of the output end triode is unstable and fluctuates greatly, so that the over-current stress is easily caused, and the service life of the optocoupler is unstable after aging, thereby causing uncontrolled quality and reliability; the phototriode is directly damaged when the power fluctuation is serious because no protective measures are taken in the circuit.

For the optical coupler used for finishing the aging of the output end, the optical coupler directly damaged by the phototriode also belongs to a better condition from the viewpoint of quality control, and because the optical coupler is removed, the potential quality hazard to goods supply products cannot be caused; there is also a case where: output power exceeding P_CMThe rated value, the output triode has born the electrical stress promptly, but has not become invalid yet, these opto-couplers can not be rejected to parameter detection this moment, they will be sneaked into in the qualified product, this is very unfavorable to the quality control of product, because this kind of life-span of suffering from the opto-coupler of electrical stress is unstable, from the quality management and control, especially avoid the emergence of this kind of condition, nevertheless present use circuit only can lead to this kind of condition to take place and can not avoid or guard against, bring uncontrollable reliability hidden danger for the opto-coupler after smelting old on the contrary.

Therefore, the utility model is provided specially.

Disclosure of Invention

The utility model discloses aim at solving and have following problem in the current photoelectric coupler circuit of smelting always:

(1) the aging power of the output end triode is unstable, the fluctuation is large, the over-current stress is easy to cause, and the service life of the optocoupler is unstable after aging, so that the quality and the reliability are not controlled.

(2) The phototriode is directly damaged when the power fluctuation is serious because no protective measures are taken in the circuit.

Therefore, the utility model provides a photoelectric coupler circuit of smelting always, as shown in figure 2. The method comprises the following steps: the device comprises an input end power supply V1, an output end power supply V2, a sampling resistor R1, a burn-in display light emitting diode D1, a burn-in optocoupler OC1, an isolation diode D2, a fault warning light emitting diode D3, a D3 protection resistor R2, a current-limiting protection triode Q1, a Q1 driving resistor R3 and a Q1 current-limiting resistor R4.

The input end power supply V1 is connected with the output end power supply V2 in series, the negative pole of V1 is grounded, and the positive pole of V1 is connected with the negative pole of V2; the positive electrode of V2 is connected with the positive electrode of D1 through R1, the negative electrode of D1 is connected with the collector electrode of the phototriode of OC1, and the emitter electrode of the phototriode of OC1 is connected with the collector electrode of Q1; one path of the positive electrode of the V1 is connected with the positive electrode end of the OC1 input transmitting end photodiode, and the other path of the positive electrode of the V1 is connected with the base electrode of the Q1 through R3; the anode end of the light emitting diode at the OC1 input end is connected with the anode of the V1, the cathode end of the light emitting diode at the OC1 input end is connected with the anode of the D2, and the cathode of the D2 is connected with the emitter of the phototriode of OC 1; one end of R2 is connected with the collector of Q1, the other end of R2 is connected with the anode of D3, and the cathode of D3 is connected with the emitter of Q1; the emitter of Q1 is grounded through R4.

Therefore, the utility model has the advantages that:

(1) the aging power is stable, and the problem of over-power or under-power aging of an output end triode is avoided

(2) The problem that the quality uncontrollable factors are introduced in the aging link of the existing aging circuit is solved. .

(3) The problem of current circuit of smelting old have the direct damage of great proportion product is solved.

(4) Has short-circuit protection, overcurrent protection, normal aging indication and short-circuit state indication functions

(5) The circuit is easy to expand in parallel, is convenient for aging of mass products, and can safely and reliably remove early failure products.

Drawings

Fig. 1 is a schematic diagram of an original burn-in circuit structure.

Fig. 2 is a schematic diagram of the unit aging circuit structure of the present invention.

In the figure: v1 is input power supply, V2 is output power supply, R1 is sampling resistor, D1 is aging display led, OC1 is aged optocoupler, D2 is isolation diode, D3 is fault warning led, R2 is protection resistor, Q1 is current limiting protection triode, R3 is driving resistor, R4 is current limiting resistor.

Detailed Description

The operating state of the circuit shown in fig. 2 is analyzed as follows:

(1) output burn-in power analysis

The aging power of a triode at the output end of the optical coupler of the circuit is calculated by the following equation set:

solving the equation set to obtain:

P_C＝I_C·(V₂-V_R1-V_D1+V_F+V_D2)

in the above formula V_R1For R1 to sample the voltage across the resistor, R1 is usually a resistor with a small resistance, the voltage across the resistor is controlled within tens of millivolts, and is negligible, and V is_D1、V_F、V_D2Are diode forward voltage drops which vary little, can be considered as a constant value, and V_D1Approximately equal to V_FAnd V_D2The sum (the device is selected and ensured) can be mutually offset, so the aging power of the triode at the output end of the optical coupler is as follows:

P_C≈I_C·V₂

as can be seen from the above equation, the influence P_CIs that I is_CAnd V₂，V₂Guaranteed by power supply precision and only I remains_CIs influencing the aging power P_COf (c) is determined. Then, I_CHow stable isIs there?

(2) Output terminal I_CAmperometry

The circuit principle shows that:

in the circuit, Q1 is designed to be in saturation conduction, when the ratio of collector current to base current of Q1 is far less than the amplification factor, V_Q1CEAbout 0.3V, V_F、V_D2The value of the voltage difference is basically kept unchanged, the forward voltage drop of a diode at the input end of the optical coupler is usually about 1.1V, and V is_D2Around 0.6V, V_FAnd V_D2The sum of the forward pressure drops of (a) is about 1.7V. Due to V_Q1CE、V_F、V_D2If the value of (d) remains substantially unchanged, then:

V_R4＝V₁-1.7-0.3＝V₁-2

can see V_R4Voltage is composed of V₁Supply voltage determination, once V₁Voltage is fixed then V_R4Almost constant, and then I_EConstant, the upper limit of the current in the circuit is limited to I_EAnd will not generate significant current as in the circuit of fig. 1. In FIG. 1, I_C＝I_FX CTR, the difference in CTR leading to I_CThe PC power is increased due to the current change and the increase of the IC current, the possibility that the actual power exceeds the rated power exists, and in an extreme case, the product is likely to be subjected to thermal breakdown, the loop resistance is small at the moment, and then a large current is generated. When the circuit of FIG. 1 is used for actual aging, the phenomenon of triode breakdown at the output end also occurs; and an open circuit phenomenon exists, wherein the open circuit condition is that short circuit occurs firstly, and other components of the loop are not damaged, so that the bonding lead in the triode at the output end of the optical coupler is fused due to overcurrent.

Further calculate I_BCurrent:

in the formula V_Q1BEAbout 0.7V, R3 can be selected to be a larger resistor, so that I_BIs much less than I_CThen omit I_BThen, the following can be obtained:

I_C＝I_E-I_F

in the above formula I_CAnd I_FThe distribution ratio of (A) is related to the CTR of the actual opto-coupler product (in terms of I)_C＝I_FX CTR distribution) due to total current I_ERemains unchanged, if CTR becomes small, I_CWill be reduced by_FWill increase, I_FIncrease and decrease_CIs increased to further maintain I_CSubstantially stable and vice versa.

(3) Triode Q1 working state analysis

Determine whether Q1 is conducting in saturation: in-circuit I by calculating Q1_CAnd I_BThe ratio of (a) to (b) is usually several tens, and for safety, a transistor with a magnification of more than 150 times may be used to ensure that Q1 enters a saturated conduction state. The parameter indexes have no problem in circuit design and device selection; for need of larger I_CThe current optocoupler can ensure that the Q1 triode has enough driving current by reducing R3. Therefore, the Q1 in the circuit of fig. 2 is guaranteed to operate in a saturated on-state.

The circuit shown in fig. 2 has the following functions:

the circuit has the following functions:

(1) the aging indicating function: only the D1 indicator light is on to indicate that the product is aging normally.

(2) Short circuit indication function: the simultaneous lighting of D1 and D3 indicates that the output end of the optical coupler is abnormal, and the output end is usually short-circuited or has a small resistance value.

(3) Overcurrent protection and short-circuit protection functions: total current limit of circuit is I_EEven if the output end of the optical coupler is short-circuited, the current is also limited to I_EAnd the damage to products and other components in the circuit due to overlarge current is prevented.

As shown in fig. 2:

1. selection of R4, R3

Aiming at different optocouplers, because the required currents are inconsistent, potentiometers can be adopted for R4 and R3, and in consideration of the problem of automatic control, digital potentiometers can be adopted, and the value of R4 is determined by the required I_EThe current and the voltage of V1 determine that R3 can select about 10 times of R4 value.

2. Selection of R2

When the R2 is short-circuited at the output end of the optical coupler, the current-limiting resistor of the indicator light D3 can be selected to be about 20K omega.

3. Selection of Q1

Q1 selecting V generally_(BR)CEAnd when the voltage is more than 100V, the current is more than 2 times IE, and the current amplification factor beta is more than 150.

Claims

1. A photoelectric coupler burn-in circuit is characterized by comprising: an input end power supply V1, an output end power supply V2, a sampling resistor R1, a burn-in display light emitting diode D1, a burn-in optocoupler OC1, an isolation diode D2, a fault warning light emitting diode D3, a D3 protection resistor R2, a current-limiting protection triode Q1, a Q1 driving resistor R3 and a Q1 current-limiting resistor R4;

2. The aging circuit of a photoelectric coupler as claimed in claim 1, wherein said R3, R4 are potentiometers.

3. The aging circuit of a photoelectric coupler as claimed in claim 2, wherein said R3, R4 are digital potentiometers.

4. The aging circuit of a photoelectric coupler as claimed in claim 1, wherein the value of R4 is represented by I_EThe resistance value of R3 was determined to be about 10 times that of R4 by V1-2.

5. The aging circuit of a photocoupler as claimed in claim 1, wherein said R2 is of a resistance of about 20K Ω.

6. The aging circuit of a photoelectric coupler as claimed in claim 1, wherein the V of Q1_(BR)CEGreater than 100V, the current amplification of Q1 is greater than 150.