High-voltage protection circuit in ultrasonic diagnosis equipment

Abstract

The utility model discloses a high-voltage protection circuit in ultrasonic diagnosis equipment. In the circuit, R1 is used for current detection; the R2 and the VR1 form a voltage division network to provide input voltage for the voltage detection circuit, and the voltage division network can also sense the change of voltage drop on the R1; u1 is used for voltage detection, and the output of the U1 is 3.3 V; the Q1, the Q2, the R4, the R5 and the R6 form a protection switch circuit. Compared with the existing various common protection circuits, the high-voltage protection circuit in the ultrasonic diagnosis equipment has the advantages of wide protection voltage range, capability of detecting both high voltage and low voltage, capability of setting detection current, stable and reliable work, few devices and low cost.

Description

Technical Field

[0001] The utility model relates to the technical field of ultrasonic equipment protection circuits, in particular to a high-voltage protection circuit in ultrasonic diagnostic equipment. Background Art

[0002] In portable ultrasonic diagnostic equipment, the high-voltage switch chip loads ultrasonic waves onto the ultrasonic probe transducer and transmits them to the target. The ultrasonic waves are generated by the high-voltage switch chip, and the voltage reaches 60 to 90V during transmission. In production testing, there are often some abnormal operations that burn out the high-voltage chip and ultrasonic probe. This circuit is designed to solve this problem.

[0003] Some of the existing protection circuits are for low voltage and high current scenarios, such as Figure 1 Protection circuits can be used for 5V short-circuit protection of USB bus; others use voltage-side current detection chips for protection. These protection circuits are very effective in low-voltage and high-current applications. The working voltage is not higher than 20V. Even if there is, the cost is very high. However, they are not suitable for high-voltage and low-current application scenarios. For example, the protection of high-voltage working scenarios such as 40V, 60V, and 90V is completely inapplicable, because the Vbe voltage of the switching transistor is 0.7V, and the Vgs voltage of the MOS tube is ±20, which means that the Vgs and Vbe of the transistors loaded on these protection circuits will exceed these withstand voltage values ​​and will be burned. The following circuit is a very commonly used protection circuit. It is easy to implement short-circuit protection for voltages of 5V or less, but it cannot be implemented for 60V high-voltage protection, even if the withstand voltage values ​​of Q1 and Q2 are increased. Utility Model Content

[0004] The main purpose of the utility model is to provide a high-voltage protection circuit in ultrasonic diagnostic equipment, which cuts off the high-voltage output when the high-voltage switch chip at the rear end has an abnormality such as overcurrent or short circuit, so as to protect the device from damage.

[0005] The utility model proposes a high-voltage protection circuit in an ultrasonic diagnostic device, wherein:

[0006] R1, for current detection;

[0007] R2 and VR1 form a voltage divider network to provide input voltage for the voltage detection circuit;

[0008] U1 is used for voltage detection, and its output is 3.3V;

[0009] Q1, Q2, R4, R5, and R6 form a protection switch circuit.

[0010] Among them, the left side of R1 is connected to the 60V voltage input, and the right side of R1 is connected to C1 pin 1, R2 upper pin, R5 upper pin, R4 upper pin, and Q2 pin E;

[0011] The lower pin of R5 is connected together with the lower pin of R6 and pin C of Q1.

[0012] Preferably, when R1 is used for current detection, if there is a 10mA current on Q2, there is a 2V voltage drop on R1, and a 20mA current has a 4V voltage drop, and so on.

[0013] Preferably, a voltage divider network composed of R2 and VR1 provides an input voltage to the voltage detection circuit, which can sense the change of the voltage drop across R1.

[0014] Preferably, U1 performs voltage detection, and its output is 3.3V; determine the load current of the rear-end high-voltage circuit, and on this basis increase 20mA as a margin, adjust the resistance value of VR1 so that U1 outputs 3.3V, then increase the load by 10mA, and adjust VR1 so that the voltage output of U1 is 0V.

[0015] Preferably, a protection switch circuit is composed of Q1, Q2, R4, R5, and R6. When U1 has a 3.3V output, it indicates that the back-end circuit is working normally, and Q1 and Q2 transistors are turned on to power the back end. At this time, the voltage drop of the protection circuit is extremely small and does not affect the power supply of the back-end circuit. When the back-end circuit is abnormal and the current is too large to exceed the set value, U1 output is 0, Q1 and Q2 are turned off, and the power supply to the back-end circuit is stopped until the abnormality of the back-end circuit is eliminated, and the protection circuit turns on Q1 and Q2 again to resume power supply.

[0016] The utility model discloses a high-voltage protection circuit in ultrasonic diagnostic equipment. Compared with various existing commonly used protection circuits, the protection voltage range is wide, both high voltage and low voltage can be detected, the detection current can be set, the operation is stable and reliable, the number of components is small, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 This is a high voltage protection circuit diagram for conventional ultrasonic diagnostic equipment;

[0019] Figure 2 A high voltage protection circuit in an ultrasonic diagnostic device according to an embodiment of the utility model Figure 1 ;

[0020] Figure 3A high voltage protection circuit in an ultrasonic diagnostic device according to an embodiment of the utility model Figure 2 .

[0021] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0023] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0025] The utility model proposes a high-voltage protection circuit in an ultrasonic diagnostic device, referring to Figure 2 In this circuit, R1 is used for current detection. If there is a 10mA current on Q2, there will be a 2V voltage drop on R1. A 20mA current will cause a 4V voltage drop, and so on.

[0026] The voltage divider network composed of R2 and VR1 provides input voltage to the voltage detection circuit, which can also sense the change of voltage drop on R1;

[0027] U1 performs voltage detection, and its output is 3.3V; determine the load current of the rear high-voltage circuit, and increase 20mA as a margin on this basis, adjust the resistance value of VR1, so that U1 outputs 3.3V, then increase the load by 10mA, and adjust VR1 so that the voltage output of U1 is 0V;

[0028] Among them, the left side of R1 is connected to the 60V voltage input, and the right side of R1 is connected to C1 pin 1, R2 upper pin, R5 upper pin, R4 upper pin, and Q2 pin E;

[0029] The lower pin of R5 is connected together with the lower pin of R6 and pin C of Q1.

[0030] The protection switch circuit is composed of Q1, Q2, R4, R5, and R6. When U1 has a 3.3V output, it means that the back-end circuit is working normally. The Q1 and Q2 transistors are turned on to power the back-end. At this time, the voltage drop of the protection circuit is very small and does not affect the power supply of the back-end circuit. When the back-end circuit is abnormal and the current is too large to exceed the set value, U1 output is 0, Q1 and Q2 are turned off, and the power supply to the back-end circuit is stopped until the abnormality of the back-end circuit is eliminated. The protection circuit turns on Q1 and Q2 again to restore the power supply.

[0031] Further, refer to Figure 3 ,

[0032] ①Connect one end of resistor R1 to an external 60V voltage;

[0033] ② Connect any end of resistors R2, R3, C3, the common end of VR1, and the VIN end of U1. This is voltage division. Adjust the value of VR1 to the minimum input voltage of U1 so that U1 outputs a high voltage.

[0034] ③ Connect any end of C1, R2, R4, R5 to the emitter E end of Q2, where is the voltage after current limiting sampling by R1;

[0035] ④ Connect the collector C terminal of Q2 to either end of C2, where the output voltage is for the back-end circuit;

[0036] ⑤ Connect any end of resistors R4 and R6 to the base B of Q2. The voltage here determines whether the switch tube Q2 is on or off.

[0037] ⑥ Connect any end of resistors R5 and R6 to the collector C of Q1. The high and low voltages here will also determine the on and off of Q2.

[0038] ⑦ Connect either end of resistor R3, OUT end of U1, and base B end of Q1. The high and low voltages here determine the on and off of Q1.

[0039] The working condition of this circuit is: the voltage of ① goes to ③ through R1; the voltage of ② makes ⑦ have 3.3V, then Q1 is turned on and ⑥ is turned on to ground, making the voltage of ⑤ 0 and turning on Q2, so the voltage of ③ goes to ④ through Q2 for use by the back end. If the back end circuit works normally, the protection circuit works well.

[0040] When the back-end circuit is overloaded or short-circuited, a large voltage drop will be generated on R1, making the voltage at ② very low, and U1 output is 0, so that there is no voltage at ⑦ and Q1 is cut off, ⑤ is a high voltage, Q2 is cut off, and there is no voltage at ④, thereby protecting the front end of the power supply from burning out.

[0041] Of course, in the circuit of this embodiment, C1 and C2 can be omitted and all functions can be achieved, and Q2 can be replaced by a PMOS tube.

[0042] A high voltage protection circuit in an ultrasonic diagnostic device of the utility model:

[0043] 1. Connection relationship of current and voltage detection circuit, VR1, R2 voltage divider senses the voltage drop change caused by R1 load change;

[0044] 2. VR1 adjusts the input voltage of U1 in the circuit and can accurately set the detection current;

[0045] 3. The connection relationship of R6 in the switch circuit of Q1, Q2, R4, R5, R6. It plays a buffering role and can ensure that Q2 can open normally and work stably during high voltage protection. If there is no R6, Q2 will burn out.

[0046] 4. The connection relationship of the entire protection circuit, Figure 2 The parameters in the circuit can provide 60V high voltage protection, and other voltages can be achieved by simply adjusting the parameters.

[0047] The above description is only a preferred embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the utility model concept, or directly / indirectly used in other related technical fields are included in the patent protection scope of the utility model.

Claims

1. A high voltage protection circuit in an ultrasonic diagnostic device, characterized in that: in: R1, for current detection; R2 and VR1 form a voltage divider network to provide input voltage for the voltage detection circuit; U1 is used for voltage detection, and its output is 3.3V; Q1, Q2, R4, R5, and R6 form a protection switch circuit; Among them, the left side of R1 is connected to the 60V voltage input, and the right side of R1 is connected to C1 pin 1, R2 upper pin, R5 upper pin, R4 upper pin, and Q2 pin E; The lower pin of R5 is connected together with the lower pin of R6 and pin C of Q1.

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