CN213185485U

CN213185485U - Digital set-top box power protection circuit

Info

Publication number: CN213185485U
Application number: CN202021680961.9U
Authority: CN
Inventors: 李峰
Original assignee: Shenzhen Goodidea Technology Co ltd
Current assignee: Shenzhen Goodidea Technology Co ltd
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2021-05-11
Anticipated expiration: 2030-08-12

Abstract

The utility model discloses a digital set-top box power protection circuit, which relates to the technical field of set-top boxes and comprises a power input voltage sampling circuit and a power output signal switching circuit, the power output signal switching circuit comprises a field effect tube 1M2, a resistor 1R89 and a resistor 1R90, a G pole of the field effect tube 1M2 is connected with the resistor 1R89 and the resistor 1R90 in series, the power input voltage sampling circuit comprises a divider resistor 1R87, a divider resistor 1R88 and a triode 1Q2, the divider resistor 1R87 is connected with a divider resistor 1R88 in series, the divider resistor 1R87 is also connected with an S pole of the field effect tube 1M2, a base electrode of the triode 1Q2 is connected between the divider resistor 1R87 and the divider resistor 1R88, an emitter electrode of the triode 1Q2 is connected with the S pole of the field effect tube 1M2, a collector electrode of the triode 1Q2 is connected between the resistor 1R 465 and the resistor 1R90, the conduction and the cutoff, can protect back level step-down circuit, the utility model discloses simple structure, it is compatible strong, protection response time is fast (2-3us) moreover, can effectively protect back level step-down circuit not receive the damage.

Description

Digital set-top box power protection circuit

Technical Field

The utility model relates to a digital set-top box technical field, concretely relates to digital set-top box power protection circuit.

Background

With the continuous development of network and electronic technology, the application of network digital set-top box products in families has become very wide. Because the power interface of the network digital set-top box generally adopts the 'big round head' interface with general specification, and the adapter power supply which accords with the big round head interface on the market has multiple voltage output specifications, the user directly purchases and uses the adapter power supply and has larger risk to damage the set-top box.

At present, a power supply protection circuit of a network digital set top box is designed by adopting a special overvoltage turn-off protection chip, so that the cost is high, the protection response time is slow (100us-1ms), certain requirements are imposed on a post-stage step-down circuit, the universality is poor, and the post-stage step-down circuit cannot be reliably protected from being damaged.

SUMMERY OF THE UTILITY MODEL

In order to overcome the not enough of prior art, the utility model provides a digital STB power protection circuit can protect the back level drop circuit not to receive the damage.

The utility model provides a technical scheme that its technical problem adopted is: the digital set top box power supply protection circuit is improved in that the digital set top box power supply protection circuit comprises a power supply input voltage sampling circuit and a power supply output signal switch circuit, wherein the power supply input voltage sampling circuit is electrically connected with the power supply output signal switch circuit;

the power output signal switch circuit comprises a field effect transistor 1M2, a resistor 1R89 and a resistor 1R90, wherein the S pole of the field effect transistor 1M2 is electrically connected with the power input voltage sampling circuit, the G pole of the field effect transistor 1M2 is connected with the resistor 1R89 and the resistor 1R90 in series, and the resistor 1R90 is also grounded;

the power input voltage sampling circuit comprises a divider resistor 1R87, a divider resistor 1R88 and a triode 1Q2, the divider resistor 1R87 and the divider resistor 1R88 are connected in series, the divider resistor 1R88 is grounded, the divider resistor 1R87 is connected with the S pole of a field-effect tube 1M2, the base electrode of the triode 1Q2 is connected between the divider resistor 1R87 and the divider resistor 1R88, the emitter electrode of the triode 1Q2 is connected with the S pole of the field-effect tube 1M2, the collector electrode of the triode 1Q2 is connected between the resistor 1R89 and the resistor 1R90, and the rear-stage voltage reduction circuit can be effectively protected by switching on and off the field-effect tube 1M 2.

As an improvement of the technical scheme, a capacitor 1C49 is arranged between the S pole and the G pole of the field effect transistor 1M 2.

As an improvement of the above technical solution, the D pole of the field effect transistor 1M2 is connected with a filter circuit.

As an improvement of the above technical solution, the filter circuit includes a capacitor 1C51, a capacitor 1C50, and a polar capacitor 1EC2, and the capacitor 1C51, the capacitor 1C50, and the polar capacitor 1EC2 are connected in parallel;

the negative pole of the polar capacitor 1EC2 is grounded, and the positive pole is provided with a 5V voltage interface and a direct-current voltage input interface.

As an improvement of the technical scheme, an adapter socket is arranged on the S pole of the field effect transistor, and the adapter socket is further connected with a direct current 5V voltage input end.

As an improvement of the technical scheme, the resistance value of the resistor 1R90 is 10K.

As an improvement of the technical scheme, the model of the triode 1Q2 is MMBT 3906.

As an improvement of the technical scheme, the type of the field effect transistor 1M2 is AO 3415.

The utility model has the advantages that: the utility model discloses simple structure, it is compatible strong, whole circuit occupy the integrated circuit board area less, and protection response time is fast (2-3us), can effectively protect the back-stage step-down circuit not receive the damage.

Drawings

The present invention will be further explained with reference to the drawings and examples.

Fig. 1 is a schematic circuit diagram of the present invention.

Detailed Description

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive labor based on the embodiments of the present invention all belong to the protection scope of the present invention. In addition, all the connection/connection relations referred to in the patent do not mean that the components are directly connected, but mean that a better connection structure can be formed by adding or reducing connection auxiliary components according to specific implementation conditions. The utility model discloses each technical feature in the creation can the interactive combination under the prerequisite that does not contradict conflict each other.

Referring to fig. 1, the utility model discloses a digital set-top box power protection circuit, which comprises a power input voltage sampling circuit 1 and a power output signal switch circuit 2, wherein the power input voltage sampling circuit 1 is electrically connected with the power output signal switch circuit 2; power output signal switch circuit 2 includes field effect transistor 1M2, resistance 1R89 and resistance 1R90, field effect transistor 1M2 model is AO3415, resistance 1R90 resistance is 10K, field effect transistor 1M2 'S the S utmost point and power input voltage sampling circuit 1 electric connection, field effect transistor 1M 2' S the G utmost point and resistance 1R89 and resistance 1R90 establish ties, resistance 1R90 still ground connection, through field effect transistor 1M2 switch on with cut off, can effectively protect back level step-down circuit.

In the above embodiment, the power input voltage sampling circuit 1 transmits the voltage signal to the fet 1M2, the fet 1M2 recognizes the voltage signal, the fet 1M2 is turned on at low level, and the fet 1M2 is turned off at high and low levels, thereby effectively protecting the subsequent step-down circuit.

The S pole of the field effect transistor is provided with an adapter socket, and the adapter socket is also connected with a direct current 5V voltage input end; the D pole of the field effect transistor 1M2 is connected with a filter circuit 3, the filter circuit 3 comprises a capacitor 1C51, a capacitor 1C50 and a polar capacitor 1EC2, the capacitor 1C51, the capacitor 1C50 and the polar capacitor 1EC2 are connected in parallel, the negative pole of the polar capacitor 1EC2 is grounded, and the positive pole is provided with a 5V voltage interface and a direct-current voltage input interface. The power input voltage sampling circuit comprises a divider resistor 1R87, a divider resistor 1R88 and a triode 1Q2, wherein the model of the triode 1Q2 is MMBT3906, the divider resistor 1R87 and the divider resistor 1R88 are connected in series, the divider resistor 1R88 is also grounded, the divider resistor 1R87 is also connected with the S pole of the field-effect tube 1M2, the base of the triode 1Q2 is connected between the divider resistor 1R87 and the divider resistor 1R88, the emitter of the triode 1Q2 is connected with the S pole of the field-effect tube 1M2, the collector of the triode 1Q2 is connected between the resistor 1R89 and the resistor 1R90, and a capacitor 1C49 is arranged between the S pole and the G pole of the field-effect tube 1M 2.

In the above embodiment, the filter circuit 3 belongs to a very mature technical means, and the present invention will not be summarized in detail on the filter circuit 3. When the input voltage of the power supply is in a normal range, the triode 1Q2 can be cut off under the action of the voltage division output of the voltage division resistor 1R87 and the voltage division resistor 1R88, and the collector of the triode 1Q2 is controlled to output a low level; when the power output is higher than the normal range, the voltage dividing resistor 1R87 and the voltage dividing resistor 1R88 divide the voltage output, so that the triode 1Q2 is conducted, and the collector of the triode 1Q2 is controlled to output high level.

When the utility model is implemented specifically, when the power input voltage is in the normal range, the divider resistance 1R87 and the divider resistance 1R88 divide the voltage and output to cut off the triode 1Q2, and because of the effect of the resistance 1R90, the collector of the triode 1Q2 outputs the low level, the field effect transistor 1M2 is conducted, and the rear-stage circuit works normally; when the power output is higher than the normal range, the voltage dividing output of the voltage dividing resistor 1R87 and the voltage dividing output of the voltage dividing resistor 1R88 enables the triode 1Q2 to be conducted and output high level, the field effect transistor 1M2 is cut off, the power supply path is cut off, and the rear-stage buck chip is protected.

While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined by the appended claims.

Claims

1. A power supply protection circuit of a digital set top box is characterized by comprising a power supply input voltage sampling circuit and a power supply output signal switch circuit, wherein the power supply input voltage sampling circuit is electrically connected with the power supply output signal switch circuit;

2. The power protection circuit of claim 1, wherein a capacitor 1C49 is provided between S pole and G pole of said FET 1M 2.

3. The power protection circuit of claim 1, wherein a filter circuit is connected to the D pole of the fet 1M 2.

4. The digital set-top box power protection circuit as claimed in claim 3, wherein the filter circuit comprises a capacitor 1C51, a capacitor 1C50 and a polar capacitor 1EC2, and the capacitor 1C51, the capacitor 1C50 and the polar capacitor 1EC2 are connected in parallel;

5. The digital set-top box power supply protection circuit as claimed in claim 1, wherein an adapter socket is provided at the S-pole of the fet, and the adapter socket is further connected to a dc 5V voltage input terminal.

6. The digital set-top box power protection circuit of claim 1, wherein the resistor 1R90 is 10K.

7. The digital set-top box power protection circuit of claim 1, wherein the triode 1Q2 model is MMBT 3906.

8. The power protection circuit of claim 1, wherein said fet 1M2 is model AO 3415.