Wide voltage input circuit supporting car navigation screen and control method thereof

Abstract

The application provides a wide voltage input circuit for supporting a vehicle navigation screen, comprising a voltage detection control unit, a power input filter unit electrically connected with a storage battery, a DC / DC voltage reduction unit electrically connected with a load, a low-voltage output backup circuit electrically connected with the load, the input end of the voltage detection control unit, the input end of the DC / DC voltage reduction unit and the input end of the low-voltage output backup circuit are all electrically connected with the output end of the power input filter unit, and the enable end of the DC / DC voltage reduction unit and the enable end of the low-voltage output backup circuit are all electrically connected with the output end of the voltage detection control unit. The application provides a hardware circuit with high cost performance and wide input voltage support, and solves the problem of narrow voltage input range of similar products and abnormal working phenomenon caused by low storage battery voltage in some scenes. The application further provides a control method of the wide voltage input circuit for supporting the vehicle navigation screen.

Description

Technical Field

[0001] This invention relates to the field of power supply circuit design for vehicle navigation screens, and more particularly to a wide voltage input circuit and its control method that supports vehicle navigation screens. Background Technology

[0002] Currently, most in-vehicle navigation screens on the market do not have a wide enough input voltage range, which can cause the screen to go black when the engine is started, affecting the customer experience.

[0003] Therefore, it is necessary to design a wide voltage input circuit that supports in-vehicle navigation screens to overcome the above problems. Summary of the Invention

[0004] This invention provides a wide voltage input circuit and control method for supporting in-vehicle navigation screens, applicable to navigation / instrument displays in commercial vehicles. The purpose is to prevent the display from being affected by the voltage surge caused by the engine starting when the battery is pulled up. This invention solves at least some of the problems in the prior art.

[0005] This invention is implemented as follows:

[0006] This invention provides a wide voltage input circuit supporting in-vehicle navigation screens, including a voltage detection and control unit, a power input filter unit electrically connected to a battery, a DC / DC step-down unit electrically connected to a load, and a low-voltage output backup circuit electrically connected to the load. The input terminals of the voltage detection and control unit, the DC / DC step-down unit, and the low-voltage output backup circuit are all electrically connected to the output terminal of the power input filter unit. The enable terminals of the DC / DC step-down unit and the low-voltage output backup circuit are all electrically connected to the output terminal of the voltage detection and control unit.

[0007] Preferably, the voltage detection and control unit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a comparator. The reference voltage is connected to the input terminal of the fourth resistor R4 through the third resistor R3. The output terminal of the fourth resistor R4 is grounded. The input terminal of the fourth resistor R4 is electrically connected to the negative input terminal of the comparator. The positive input terminal of the comparator is electrically connected to the output terminal of the power input filter unit through the first resistor R1. The positive input terminal of the comparator is grounded through the second resistor R2. The enable terminal of the DC / DC step-down unit and the enable terminal of the low-voltage output backup circuit are both electrically connected to the output terminal of the comparator.

[0008] Preferably, the comparator is an LM2902 comparator.

[0009] Preferably, the power input filtering unit includes diode S3M, diode SM8S36A, trimmer resistor LFTB1487-302N-4.5A, and inductor MSS1278-473MD. The battery is connected in sequence to diode S3M, diode SM8S36A, trimmer resistor LFTB1487-302N-4.5A, and inductor MSS1278-473MD, and then connected to the input terminal of the first resistor R1.

[0010] Preferably, the DC / DC step-down unit includes a step-down converter TPS54561-Q1, an inductor SMTER65-6R8M-6A, a ferrite bead FBMA-11-322513-301A30T, and a diode MBRS540T3G. The output terminal of the power input filter unit is sequentially connected to the step-down converter TPS54561-Q1, the inductor SMTER65-6R8M-6A, the ferrite bead FBMA-11-322513-301A30T, and the diode MBRS540T3G, and then connected to the load. The output terminal OUT of the voltage detection and control unit is electrically connected to the EN enable port of the step-down converter TPS54561-Q1.

[0011] Preferably, the low-voltage output backup circuit includes a 2N7002 transistor, a FDD9510L-F085 power MOSFET, and an MSS1278-473MD inductor. The output terminal OUT of the voltage detection and control unit is electrically connected to the base of the 2N7002 transistor, the emitter of the 2N7002 transistor is grounded, the collector of the 2N7002 transistor is electrically connected to the gate of the FDD9510L-F085 power MOSFET, the source of the FDD9510L-F085 power MOSFET is electrically connected to the output terminal of the power input filter unit, and the drain of the FDD9510L-F085 power MOSFET is connected to the load through the MSS1278-473MD inductor.

[0012] This invention provides a control method for a wide voltage input circuit supporting in-vehicle navigation screens: VIN is the power input voltage after filtering by the power input filter unit; when the navigation screen is displaying normally, the voltage output by the DC / DC step-down unit is V1.

[0013] When the filtered power input voltage VIN≥V1, the output terminal OUT of the voltage detection and control unit outputs a high level, the DC / DC step-down unit is enabled, the low-voltage output backup circuit does not work, and the DC / DC step-down unit normally supplies power to the downstream load.

[0014] When the filtered power input voltage VIN < V1, the output terminal OUT of the voltage detection control unit outputs a low level, the DC / DC step-down unit does not operate, and the low-voltage output backup circuit operates, so that the power input voltage VIN is directly input to the subsequent load.

[0015] The present invention has the following beneficial effects:

[0016] 1. The wide voltage input circuit supporting an on-board navigation screen provided by the present invention has the advantages of wide input voltage range, low cost of circuit implementation, pure hardware control and fast system response.

[0017] 2. The present invention provides a high cost-effective hardware circuit supporting a wide input voltage, which solves the problem of abnormal operation caused by the narrow voltage input range of similar products in some scenarios due to the pull-down of battery voltage. With the circuit provided by the present invention, when an automobile starts the engine, the display screen will not be affected and can display normally. Description of Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required for describing the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

[0019] Figure 1 is a principle block diagram of a wide voltage input circuit supporting an on-board navigation screen provided by an embodiment of the present invention;

[0020] Figure 2 is a circuit diagram of a voltage detection control unit provided by an embodiment of the present invention;

[0021] Figure 3 is a circuit diagram of a power input filtering unit provided by an embodiment of the present invention;

[0022] Figure 4 is a circuit diagram of a DC / DC step-down unit provided by an embodiment of the present invention;

[0023] Figure 5 is an enlarged view of part A in Figure 4 provided by an embodiment of the present invention;

[0024] Figure 6 is an enlarged view of part B in Figure 4 provided by an embodiment of the present invention;

[0025] Figure 7 is a low-voltage output backup circuit diagram provided by an embodiment of the present invention. Detailed Description

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figures 1-7 This invention provides a wide voltage input circuit supporting in-vehicle navigation screens, including a voltage detection and control unit, a power input filter unit electrically connected to a battery, a DC / DC step-down unit electrically connected to the in-vehicle navigation screen, and a low-voltage output backup circuit electrically connected to the in-vehicle navigation screen. The input terminals of the voltage detection and control unit, the DC / DC step-down unit, and the low-voltage output backup circuit are all electrically connected to the output terminal VIN of the power input filter unit. The enable terminals of the DC / DC step-down unit and the low-voltage output backup circuit are both electrically connected to the output terminal OUT of the voltage detection and control unit. This circuit is used in commercial vehicle navigation / instrument displays, solving the problem that the display screen's normal display is affected when the battery voltage is pulled up during engine start-up. This product consists of four parts: a power input filter / protection unit, a voltage detection and control unit, a DC / DC step-down unit, and a low-voltage output backup circuit. Figure 1 This is a block diagram illustrating the principle.

[0028] like Figure 2 The voltage detection and control unit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a comparator LM2902. The reference voltage VCC_5V is connected to the input terminal of the fourth resistor R4 through the third resistor R3. The output terminal of the fourth resistor R4 is grounded. The input terminal of the fourth resistor R4 is electrically connected to the negative input terminal of the comparator LM2902. The positive input terminal of the comparator LM2902 is electrically connected to the output terminal VIN of the power input filter unit through the first resistor R1. VIN is the power input voltage after filtering by the power input filter unit. The positive input terminal of the comparator LM2902 is grounded through the second resistor R2. The enable terminal of the DC / DC step-down unit and the enable terminal of the low-voltage output backup circuit are both electrically connected to the output terminal OUT of the comparator LM2902. The output terminal of the comparator LM2902 is connected to the power port V+ of the comparator LM2902 through a resistor R472.

[0029] Embodiments of the present invention further provide a control method of a wide-voltage input circuit supporting a vehicle-mounted navigation screen: VIN is the power input voltage filtered by the power input filtering unit, when the navigation screen displays normally, the voltage output by the DC / DC step-down unit is V1,

[0030] When the filtered power input voltage VIN ≥ V1, the output terminal OUT of the voltage detection control unit outputs a high level, the DC / DC step-down unit is enabled, the low-voltage output backup circuit does not work, and the DC / DC step-down unit normally supplies power to the rear load;

[0031] When the filtered power input voltage VIN < V1, the output terminal OUT of the voltage detection control unit outputs a low level, the DC / DC step-down unit does not work, the low-voltage output backup circuit is enabled, and the low-voltage output backup circuit works, so that the power input voltage VIN is directly input to the subsequent load.

[0032] For example Figure 3 , the power input filtering unit comprises a diode S3M, a diode SM8S36A, a trimmer resistor LFTB1487-302N-4.5A, and an inductor MSS1278-473MD. The storage battery is electrically connected to the diode S3M, the diode SM8S36A, the trimmer resistor LFTB1487-302N-4.5A, and the inductor MSS1278-473MD in sequence, and then connected to the input terminal of the first resistor R1. The power input filtering / protection unit mainly comprises protection components for anti-reverse connection, filtering and surge suppression, which filter the input power and protect the back-end load.

[0033] For example Figures 4-6 , the DC / DC step-down unit comprises a step-down converter TPS54561-Q1, an inductor SMTER65-6R8M-6A, a bead FBMA-11-322513-301A30T, and a diode MBRS540T3G. The output terminal VIN of the power input filtering unit is electrically connected to the step-down converter TPS54561-Q1, the inductor SMTER65-6R8M-6A, the bead FBMA-11-322513-301A30T, and the diode MBRS540T3G in sequence, and then connected to the load. The output terminal OUT of the voltage detection control unit is electrically connected to the EN enable port of the step-down converter TPS54561-Q1. The DC / DC step-down unit mainly comprises a high-current power IC (navigation requires high power consumption) and peripheral components.

[0034] For example Figure 7The low-voltage output backup circuit includes a 2N7002 transistor, a FDD9510L-F085 power MOSFET, and an MSS1278-473MD inductor. The output terminal OUT of the voltage detection and control unit is electrically connected to the base of the 2N7002 transistor, the emitter of the 2N7002 transistor is grounded, the collector of the 2N7002 transistor is electrically connected to the gate of the FDD9510L-F085 power MOSFET, the source of the FDD9510L-F085 power MOSFET is electrically connected to the output terminal VIN of the power input filter unit, and the drain of the FDD9510L-F085 power MOSFET is connected to the load through the MSS1278-473MD inductor. The low-voltage output backup circuit is a switching power supply circuit composed of a high-current PMOS circuit.

[0035] The specific circuit of the voltage detection and control unit is as follows: Figure 2 Where VIN is the filtered power input voltage, R3 and R4 are the input voltage divider network, R1 and R2 are the input comparator network, and OUT is the output after comparison, which is connected to the enable of the DC / DC step-down unit and the enable of the low-voltage input backup circuit.

[0036] For example, the DC / DC output voltage is set to 12V, R1 = 30KΩ, R2 = 10KΩ, R3 = 2KΩ, and R4 = 3KΩ.

[0037] 1. When VIN≥12V, OUT outputs a high level, the DC / DC step-down unit is enabled, the low-voltage output backup circuit does not work, and the DC / DC normally supplies power to the downstream load.

[0038] 2. When VIN < 12V, OUT outputs a low level, the DC / DC step-down unit does not work, and the low-voltage output backup circuit works, thus directly inputting the input voltage to the subsequent load.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wide voltage input circuit supporting in-vehicle navigation screens, characterized in that: It comprises a voltage detection control unit, a power input filtering unit electrically connected to a storage battery, a DC / DC step-down unit electrically connected to a load, and a low-voltage output backup circuit electrically connected to the load. The input terminal of the voltage detection control unit, the input terminal of the DC / DC step-down unit and the input terminal of the low-voltage output backup circuit are all electrically connected to the output terminal of the power input filtering unit. The enable terminal of the DC / DC step-down unit and the enable terminal of the low-voltage output backup circuit are both electrically connected to the output terminal of the voltage detection control unit; wherein, VIN is the power input voltage filtered by the power input filtering unit, and when the navigation screen displays normally, the voltage output by the DC / DC step-down unit is V1; when the filtered power input voltage VIN≥V1, the output terminal OUT of the voltage detection control unit outputs a high level, the DC / DC step-down unit is enabled, the low-voltage output backup circuit does not operate, and the DC / DC step-down unit normally supplies power to the subsequent load; when the filtered power input voltage VIN<V1, the output terminal OUT of the voltage detection control unit outputs a low level, the DC / DC step-down unit does not operate, the low-voltage output backup circuit is enabled and operates, so that the power input voltage VIN is directly input to the subsequent load; wherein, the voltage detection control unit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a comparator. A reference voltage is connected to the input terminal of the fourth resistor R4 through the third resistor R3, the output terminal of the fourth resistor R4 is grounded, the input terminal of the fourth resistor R4 is electrically connected to the negative input terminal of the comparator, the positive input terminal of the comparator is electrically connected to the output terminal of the power input filtering unit through the first resistor R1, the positive input terminal of the comparator is grounded through the second resistor R2, and the enable terminal of the DC / DC step-down unit and the enable terminal of the low-voltage output backup circuit are both electrically connected to the output terminal of the comparator; the DC / DC step-down unit comprises a step-down converter TPS54561-Q1, an inductor SMTER65-6R8M-6A, a magnetic bead FBMA-11-322513-301A30T, and a diode MBRS540T3G. The output terminal of the power input filtering unit is electrically connected to the step-down converter TPS54561-Q1, the inductor SMTER65-6R8M-6A, the magnetic bead FBMA-11-322513-301A30T, and the diode MBRS540T3G in sequence and then connected to the load, and the output terminal OUT of the voltage detection control unit is electrically connected to the EN enable port of the step-down converter TPS54561-Q1;The low-voltage output backup circuit includes a 2N7002 transistor, a FDD9510L-F085 power MOSFET, and an MSS1278-473MD inductor. The output terminal OUT of the voltage detection and control unit is electrically connected to the base of the 2N7002 transistor. The emitter of the 2N7002 transistor is grounded. The collector of the 2N7002 transistor is electrically connected to the gate of the FDD9510L-F085 power MOSFET. The source of the FDD9510L-F085 power MOSFET is electrically connected to the output terminal of the power input filter unit. The drain of the FDD9510L-F085 power MOSFET is connected to the load through the MSS1278-473MD inductor.

2. The wide voltage input circuit supporting in-vehicle navigation screens as described in claim 1, characterized in that: Said comparator is the LM2902 comparator.

3. The wide voltage input circuit supporting in-vehicle navigation screens as described in claim 1, characterized in that: Said power input filtering unit comprises a diode S3M, a diode SM8S36A, a trimming potentiometer LFTB1487-302N-4.5A, and an inductor MSS1278-473MD, and the storage battery is electrically connected to the diode S3M, the diode SM8S36A, the trimming potentiometer LFTB1487-302N-4.5A, and the inductor MSS1278-473MD in sequence and then connected to the input end of said first resistor R1.

4. A control method for a wide voltage input circuit supporting an in-vehicle navigation screen as described in any one of claims 1 to 3, characterized in that: VIN is the power input voltage filtered by the power input filtering unit, when the navigation screen displays normally, the voltage output by the DC / DC step-down unit is V1, When the filtered power input voltage VIN≥V1, the output terminal OUT of the voltage detection control unit outputs a high level, the DC / DC step-down unit is enabled, the low-voltage output backup circuit does not operate, and the DC / DC step-down unit normally supplies power to subsequent loads; When the filtered power input voltage VIN<V1, the output terminal OUT of the voltage detection control unit outputs a low level, the DC / DC step-down unit does not operate, the low-voltage output backup circuit operates, thereby directly inputting the power input voltage VIN to subsequent loads.

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