A kind of vehicle-mounted memory card interface short-circuit protectionTechnical field
The present invention relates to car-mounted terminal technical field, particularly a kind of vehicle-mounted memory card interface short-circuit protection that a kind of vehicle-mounted memory card connects.
Background technology
Existing car-mounted terminal is general all with external storage card, and especially TF card, deposits for media play or map.But due in use procedure, storage card has plug behavior, or storage card itself may be damaged, and these all likely cause the power supply short circuit at memory card interface place.And due to generally, it is by powering in machine that the power supply of memory card interface all have employed 3.3V, and therefore, the above-mentioned power supply short circuit caused directly may cause complete machine cisco unity malfunction or other device failure.
Therefore; if a kind of vehicle-mounted memory card interface short-circuit protection can be designed; memory card interface can be cut off rapidly when power supply short circuit power to the 3.3V of storage card; thus device in protection machine is not damaged; and can recover rapidly, to its power supply, to have a very big significance the safe and stable operation of whole onboard system after short-circuit bar removes.
Summary of the invention
The object of the invention is to the problem overcoming above-mentioned prior art, a kind of vehicle-mounted memory card interface short-circuit protection is provided.
The object of the invention is to be achieved through the following technical solutions:
A kind of vehicle-mounted memory card interface short-circuit protection, comprises memory card interface seat, and described memory card interface seat comprises power supply pin and inserts detection pin;
Described power supply pin is connected to power supply by PTC overcurrent protection resistance, and described insertion detects pin and connects micro-control unit.
Further, described power supply pin is also connected to micro-control unit, and described micro-control unit and described PTC overcurrent protection resistor coupled in parallel.
Further, the second resistance is in series with between described power supply pin and micro-control unit.
Further, described insertion detects between pin and described micro-control unit and is in series with the first resistance.
Further, described PTC overcurrent protection resistance is held by the D of metal-oxide-semiconductor with between power supply and S holds and is connected.
Further, the D end of described metal-oxide-semiconductor is connected with PTC overcurrent protection resistance, and the S end of described metal-oxide-semiconductor is connected with power supply.
Further, the G end of described metal-oxide-semiconductor is connected to micro-control unit.
Further, the G of described metal-oxide-semiconductor holds and be in series with the 3rd resistance, transistor and the 4th resistance successively between micro-control unit.
Further, the described 4th between resistance and micro-control unit, also switch is in series with.
Further, described power supply is 3.3V power supply.
Vehicle-mounted memory card interface short-circuit protection of the present invention; memory card interface can be realized cut off rapidly when power supply short circuit and power to the 3.3V of storage card; thus device in protection machine is not damaged; and can automatically recover rapidly its power supply after short-circuit bar removes; make whole onboard system safe and stable operation; also ensure that the security of device in machine, avoid the irreversible damage that device in machine occurs due to short circuit accident.
Accompanying drawing explanation
Fig. 1 is the structural drawing of vehicle-mounted memory card interface short-circuit protection of the present invention.
Embodiment
According to drawings and embodiments the present invention is described in further detail below.
As shown in Figure 1, a kind of vehicle-mounted memory card interface short-circuit protection described in the embodiment of the present invention, comprises memory card interface seat, and described memory card interface seat comprises power supply pin and inserts detection pin;
Described power supply pin is connected to power supply by PTC overcurrent protection resistance, and described insertion detects pin and connects micro-control unit.
By arranging PTC overcurrent protection resistance in above-described embodiment, in memory card interface generation power supply short circuit moment, when electric current increases, overcurrent protection resistance is had an effect, cut off power supply, and insertion detection pin is connected with micro-control unit, whether real-time detection has storage card to insert memory card interface, when having detected that storage card inserts, i.e. automatic recovery of power supply, if now still there is short circuit phenomenon, then overcurrent protection resistance continues to have an effect, cut off power supply, until insert correct and connect safe storage card, occur without short circuit phenomenon, just continued power can be realized, ensure the connection of storage card and normal operation.
Particularly, when there being the storage cards such as TF card to insert, detection pin is low level, and when inserting without storage cards such as TF cards, detecting pin is high level.The rated current of PTC overcurrent protection resistance can be set to 500 milliamperes.When exceeding rated current, PTC protects disconnection due to heating.So when the power supply pin shorted to earth of the memory card interface of external TF card etc., the electric current flowing through PTC increases instantaneously, and PTC disconnects fast due to heating, cuts off 3.3V and powers, play the effect of protection internal components and 3.3V stable power-supplying.
As a kind of preferred embodiment of the present invention, described power supply pin is also connected to micro-control unit, and described micro-control unit and described PTC overcurrent protection resistor coupled in parallel.The parameters such as the electrical condition of power supply pin and current value feed back to micro-control unit, timely so that micro-control unit judges whether again to power.
As shown in Figure 1, as a kind of preferred embodiment of the present invention, the second resistance is in series with between described power supply pin and micro-control unit, described insertion detects between pin and described micro-control unit and is in series with the first resistance, described PTC overcurrent protection resistance is held by the D of metal-oxide-semiconductor with between power supply and S holds and is connected, the D end of described metal-oxide-semiconductor is connected with PTC overcurrent protection resistance, the S end of described metal-oxide-semiconductor is connected with power supply, the G end of described metal-oxide-semiconductor is connected to micro-control unit, the 3rd resistance is in series with successively between the G end of described metal-oxide-semiconductor and micro-control unit, transistor and the 4th resistance, described 4th is also in series with switch between resistance and micro-control unit, described power supply is 3.3V power supply.
In above-described embodiment, metal-oxide-semiconductor is equivalent to a power switch, and when the 4th resistance terminal provides high level, metal-oxide-semiconductor conducting, the memory card interface of inner 3.3V to TF card etc. is powered.During normal work, MCU micro-control unit provides high level, and metal-oxide-semiconductor conducting is powered to storage cards such as TF cards.The power supply pin of memory card interface J1 is detected with detection pin simultaneously.When detecting that power supply pin is high level, when detection pin is low level, illustrate that storage card normally connects.When detecting that power supply pin is low level, when detection pin is low level, illustrate that storage card is for electrical short.MCU micro-control unit provides low level, and metal-oxide-semiconductor turns off, and namely cuts off the inner power supply to external connection of storage card.After external connection of storage card Interface status is normal, after namely short-circuit conditions is got rid of, the conducting of MCU micro-control unit controls metal-oxide-semiconductor, restores electricity, thus realizes Based Intelligent Control.
The foregoing is only explanation embodiments of the present invention; be not limited to the present invention, for a person skilled in the art, within the spirit and principles in the present invention all; any amendment of doing, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.