Title

Power supply protection device technical field

The present utility model relates to circuit power supply management, in particular to power supply protection for electronic devices. background art

In present-day circuit design there is often a requirement to provide a double power supply for a specific electronic device; at the same time, to avoid damage to the electronic device due to power source input errors, a protection device is often provided in a power supply circuit to adapt to the double power supply and avoid damage due to power source wiring errors. Fig. 1 shows a schematic drawing of a circuit system having a conventional power supply protection device. As shown in the figure, the circuit system uses two power sources Vssl and Vss2 to supply power to an electronic device EL, and diodes Dl, D2 and D3 are used in the circuit system for power supply protection. The power source Vssl is connected via the diode Dl to the electronic device EL to supply power to it, while the power source Vss2 is connected via the diode D2 to the electronic device EL to supply power to it, wherein the diodes Dl and D2 are connected to the electronic device EL at a common node “Node”. The circuit system may also comprise other electronic elements, e.g. a noise filter, etc., which are represented here by the symbols SI, S2, S3 in a uniform way; the elements or circuits SI, S2, S3 may or may not be present, depending on the needs of circuit design.

According to the protection circuit shown in Fig. 1, when the voltage is reverse- connected at the node “Node”, damage to EL is prevented; for example, when VSS1/VSS2 is connected to GND and GND is connected to a power supply power source, the diode D1 or D2 will block the voltage of VSS1/VSS2 and thereby prevent damage to EL. Since D1 and D2 are not detectable in the circuit, diode D3 performs another type of protection, being used to prevent a situation where a short circuit occurs at D1 or D2, and VSS1/VSS2 and GNS are reverse- connected; EL will still not be damaged. Thus, the protection device formed by diodes Dl, D2 and D3 can essentially achieve the objective of power supply protection of the electronic device EL.

However, in this power supply protection device, the use of diode D3 for voltage- limiting protection will inevitably result in circuit layout space being taken up, and will also lead to a cost increase; furthermore, this type of circuit protection cannot effectively provide advance warning of circuit faults. summary of the invention

The present utility model provides a power supply protection device, which can monitor power supply line faults in real time, and issue an alert signal when a fault occurs, thereby providing support for circuit maintenance.

According to one aspect of the present utility model, a power supply protection circuit is provided, comprising: a first polarity protection circuit, for receiving a first power source voltage to supply power to a target electronic component; a first monitoring module, configured to monitor an output voltage of the first polarity protection circuit, and output an alert signal indicating a fault in the first polarity protection circuit when a voltage difference between the output voltage of the first polarity protection circuit and the first power source voltage is less than a polarity monitoring threshold.

In a preferred embodiment, the power supply protection circuit further comprises a second polarity protection circuit, for receiving a second power source voltage to supply power to the target electronic component, wherein output terminals of the first polarity protection circuit and second polarity protection circuit are connected at the same node to provide the output voltage to supply power to the target electronic component; the first monitoring module is configured to read the output voltage at the node, and output an alert signal indicating a fault in either the first polarity protection circuit or the second polarity protection circuit when a voltage difference between the output voltage and one of the first power source voltage and second power source voltage is less than the polarity monitoring threshold. brief description of the drawings

Fig. 1 shows a schematic drawing of a power supply protection device in the prior art.

Fig. 2 shows a schematic drawing of a power supply protection device according to an example.

Fig. 3 shows a schematic drawing of a power supply protection device according to another example.

Fig. 4 shows a schematic drawing of a power supply protection device according to another example. detailed description of embodiments

The technical solution in embodiments of the present utility model is described clearly and completely below with reference to the drawings in embodiments of the present utility model; obviously, the embodiments described are merely intended to explain the present utility model, and are non-limiting.

Fig. 2 shows a schematic drawing of a circuit protection device 200 according to the present utility model, wherein power sources Vssl and Vss2 supply power to an electronic device EL via the circuit protection device 200. As shown in the figure, the circuit protection device 200 comprises a first polarity protection circuit PPC1 and a second polarity protection circuit PPC2; output terminals of protection circuit PPC1 and protection circuit PPC2 are connected to a common node “Node” and connected via the node “Node” to the electronic device EL; an input terminal of protection circuit PPC1 receives power source Vssl, and an input terminal of protection circuit PPC2 receives power source Vss2, such that power sources Vssl and Vss2 realize the supply of power to the device EL at the node “Node” via their respective connected polarity protection circuits PPC1 and PCC2. According to the present utility model, the polarity protection circuits PPC1 and PCC2 can be realized using any circuit or element capable of preventing power source polarity connection errors, e.g. diode D1 or D2 shown in Fig. 1, etc. Furthermore, due to the intrinsic design of the polarity protection circuits PPC1 and PCC2, when conducting to allow the power sources Vssl and Vss2 to supply power to the electronic device EL, a voltage drop AV will generally arise across the polarity protection circuits PPC1 and PCC2; for example, in the case of a diode D, the voltage drop thereof is generally 0.7 V.

In addition, the circuit protection device 200 further comprises a voltage monitoring module MB1, which is connected to the node “Node” and used to read a voltage Vout at the node; obviously, due to the voltage drop AV across polarity protection circuit PPC1 or PCC2, Vout is the true power supply voltage of the electronic device EL, i.e. Vout = Max(Vssl, Vss2) - AV. It must be noted here that the voltage drop AV across polarity protection circuit PPC1 or PCC2 may be the same or different. In the description below, an explanation is given in the case where polarity protection circuit PPC1 or PCC2 is realized using the same component and has the same voltage drop AV. For example, when diodes D1 and D2 are used for implementation, the forward conduction voltage of diodes D2 and Dl, i.e. the voltage drop thereof, is AV = 0.7 V.

By monitoring the output voltage Vout at the node “Node”, the voltage monitoring module MB1 can determine whether a fault has occurred in the power supply circuit or whether there is a power source input error. Specifically, after the voltage monitoring module MB1 has read the output voltage Vout at the node “Node”, the following operations are performed.

First of all, the voltage difference VDIFFI between the output voltage Vout and the power source voltage Vssl and the voltage difference VDIFF2 between the output voltage Vout and the power source voltage Vss2 are calculated, i.e. VDIFFI = Vssl - Vout, VDIFF2 = Vss2 - Vout. Next, the voltage monitoring module MB1 separately compares the absolute values \VDIFF1\ and \VDIFF2\ of the calculated voltage differences with the voltage drop AV. For example, if \VDIFF1\ < DV, this indicates that polarity protection circuit PPC1 has developed a short circuit fault, so the voltage monitoring module MB1 outputs an alert signal Alertl indicating a short circuit fault in polarity protection circuit PPC1. If \VDIFF2\ < DV, this means that polarity protection circuit PPC2 has developed a short circuit fault, so the voltage monitoring module MB1 outputs an alert signal Alert2 indicating a short circuit fault in polarity protection circuit PPC2. In the present utility model, AV is also called the polarity monitoring threshold. Taking as an example the case where power source Vssl = 3.5 V and Vss2 = 5V and diodes D1 and D2 are used to realize the polarity protection circuits PPC1 and PPC2, if diode D1 experiences breakdown, the output terminal voltage Vout is essentially 3.5 Volts, so the voltage difference between the two ends of Dl, i.e. VDIFFI, is close to zero, which is less than the polarity monitoring threshold 0.7 V of the diode; it can thereby be determined that diode Dl has experienced breakdown, so the voltage monitoring module MB1 outputs an alert signal Alertl. If diode D2 experiences breakdown, the output terminal voltage Vout is essentially 5 Volts, so the voltage difference between the two ends of D2, i.e. VDIFF2, is close to zero, which is less than the polarity monitoring threshold 0.7 V of the diode; it can thereby be determined that diode D2 has experienced breakdown, so the voltage monitoring module MB1 outputs an alert signal Alert2.

In the example above, an explanation has been given in the case where the polarity protection circuits PPC1 and PPC2 have the same polarity monitoring threshold AV; if polarity protection circuits PPC1 and PPC2 have different polarity monitoring thresholds AVi and AV2, i.e. the respective voltage drops across polarity protection circuits PPC1 and PPC2 are different, the method of diagnosing faults in the polarity protection circuits is similar, but the respective polarity monitoring thresholds AVi and AV2 are used. For example: if \VDIFF1\ < DV1, this means that polarity protection circuit PPC1 has developed a short circuit fault, and if \VDIFF2\ < DV2, this means that polarity protection circuit PPC2 has developed a short circuit fault. Thus, the solution according to this example is suitable for different types of polarity protection circuit scenarios.

In addition, in the example above, an explanation has been given in the case where two power sources Vss2 and Vssl are used to supply power to the electronic device EL, but the solution of the present utility model is obviously also suitable in situations where a single power source supplies power or three or more power sources supply power, wherein a polarity protection circuit PPC and a common voltage monitoring module MB1 are provided in each power source power supply line.

In addition, the embodiment above relates to the case where the first power source voltage Vssl and the second power source voltage Vss2 are different; if the power supply voltages of the first power source voltage Vss2 and the second power source voltage Vssl are the same, the monitoring module MB1 may be configured to output an alert signal, indicating that either polarity protection circuit PPC1 or polarity protection circuit PPC2 might have developed a fault, when the voltage difference VDIFF between the output voltage Vout and either power source voltage is less than the polarity monitoring threshold AV.

Fig. 3 shows an exemplary embodiment of the power supply protection device 200. As shown in the figure, the polarity protection circuits PPC2 and PPC1 therein are realized by diodes D1 and D2 respectively, while the voltage monitoring module MB1 can be realized by an analog/digital converter A/D and an arithmetic logic unit ALU, wherein the analog/digital converter A/D converts the output voltage Vout acquired from the node “Node” to a digital signal to be processed by the arithmetic logic unit ALU; the arithmetic logic unit ALU realizes the operations described above that are performed after the output voltage Vout is read, in order to judge whether the polarity protection circuits PPC2 and PPC1 have developed a short circuit fault.

According to another example of the present utility model, an additional voltage monitoring circuit may also be provided to perform real-time monitoring of the voltages Vssl and Vss2 outputted by the power source end, and provide the power source output voltages obtained by monitoring to the voltage monitoring module MB1. Fig. 4 shows a schematic drawing of a power supply protection device 400 according to this example. As shown in the figure, in addition to the polarity protection circuits PPC2 and PPC1 and the voltage monitoring module MB1, the power supply protection device 400 further comprises a second voltage monitoring module MB2 and a third voltage monitoring module MB3, wherein voltage monitoring module MB2 monitors an actual output voltage of power source Vssl, denoted Vssl’ below, and provides the voltage value Vssl’ obtained by monitoring to the voltage monitoring module MB1, while voltage monitoring module MB3 monitors an actual output voltage Vss2’ of power source Vss2, and provides the voltage value Vss2’ obtained by monitoring to the voltage monitoring module MB1; based on the actual output voltages Vssl’ and Vss2’ of the power sources provided by the voltage monitoring modules MB2 and MB3 and the output voltage Vout read from the node “Node”, the voltage monitoring module MB1 judges whether the polarity protection circuits PPC2 and PPC1 have developed a short circuit fault, by the operations described above. Specifically, VDIFFI = Vssl' - Vout, VDIFF2 = Vss2 - Vout. Next, the voltage monitoring module MB1 separately compares the absolute values \VDIFF1\ and \VDIFF2\ of the calculated voltage differences with the voltage drop AV. If \VDIFF1\ < DV, this indicates that polarity protection circuit PPC1 has developed a short circuit fault, so the voltage monitoring module MB1 outputs an alert signal Alertl indicating a short circuit fault in polarity protection circuit PPC1. If \VDIFF2\ < DV, this means that polarity protection circuit PPC2 has developed a short circuit fault, so the voltage monitoring module MB1 outputs an alert signal Alert2 indicating a short circuit fault in polarity protection circuit PPC2. Thus, according to this example, erroneous judgements due to fluctuation in the power source output voltages can be avoided. In a preferred example, the voltage monitoring modules MB1, MB3MB2 and MB3 may be integrated in a chip or integrated circuit, and it is thereby possible to conveniently multiple power source voltages, so a very large amount of circuit layout space can be saved.

According to another example of the present utility model, the voltage monitoring module MB1 may also determine whether a power source connection error is present by monitoring the output voltage Vout at the node “Node”. Taking the scenario shown in Fig. 3 as an example, suppose that in normal conditions, the voltage supplied by power source Vssl is 3.5 V, and the voltage supplied by power source Vss2 is 5 V. When the diodes D1 and D2 are in a normal state, the output voltage at the node “Node” is 5 V - 0.7 V = 4.3 V, wherein the forward conduction voltage of diodes D2 and D1 is 0.7 V. Thus, in normal conditions, the voltage difference between the output voltage Vout and power source Vssl is Vout - Vssl = 4.3 V - 3.5 V = 0.8 V.

If power source end Vssl is connected wrongly, e.g. connected to ground, the voltage difference between the output voltage Vout and power source end Vssl is Vout - Vssl = 4.3 - 0 = 4.3 V, which is much larger than the voltage difference of 0.8 V between the output voltage Vout and power source Vssl in normal conditions, so it can be judged that power source Vssl has suffered a wiring error. Here, a power source fault threshold VT can be set to check whether a wiring error has occurred; for example, for power source Vssl, the power source fault threshold Vn thereof can be set to be < Vssl, e.g. Vn = 2.5 V, and if Vout - Vssl > Vn, this indicates that power source Vssl has suffered an error. Similarly, in order to detect whether power source Vss2 has suffered a wiring error, the power source fault V _T 2 of power source Vss2 can be set to be < 5 V, e.g. 3.5 V, i.e. if Vout - Vss2 > V _T 2, this indicates that power source Vss2 has suffered an error. In another example, the same power source fault threshold VT may be set for power sources Vss2 and Vssl, e.g. 3 V.

The present utility model has been presented and explained in detail above through the drawings and preferred embodiments, but is not limited to these disclosed embodiments. Based on the detailed disclosure above, those skilled in the art can make any changes, including combination, substitution, addition and deletion of features, etc., and all such solutions should be regarded as falling within the scope of protection defined by the attached claims.