CN112003464A - Power-down holding circuit for switching power supply of airborne electronic equipment - Google Patents
Power-down holding circuit for switching power supply of airborne electronic equipment Download PDFInfo
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- CN112003464A CN112003464A CN202010612915.3A CN202010612915A CN112003464A CN 112003464 A CN112003464 A CN 112003464A CN 202010612915 A CN202010612915 A CN 202010612915A CN 112003464 A CN112003464 A CN 112003464A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
- H02M1/322—Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
Abstract
The invention discloses a power-down holding circuit of a switching power supply of airborne electronic equipment, which utilizes a flyback switching power supply circuit to perform voltage reduction processing on an input airborne direct-current power supply on one hand to convert the input airborne direct-current power supply into working power supply output, and performs voltage boosting conversion on the other hand to improve the charging voltage of an energy storage capacitor, thereby reducing the capacity value requirement of the energy storage capacitor, so that the energy storage capacitor with smaller capacity can meet the specified power-down holding time, and being beneficial to realizing the miniaturization requirement and the light requirement of the airborne equipment. And the voltage of the airborne input power supply is monitored through the first comparator circuit, and the on-off of the switch circuit is controlled according to the monitoring result, so that the output state of the power-down holding power supply is controlled, the automatic switching between the airborne direct-current power supply and the power-down holding power supply can be realized, in addition, the isolation and the power supply switching between the airborne direct-current power supply and the power-down holding power supply are realized through the power supply input circuit, and the reliability and the safety of the power supply switching are ensured.
Description
Technical Field
The invention relates to the technical field of circuits of aviation airborne electronic equipment, in particular to a power-down holding circuit of a switching power supply of airborne electronic equipment.
Background
In order to meet the reliability requirement of the equipment, the onboard electronic equipment needs to perform necessary operations such as data processing, storage and transmission when the power supply is powered off. In addition, the airworthiness approval standard RTCA-DO-160 of civil aviation airborne electronic equipment requires that B-type direct current power supply equipment meets the applicable performance standard when the power supply is subjected to 50ms instantaneous interruption. Therefore, the on-board electronic equipment switching power supply is generally required to have an instantaneous power-down holding function.
Currently, a typical instantaneous power-down holding circuit is implemented by connecting a large-capacity capacitor in parallel at an input end of a power supply, but the large-capacity capacitor generally has the disadvantages of large size, heavy weight and the like, and is not beneficial to reducing the size and the weight of airborne electronic equipment.
Disclosure of Invention
The invention provides a power-down holding circuit of a switching power supply of airborne electronic equipment, which aims to solve the technical problems that the conventional instantaneous power-down holding circuit is large in size and weight and is not beneficial to reducing the size and weight of the airborne electronic equipment due to the adoption of a large-capacity capacitor.
According to one aspect of the invention, a power failure holding circuit of a switching power supply of an airborne electronic device is provided, which comprises a power supply input circuit, a flyback switching power supply circuit, a first comparator circuit and a switch circuit, wherein the power supply input circuit is respectively connected with an airborne direct-current power supply and the flyback switching power supply circuit;
the power input circuit is used for realizing isolation and power supply switching between an airborne direct-current power supply and a power-down maintaining power supply, the flyback switching power supply circuit is used for carrying out voltage reduction conversion on the input airborne direct-current power supply to serve as working power supply output and carrying out voltage boosting conversion on the input airborne direct-current power supply to charge an energy storage capacitor when the airborne direct-current power supply normally supplies power, and is also used for serving as power-down maintaining power supply output when the airborne direct-current power supply is powered down, the switching circuit is used for controlling the flyback switching power supply circuit to be switched on and off as the power-down maintaining power supply output, and the first comparator circuit is used for monitoring the voltage state of the airborne direct-current power supply and outputting a control signal to control the switching circuit to be switched on or switched off.
Further, the first comparator circuit is also coupled to the processor and is configured to indicate whether the power-down retention power supply is enabled.
Further, the power input circuit comprises a diode V1, a diode V2, a resistor R1 and a capacitor C1, the positive terminal of the diode V1 is connected with the onboard dc power supply, the negative terminal of the diode V1 is connected with the negative terminal of the diode V2, the first terminal of the resistor R1, the first terminal of the capacitor C1 and the flyback switching power supply circuit, the positive terminal of the diode V2 and the second terminal of the resistor R1 are connected with the switching circuit, the second terminal of the capacitor C1 is grounded, and the diode V1 and the diode V2 are used for realizing isolation and power supply switching between the onboard dc power supply and the power-down holding power supply.
Further, the flyback switching power supply circuit comprises a transformer T1, a field effect switch tube V3, a rectifier diode V4, a rectifier diode V5, a resistor R2, a capacitor C2, a voltage regulator tube V6 and an energy storage capacitor C3, wherein the upper end of an input winding of the transformer T1 is connected with the negative end of the diode V1, the lower end of the input winding is connected with the drain of the field effect switch tube V3, the source of the field effect switch tube V3 is grounded, the input winding of the transformer T1 and the field effect switch tube V3 form a chopper circuit, the upper end of a step-down output winding of the transformer T1 is connected with the positive end of the rectifier diode V4, the lower end of the step-down output winding is connected with the second end of the capacitor C2, the negative end of the rectifier diode V4 is connected with the first end of the capacitor C2, the negative end of the rectifier diode V4 serves as an output end of a working power supply, the upper end of a step-up output, the negative end of a rectifier diode V5 is connected with the first end of a resistor R2, the second end of a resistor R2 is respectively connected with the negative end of a voltage regulator tube V6 and the first end of an energy storage capacitor C3, the positive end of a voltage regulator tube V6 and the second end of an energy storage capacitor C3 are both connected with the lower end of a boosting output winding of a transformer T1, the second end of the energy storage capacitor C3 is grounded, the voltage stabilizing value of the voltage regulator tube V6 is higher than the initial charging voltage of the energy storage capacitor C3, and the voltage regulator tube V6 is used for conducting reversely when the power failure holding power supply voltage is abnormally increased and exceeds the voltage stabilizing value of the voltage regulator tube V6 so as to limit the output voltage of the power failure holding power supply to the voltage stabilizing value.
Further, the first comparator circuit includes a resistor R10, a resistor R11, a comparator N3, a resistor R12, and a diode V9, a first end of the resistor R10 is connected to the onboard dc power supply, a second end of the resistor R10 is connected to a first end of the resistor R11, a first end of the resistor R12, and a positive input terminal of the comparator N3, a second end of the resistor R11 is grounded, a negative input terminal of the comparator N3 is connected to the reference power supply, a second end of the resistor R12 is connected to a positive terminal of the diode V9, a negative terminal of the diode V9 is connected to an output terminal of the comparator N3, an output terminal of the comparator N3 is further connected to the switching circuit and the processor, the resistor R10 and the resistor R11 form an onboard dc power supply voltage sampling threshold, the resistor R12 and the diode V9 form a feedback loop and are used for introducing positive feedback to implement the hysteresis loop of the comparator N3 when the output voltage of the comparator N3 is lower than the voltage of the onboard dc power supply, and for cutting off the positive feedback loop 3 when the positive feedback voltage is higher than the positive voltage V3 The switching speed of the output of comparator N3 is low.
Further, the switching circuit includes a P communication enhancement type fet V7, an NPN transistor V8, a resistor R6, a resistor R13, and a resistor R14, wherein a source of the P communication enhancement type fet V7 and a first end of the resistor R6 are connected to a second end of the resistor R2, a drain of the P communication enhancement type fet V7 is connected to a positive terminal of the diode V2 and a second end of the resistor R1, a gate of the P communication enhancement type fet V7 is connected to a second end of the resistor R6 and a collector of the NPN transistor V8, a base of the NPN transistor V8 and a first end of the resistor R13 are connected to the reference power source, an emitter of the transistor V8 is connected to a first end of the resistor R14, a second end of the resistor R14 and a second end of the resistor R13 are connected to an output terminal of the comparator N3, the P communication enhancement type fet V7 is used for controlling a switch of the NPN transistor V7 for turning on or turning off the P communication enhancement type fet 7 or the communication enhancement type fet 7, when the comparator N3 outputs a high level, the NPN triode V8 is controlled to be cut off, the P communication enhancement type field effect transistor V7 is controlled to be cut off, the power failure keeps the output disconnected, when the comparator N3 outputs a low level, the NPN triode V8 is controlled to be conducted, the P communication enhancement type field effect transistor V7 is controlled to be conducted, and the power failure keeps the output started.
And the second comparator circuit is used for indicating whether the power-down maintaining power supply is charged or not, and is respectively connected with the flyback switching power supply circuit and the processor.
Further, the second comparator circuit includes a resistor R7, a resistor R8, a resistor R9, a comparator N2, and a resistor R16, a first end of the resistor R7 is connected with a second end of the resistor R2, a second end of the resistor R7 is respectively connected with a first end of the resistor R8, a first end of the resistor R9 and an anode input end of the comparator N2, a second end of the resistor R8 is grounded, a cathode input end of the comparator N2 is connected with a reference power supply, an output end of the comparator N2 is respectively connected with a second end of the resistor R9, a second end of the resistor R16 and the processor, a first end of the resistor R16 serves as an output end, the resistor R7 and the resistor R8 form a power-down holding power supply voltage sampling circuit, and the resistor R9 is used for introducing positive feedback to the comparator N2, when the power is off and the power supply is kept fully charged, the comparator N2 outputs a low level to the processor, and when the power is off and the power supply is kept fully charged, the comparator N2 outputs a high level to the processor.
And further, the power failure protection circuit further comprises a third comparator circuit used for indicating whether the power failure maintaining power supply voltage is about to be lower than the lowest working voltage of the system, and the third comparator circuit is respectively connected with the flyback switching power supply circuit and the processor.
Further, the third comparator circuit includes a resistor R3, a resistor R4, a resistor R5, a resistor R15, and a comparator N1, a first end of the resistor R3 is connected with a first end of the energy storage capacitor C3, a second end of the resistor R3 is respectively connected with a first end of the resistor R4, a first end of the resistor R5 and an anode input end of the comparator N1, a second end of the resistor R4 is connected with a second end of the energy storage capacitor C3 and grounded, a cathode input end of the comparator N1 is connected with a reference power supply, an output end of the comparator N1 is respectively connected with a second end of the resistor R5, a second end of the resistor R15 and the processor, the first end of the resistor R15 is an output end, the resistor R3 and the resistor R4 form a power-down holding power supply voltage sampling circuit, the resistor R5 is used for introducing positive feedback to the comparator N1, when the power-off holding power supply voltage is about to be lower than the lowest working voltage of the system, the comparator N1 outputs a low level to the processor.
The invention has the following effects:
according to the power-down holding circuit of the switching power supply of the airborne electronic equipment, the flyback switching power supply circuit is utilized to perform voltage reduction processing on an input airborne direct-current power supply to convert the input airborne direct-current power supply into working power supply output on one hand, and perform voltage boosting conversion on the other hand to improve the charging voltage of the energy storage capacitor, so that the capacity value requirement of the energy storage capacitor is reduced, the energy storage capacitor with smaller capacity can meet the specified power-down holding time, the capacitor with small capacity has smaller volume and weight, and the miniaturization requirement and the light requirement of the airborne equipment are favorably realized. And the voltage condition of the airborne input power supply is monitored through the first comparator circuit, and the control signal is output according to the monitoring result to control the on-off of the switch circuit, so that the output state of the power-down holding power supply is controlled, the automatic switching between the airborne direct-current power supply and the power-down holding power supply can be realized, in addition, the isolation and power supply switching between the airborne direct-current power supply and the power-down holding power supply are realized through the power supply input circuit, and the reliability and the safety of power supply switching are ensured.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic block diagram of a power-down holding circuit of a switching power supply of an onboard electronic device according to a preferred embodiment of the present invention.
Fig. 2 is a schematic circuit diagram of a power down hold circuit of a switching power supply of an on-board electronic device in accordance with a preferred embodiment of the present invention.
Description of the reference numerals
100. A power input circuit; 101. a flyback switching power supply circuit; 102. a first comparator circuit; 103. a switching circuit; 104. a second comparator circuit; 105. a third comparator circuit.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the accompanying drawings, but the invention can be embodied in many different forms, which are defined and covered by the following description.
As shown in fig. 1, a first embodiment of the present invention provides a power down holding circuit for a switching power supply of an airborne electronic device, including a power input circuit 100, a flyback switching power supply circuit 101, a first comparator circuit 102 and a switch circuit 103, where the power input circuit 100 is respectively connected with an airborne dc power supply and the flyback switching power supply circuit 101, the switch circuit 103 is respectively connected with the flyback switching power supply circuit 101 and the power input circuit 100, and the first comparator circuit 102 is respectively connected with the airborne dc power supply and the switch circuit 103. The power input circuit 100 is used for realizing isolation and power supply switching between an airborne direct-current power supply and a power failure holding power supply, the flyback switching power supply circuit 101 is used for performing voltage reduction conversion on the input airborne direct-current power supply to serve as working power supply output and performing voltage boosting conversion on the input airborne direct-current power supply to charge an energy storage capacitor when the airborne direct-current power supply normally supplies power, and is also used for serving as power failure holding power supply output when the airborne direct-current power supply fails to supply power, the switching circuit 103 is used for controlling the flyback switching power supply circuit 101 to be connected or disconnected with the power failure holding power supply output, and the first comparator circuit 102 is used for monitoring the voltage state of the airborne direct-current power supply and outputting a control signal to control the connection or disconnection of the switching circuit 103 according to a monitoring.
It will be appreciated that the on-board dc power is provided by the aircraft, typically 28V dc power or 14V dc power. When the onboard dc power supply supplies power normally, the flyback switching power supply circuit 101 steps down the input onboard dc voltage to output as a normal operating power supply (generally 5V dc), and steps up the input onboard dc voltage to charge the energy storage capacitor, for example, 40V dc, thereby increasing the charging voltage of the energy storage capacitor and reducing the capacitance requirement of the energy storage capacitor. Specifically, the capacitance value of the energy storage capacitor can be determined by equation (1),
wherein C represents the capacitance value of the energy storage capacitor to be selected, and the unit is F and U1Represents the initial charging voltage of the energy storage capacitor with the unit of V and U2The minimum working voltage required by the normal work of the system is represented by V, P represents the power consumption of the system and is represented by W, and T represents the moment of power failure maintenance and is represented by s. Therefore, the voltage of the airborne direct-current power supply is increased through the flyback switching power supply circuit 101, so that the initial charging voltage of the energy storage capacitor is increased, the capacity value requirement is reduced, the specified power failure holding time can be met by the energy storage capacitor with smaller capacitance, the capacitor with small capacitance has smaller volume and weight, and the miniaturization requirement and the light requirement of airborne equipment are favorably realized. When the airborne direct-current power supply is powered down, the energy storage capacitor is used as a power-down maintaining power supply to output electric energy, so that the normal power supply of the working power supply is ensured in a short time, the device can perform operations of storing and transmitting important data and the like within enough corresponding time when the power is down, the reliability of the device is improved, and the device can meet the performance requirements of the civil aviation airworthiness approval standard RTCA-DO-160 when the power of the B-type direct-current power supply device is instantaneously interrupted. In addition, the first comparator circuit 102 monitors the voltage condition of the onboard input power supply and outputs a control signal to control the on or off of the switch circuit 103 according to the monitoring result, so as to control the output state of the power-down maintaining power supply, for example, when the first comparator circuit 102 monitors that the onboard direct current power supply has the power-down condition, the first comparator circuit 10 monitors that the onboard direct current power supply has the power-down condition2, outputting a control signal to control the switch circuit 103 to be switched on so as to control the power failure to keep the power supply output electric energy, wherein the equipment is instantly powered by the power failure to keep the power supply, and when the first comparator circuit 102 monitors that the onboard direct-current power supply recovers to normal voltage, the first comparator circuit 102 also outputs a corresponding control signal to control the switch circuit 103 to be switched off so as to control the power failure to keep the power supply not to output and automatically switch to the onboard direct-current power supply to supply power.
It can be understood that, in the power-down holding circuit of the switching power supply of the airborne electronic device in this embodiment, the flyback switching power supply circuit 101 is utilized to perform voltage reduction processing on the input airborne dc power supply to convert the input airborne dc power supply into the working power supply output on the one hand, and perform voltage boost conversion on the input airborne dc power supply to improve the charging voltage of the energy storage capacitor on the other hand, so that the capacity value requirement of the energy storage capacitor is reduced, and the energy storage capacitor with smaller capacity can meet the specified power-down holding time, and the capacitor with smaller capacity has smaller volume and weight, which is beneficial to realizing the miniaturization requirement and the light requirement of the airborne device. In addition, the voltage condition of the airborne input power supply is monitored through the first comparator circuit 102, and the on-off of the switch circuit 103 is controlled according to the monitoring result to output a control signal, so that the output state of the power-down holding power supply is controlled, automatic switching between the airborne direct-current power supply and the power-down holding power supply can be realized, in addition, the isolation and power supply switching between the airborne direct-current power supply and the power-down holding power supply are realized through the power supply input circuit 100, and the reliability and the safety of power supply switching are ensured.
In addition, the first comparator circuit 102 is further connected to the processor and is configured to indicate whether the power-down holding power supply is enabled, and the processor may determine whether the power-down holding power supply is enabled according to a signal output by the first comparator circuit 102.
Specifically, as shown in fig. 2, the power input circuit 100 includes a diode V1, a diode V2, a resistor R1, and a capacitor C1, an anode of the diode V1 is connected to the onboard dc power supply, a cathode of the diode V1 is connected to a cathode of the diode V2, a first end of the resistor R1, a first end of the capacitor C1, and the flyback switching power supply circuit 101, an anode of the diode V2 and a second end of the resistor R1 are both connected to the switch circuit 103, a second end of the capacitor C1 is grounded, the diode V1 and the diode V2 are used for achieving isolation and power supply switching between the onboard dc power supply and the power-down retention power supply, so as to ensure reliability and safety of power supply switching, the capacitor C1 is a filter capacitor, and a VPP voltage output by the power input power supply 100 represents a voltage finally input to the flyback switching power supply circuit 101.
The flyback switching power supply circuit 101 comprises a transformer T1, a field effect switch tube V3, a rectifier diode V4, a rectifier diode V5, a resistor R2, a capacitor C2, a voltage regulator tube V6 and an energy storage capacitor C3, wherein the upper end of an input winding of the transformer T1 is connected with the negative end of a diode V1, the lower end of the input winding is connected with the drain electrode of a field effect switch tube V3, the source electrode of the field effect switch tube V3 is grounded, an input winding of the transformer T1 and the field effect switch tube V3 form a chopper circuit, the upper end of a step-down output winding of the transformer T1 is connected with the positive end of a rectifier diode V4, the lower end of the step-down output winding is connected with the second end of a capacitor C2, the negative end of the rectifier diode V4 is connected with the first end of a capacitor C2, the negative end of a rectifier diode V9 serves as a working power supply output end, the upper end of a step-up output winding of the transformer T1 is connected with, the second end of the resistor R2 is respectively connected with the negative end of a voltage regulator tube V6 and the first end of an energy storage capacitor C3, the positive end of the voltage regulator tube V6 and the second end of the energy storage capacitor C3 are both connected with the lower end of a boosting output winding of the transformer T1, the second end of the energy storage capacitor C3 is grounded, and the energy storage capacitor C3 is used as a power-down maintaining power supply to output when the onboard direct-current power supply is powered down. And the voltage-stabilizing tube V6 has a voltage-stabilizing value higher than the initial charging voltage of the energy-storage capacitor C3, and the voltage-stabilizing tube V6 is used for conducting in reverse direction when the voltage of the power-down holding power supply abnormally rises and exceeds the voltage-stabilizing value of the voltage-stabilizing tube V6, so as to limit the output voltage of the power-down holding power supply to the voltage-stabilizing value. For example, the initial charging voltage of the energy storage capacitor C3 is 40V, and the voltage regulator V6 may be a 47V voltage regulator, so that when the power supply voltage is abnormally increased to exceed 47V due to power failure, the voltage regulator V6 is turned on in the reverse direction, and the voltage can be limited to 47V, thereby protecting the subsequent circuits.
The first comparator circuit 102 comprises a resistor R10, a resistor R11, a comparator N3, a resistor R12 and a diode V9, wherein a first end of the resistor R10 is connected with an onboard direct-current power supply, the comparator N3 is a voltage comparator with open-drain output, a second end of the resistor R10 is respectively connected with a first end of the resistor R11, a first end of the resistor R12 and an anode input end of the comparator N3, a second end of the resistor R11 is grounded, a cathode input end of the comparator N3 is connected with a reference power source VREF1 and converted from VPP, a second end of the resistor R12 is connected with an anode end of the diode V9, a cathode end of the diode V9 is connected with an output end of the comparator N3, and an output end of the comparator N3 is further connected with the switch circuit 103 and the processor. The resistor R10 and the resistor R11 form an onboard direct-current power supply voltage sampling circuit, the voltage sampling proportion can be adjusted by adjusting the resistance proportion of the resistor R10 and the resistor R11, the resistor R12 and the diode V9 form a feedback loop, the feedback loop is used for introducing positive feedback when the output voltage of the comparator N3 is lower than the threshold voltage so as to realize hysteresis of the comparator N3, and the positive feedback loop is cut off by utilizing the unidirectional conductivity of the diode V9 when the output voltage of the comparator N3 is higher than the threshold voltage so as to reduce the conversion speed of the output of the comparator N3, so that the switching speed of the power-down holding power supply and the onboard direct-current power supply is reduced by controlling the switching circuit 103, and the impact of the power supply switching process is reduced. The output signal of the comparator N3 is used not only as a control signal for the switching circuit 103 to control the switching between the power down holding power supply and the on-board dc power supply, but also as a voltage monitoring signal to the processor for indicating that the power down holding power supply is enabled. When the onboard direct-current power supply supplies power normally, the comparator N3 outputs a high-level signal, the switch circuit 103 is controlled to be disconnected, and the power supply is kept not to be started after power failure; when the power failure occurs in the onboard direct-current power supply, the comparator N3 outputs a low level signal to control the switching circuit 103 to be switched on, and the power failure keeps the power supply on. The processor may determine whether the power down hold power supply is enabled based on the comparator N3 outputting a low signal or a high signal.
The switch circuit 103 comprises a P communication enhancement type field effect transistor V7, an NPN triode V8, a resistor R6, a resistor R13 and a resistor R14, wherein a source of the P communication enhancement type field effect transistor V7 and a first end of the resistor R6 are both connected with a second end of the resistor R2, a drain of the P communication enhancement type field effect transistor V7 is connected with a positive electrode end of the diode V2 and a second end of the resistor R1, a gate of the P communication enhancement type field effect transistor V7 is connected with a second end of the resistor R6 and a collector of the NPN triode V8, a base of the NPN triode V8 and a first end of the resistor R13 are connected with a reference power supply 2, an emitter of the VREF triode V8 is connected with a first end of the resistor R14, and a second end of the resistor R14 and a second end of the resistor R13 are both connected with an output end of the comparator N. The P communication enhancement type field effect transistor V7 is used for controlling a switch of a power-down maintaining power supply, and the NPN triode V8 and the resistor R14 are used for controlling the P communication enhancement type field effect transistor V7 to be switched on or switched off according to an output signal of the comparator N3. When the comparator N3 outputs a high level, the NPN triode V8 is controlled to be cut off, the P communication enhanced field effect transistor V7 is controlled to be cut off, the power failure keeps the output disconnected, and when the comparator N3 outputs a low level, the NPN triode V8 is controlled to be conducted, the P communication enhanced field effect transistor V7 is controlled to be conducted, the power failure keeps the output started. In addition, the resistor R1 in the power input circuit 100 also realizes that the drain voltage of the P-channel enhancement type fet V7 is fixed as the input power voltage when the onboard dc power supply supplies power, and the resistor R13 is pulled up to the reference power source VREF2, so that the open-drain output comparator N3 has the capability of outputting a high level.
In addition, as preferable, the on-board electronic device switching power supply power-down holding circuit further includes a second comparator circuit 104 for indicating whether the power-down holding power supply is charged or not, and the second comparator circuit 104 is connected to the flyback switching power supply circuit 101 and the processor, respectively. The second comparator circuit 104 may monitor the voltage of the energy storage capacitor C3 in the flyback switching power supply circuit 101, and when the energy storage capacitor C3 is charged, the second comparator circuit 104 outputs a high level signal to the processor to indicate that the power down keeps the power supply fully charged.
Specifically, the second comparator circuit 104 includes a resistor R7, a resistor R8, a resistor R9, a comparator N2, and a resistor R16, the comparator N2 is a voltage comparator with open-drain output, the resistor R16 is a pull-up resistor, a first end of the resistor R7 is connected to a second end of the resistor R2, a second end of the resistor R7 is connected to a first end of the resistor R8, a first end of the resistor R9, and a positive input end of the comparator N2, a second end of the resistor R8 is grounded, a negative input end of the comparator N2 is connected to a reference power source VREF1, an output end of the comparator N2 is connected to a second end of the resistor R9, a second end of the resistor R16, and the processor, a first end of the resistor R16 serves as an output end, the resistor R7 and the resistor R8 constitute a power-down holding power source voltage sampling circuit, the sampling circuit can be adjusted by adjusting a resistance ratio of the resistor R8 and the resistor R8, and the positive feedback resistor R8 is used for introducing the positive feedback comparator N8, the switching speed of the output voltage of the comparator N2 can be improved, and hysteresis of the comparator N2 can be realized. When the power is off and the power supply is kept fully charged, the comparator N2 outputs a low level to the processor, and when the power is off and the power supply is kept fully charged, the comparator N2 outputs a high level to the processor.
In addition, as is preferable, the on-board electronic device switching power supply power-down holding circuit further includes a third comparator circuit 105 for indicating whether the power-down holding power supply voltage is about to be lower than the lowest operating voltage of the system, and the third comparator circuit 105 is connected to the flyback switching power supply circuit 101 and the processor, respectively. The third comparator circuit 105 may monitor the voltage across the energy storage capacitor C3 in the flyback switching power supply circuit 101, and when the voltage across the energy storage capacitor C3 is about to be lower than the minimum operating voltage of the system, the third comparator circuit 105 outputs a low level signal to the processor.
Specifically, the third comparator circuit 105 includes a resistor R3, a resistor R4, a resistor R5, a resistor R15, and a comparator N1, the comparator N1 is a voltage comparator with open-drain output, the resistor R15 is a pull-up resistor, a first end of the resistor R3 is connected to a first end of the energy storage capacitor C3, a second end of the resistor R3 is connected to a first end of the resistor R4, a first end of the resistor R5, and a positive input end of the comparator N1, a second end of the resistor R4 is connected to a second end of the energy storage capacitor C3 and grounded, a negative input end of the comparator N1 is connected to a reference power supply, an output end of the comparator N1 is connected to a second end of the resistor R5, a second end of the resistor R15, and a processor, a first end of the resistor R15 is an output end, the resistor R3 and the resistor R4 form a power-down holding power supply voltage sampling circuit, and a ratio of the sampled voltage can be adjusted by adjusting resistance of the resistor R3 and the resistor R4, the resistor R5 is used for introducing positive feedback to the comparator N1, so that the switching speed of the output voltage of the comparator N1 can be improved, and hysteresis of the comparator N2 can be realized. When the power-off holding power supply voltage is about to be lower than the lowest working voltage of the system, the comparator N1 outputs a low level to the processor.
According to the power-down holding circuit of the on-board electronic equipment switching power supply, the triple monitoring of the power-down holding power supply voltage can be realized by arranging the three comparator circuits, whether the power-down holding power supply is started or not, whether the power-down holding power supply is fully charged or not and whether the power-down holding power supply voltage is about to be lower than the lowest working voltage of a system or not can be simultaneously detected, and therefore the equipment can perform more appropriate processing according to the monitoring result of the power-down holding power supply voltage. For example, when power failure is detected and the power supply is kept enabled, the device can immediately start the work of saving important data and the like; when a power failure is detected to keep the power supply fully charged, the equipment can start certain operations which can be started only under the state of having the power failure holding capacity; when the power-down holding power supply voltage is detected to be lower than the lowest working voltage of the system, the equipment can immediately execute ending work in the power-down holding period, such as calculating and storing the power-down holding time, and the power-down holding time can be specifically set according to actual needs. In addition, the output of the first comparator circuit 102 not only has a monitoring function, but also realizes the on-off control of the power-down holding power supply, and the switching speed of the power-down holding power supply can be effectively reduced and the impact of the switching process is reduced by adding a diode in a feedback loop.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The power failure holding circuit of the switching power supply of the airborne electronic equipment is characterized by comprising a power supply input circuit (100), a flyback switching power supply circuit (101), a first comparator circuit (102) and a switching circuit (103), wherein the power supply input circuit (100) is respectively connected with an airborne direct-current power supply and the flyback switching power supply circuit (101), the switching circuit (103) is respectively connected with the flyback switching power supply circuit (101) and the power supply input circuit (100), and the first comparator circuit (102) is respectively connected with the airborne direct-current power supply and the switching circuit (103);
the power supply input circuit (100) is used for realizing isolation and power supply switching between an airborne direct-current power supply and a power failure holding power supply, the flyback switching power supply circuit (101) is used for performing voltage reduction conversion on the input airborne direct-current power supply to serve as working power supply output and performing voltage boosting conversion on the input airborne direct-current power supply to charge an energy storage capacitor when the airborne direct-current power supply normally supplies power, and is also used for performing power failure holding power supply output when the airborne direct-current power supply fails to supply power, the switching circuit (103) is used for controlling the flyback switching power supply circuit (101) to be connected or disconnected with the power failure holding power supply output, and the first comparator circuit (102) is used for monitoring the voltage state of the airborne direct-current power supply and outputting a control signal to control the connection or disconnection of the switching circuit (103) according to a monitoring result.
2. The on-board electronics switching power supply power down retention circuit of claim 1,
the first comparator circuit (102) is also coupled to the processor and is operable to indicate whether the power-down retention supply is enabled.
3. The on-board electronics switching power supply power down retention circuit of claim 2,
the power input circuit (100) comprises a diode V1, a diode V2, a resistor R1 and a capacitor C1, wherein the positive end of the diode V1 is connected with an airborne direct-current power supply, the negative end of the diode V1 is respectively connected with the negative end of a diode V2, the first end of a resistor R1, the first end of the capacitor C1 and the flyback switching power supply circuit (101), the positive end of a diode V2 and the second end of the resistor R1 are both connected with a switching circuit (103), the second end of the capacitor C1 is grounded, and the diode V1 and the diode V2 are used for realizing isolation and power supply switching between the airborne direct-current power supply and a power-down maintaining power supply.
4. The on-board electronics switching power supply power down retention circuit of claim 3,
the flyback switching power supply circuit (101) comprises a transformer T1, a field effect switch tube V3, a rectifier diode V4, a rectifier diode V5, a resistor R2, a capacitor C2, a voltage regulator tube V6 and an energy storage capacitor C3, wherein the upper end of an input winding of the transformer T1 is connected with the negative end of a diode V1, the lower end of the input winding is connected with the drain electrode of a field effect switch tube V3, the source electrode of the field effect switch tube V3 is grounded, an input winding of the transformer T1 and the field effect switch tube V3 form a chopper circuit, the upper end of a voltage reduction output winding of the transformer T1 is connected with the positive end of a rectifier diode V4, the lower end of the voltage reduction output winding is connected with the second end of a capacitor C2, the negative end of the rectifier diode V4 is connected with the first end of the capacitor C2, the negative end of the rectifier diode V5739 serves as an output end of a working power supply, the upper end of a voltage boosting output winding of the transformer T1 is connected with the positive end of a rectifier diode, the second end of the resistor R2 is respectively connected with the negative end of a voltage regulator tube V6 and the first end of an energy storage capacitor C3, the positive end of the voltage regulator tube V6 and the second end of the energy storage capacitor C3 are both connected with the lower end of a boosting output winding of a transformer T1, the second end of the energy storage capacitor C3 is grounded, the voltage stabilizing value of the voltage regulator tube V6 is higher than the initial charging voltage of the energy storage capacitor C3, and the voltage regulator tube V6 is used for conducting in a reverse direction when the power-down maintaining power supply voltage abnormally rises and exceeds the voltage stabilizing value of the voltage regulator tube V6, so that the output voltage of the power-down maintaining power supply is limited to be the voltage stabilizing value.
5. The on-board electronics switching power supply power down retention circuit of claim 4,
the first comparator circuit (102) comprises a resistor R10, a resistor R11, a comparator N3, a resistor R12 and a diode V9, a first end of the resistor R10 is connected with an onboard direct-current power supply, a second end of the resistor R10 is respectively connected with a first end of the resistor R11, a first end of the resistor R12 and a positive input end of the comparator N3, a second end of the resistor R11 is grounded, a negative input end of the comparator N3 is connected with a reference power supply, a second end of the resistor R12 is connected with a positive end of a diode V9, a negative end of the diode V9 is connected with an output end of the comparator N3, an output end of the comparator N3 is further connected with a switching circuit (103) and a processor, the resistor R10 and the resistor R11 form an onboard direct-current power supply voltage threshold sampling circuit, the resistor R12 and the diode V9 form a feedback loop and are used for introducing positive feedback to realize the hysteresis loop of the comparator N3 when the output voltage of the comparator N3 is lower than the positive feedback voltage output voltage of the positive feedback loop 3 and for cutting off the positive feedback loop 3 when the The switching speed of the output of comparator N3 is reduced.
6. The on-board electronics switching power supply power down retention circuit of claim 5,
the switching circuit (103) comprises a P communication enhancement type field effect transistor V7, an NPN triode V8, a resistor R6, a resistor R13 and a resistor R14, wherein a source electrode of the P communication enhancement type field effect transistor V7 and a first end of a resistor R6 are connected with a second end of a resistor R2, a drain electrode of the P communication enhancement type field effect transistor V7 is connected with an anode electrode of a diode V2 and a second end of a resistor R1, a gate electrode of the P communication enhancement type field effect transistor V7 is connected with a second end of a resistor R6 and a collector electrode of an NPN triode V8, a base electrode of an NPN V8 and a first end of a resistor R13 are connected with a reference power supply, an emitter electrode of an NPN 8 is connected with a first end of a resistor R14, a second end of a resistor R14 and a second end of a resistor R13 are connected with an output end of a comparator N3, the P communication enhancement type field effect transistor V7 is used for controlling a switch of the NPN 7 or the NPN 7 to turn-on or turn-off of the NPN 7 according, when the comparator N3 outputs a high level, the NPN triode V8 is controlled to be cut off, the P communication enhancement type field effect transistor V7 is controlled to be cut off, the power failure keeps the output disconnected, when the comparator N3 outputs a low level, the NPN triode V8 is controlled to be conducted, the P communication enhancement type field effect transistor V7 is controlled to be conducted, and the power failure keeps the output started.
7. The on-board electronics switching power supply power down retention circuit of claim 4,
the power-down protection circuit further comprises a second comparator circuit (104) used for indicating whether the power-down protection power supply is charged or not, and the second comparator circuit (104) is connected with the flyback switching power supply circuit (101) and the processor respectively.
8. The on-board electronics switching power supply power down retention circuit of claim 7,
the second comparator circuit (104) includes a resistor R7, a resistor R8, a resistor R9, a comparator N2, and a resistor R16, a first end of the resistor R7 is connected with a second end of the resistor R2, a second end of the resistor R7 is respectively connected with a first end of the resistor R8, a first end of the resistor R9 and an anode input end of the comparator N2, a second end of the resistor R8 is grounded, a cathode input end of the comparator N2 is connected with a reference power supply, an output end of the comparator N2 is respectively connected with a second end of the resistor R9, a second end of the resistor R16 and the processor, a first end of the resistor R16 serves as an output end, the resistor R7 and the resistor R8 form a power-down holding power supply voltage sampling circuit, and the resistor R9 is used for introducing positive feedback to the comparator N2, when the power is off and the power supply is kept fully charged, the comparator N2 outputs a low level to the processor, and when the power is off and the power supply is kept fully charged, the comparator N2 outputs a high level to the processor.
9. The on-board electronics switching power supply power down retention circuit of claim 4,
the power-down protection circuit further comprises a third comparator circuit (105) used for indicating whether the power-down maintaining power supply voltage is about to be lower than the lowest working voltage of the system, wherein the third comparator circuit (105) is respectively connected with the flyback switching power supply circuit (101) and the processor.
10. The on-board electronics switching power supply power down retention circuit of claim 9,
the third comparator circuit (105) includes a resistor R3, a resistor R4, a resistor R5, a resistor R15, and a comparator N1, a first end of the resistor R3 is connected with a first end of the energy storage capacitor C3, a second end of the resistor R3 is respectively connected with a first end of the resistor R4, a first end of the resistor R5 and an anode input end of the comparator N1, a second end of the resistor R4 is connected with a second end of the energy storage capacitor C3 and grounded, a cathode input end of the comparator N1 is connected with a reference power supply, an output end of the comparator N1 is respectively connected with a second end of the resistor R5, a second end of the resistor R15 and the processor, the first end of the resistor R15 is an output end, the resistor R3 and the resistor R4 form a power-down holding power supply voltage sampling circuit, the resistor R5 is used for introducing positive feedback to the comparator N1, when the power-off holding power supply voltage is about to be lower than the lowest working voltage of the system, the comparator N1 outputs a low level to the processor.
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Application publication date: 20201127 |