CN114614437A - Undervoltage delay protection circuit and power supply system - Google Patents
Undervoltage delay protection circuit and power supply system Download PDFInfo
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- CN114614437A CN114614437A CN202210329382.7A CN202210329382A CN114614437A CN 114614437 A CN114614437 A CN 114614437A CN 202210329382 A CN202210329382 A CN 202210329382A CN 114614437 A CN114614437 A CN 114614437A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/207—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage also responsive to under-voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/027—Details with automatic disconnection after a predetermined time
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
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Abstract
The invention relates to an undervoltage delay protection circuit and a power supply system, wherein the circuit comprises: the first comparison control circuit is used for acquiring the output voltage of the standby power supply, generating a delay trigger signal to the delay control circuit when the output voltage is lower than the lower limit value of the first hysteresis voltage, and generating a delay turn-off signal to the delay control circuit when the output voltage is higher than the upper limit value of the first hysteresis voltage; the delay control circuit is used for starting delay according to the delay trigger signal or cutting off delay according to the delay cut-off signal and outputting a corresponding control signal to the second comparison control circuit; the second comparison control circuit is used for acquiring the output voltage of the standby power supply, generating a switching-on signal to the main power switch tube when the output voltage is higher than the upper limit value of the second hysteresis voltage, and generating a switching-off signal to the main power control circuit when the output voltage or the control signal is lower than the lower limit value of the second hysteresis voltage; the main power control circuit is used for controlling the opening and closing of the main power switch tube; the method has the advantages of low power consumption, high delay precision and the like.
Description
Technical Field
The invention relates to the technical field of switching power supplies, in particular to an undervoltage delay protection circuit and a power supply system.
Background
In recent years, the share of a switching power supply on the market is increasing day by day, in part of industrial fields, equipment is required to be capable of operating stably for a long time, and it is required to ensure that an input power supply end works stably for a long time.
The current delay undervoltage protection scheme which is widely applied is a delay undervoltage protection scheme formed by operational amplifiers, and the scheme has the advantages of simple circuit and easy realization, but has the following defects:
(1) when the voltage is undervoltage, the standby current is large;
(2) the delay precision is low;
(3) the later maintenance cost is high.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide an ultra-low power consumption under-voltage delay protection circuit and a power supply system, so as to solve the problem that the standby power supply enters an under-voltage state to cause the shutdown and restart of the device when the voltage of the storage battery of the standby power supply drops during switching power supplies, enhance the reliability of the power supply system, reduce the power consumption of the circuit, and freely adjust internal parameters.
The technical scheme adopted by the invention is as follows:
in a first aspect, an under-voltage delay protection circuit is provided, which is applied to a power supply system including a switching power supply, a standby power supply and a main power switch tube, and includes: the circuit comprises a first comparison control circuit, a delay control circuit, a second comparison control circuit and a main power control circuit;
the input end of the first comparison control circuit is used for being connected with the output end of a standby power supply, the output end of the first comparison control circuit is connected with the delay control circuit and is used for collecting the output voltage of the standby power supply, generating a delay trigger signal to the delay control circuit when the output voltage is lower than the lower limit value of a first hysteresis voltage, and generating a delay turn-off signal to the delay control circuit when the output voltage is higher than the upper limit value of the first hysteresis voltage;
the output end of the delay control circuit is connected with the first input end of the second comparison control circuit, and is used for starting delay according to the delay trigger signal or stopping delay according to the delay shutdown signal and outputting a corresponding control signal to the second comparison control circuit;
the second input end of the second comparison control circuit is used for being connected with the output end of a standby power supply, the output end of the second comparison control circuit is connected with the input end of the main power control circuit and is used for collecting the output voltage of the standby power supply, when the output voltage is higher than the upper limit value of the second hysteresis voltage, a turn-on signal is generated to the main power control circuit, and when the output voltage or the control signal is lower than the lower limit value of the second hysteresis voltage, a turn-off signal is generated to the main power control circuit;
the output end of the main power control circuit is used for being connected with the control end of the main power switch tube and controlling the opening and closing of the main power switch tube;
the first hysteresis voltage upper limit value is smaller than the second hysteresis voltage upper limit value and is larger than or equal to the first hysteresis voltage lower limit value, and the first hysteresis voltage lower limit value is larger than the second hysteresis voltage lower limit value.
Preferably, the delay control circuit comprises a capacitor C2, a resistor R7, a resistor R13, a triode Q2 and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and the base electrode of the triode Q2, and then is used as the input end of the delay control circuit to be connected with the output end of the first comparison control circuit; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit as an output end of the delay control circuit; the other end of the capacitor C2, the other end of the resistor R7 and the collector of the triode Q2 are all used for being connected with the negative output end of the standby power supply.
Preferably, the first comparison control circuit includes: the first end of the first voltage division unit is used as the input end of a first comparison control circuit and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and is used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, the third end of the first comparison unit is used for being connected with the positive output end of the standby power supply, comparing the sampling voltage with the upper limit value or the lower limit value of the first hysteresis voltage and outputting a corresponding comparison result to the control circuit; the second end of the first control unit is used for accessing a power supply voltage, and the third end of the first control unit is used as the output end of the first comparison control circuit and is connected with the input end of the delay control circuit, and is used for outputting a delay trigger signal or a delay turn-off signal to the delay control circuit according to the comparison result.
Preferably, the first control unit includes a resistor R4, a resistor R5, a resistor R6, a transistor Q1, and a diode D1; one end of the resistor R5 is used as the input end of the first control unit and is connected with the second end of the first comparison unit, and the other end of the resistor R5 is connected with the base electrode of the triode Q1 and one end of the resistor R4; the other end of the resistor R4 is connected with an emitting electrode of the triode Q1 and then serves as a second end of the first control unit to be connected with a power supply voltage; the collector of the triode Q1 is connected with one end of the resistor R6; the other end of the resistor R6 is connected with the anode of the diode D1; the cathode of the diode D1 is connected as the output of the first control unit to the input of the delay control circuit.
Preferably, the first control unit further includes a resistor R3, one end of the resistor R3 is connected to the other end of the resistor R6 and the anode of the diode D1, respectively, and the other end is connected to the first end of the first comparing unit.
Preferably, the delay control circuit comprises a capacitor C2, a resistor R7, a resistor R13, a resistor R20, a voltage regulator tube D7, a triode Q2 and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and is used for accessing power supply voltage; the other end of the capacitor C2 is connected with the other end of the resistor R7 and the cathode of the voltage regulator tube D7, and then is used as the input end of the delay control circuit to be connected with the output end of the first comparison control circuit; the anode of the voltage regulator tube D7 is connected with the base of the triode Q2 and one end of the resistor R20; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit as an output end of the delay control circuit; the other end of the resistor R20 and the collector of the triode Q2 are both used for being connected with the negative output end of the standby power supply.
Preferably, the first comparison control circuit includes: the first end of the first voltage division unit is used as the input end of a first comparison control circuit and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and the fourth end of the first control unit and is used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, and the third end of the first comparison unit is used for being connected with the negative output end of the standby power supply; the second end of the first control unit is used for accessing a power supply voltage, and the third end of the first control unit is used as the output end of the first comparison control circuit and is connected with the input end of the delay control circuit.
Preferably, the first control unit comprises a resistor R3, a resistor R4, a resistor R5, a diode D1 and a transistor Q1; one end of the resistor R3 is used as the fourth end of the first control unit and is connected with the third end of the first voltage division unit and the first end of the first comparison unit; the other end of the resistor R3 is connected with the collector of the triode Q1; an emitter of the triode Q1 is connected with one end of the resistor R4 and then serves as a second end of the first control unit to be connected with a power supply voltage; the other end of the resistor R4 is connected with the other end of the resistor R5 and the cathode of the diode D1; the anode of the diode D1 is used as the third end of the first control unit and is connected with the input end of the delay control circuit; the other end of the resistor R5 is connected as a first end of the first control unit to a second end of the first comparison unit.
Preferably, the first comparison control circuit further includes a first filtering unit, a first end of the first filtering unit is connected to a first end of the first comparing unit, and a second end of the first filtering unit is used for being connected to a negative output end of the standby power supply, and is used for filtering a signal input to the first comparing unit.
Preferably, the second comparison control circuit includes a second voltage division unit, a second comparison unit, and a second control unit; the first end of the second voltage division unit is used as the second input end of the second comparison control circuit and is used for being connected with the positive output end of the standby power supply, the second end of the second voltage division unit is used for being connected with the negative output end of the standby power supply, and the third end of the second voltage division unit is connected with the first end of the second comparison unit; the first end of the second control unit is connected with the third end of the second control unit and then serves as the first input end of the second comparison control circuit to be connected with the output end of the delay control circuit, the second end and the first end of the second control unit are respectively used as the output end of the delay control circuit to be connected with the input end of the main power control circuit, and the third end is used for being connected with the negative output end of the standby power supply; the second end of the second control unit is used for connecting the power supply voltage.
Preferably, the second comparison control circuit further comprises a resistor R12, and the first terminal of the second comparison unit is connected to the third terminal of the second control unit through a resistor R12.
Preferably, the second comparison control circuit further includes a second filtering unit, a first end of the second filtering unit is connected to a third end of the second voltage division unit and a first end of the second comparing unit, a second end of the second filtering unit is connected to a second end of the second control unit, the third end of the second filtering unit is used for being connected to a negative output end of the standby power supply, and the second filtering unit is used for filtering a signal input to the second comparing unit.
In a second aspect, a power supply system is provided, which includes a switching power supply, a standby power supply, a main power switch tube, and the undervoltage delay protection circuit as described above; the switching power supply is used for being connected with a load; the standby power supply is connected with the input end of the undervoltage delay protection circuit, the output end of the undervoltage delay protection circuit is connected with the control end of the main power switch tube, and the main power switch tube is connected between the negative output end of the standby power supply and the load in series.
Compared with the prior art, the invention has the following remarkable effects:
1. the undervoltage delay protection circuit is built through discrete devices, when the storage battery is in power shortage and the direct current-to-direct current power supply module is under-voltage, the main power switch tube is closed, only the undervoltage delay protection circuit needs to supply power, at the moment, the undervoltage delay protection circuit can maintain normal work only by consuming microampere-level current of the battery, and the low-power-consumption mode can ensure that the battery can not consume the residual electric quantity completely under the long-term storage battery power supply standby condition, has small loss on the storage battery, and improves the endurance life of the storage battery;
2. the undervoltage delay protection circuit has an undervoltage delay protection function, when the AC-DC power supply module and the DC-DC power supply module supply power for the load to be switched, the power supply voltage of the storage battery can be instantly pulled to an undervoltage point and then can be recovered to be normal, and when the delay protection circuit detects that the power supply voltage is below the undervoltage point or the undervoltage point, the undervoltage delay protection function is started, so that the switching tube is controlled to be continuously conducted under the condition that the power supply voltage of the storage battery is below the undervoltage point or the undervoltage point due to switching, and the reliability of the power supply is improved.
Drawings
FIG. 1 is a schematic block diagram of an under-voltage delay protection circuit of the present invention;
FIG. 2 is a schematic circuit diagram of an embodiment of an under-voltage delay protection circuit according to a first embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of another embodiment of the under-voltage delay protection circuit according to the first embodiment of the present invention;
fig. 4 is a schematic circuit diagram of another embodiment of the under-voltage delay protection circuit according to the second embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to the following embodiments and the accompanying drawings to help those skilled in the art to better understand the inventive concept of the present invention, but the scope of the claims of the present invention is not limited to the following embodiments, and all other embodiments obtained without inventive efforts by those skilled in the art will fall within the scope of the present invention without departing from the inventive concept of the present invention.
First embodiment
Fig. 1 is a schematic block diagram of the under-voltage delay protection circuit in this embodiment, and the under-voltage delay protection circuit in this embodiment is applied to a power supply system including a switching power supply, a standby power supply, and a main power switch tube, and the power supply system is used for supplying power to a load, and in this embodiment, a under-voltage delay protection circuit is provided, which includes: the circuit comprises a first comparison control circuit 100, a delay control circuit 200, a second comparison control circuit 300 and a main power control circuit 500;
the input end of the first comparison control circuit 100 is used for being connected with the output end of a standby power supply, the output end of the first comparison control circuit is connected with the delay control circuit 200, and the delay control circuit is used for acquiring the output voltage of the standby power supply, generating a delay trigger signal to the delay control circuit 200 when the output voltage is lower than the lower limit value of the first hysteresis voltage, and generating a delay turn-off signal to the delay control circuit 200 when the output voltage is higher than the upper limit value of the first hysteresis voltage;
the output end of the delay control circuit 200 is connected to the first input end of the second comparison control circuit 300, and is configured to start a delay according to the delay trigger signal or turn off the delay according to the delay off signal, and output a corresponding control signal to the second comparison control circuit 300;
a second input end of the second comparison control circuit 300 is configured to be connected to an output end of a standby power supply, and an output end of the second comparison control circuit is connected to an input end of the main power control circuit 500, and is configured to collect an output voltage of the standby power supply, generate a turn-on signal to the main power control circuit 500 when the output voltage is higher than a second hysteresis voltage upper limit value, and generate a turn-off signal to the main power control circuit 500 when the output voltage or the control signal is lower than the second hysteresis voltage lower limit value;
the output end of the main power control circuit 500 is connected to the control end of the main power switch tube, and is used for controlling the on and off of the main power switch tube;
the first hysteresis voltage upper limit value is smaller than the second hysteresis voltage upper limit value and is larger than or equal to the first hysteresis voltage lower limit value, and the first hysteresis voltage lower limit value is larger than the second hysteresis voltage lower limit value.
Specifically, the main power switch tube is an MOS tube, and the main power MOS tube is connected in series in a line between the standby power supply and the load.
The invention conception of the application is as follows: the first comparison control circuit 100 and the second comparison control circuit 300 sample the input voltage (i.e. the output voltage of the standby power supply), when the input voltage drops to the comparison first lower limit value of the hysteresis voltage but is not lower than the second lower limit value of the hysteresis voltage, the first comparison control circuit 100 gives a delay trigger signal to the delay control circuit 200, the delay control circuit 200 starts to delay, and after reaching the delay time, gives a control signal to the second comparison control circuit 300, forcibly causes the second comparison control circuit 300 to give a turn-off signal to the main power control circuit 500 to turn off the main power MOS transistor, so that when the power grid fails, the dc-to-dc switching power supply module switched to the standby power supply by the ac-to-dc switching power supply module causes the voltage of the storage battery of the standby power supply to drop, and the storage battery is instantaneously in an undervoltage state, the delay control circuit 200 delays, the main power switch tube is kept on during the period from the instant drop of the storage battery to the under-voltage state to the under-voltage recovery, so that the problem of the turn-off and restart of the electric equipment caused by the instant drop of the storage battery voltage in the switching process can be solved; when the input voltage drops below the lower limit value of the second hysteresis voltage, the second comparison control circuit 300 gives a turn-off signal to the main power control circuit 500, the main power control circuit 500 gives a turn-off signal of a previous stage to the main power MOS tube to turn off the main circuit, and the whole circuit only needs to consume input extremely small current under the condition of undervoltage, so that the undervoltage delay protection circuit with ultralow power consumption is finally realized.
Specifically, a first end of the main power switch tube is used for being connected with a negative output end of the standby power supply, and a second end of the main power switch tube is used for being connected with a load of a power supply system;
the power supply system further comprises a power supply circuit 400, wherein an input end of the power supply circuit 400 is connected with an output end of the standby power supply, and output ends of the power supply circuit 400 are respectively connected with the first comparison control circuit 100, the delay control circuit 200, the second comparison control circuit 300 and the main power control circuit 500, and are used for providing 24V power supply voltage for the first comparison control circuit 100, the delay control circuit 200, the second comparison control circuit 300 and the main power control circuit 500;
when the voltage of the storage battery is insufficient and in a charging state, when the input voltage is higher than the upper limit value of the first hysteresis voltage of the first comparison control circuit 100, a charging trigger signal is given to the delay control circuit 200, the delay control circuit 200 enters a preparation timing state, when the input voltage continuously rises and exceeds the upper limit value of the second hysteresis voltage of the second comparison control circuit 300, the second comparison control circuit 300 gives a switching-on trigger signal to the main power circuit, and then the main power control circuit 500 controls the main power MOS tube to control the switching-on of the main circuit.
When the battery was in under-voltage state at the electric quantity exhaustion, under-voltage time delay control circuit 200 control main power switch tube closed, only under-voltage time delay protection circuit needed the power supply, under-voltage time delay protection circuit only need consume the current of battery microampere rank this moment just can maintain normal work, this kind of low-power consumption mode under long-term battery power supply standby, can guarantee that the battery can not be totally with the electric quantity consumption that only exists to cause irreversible damage as for the battery.
As shown in fig. 2, as a specific embodiment of the under-voltage delay control circuit 200, the delay control circuit 200 includes a capacitor C2, a resistor R7, a resistor R13, a transistor Q2, and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and the base of the transistor Q2, and then is used as the input end of the delay control circuit 200 and connected with the output end of the first comparison control circuit 100; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit 300 as an output end of the delay control circuit 200; the other end of the capacitor C2, the other end of the resistor R7 and the collector of the triode Q2 are all used for being connected with the negative output end of the standby power supply.
Specifically, when the battery is in a charging state, when the output voltage of the backup power supply is greater than the upper limit value of the first hysteresis voltage, the first comparison control circuit 100 sends a charging trigger signal to the delay control circuit 200, the delay control circuit 200 charges the capacitor C2 through the charging trigger signal sent by the first comparison control circuit 100, the voltage on the capacitor C2 is always at the magnitude of V3, when the output voltage of the backup power supply is less than the lower limit value of the first hysteresis voltage, the first comparison control circuit 100 generates a delay trigger signal to the delay control circuit 200, so that the capacitor C1 discharges through the resistor R7, when the voltage V3 drops to a certain degree, the transistor Q2 is turned on, the diode D2 and the resistor R13 serve as the output of the delay control circuit 200, the switching state of the transistor Q2 further affects the output, so as to affect the first output end of the second comparison control circuit 300, the purpose of delay undervoltage control is realized.
As a specific embodiment of the first comparison control circuit 100, the first comparison control circuit 100 includes: the first end of the first voltage division unit is used as the input end of the first comparison control circuit 100 and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and is used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, the third end of the first comparison unit is used for being connected with the positive output end of the standby power supply, comparing the sampling voltage with the upper limit value or the lower limit value of the first hysteresis voltage and outputting a corresponding comparison result to the control circuit; the second terminal of the first control unit is used for accessing a power supply voltage, and the third terminal is used as the output terminal of the first comparison control circuit 100 and connected with the input terminal of the delay control circuit 200, and is used for outputting a delay trigger signal or a delay turn-off signal to the delay control circuit 200 according to the comparison result.
Specifically, the first voltage dividing unit includes a resistor R1 and a resistor R2, one end of the resistor R1 is used as an input end of the first comparison control circuit 100 and is connected to a positive output end of the standby power supply, the other end of the resistor R2 is connected to a third end of the first voltage dividing unit and is connected to a first end of the first comparison unit, and the other end of the resistor R2 is used as a second end of the first voltage dividing unit and is connected to a negative output end of the standby power supply.
Specifically, the first control unit comprises a resistor R4, a resistor R5, a resistor R6, a triode Q1 and a diode D1; one end of the resistor R5 is used as the input end of the first control unit and is connected with the second end of the first comparison unit, and the other end of the resistor R5 is connected with the base electrode of the triode Q1 and one end of the resistor R4; the other end of the resistor R4 is connected with an emitter of the triode Q1 and then serves as a second end of the first control unit for connecting power supply voltage; the collector of the triode Q1 is connected with one end of the resistor R6; the other end of the resistor R6 is connected with the anode of the diode D1; the cathode of the diode D1 is connected as the output of the first control unit to the input of the delay control circuit 200.
Specifically, the first comparison unit is a chip U1 of model TL 431.
The operating principle of the first comparison control circuit 100 is: the upper limit value of the first hysteresis voltage is equal to the lower limit value of the first hysteresis voltage, the first proportional control circuit samples the input voltage (the output voltage of the standby power supply) by using a resistance sampling mode, that is, one end of a resistor R1 is connected to the positive output end of the standby power supply, one end of a resistor R2 is connected to the negative input end of the standby power supply, the other ends of a resistor R1 and a resistor R2 are connected to a reference level of a chip U1, the chip U1 compares the voltage of the reference level with an internal reference voltage (the upper limit value of the first hysteresis voltage and the lower limit value of the second hysteresis voltage), then the cathode of the chip U1 is used as the output of logic judgment, the resistor R5 is used for limiting the base level of the Q1 when the Q1 triode works, the resistor R4 is used for ensuring that the voltage of the base level of the Q1 triode only has two states, and the Q1 is mainly used for switching the charging trigger signal of the delay control circuit 200 after the chip U1 is judged, when the input voltage is greater than the upper limit value of the first hysteresis voltage, the triode Q1 is switched on, so that the delay control circuit 200 enters a ready-to-time state, and when the input voltage is less than the lower limit value of the first hysteresis voltage, the triode Q1 is switched off, so that the delay control circuit 200 enters a delay starting state; resistor R6 is used for limiting collector current after transistor Q1 is turned on, and diode D1 is used for unidirectional conduction and increasing reverse voltage resistance for transistor Q1.
As shown in fig. 3, in the present embodiment, the first upper limit value of the hysteresis voltage is greater than the lower limit value of the hysteresis voltage, the first control unit further includes a resistor R3, one end of the resistor R3 is connected to the other end of the resistor R6 and the anode of the diode D1, and the other end is connected to the first end of the first comparing unit. The resistor R3 provides hysteresis voltage for the chip U1, the input voltage fluctuates greatly at the time of undervoltage turn-off, the hysteresis voltage can be increased by reducing the resistor R3, repeated judgment of the chip U1 caused by overlarge input voltage fluctuation is prevented, and the reliability of the undervoltage delay protection circuit of the embodiment is improved.
Further, the first comparison control circuit 100 further includes a first filtering unit, a first end of the first filtering unit is connected to a first end of the first comparing unit, and a second end of the first filtering unit is connected to the negative output end of the standby power supply, and is configured to filter a signal input to the first comparing unit.
Specifically, the first filtering unit is a capacitor C1, and the capacitor C1 is used for filtering an input signal of a reference level of the chip U1 to filter high-frequency interference.
As a specific embodiment of the second comparison control circuit 300, the second comparison control circuit 300 includes a second voltage division unit, a second comparison unit, and a second control unit; a first end of the second voltage division unit is used as a second input end of the second comparison control circuit 300 and is used for being connected with a positive output end of the standby power supply, a second end of the second voltage division unit is used for being connected with a negative output end of the standby power supply, and a third end of the second voltage division unit is connected with a first end of the second comparison unit; the first end of the second control unit is connected with the third end of the second control unit, and then is used as the first input end of the second comparison control circuit 300 to be connected with the output end of the delay control circuit 200, the second end and the first end of the second control unit are respectively used as the output end of the delay control circuit 200 to be connected with the input end of the main power control circuit 500, and the third end is used for being connected with the negative output end of the standby power supply; the second end of the second control unit is used for connecting the power supply voltage.
Specifically, referring to fig. 2, the second voltage dividing unit includes a resistor R8 and a resistor R9, the second comparing unit is a chip U2, and the second control unit includes a resistor R10, a resistor R11, a resistor R14, and a transistor Q3; the connection relationship of each component of the second comparison control circuit 300 is as follows: one end of a resistor R8 is used as a second input end of the second comparison control circuit 300 to connect a positive output end of the standby power supply, the other end of the resistor R8 is connected with one end of the resistor R9 and with the reference level of the chip U2, the other end of the resistor R9 and the anode of the chip U2 are connected with a negative output end of the standby power supply, the cathode of the chip U2 and one end of the resistor R11 are used as the output end of the second comparison control circuit 300, the other end of the resistor R11 and one end of the resistor R10 are connected with the base level of the transistor Q3, the other end of the resistor R10 and the emitting level of the transistor Q3 are connected with an output end of the power supply circuit 400, specifically, the output end of the power supply circuit 400 is a 24V dc power supply terminal, the collector of the transistor Q3 is connected with one end of the resistor R14, the other end of the resistor R14 and the reference level of the chip U2 and the other end of the resistor R13 are connected together, as a first input terminal of the second comparison control circuit 300; specifically, the second comparing unit is a chip U2 with model number TL 431.
The second comparison control circuit 300 operates on the following principle: the input voltage is sampled by a resistor R8 and a resistor R9, the sampled voltage signal is provided for a reference level of a chip U2, the reference level of the chip U2 and an internal reference voltage (a second hysteretic voltage upper limit value) are compared, a cathode of the chip U2 is used as an output of an internal comparison result, a resistor R11 limits a base level current of a transistor Q3, the resistor R10 ensures that the base level of the transistor Q3 is in a high-low level two states, the resistor R14 provides hysteretic voltage for the chip U2 when the transistor Q3 is turned on, wherein V6 is the hysteretic voltage of the chip U2, the hysteresis voltage can be interfered by a delay control circuit 200, and when the delay control circuit 200 delays, the hysteretic voltage V6 is pulled down to the second hysteretic voltage lower limit value of the chip U2 by a transistor Q2, a diode D2 and a resistor R13, logic of the chip U2 is performed, and the cathode of the chip U2 is turned off.
Specifically, the second comparison control circuit 300 further includes a resistor R12, and the first terminal of the second comparison unit is connected to the third terminal of the second control unit through a resistor R12.
Specifically, the second comparison control circuit 300 further includes a second filtering unit, a first end of the second filtering unit is connected to the third end of the second voltage dividing unit and the first end of the second comparing unit, a second end of the second filtering unit is connected to the second end of the second control unit, and a third end of the second filtering unit is used for being connected to the negative output end of the standby power supply.
Specifically, the second filtering unit includes a capacitor C3 and a capacitor C4, two ends of a resistor R9 are connected to two ends of a capacitor C3, one end of a resistor R12 is connected to a reference level of the chip U2, the other end of the resistor R12 is connected to the other end of the resistor R14 and the other end of the resistor R13, one end of the capacitor C4 is connected to a negative electrode of the power supply input terminal, the other ends of the resistor R12, the resistor R13 and the resistor R14 are connected to the other end of the capacitor C4, referring to fig. 3, for a circuit schematic diagram of another embodiment of the ultra-low power consumption under-voltage delay protection circuit of the present invention, the capacitor C3 filters input signals collected by the resistor R8 and the resistor R9, the addition of the resistor R12 can adjust the magnitude of the hysteresis voltage of the chip U2 when the hysteresis voltage is affected, and the capacitor C4 acts on the filter chip to remove the interference of the hysteresis portion of the U2.
As a specific embodiment of the power supply circuit 400, as shown in fig. 2, the power supply circuit 400 includes a diode D3, a resistor R15, a voltage regulator tube D4, a capacitor C5, a capacitor C6, a transistor Q4, and a transistor Q5, an anode of the diode D3 is used as an input terminal of the power supply circuit 400 and is connected to a positive output terminal of the standby power supply, and a cathode is connected to one end of the resistor R15 and an emitter of the transistor Q5; the other end of the resistor R15 is connected with the cathode of a voltage regulator tube D4, the base electrode of the triode Q4 and one end of the capacitor C5; the collector of the triode Q4 is connected with the base of the triode Q5, and the emitter of the triode Q4 is connected with one end of the capacitor C6 and the collector of the triode Q5 to be used as the output end of the power supply circuit 400; the anode of the voltage regulator tube D4, the other end of the capacitor C5 and the other end of the capacitor C6 are connected together and then are used for connecting the negative output end of the standby power supply; the circuit mainly generates a 24V direct-current voltage to supply power for partial circuits.
As a specific embodiment of the main power control circuit 500, as shown in fig. 2, the main power control circuit 500 includes an optocoupler U3, a diode D5, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a voltage regulator tube D6, a transistor Q6, a transistor Q7, a capacitor C7, and a capacitor C8, wherein a positive input terminal of the optocoupler U3 is connected with one end of the resistor R11, a negative input terminal is connected with a cathode of the chip U2, a first output terminal is connected with one end of the resistor R16, a second output terminal is connected with one end of the capacitor C7, a cathode of the voltage regulator tube D6, one end of the resistor R17, a base of the transistor Q6, and a base of the transistor Q7; the other end of the resistor R16 is connected with the collector of the triode Q6 and the cathode of the diode D5; the anode of the diode D5 is used for being connected with the positive output end of the standby power supply; the emitter of the triode Q6 is connected with one end of the resistor R18 and the emitter of the triode Q7; the other end of the resistor R18 is connected with one end of the capacitor C8, one end of the resistor R19 and the grid electrode of the main power tube Q8; the other end of the capacitor C7, the anode of the voltage regulator tube D6, the other end of the resistor R17, the collector of the triode Q7, the other end of the capacitor C8, the other end of the resistor R19 and the source of the main power tube Q8 are all used for being connected with the negative output end of the standby power supply; the main power control circuit 500 only needs to convert the preceding stage judgment logic signal into a driving signal to control the mos transistor Q8.
The working principle of the under-voltage delay control circuit 200 described in this embodiment is as follows:
when the input voltage rises and V1 exceeds the internal comparison voltage of the chip U1, the cathode of U1 of the chip is opened, the triode Q1 is turned on, hysteresis is formed for the chip U1 through the resistor R3, the C2 is charged through the resistor R6 and the diode D1, the delay control circuit 200 enters a ready delay state, when the input voltage rises to a second hysteresis voltage upper limit value exceeding the internal comparison voltage of the chip U2, the cathode of the chip U2 is opened, the triode Q3 is conducted, hysteresis is formed for the chip U2 through the resistor R14 and the resistor R12, the optocoupler U3 is conducted, the MOS transistor Q8 is opened through the triode Q6, the main loop is opened, and the rear-stage load works normally.
When the input voltage is reduced to be lower than the lower limit value of the first hysteresis voltage of the chip U1 but not lower than the lower limit value of the second hysteresis voltage of the chip U2, the input voltage enters undervoltage, the cathode of the chip U1 is turned off, the triode Q1 is turned off, the capacitor C2 starts to delay through the resistor R7, the triode Q2 is turned on when the delay reaches a set value, the diode D2 is turned on, the hysteresis voltage of the second comparison control circuit 300 is pulled down through the R13 and is lower than the lower limit value of the second hysteresis voltage in the chip U2, the cathode of the chip U2 is turned off, the optocoupler U3 is turned on, the MOS transistor Q8 is turned off through the triode Q7, and the main loop is turned off, so that the function of delay turn-off after the input voltage is lower than the undervoltage point is formed.
When the input voltage drops to be lower than the lower limit value of the second hysteresis voltage of the chip U2, the cathode of the chip U2 is turned off, the MOS is turned off through the main power control circuit 500, and when the input voltage is smaller than the lower limit value of the first hysteresis voltage of the chip U1 and the second input voltage is larger than the lower limit value of the hysteresis voltage of the chip U2, the delay turn-off function is effective.
Second embodiment
As shown in fig. 4, unlike the first embodiment, in the present embodiment, the delay control circuit 200 includes a capacitor C2, a resistor R7, a resistor R13, a resistor R20, a voltage regulator D7, a transistor Q2, and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and is used for accessing power supply voltage; the other end of the capacitor C2 is connected with the other end of the resistor R7 and the cathode of the voltage regulator tube D7, and then is used as the input end of the delay control circuit 200 to be connected with the output end of the first comparison control circuit 100; the anode of the voltage regulator tube D7 is connected with the base of the triode Q2 and one end of the resistor R20; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit 300 as an output end of the delay control circuit 200; the other end of the resistor R20 and the collector of the triode Q2 are both used for being connected with the negative output end of the standby power supply.
As a specific embodiment of the first comparison control circuit 100, the first comparison control circuit 100 includes: the first end of the first voltage division unit is used as the input end of the first comparison control circuit 100 and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and the fourth end of the first control unit, and the first voltage division unit, the first comparison unit and the first control unit are used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, and the third end of the first comparison unit is used for being connected with the negative output end of the standby power supply; the second terminal of the first control unit is used for accessing a power supply voltage, and the third terminal is used as the output terminal of the first comparison control circuit 100 and connected with the input terminal of the delay control circuit 200.
Specifically, the first voltage dividing unit includes a resistor R1 and a resistor R2, one end of the resistor R1 is used as an input end of the first comparison control circuit 100 and is connected to a positive output end of the standby power supply, the other end of the resistor R2 is connected to a third end of the first voltage dividing unit and is connected to a first end of the first comparison unit, and the other end of the resistor R2 is used as a second end of the first voltage dividing unit and is connected to a negative output end of the standby power supply.
The first control unit comprises a resistor R3, a resistor R4, a resistor R5, a diode D1 and a triode Q1; one end of the resistor R3 is used as the fourth end of the first control unit and is connected with the third end of the first voltage division unit and the first end of the first comparison unit; the other end of the resistor R3 is connected with the collector of the triode Q1; an emitter of the triode Q1 is connected with one end of the resistor R4, and then serves as a second end of the first control unit for accessing power supply voltage; the other end of the resistor R4 is connected with the other end of the resistor R5 and the cathode of the diode D1; the anode of the diode D1 is connected to the input terminal of the delay control circuit 200 as the third terminal of the first control unit; the other end of the resistor R5 is connected as a first end of the first control unit to a second end of the first comparison unit.
Specifically, the first comparison unit is a chip U1 of model TL 431.
The working principle of the first comparison control circuit 100 and the delay control circuit 200 is as follows: when the voltage V1 of the sampling input voltage is larger than the upper limit value of the first hysteresis voltage in the chip U1, the cathode of the chip U1 is pulled down, the triode Q1 is conducted, the hysteresis voltage is provided for the chip U1 through the resistor R3, the capacitor C2 starts to charge, when the voltage V1 is lower than the lower limit value of the first hysteresis voltage, the chip U1 is turned off, the triode Q1 is turned off, the capacitor C2 discharges through the R7, when the cathode voltage of the voltage regulator tube D7 rises to exceed the voltage stabilizing value of the voltage regulator tube, the voltage V3 rises, the triode Q2 is conducted, the hysteresis voltage of the second proportional control circuit is pulled down through the diode D2 and the resistor R13, and the MOS tube is turned off by the main power control circuit 500.
The operation principle of the under-voltage delay protection circuit of the present embodiment is analyzed with reference to fig. 4 as follows:
when the input voltage rises and V1 exceeds the internal comparison voltage of the chip U1, the cathode of U1 of the chip is opened, a triode Q1 is turned on, hysteresis is formed on the chip U1 through a resistor R3, C2 is charged through the resistor R6 and a diode D1, the delay control circuit 200 enters a ready delay state, when the input voltage rises to a second hysteresis voltage upper limit value exceeding the internal comparison voltage of the chip U2, the cathode of the chip U2 is opened, a triode Q3 is conducted, hysteresis is formed on the chip U2 through a resistor R14 and a resistor R12, at the moment, an optical coupler U3 is conducted, a MOS transistor Q8 is opened through the triode Q6, a main loop is opened, and a rear-stage load works normally; specifically, the second comparing unit is a chip U2 with model number TL 431.
When the input voltage is reduced to be lower than the lower limit value of the first hysteresis voltage of the chip U1 but not lower than the lower limit value of the second hysteresis voltage of the chip U2, the input voltage enters undervoltage, the cathode of the chip U1 is turned off, the triode Q1 is turned off, the capacitor C2 starts to delay through the resistor R7, the triode Q2 is turned on when the delay reaches a set value, the diode D2 is turned on, the hysteresis voltage of the second comparison control circuit 300 is pulled down through the R13 and is lower than the lower limit value of the second hysteresis voltage in the chip U2, the cathode of the chip U2 is turned off, the optocoupler U3 is turned on, the MOS transistor Q8 is turned off through the triode Q7, and the main loop is turned off, so that the function of delay turn-off after the input voltage is lower than the undervoltage point is formed.
When the input voltage drops to be lower than the lower limit value of the second hysteresis voltage of the chip U2, the cathode of the chip U2 is turned off, the MOS is turned off through the main power control circuit 500, and when the input voltage is smaller than the lower limit value of the first hysteresis voltage of the chip U1 and the second hysteresis voltage is larger than the lower limit value of the hysteresis voltage of the chip U2, the delay turn-off function is effective.
Third embodiment
In this embodiment, a power supply system is provided, which includes a switching power supply, a standby power supply, a main power switch tube, and the undervoltage delay protection circuit according to the first embodiment and the second embodiment; the switch power supply is used for load connection, the standby power supply is connected with the input end of the under-voltage delay protection circuit, the output end of the under-voltage delay protection circuit is connected with the control end of the main power switch tube, and the main power switch tube is connected between the negative output end of the standby power supply and a load in series.
Specifically, under the power grid power supply condition, when switching power supply supplies power, main power switch tube switches on, and switching power supply and stand-by power supply all are connected with the load, because switching power supply voltage is higher to only switching power supply supplies power for the load, when the electric wire netting has a power failure, also when switching power supply has a power failure, stand-by power supply supplies power for the consumer.
The present invention is not limited to the above embodiments, and various other equivalent modifications, substitutions or alterations can be made on the basis of the above description and the common general technical knowledge and conventional means in the field without departing from the basic technical idea of the invention.
Claims (13)
1. The utility model provides an under-voltage time delay protection circuit, is applied to the power supply system including switching power supply, stand-by power supply and main power switch tube, its characterized in that includes: the circuit comprises a first comparison control circuit, a delay control circuit, a second comparison control circuit and a main power control circuit;
the input end of the first comparison control circuit is used for being connected with the output end of a standby power supply, the output end of the first comparison control circuit is connected with the delay control circuit and is used for collecting the output voltage of the standby power supply, generating a delay trigger signal to the delay control circuit when the output voltage is lower than the lower limit value of a first hysteresis voltage, and generating a delay turn-off signal to the delay control circuit when the output voltage is higher than the upper limit value of the first hysteresis voltage;
the output end of the delay control circuit is connected with the first input end of the second comparison control circuit, and is used for starting delay according to the delay trigger signal or stopping delay according to the delay shutdown signal and outputting a corresponding control signal to the second comparison control circuit;
the second input end of the second comparison control circuit is used for being connected with the output end of a standby power supply, the output end of the second comparison control circuit is connected with the input end of the main power control circuit and is used for collecting the output voltage of the standby power supply, when the output voltage is higher than the upper limit value of the second hysteresis voltage, a turn-on signal is generated to the main power control circuit, and when the output voltage or the control signal is lower than the lower limit value of the second hysteresis voltage, a turn-off signal is generated to the main power control circuit;
the output end of the main power control circuit is used for being connected with the control end of a main power switch tube and controlling the opening and closing of the main power switch tube;
the first hysteresis voltage upper limit value is smaller than the second hysteresis voltage upper limit value and is larger than or equal to the first hysteresis voltage lower limit value, and the first hysteresis voltage lower limit value is larger than the second hysteresis voltage lower limit value.
2. The undervoltage delay protection circuit of claim 1, wherein the delay control circuit comprises a capacitor C2, a resistor R7, a resistor R13, a transistor Q2, and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and the base electrode of the triode Q2, and then is used as the input end of the delay control circuit to be connected with the output end of the first comparison control circuit; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit as an output end of the delay control circuit; the other end of the capacitor C2, the other end of the resistor R7 and the collector of the triode Q2 are all used for being connected with the negative output end of the standby power supply.
3. The undervoltage delay protection circuit of claim 2, wherein the first comparison control circuit comprises: the first end of the first voltage division unit is used as the input end of a first comparison control circuit and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and is used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, the third end of the first comparison unit is used for being connected with the positive output end of the standby power supply, comparing the sampling voltage with the upper limit value or the lower limit value of the first hysteresis voltage and outputting a corresponding comparison result to the control circuit; the second end of the first control unit is used for accessing a power supply voltage, and the third end of the first control unit is used as the output end of the first comparison control circuit to be connected with the input end of the delay control circuit and used for outputting a delay trigger signal or a delay turn-off signal to the delay control circuit according to the comparison result.
4. The undervoltage delay protection circuit of claim 3, wherein the first control unit comprises a resistor R4, a resistor R5, a resistor R6, a transistor Q1, and a diode D1; one end of the resistor R5 is used as the input end of the first control unit and is connected with the second end of the first comparison unit, and the other end of the resistor R5 is connected with the base electrode of the triode Q1 and one end of the resistor R4; the other end of the resistor R4 is connected with an emitting electrode of the triode Q1 and then serves as a second end of the first control unit to be connected with a power supply voltage; the collector of the triode Q1 is connected with one end of the resistor R6; the other end of the resistor R6 is connected with the anode of the diode D1; the cathode of the diode D1 is connected as the output of the first control unit to the input of the delay control circuit.
5. The undervoltage delay protection circuit according to claim 4, wherein the first control unit further comprises a resistor R3, one end of the resistor R3 is connected to the other end of the resistor R6 and the anode of the diode D1, and the other end is connected to the first end of the first comparing unit.
6. The undervoltage delay protection circuit of claim 1, wherein the delay control circuit comprises a capacitor C2, a resistor R7, a resistor R13, a resistor R20, a voltage regulator D7, a transistor Q2, and a diode D2; one end of the capacitor C2 is connected with one end of the resistor R7 and is used for accessing power supply voltage; the other end of the capacitor C2 is connected with the other end of the resistor R7 and the cathode of the voltage-regulator tube D7, and then is used as the input end of the delay control circuit to be connected with the output end of the first comparison control circuit; the anode of the voltage regulator tube D7 is connected with the base of the triode Q2 and one end of the resistor R20; an emitter of the triode Q2 is connected with a cathode of the diode D2, an anode of the diode D2 is connected with one end of the resistor R13, and the other end of the resistor R13 is connected with a first input end of the second comparison control circuit as an output end of the delay control circuit; the other end of the resistor R20 and the collector of the triode Q2 are both used for being connected with the negative output end of the standby power supply.
7. The undervoltage delay protection circuit of claim 6, wherein the first comparison control circuit comprises: the first end of the first voltage division unit is used as the input end of a first comparison control circuit and is connected with the positive output end of the standby power supply, the second end of the first voltage division unit is used for being connected with the negative output end of the standby power supply, the third end of the first voltage division unit is connected with the first end of the first comparison unit and the fourth end of the first control unit and is used for carrying out voltage division sampling on the output voltage of the standby power supply and outputting the sampling voltage to the first comparison unit; the second end of the first comparison unit is connected with the first end of the first control unit, and the third end of the first comparison unit is used for being connected with the negative output end of the standby power supply; the second end of the first control unit is used for accessing a power supply voltage, and the third end of the first control unit is used as the output end of the first comparison control circuit and is connected with the input end of the delay control circuit.
8. The undervoltage delay protection circuit of claim 7, wherein the first control unit comprises a resistor R3, a resistor R4, a resistor R5, a diode D1, and a transistor Q1; one end of the resistor R3 is used as the fourth end of the first control unit and is connected with the third end of the first voltage division unit and the first end of the first comparison unit; the other end of the resistor R3 is connected with the collector of the triode Q1; an emitter of the triode Q1 is connected with one end of the resistor R4, and then serves as a second end of the first control unit for accessing power supply voltage; the other end of the resistor R4 is connected with the other end of the resistor R5 and the cathode of the diode D1; the anode of the diode D1 is used as the third end of the first control unit and is connected with the input end of the delay control circuit; the other end of the resistor R5 is connected as a first end of the first control unit to a second end of the first comparison unit.
9. The undervoltage delay protection circuit according to any of claims 3-8, wherein the first comparison control circuit further comprises a first filtering unit, a first end of the first filtering unit is connected to a first end of the first comparison unit, and a second end of the first filtering unit is connected to a negative output terminal of the standby power supply for filtering a signal input to the first comparison unit.
10. The undervoltage delay protection circuit of claim 1, wherein the second comparison control circuit comprises a second voltage division unit, a second comparison unit, and a second control unit; the first end of the second voltage division unit is used as the second input end of the second comparison control circuit and is used for being connected with the positive output end of the standby power supply, the second end of the second voltage division unit is used for being connected with the negative output end of the standby power supply, and the third end of the second voltage division unit is connected with the first end of the second comparison unit; the first end of the second control unit is connected with the third end of the second control unit and then serves as the first input end of the second comparison control circuit to be connected with the output end of the delay control circuit, the second end and the first end of the second control unit are respectively used as the output end of the delay control circuit to be connected with the input end of the main power control circuit, and the third end is used for being connected with the negative output end of the standby power supply; the second end of the second control unit is used for connecting the power supply voltage.
11. The undervoltage delay protection circuit of claim 10, wherein the second comparison control circuit further comprises a resistor R12, and the first terminal of the second comparison unit is connected to the third terminal of the second control unit through a resistor R12.
12. The undervoltage delay protection circuit according to any one of claims 10 or 11, wherein the second comparison control circuit further comprises a second filtering unit, a first end of the second filtering unit is connected to a third end of the second voltage divider and a first end of the second comparing unit, a second end of the second filtering unit is connected to a second end of the second control unit, and a third end of the second filtering unit is configured to be connected to a negative output terminal of the standby power supply.
13. A power supply system comprising a switching power supply, a standby power supply, a main power switch tube and an undervoltage delay protection circuit according to any one of claims 1 to 12; the switch power supply is used for being connected with a load; the standby power supply is connected with the input end of the undervoltage delay protection circuit, the output end of the undervoltage delay protection circuit is connected with the control end of the main power switch tube, and the main power switch tube is connected between the negative output end of the standby power supply and the load in series.
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| KR20200140972A (en) * | 2019-06-07 | 2020-12-17 | 삼성전자주식회사 | Voltage monitoring device and electronic device including the same |
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| CN114614437B (en) | 2023-10-20 |
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