CN210780537U - High-voltage starting circuit for switching power supply and capable of effectively reducing standby power consumption - Google Patents
High-voltage starting circuit for switching power supply and capable of effectively reducing standby power consumption Download PDFInfo
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- CN210780537U CN210780537U CN201921840403.1U CN201921840403U CN210780537U CN 210780537 U CN210780537 U CN 210780537U CN 201921840403 U CN201921840403 U CN 201921840403U CN 210780537 U CN210780537 U CN 210780537U
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Abstract
A high-voltage starting circuit which is simple in structure, is used for a switching power supply and can effectively reduce standby power consumption. The timing circuit comprises a working voltage input end connected with a primary winding of a transformer of the switching power supply, a pulse voltage output end connected with a power supply end of a main control chip of the switching power supply and a grounding end connected with a ground leg of the main control chip, wherein a timing chip and a self-locking circuit are arranged between the working voltage input end and the pulse voltage output end; and the self-locking circuit locks the high-voltage starting circuit in a standby state after delaying the set time, and enables the leakage current between the working voltage input end and the grounding end to be less than 0.1 mA. The standby power consumption can be reduced to 28mW from 73mW (220VAC input and no-load loss) in the prior art.
Description
Technical Field
The utility model relates to a chip starting circuit, in particular to a control circuit for switching power supply high voltage starting circuit.
Background
Generally, a main control chip in a switching power supply needs a high-voltage starting circuit to provide a starting voltage for the main control chip at the moment of starting, and when the main control chip enters a normal working state, the task of the high-voltage starting circuit is completed.
In the high-voltage starting circuit in the prior art, technicians in the same line mostly adopt two triodes and a plurality of resistors to form a self-locking circuit, and after the high-voltage starting circuit finishes starting the main control chip, the high-voltage starting circuit enters a standby state. As shown in fig. 1, the high voltage start circuit includes a PNP transistor Q1, an NPN transistor Q2, a diode D1, a bias resistor R1, a resistor R3, and a capacitor C1.
The "Pin H" end in the high-voltage starting circuit is connected with the primary side of a switching power supply transformer through a resistor R32 and a resistor R33 in a switching power supply (shown in a circuit schematic diagram in figure 2); one path of a 'Pin E' end in the high-voltage starting circuit is connected with an auxiliary winding of the transformer through a second MOS tube, a diode D2 and a resistor R12 in the switching power supply, and the other path of the 'Pin E' end is connected with a power supply end VDD of the main control chip; and the 'Pin G' in the high-voltage starting circuit is connected with the grounding end GND of the main control chip.
The working principle of starting the main control chip is as follows:
at the moment of starting up, a "Pin H" end in the high-voltage starting circuit obtains voltage, a first high-level pulse voltage for starting the main control chip U1 is provided for the main control chip U1 of the switching power supply through the resistor R1 and the "Pin E" end, meanwhile, the transistor Q1 is turned on through the bias resistor R1 and then charges the capacitor C1, when the electric quantity of the capacitor C1 reaches the threshold value of the transistor Q2, the transistor Q2 is turned on and pulls down the collector potential of the transistor Q2, the diode D1 is turned off, the "Pin E" end does not supply power to the main control chip U1 any more (at this time, the auxiliary winding of the transformer provides normal working voltage for the main control chip U1), and thus, the high-voltage starting circuit completes the task of starting up the main control chip. At the same time, the base of the transistor Q1 is also low and continues to be turned on, and the transistor Q2 continues to be turned on, at which time the high voltage start-up circuit is locked and in standby.
The capacitor C1 in the high voltage start-up circuit is used for the delayed conduction of the transistor Q2.
The high-voltage starting circuit has the following defects:
the transistor Q1 needs to be configured with a bias resistor R1 to work normally, and when the high voltage start-up circuit is in a standby state, since the collector potential of the transistor Q2 is low and the "Pin H" terminal is still at a high potential, a large current still flows through the bias resistor R1, so that the standby power consumption of the high voltage start-up circuit in the standby state is still large.
SUMMERY OF THE UTILITY MODEL
The to-be-solved technical problem of the utility model is to provide a simple structure for switching power supply just can effectively reduce standby power consumption's high-voltage starting circuit.
In order to solve the technical problem, the utility model discloses a technical scheme be:
the utility model discloses a high-voltage starting circuit that is used for switching power supply and can effectively reduce stand-by power consumption, include the operating voltage input end of being connected with switching power supply's transformer primary winding, the pulse voltage output end of being connected with switching power supply's main control chip's feeder ear and with the earthing terminal that main control chip's lower margin is connected, its characterized in that: a timing chip and a self-locking circuit are also arranged between the working voltage input end and the pulse voltage output end, wherein,
the timing chip enables the pulse voltage output end to output high level at the moment of starting the switch power supply, and enables the pulse voltage output end and the voltage output end of the timing chip to be in an open circuit state after delaying for a set time;
and the self-locking circuit locks the high-voltage starting circuit in a standby state after the delay setting time, and enables the leakage current between the working voltage input end and the grounding end to be less than 0.1 mA.
The working voltage input end is connected with a primary winding of a switching power supply transformer through a resistor R32 and a resistor R33 in the switching power supply; one path of the pulse voltage output end is connected with an auxiliary winding of the transformer through a second MOS tube, a diode D2 and a resistor R12 in the switch power supply, and the other path of the pulse voltage output end is connected with a power supply end VDD of the main control chip.
The timing chip is a TI brand NE555DG4 model chip, and each terminal pin of the timing chip is connected as follows:
the power supply end of the power supply is connected with the working voltage input end;
the voltage output end of the pulse voltage output circuit is connected with the pulse voltage output end through the anode and the cathode of a diode D1;
one path of the reset end of the reset circuit is connected with the self-locking circuit, and the other path of the reset end of the reset circuit is connected with the working voltage input end through a resistor R4;
after the threshold voltage end is connected with the trigger end, one path is grounded through a capacitor C3, and the other path is connected with the working voltage input end through a resistor R3 and a resistor R1;
the discharge end of the resistor is connected in parallel with the joint of the resistor R1 and the resistor R3;
a resistor R2 is provided between the anode of the diode D1 and ground.
The self-locking circuit is composed of an N-type MOS tube Q1 and a P-type MOS tube Q2, wherein,
a MOS transistor Q1, the source of which is grounded; one path of a grid of the timing chip is connected with a voltage output end of the timing chip through a resistor R7 through the anode and the cathode of a voltage stabilizing diode ZD1, the other path of the grid of the timing chip is connected with a source electrode of an MOS tube Q2, and a capacitor C3 is bridged between the grid and the source electrode; the drain electrode of the timing chip, the grid electrode of the MOS tube Q2 and the reset end of the timing chip are connected in parallel and are connected with the working voltage input end through a high-resistance resistor R4;
the drain electrode of the MOS tube Q2 is connected with the working voltage input end;
the resistance value of the high-resistance resistor R4 is not less than 5 megaohms.
The voltage stabilizing diode ZD1 is a VIHAY model BZX84-C10 diode.
The model of the diode D1 is 1N4148 WS.
Adopt on switching power supply the utility model discloses a high-voltage starting circuit can effectively reduce its stand-by power consumption after accomplishing the normal work of starting switching power supply, and this stand-by power consumption can be reduced to 28mW by 73mW (220VAC input, no-load loss) among the prior art.
Drawings
Fig. 1 is a schematic diagram of a high voltage start-up circuit for a switching power supply in the prior art.
Fig. 2 is a circuit schematic of a switching power supply.
Fig. 3 is a schematic diagram of the high voltage start circuit of the present invention.
Fig. 4 is a logic block diagram of the internal of the timing chip used in the circuit of fig. 3.
The reference numbers are as follows:
Detailed Description
The utility model discloses a components and parts such as high pressure starting circuit that is used for switching power supply and can effectively reduce stand-by power consumption comprises timing chip, self-locking circuit and a plurality of resistance, electric capacity.
The function is as follows: the switching power supply (the circuit schematic diagram of the switching power supply is shown in fig. 2) is used for starting a main control chip U1 in the switching power supply to enter a normal working state at the moment of starting.
Like the high-voltage starting circuit among the prior art, the utility model discloses a several important nodes of high-voltage starting circuit and switching power supply's connected mode as follows:
the working voltage input end (i.e. the "Pin H" end in fig. 3) is connected to the primary winding of the transformer of the switching power supply and obtains voltage at the moment of starting the switching power supply, and in the switching power supply, a resistor R32 and a resistor R33 for voltage division are connected in series between the working voltage input end and the primary winding of the transformer.
The pulse voltage output terminal (i.e. the "Pin E" terminal in fig. 3) is connected to the power supply terminal of the main control chip of the switching power supply (i.e. the "VDD" terminal of Pin 5 of the main control chip U1 in fig. 2) and is ready to provide a high-potential pulse voltage for the main control chip to start its operation.
The ground terminal (i.e. the "Pin G" terminal in fig. 3) is connected to the ground of the main control chip.
When the main control chip U1 is started and works normally, the pulse voltage output end stops providing power to the main control chip, and the main control chip U1 obtains rated working voltage from the auxiliary winding of the transformer through a second MOS transistor (LDO low dropout linear regulator), a diode D2 and a resistor R12 in the switching power supply. At this point, the high-voltage starting circuit completes the starting task and enters a standby dormant state.
1. Timing chip
At the moment of starting the switching power supply, the timing chip enables the pulse voltage output end to output high level, and after the set time is delayed, the pulse voltage output end and the voltage input end of the timing chip are in an open circuit state.
The timing chip adopts a TI brand NE555DG4 model chip, and the pins of the TI brand NE555DG4 model chip have the following functions (shown in figure 4):
pin 1 (grounded): the ground (or common ground) is typically connected to the circuit common ground.
Pin 2 (trigger point): this pin is the time period that triggers NE555 to start it. The voltage on the upper edge of the trigger signal must be greater than 2/3VCC, and the voltage on the lower edge of the trigger signal must be less than 1/3 VCC.
Pin3 (output): when the time period begins 555 the output pin moves to a high potential that is 1.7 volts less than the supply voltage. The output returns to a low level around O volts at the end of the cycle. The maximum output current at high potential is about 200 mA.
Pin4 (reset): a low logic potential applied to this pin resets the timer and returns the output to a low potential. It is usually connected to a positive power supply or ignored.
Pin 5 (control): this pin permits the trigger and gate voltages to be changed by external voltages. This input can be used to change or adjust the output frequency when the timer is operating in a steady or oscillatory mode of operation.
Pin 6 (threshold voltage terminal): is a Threshold that is triggered when the C1 voltage discharges below 2/3 VCC.
Pin7 (discharge): this Pin has the same current output capability as the main output Pin, and Pin7 is low impedance to ground (conducting to ground) when Pin3 is low, and Pin7 is high impedance when Pin3 is high.
Pin 8(V +): this is the positive supply voltage terminal of the 555 timer IC. The supply voltage ranges from +4.5 volts (minimum) to +16 volts (maximum).
2. Self-locking circuit
After the delay setting time, namely after the pulse voltage output end and the voltage input end of the timing chip are in an open circuit state, the high-voltage starting circuit is locked in a standby state, and the working voltage input end Pin H and the grounding end Pin G are basically in the open circuit state, and the leakage current therebetween is less than 0.1 mA.
3. The specific structure of the high-voltage starting circuit of the utility model is as follows (see fig. 2 and 3):
1) connection of timing chip
A power supply end Pin 8 of the timing chip is connected with the working voltage input end Pin H;
the voltage output end Pin3 is connected with the pulse voltage output end Pin E through the anode and the cathode of a diode D1;
one path of a reset end Pin4 of the self-locking circuit is connected with the self-locking circuit, and the other path of the reset end Pin is connected with a working voltage input end Pin H through a resistor R4;
after a threshold voltage end Pin 6 is connected with a trigger end Pin 2, one path is grounded through a capacitor C3, and the other path is connected with a working voltage input end Pin H through a resistor R3 and a resistor R1;
the discharge end Pin7 is connected in parallel with the joint of the resistor R1 and the resistor R3;
a resistor R2 is provided between the anode of the diode D1 and ground.
2) Structure of self-locking circuit
The self-locking circuit is composed of an N-type MOS tube Q1 and a P-type MOS tube Q2, wherein,
a MOS transistor Q1, the source of which is grounded; one path of a grid of the timing chip is connected with a voltage output end Pin3 of the timing chip through a resistor R7 and the anode and the cathode of a voltage stabilizing diode ZD1, the other path of the grid is connected with the source electrode of a MOS tube Q2, and a capacitor C3 is bridged between the grid and the source electrode; the drain electrode of the timing chip, the grid electrode of the MOS tube Q2 and the reset end Pin4 of the timing chip are connected in parallel and then connected with the working voltage input end Pin H through a high-resistance resistor R4;
the drain electrode of the MOS tube Q2 is connected with the working voltage input end Pin H;
the resistance value of the high-resistance resistor R4 is not less than 5 megaohms.
The zener diode ZD1 is a diode model BZX84-C10 of VIHAY brand.
The model of the diode D1 is 1N4148 WS.
4. Principle of operation
The utility model discloses a NE555 pulse trigger circuit cooperation peripheral component group cost utility model discloses high-pressure starting circuit's single pulse generator to switching power supply's main control chip is supplied with to first pulse lets its start, then turns off this high-pressure starting circuit rapidly.
At the moment of starting up, the working voltage input terminal Pin H is divided into high potential from the primary winding of the switching power supply, the high potential is used for charging a capacitor C1 through a resistor R1 and a resistor R3 besides the working voltage provided for the timing chip, meanwhile, the voltage output terminal Pin3 of the timing chip outputs a high-level pulse voltage, the high-level pulse voltage is provided for the power supply terminal VDD of the switching power supply main control chip U1 through a diode D1 and a pulse voltage output terminal Pin E, and the main control chip U1 is started to work.
When the capacitor C1 is charged to be higher than the upper limit threshold of the threshold voltage terminal Pin 6, the capacitor C1 forms a discharge loop through the resistor R3, the discharge terminal Pin7 of the timing chip and the ground terminal, when the voltage of the capacitor C1 is reduced to the lower limit threshold of the threshold voltage terminal Pin 6, the internal comparator of the timing chip is turned over, the voltage output terminal Pin3 outputs a low level, the diode D1 is turned off in the reverse direction, and the pulse voltage output terminal Pin E stops supplying power to the main control chip of the switching power supply (at this time, the VCC voltage output by the transformer auxiliary winding does not flow back to the timing chip).
Meanwhile, when the voltage output terminal Pin3 is at a high level for output, the zener diode ZD1 breaks down in the reverse direction to make the gate of the MOS transistor Q1 obtain a potential, and since the reset terminal Pin4 of the timing chip is at a high potential, the MOS transistor Q1 is turned on.
The MOS transistor Q1 is conducted, the voltage of the grid electrode of the MOS transistor Q2 is pulled down, the MOS transistor Q2 is conducted, the circuit is locked after chain reaction, and the reset end Pin4 of the timing chip is continuously at a low potential until the timing chip can be released after shutdown and restart. Since the resistance of the high-resistance resistor R4 is very high, the current flowing from the working voltage input terminal Pin H to the reset terminal Pin4 through the high-resistance resistor R4 is very small (usually less than 0.1mA), so that the state can be regarded as an open circuit, that is, when the high-voltage starting circuit is in the standby sleep state, the current flowing through the resistor R32 and the resistor R33 in the switching power supply is also very small, thereby effectively reducing the power consumption.
Since the reset terminal Pin4 is continuously at the low level, the voltage output terminal Pin3 continuously outputs the low level, so that the high voltage start circuit enters a standby sleep state after the main control chip U1 of the switching power supply is started.
Since the reset terminal Pin4 is continuously at low level, the discharge terminal Pin7 and the ground terminal are in an open circuit state, the capacitor C1 will be charged again, but a discharge loop cannot be formed (the discharge condition is that the transistor Q1 inside the timing chip needs to be turned on, but the transistor Q1 is controlled by the reset terminal Pin4, therefore, after the reset terminal Pin4 is locked, the low level will be continuously maintained, the transistor Q1 will not be turned on any more, unless shutdown and restart are performed), that is: the working voltage input terminal Pin H, the resistor R1, the resistor R3, the capacitor C1 and the ground terminal are open-circuited, and the conduction current is zero.
Claims (6)
1. The utility model provides a high-voltage starting circuit that is used for switching power supply and can effectively reduce stand-by power consumption, include the operating voltage input end of being connected with switching power supply's transformer primary winding, with the pulse voltage output end that switching power supply's main control chip's power supply is connected and with the earthing terminal that main control chip's lower margin is connected, its characterized in that: a timing chip and a self-locking circuit are also arranged between the working voltage input end and the pulse voltage output end, wherein,
the timing chip enables the pulse voltage output end to output high level at the moment of starting the switch power supply, and enables the pulse voltage output end and the voltage output end of the timing chip to be in an open circuit state after delaying for a set time;
and the self-locking circuit locks the high-voltage starting circuit in a standby state after the delay setting time, and enables the leakage current between the working voltage input end and the grounding end to be less than 0.1 mA.
2. The high voltage start-up circuit for a switching power supply effective to reduce standby power consumption of claim 1, wherein: the working voltage input end is connected with a primary winding of a switching power supply transformer through a resistor R32 and a resistor R33 in the switching power supply; one path of the pulse voltage output end is connected with an auxiliary winding of the transformer through a second MOS tube, a diode D2 and a resistor R12 in the switch power supply, and the other path of the pulse voltage output end is connected with a power supply end VDD of the main control chip.
3. The high voltage start-up circuit for a switching power supply effective to reduce standby power consumption according to claim 2, wherein: the timing chip is a TI brand NE555DG4 model chip, and each terminal pin of the timing chip is connected as follows:
the power supply end of the power supply is connected with the working voltage input end;
the voltage output end of the pulse voltage output circuit is connected with the pulse voltage output end through the anode and the cathode of a diode D1;
one path of the reset end of the reset circuit is connected with the self-locking circuit, and the other path of the reset end of the reset circuit is connected with the working voltage input end through a resistor R4;
after the threshold voltage end is connected with the trigger end, one path is grounded through a capacitor C3, and the other path is connected with the working voltage input end through a resistor R3 and a resistor R1;
the discharge end of the resistor is connected in parallel with the joint of the resistor R1 and the resistor R3;
a resistor R2 is provided between the anode of the diode D1 and ground.
4. The high voltage start-up circuit for a switching power supply effective to reduce standby power consumption according to claim 3, wherein: the self-locking circuit is composed of an N-type MOS tube Q1 and a P-type MOS tube Q2, wherein,
a MOS transistor Q1, the source of which is grounded; one path of a grid of the timing chip is connected with a voltage output end of the timing chip through a resistor R7 through the anode and the cathode of a voltage stabilizing diode ZD1, the other path of the grid of the timing chip is connected with a source electrode of an MOS tube Q2, and a capacitor C3 is bridged between the grid and the source electrode; the drain electrode of the timing chip, the grid electrode of the MOS tube Q2 and the reset end of the timing chip are connected in parallel and are connected with the working voltage input end through a high-resistance resistor R4;
the drain electrode of the MOS tube Q2 is connected with the working voltage input end;
the resistance value of the high-resistance resistor R4 is not less than 5 megaohms.
5. The high voltage start-up circuit for switching power supply according to claim 4, wherein the high voltage start-up circuit comprises: the voltage stabilizing diode ZD1 is a VIHAY model BZX84-C10 diode.
6. The high voltage start-up circuit for switching power supply according to claim 4, wherein the high voltage start-up circuit comprises: the model of the diode D1 is 1N4148 WS.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921840403.1U CN210780537U (en) | 2019-10-30 | 2019-10-30 | High-voltage starting circuit for switching power supply and capable of effectively reducing standby power consumption |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921840403.1U CN210780537U (en) | 2019-10-30 | 2019-10-30 | High-voltage starting circuit for switching power supply and capable of effectively reducing standby power consumption |
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| Publication Number | Publication Date |
|---|---|
| CN210780537U true CN210780537U (en) | 2020-06-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921840403.1U Active CN210780537U (en) | 2019-10-30 | 2019-10-30 | High-voltage starting circuit for switching power supply and capable of effectively reducing standby power consumption |
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| CN (1) | CN210780537U (en) |
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