CN100438300C - Power supply detection circuit capable of saving power supply consumption in standby state - Google Patents

Abstract

The present invention provides a power detection circuit, which is advantageous in reducing unnecessary power loss in a standby state to save power consumption. The power detection circuit of the invention is used for receiving an input voltage and converting the input voltage into an output voltage with a voltage level different from that of the input voltage, and comprises the following components: an electromagnetic interference filter for eliminating common mode noise of input voltage; a bridge rectifier connected to the electromagnetic interference filter for full-wave rectifying the input voltage; a transistor switch connected to the bridge rectifier; a driver connected to the transistor switch for driving the on/off operation of the transistor switch according to a feedback value of the output voltage; and a circuit block (circuit box) connected to the EMI filter, the bridge rectifier and the driver for providing a discharge path to the EMI filter while sampling the input voltage to detect a change in the input voltage.

Description

Power detection circuit to save power consumption in standby mode

technical field

The invention relates to a power detection circuit, in particular to a power detection circuit capable of saving power consumption when operating in a standby state.

Background technique

Generally speaking, an AC/DC adapter is used to receive the input AC power and convert the AC power into a high voltage level of DC power to provide a DC/DC converter to convert the high voltage level into a different low voltage level. The voltage level used to provide the electrical power used to operate an electronic device, such as a desktop computer.

The circuit configuration of a known AC/DC converter is shown in FIG. 1 . The AC/DC adapter of FIG. 1 includes an input AC power supply Vin, an EMI filter (EMI filter) 11, a bridge rectifier (bridge rectifier) 12, an input voltage detection circuit 13, and an energy storage component 14 , a transistor switch Q1 , a driver 15 , and an output filter 16 . The EMI filter 11 is composed of an input power filter capacitor X-cap, which is used to eliminate differential-mode noise of the input voltage Vin. The input power filter capacitor X-cap is connected in parallel with three discharge resistors Rx connected in series, and the discharge resistor Rx provides a discharge path for the input power filter capacitor X-cap. The bridge rectifier 12 is composed of several diodes, and is used for full-wave rectification of the input voltage of the AC power Vin. The AC voltage output by the bridge rectifier 12 passes through the AC/DC adapter to output a DC voltage. The energy storage component 14 stores energy when the transistor switch Q1 is ON, and releases energy to the output filter 16 when the transistor switch Q1 is OFF. The output filter 16 is composed of a diode D1 and a capacitor C1 for filtering the output DC voltage. The driver 15 is used to drive the transistor switch Q1 to turn on and off according to the feedback value of the output DC voltage, so as to stabilize the voltage value of the output DC voltage. In addition, the AC/DC adapter in FIG. 1 also includes an input power detection circuit 13 , which samples the input AC voltage to detect changes in the input voltage, and provides the changes in the input voltage to the driver 15 . Generally speaking, the input power detection circuit 13 is composed of a voltage divider composed of resistors R and r, and the resistance of the resistor r is much smaller than that of the resistor R.

Most of today's portable electronic devices have a power management function, and can adjust the power distribution and set the parameters of the standby mode according to the needs of users. Therefore, the current portable electronic devices can save more power and can work for a longer period of time. However, when the system enters the standby state, although most of the active electronic components inside the voltage converter, such as the transistor switch Q1 and the driver 15, etc., have entered the power-off (shut down) state and stopped operating, some passive electronic components, such as Both the discharge resistor 3Rx and the resistors R and r of the input power detection circuit 13 will continue to receive the input AC power to generate power consumption. These unnecessary power losses caused by operating in standby mode will greatly increase the power consumption of the system.

Therefore, how to reduce the power loss caused by the resistance when the voltage converter operates in the standby state, so as to save power consumption is the goal pursued by the present invention.

Contents of the invention

The main purpose of the present invention is to provide a power detection circuit capable of saving power consumption when operating in a standby state.

According to a preferred embodiment of the present invention, in order to achieve the purpose of the present invention, a power supply detection circuit is provided, which is used to receive an input voltage and convert the input voltage into a voltage level different from the input voltage An output voltage comprising: an electromagnetic interference filter for eliminating differential mode noise of the input voltage; a bridge rectifier connected to the electromagnetic interference filter for full-wave rectification of the input voltage; a transistor switch , connected to the bridge rectifier; a driver, connected to the transistor switch, for driving the on/off operation of the transistor switch according to a feedback value of the output voltage; and a circuit block, connected to the electromagnetic interference filter The device, the bridge rectifier and the driver are used to provide a discharge path to the electromagnetic interference filter, and simultaneously sample the input voltage so as to detect the change of the input voltage.

According to the power detection circuit conceived above, it is an AC/DC adapter.

According to the power detection circuit of the above concept, the EMI filter includes at least one input power filter capacitor.

According to the power detection circuit conceived above, the bridge rectifier is composed of several diodes.

The power detection circuit according to the above concept further includes an energy storage component connected between the bridge rectifier and the transistor switch, which transmits a DC voltage according to the on/off operation of the transistor switch.

The power detection circuit according to the above concept further includes an output filter connected to the energy storage component for filtering the output voltage, and the output filter includes a diode and a capacitor.

According to the power detection circuit of the above concept, wherein the circuit block includes: a first resistor having a first end connected to the electromagnetic interference filter, and a second end; a second resistor having a first end connected to the second terminal of the first resistor, and a second terminal; a third resistor, having a first terminal connected to the second terminal of the second resistor, and a second terminal connected to the electromagnetic interference filter; A first diode with a first end connected to the first end of the second resistor and the second end of the first resistor, and a second end; a second diode with a first end connected to the first terminal of the third resistor and the second terminal of the second resistor, and a second terminal; a fourth resistor, having a first terminal connected to the second terminal of the first diode and the The second terminal of the second diode and a second terminal are connected to the driver; and a fifth resistor has a first terminal connected to the second terminal of the fourth resistor, and a second terminal connected to a ground terminal.

The present invention also provides a power detection circuit for saving standby power, used to receive an input voltage and convert the input voltage, which includes: an electromagnetic interference filter, used to eliminate the differential mode noise of the input voltage; a bridge A type rectifier connected to the electromagnetic interference filter for full-wave rectification of the input voltage; a transistor switch connected to the bridge rectifier; a driver connected to the transistor switch for a feedback value to drive the on/off operation of the transistor switch; and a power detection circuit connected to the electromagnetic interference filter, the bridge rectifier and the driver to provide a discharge path to the electromagnetic interference filter, At the same time, the input voltage is sampled so as to detect the change of the input voltage; wherein the circuit block includes: a first resistor having a first end connected to the electromagnetic interference filter, and a second end; a second resistor , having a first terminal connected to the second terminal of the first resistor, and a second terminal; a third resistor, having a first terminal connected to the second terminal of the second resistor, and a second terminal connected to To the EMI filter; a first diode having a first end connected to the first end of the second resistor and the second end of the first resistor, and a second end; a second dipole tube, having a first end connected to the first end of the third resistor and the second end of the second resistor, and a second end; a fourth resistor, having a first end connected to the first two poles The second end of the tube is connected to the second end of the second diode, and a second end is connected to the driver; and a fifth resistor has a first end connected to the second end of the fourth resistor, and A second end is connected to a ground end.

According to the power detection circuit conceived above, it is an AC/DC adapter.

According to the power detection circuit conceived above, the electromagnetic interference filter includes at least one input power filter capacitor, and the bridge rectifier is composed of several diodes.

The power detection circuit according to the above concept further includes an energy storage component connected between the bridge rectifier and the transistor switch, which transmits a DC voltage according to the on/off operation of the transistor switch.

The power detection circuit according to the above concept further includes an output filter connected to the energy storage component for filtering the output voltage, and the output filter includes a diode and a capacitor.

Description of drawings

The present invention will be explained in more detail by way of example with accompanying drawings, wherein:

Fig. 1 shows the circuit configuration of known AC/DC adapter;

FIG. 2 shows voltage waveforms associated with a known AC/DC adapter;

Figure 3 to Figure 6 show the equivalent circuit of the known AC/DC adapter of Figure 1; and

FIG. 7 shows the circuit configuration of a voltage adapter according to a preferred embodiment of the present invention.

11: EMI filter

12: Bridge rectifier

13: Input voltage detection circuit

14: Energy storage components

15: drive

16: Output filter

22: First diode

24: second diode

Detailed ways

The main feature of the present invention is to combine the internal resistance of the input power detection circuit used to detect the change of the input voltage with the resistance of the discharge path of the electromagnetic interference filter used to provide the input, so as to reduce the Power loss due to resistance. A detailed description of a preferred embodiment of the present invention is as follows.

Please refer to Fig. 2, which shows the voltage waveform diagram related to the known AC/DC adapter of Fig. 1, Fig. 2(A) is the voltage waveform diagram of the input AC voltage Vin, and Fig. 2(B) is the voltage waveform diagram of the input AC voltage Vin through The voltage waveform diagram obtained after the bridge rectifier 12 performs full-wave rectification, and FIG. 2(C) is a voltage waveform diagram of the sampled input voltage obtained by the input power detection circuit 13 . From the voltage waveform diagram in Figure 2(B), it can be seen that after the input AC voltage Vin has undergone full-wave rectification, the phase of the formed voltage is similar to that of the input AC voltage Vin, but its amplitude is a positive value, regardless of the input AC voltage. The voltage Vin is during the positive half cycle or the negative half cycle. In FIG. 2(C), the input power detection circuit 13 uses a voltage divider composed of resistors R and r to sample the input AC voltage in order to detect changes in the input voltage, so the amplitude of the obtained sampled input voltage will be Will be equal to r×Vin/(r+R). The driver 15 uses the sampled voltage to adjust the power factor of the input AC power and determine the range of the working voltage.

FIG. 7 shows the circuit configuration of a voltage adapter according to a preferred embodiment of the present invention. Next, however, we intend to refer to FIGS. 3 to 6 to illustrate how to deduce the circuit configuration of the voltage adapter of FIG. 7 from the circuit configuration of the known voltage adapter of FIG. 1, so that those familiar with the technical field can Based on this, the spirit and principle of the present invention can be understood, so as to realize the circuit design criteria of the present invention based on the teaching herein.

Please refer to FIG. 3 , which is the first equivalent circuit of the voltage adapter in FIG. 1 . According to the circuit configuration of FIG. 3, during the positive half cycle of the input AC voltage Vin, the input current will flow through a first diode 22, and the resistor R connected between the electromagnetic interference filter 11 and the first diode 22 , and a resistor r connected between the first diode 22 , a second diode 24 and the ground. Therefore, during the positive half cycle of the input AC voltage Vin, the amplitude of the sampled input voltage obtained by the input power detection circuit is r×Vin/(r+R), and its value is a positive value. Similarly, during the negative half cycle of the input AC voltage Vin, the input current will flow through the second diode 24, the resistor R connected between the discharge resistor Rx and the second diode 24, and connected to the first diode The resistor r between the tube 22, the second diode 24 and the ground. Therefore, during the negative half cycle of the input AC voltage Vin, the amplitude of the sampled input voltage obtained by the input power detection circuit is also r×Vin/(r+R), and its value is a positive value. Therefore, according to the circuit configuration of FIG. 3, the voltage waveform of the sampled input AC voltage input to the driver 15 will produce a general profile as shown in FIG. 2(C), and the circuit configuration of the voltage adapter in FIG. 3 can be regarded as Figure 1. Equivalent circuit of the voltage adapter.

Please refer to FIG. 4 , which is the second equivalent circuit of the voltage adapter in FIG. 1 . It can be clearly seen from FIG. 4 that during the positive half cycle of the input AC voltage Vin, the input current flows through the first diode 22 and the resistor 1/2R connected between the EMI filter 11 and the first diode 22 , the resistor 1/2R connected between the first diode 22 and the driver 15, and the resistor r connected between the driver 15 and the ground. Since the two resistors 1/2R are connected in series, their equivalent resistance value is R, so it can be regarded as the equivalent resistance coupled with the resistance R connected between the electromagnetic interference filter 11 and the first diode 22 in FIG. 3 resistance. Therefore, during the positive half cycle of the input AC voltage Vin, the obtained amplitude of the sampled input voltage is also r×Vin/(r+R), and its value is a positive value. Similarly, during the negative half cycle of the input AC voltage Vin, the input current will flow through the second diode 24, the resistor 1/2R connected between the discharge resistor Rx and the second diode 24, and connected to the second two The resistor 1/2R between the pole tube 24 and the driver 15, and the resistor r connected between the driver 15 and the ground terminal. Since the two resistors 1/2R are connected in series, their equivalent value is also R. Therefore, it can be regarded as an equivalent resistor coupled with the resistor R connected between the discharge resistor Rx and the second diode 24 and having a resistance value of r. Therefore, during the negative half cycle of the input AC voltage Vin, the amplitude of the sampled input voltage obtained is also r×Vin/(r+R), and its value is a positive value. Therefore, according to the circuit configuration of FIG. 4, the voltage waveform of the sampled input AC voltage input to the driver 15 will produce a general profile as shown in FIG. 2(C), and the circuit configuration of the voltage adapter in FIG. 4 can be regarded as The equivalent circuits of the voltage adapters in Fig. 1 and Fig. 3.

Please refer to FIG. 5 , which is a third equivalent circuit of the voltage adapter in FIG. 1 . In the voltage adapter of FIG. 5 , the two sets of R and 2r connected to the first diode 22 and the second diode 24 are connected in parallel, and their equivalent circuit is 1/2R and r, Therefore, the configuration of the power detection circuit in FIG. 5 can be regarded as a circuit equivalent to those in FIG. 1 , FIG. 3 and FIG. 4 .

Please refer to FIG. 6 , which is a fourth equivalent circuit of the voltage adapter in FIG. 1 . According to the circuit configuration of FIG. 6, during the positive half cycle of the input AC voltage Vin, the input current will flow through a first diode 22, the resistor 1 connected between the electromagnetic interference filter 11 and the first diode 22 /2R, and shunt the resistance R+2r between the first diode 22, the second diode 24 and the ground terminal and 1/2R+ between the first diode 22 and the electromagnetic interference filter 11 2r+1/2R. Since 1/2R+2r+1/2R is equivalent to R+2r, it can be seen that the series connection result of 1/2R+2r+1/2R between the first diode 22 and the electromagnetic interference filter 11 is the same as that in Figure 5 The first diode 22 and the second diode 24 in the group connected to the ground terminal R are equivalent to 2r. During the negative half cycle of the input AC voltage Vin, the input current will flow through the second diode 24, the resistor 1/2R connected between the EMI filter 11 and the second diode 24, and shunt to the first The resistor R+2r between the diode 22 , the second diode 24 and the ground terminal, and 1/2R+2r+1/2R between the second diode 24 and the EMI filter 11 . Since 1/2R+2r+1/2R is equivalent to R+2r, it can be seen that the series connection result of 1/2R+2r+1/2R between the second diode 24 and the electromagnetic interference filter 11 is the same as that in Figure 5 The first diode 22 and the second diode 24 in the group connected to the ground terminal R are equivalent to 2r. Therefore, the configuration of the power detection circuit in FIG. 6 can be regarded as the equivalent circuits in FIG. 1 , FIG. 3 , FIG. 4 and FIG. 5 .

Here we call the resistor 1/2R connected between the electromagnetic interference filter 11 (input power supply filter capacitor X-cap) and the anode terminal of the first diode 22 the first resistor, which will be connected to the first diode The resistance 1/2R+2r between the anode end of the tube 22 and the anode end of the second diode 24 is called the second resistance, which will be connected to the anode end of the second diode 24 and the electromagnetic interference filter 11 (input The resistor 1/2R between the power filter capacitor (X-cap) is called the third resistor, which will be connected to the resistor R between the cathode terminal of the first diode 22, the cathode terminal of the second diode 24 and the driver 15 is called the fourth resistor, and the resistor 2r connected from the driver to the ground is called the fifth resistor.

Next, in the circuit configuration of Figure 6, since the three series discharge resistors Rx are only used to provide the discharge path of the input power supply filter capacitor X-cap, they can be connected with the first resistor, the second resistor and the third resistor Combining and reducing the number of resistors used in the circuit, that is, the three discharge resistors Rx can be completely omitted, and the circuit block formed by the first resistor, the second resistor and the third resistor is used instead to provide the input power filter capacitor X-cap discharge resistor. And because 1/2R in the second resistance is much larger than 2r, it can be approximated as 1/2R. Through the above steps, the circuit configuration of the voltage adapter of the preferred embodiment of the present invention shown in FIG. 7 can be obtained .

The above description has fully explained how to derive the circuit configuration of the voltage adapter of the present invention by substituting and merging the components of the known voltage adapter circuit configuration through a series of equivalent circuits. Therefore, it can be seen from FIG. 6 that the voltage converter of the present invention provides reducing the power consumption caused by the power loss of the resistor when operating in the standby mode, and the voltage converter of the present invention is characterized in having a circuit box (circuit box) , the circuit block can provide a discharge path to the electromagnetic interference filter, and simultaneously sample the input voltage so as to detect the change of the input voltage. In detail, the composition of the circuit block includes a first resistor 1/2R, with a first end connected to the EMI filter 11, and a second end; a second resistor 1/2R, with a first One end is connected to the second end of the first resistor 1/2R, and a second end; a third resistor 1/2R has a first end connected to the second end of the second resistor 1/2R, and A second end is connected to the electromagnetic interference filter 11; a first diode 22 has a first end connected to the first end of the second resistor 1/2R and the second end of the first resistor 1/2R end, and a second end; a second diode 24, has a first end connected to the first end of the third resistor 1/2R and the second end of the second resistor 1/2R, and a first end Two terminals, and a fourth resistor R, have a first terminal connected to the second terminal of the first diode 22 and the second terminal of the second diode 24, and a second terminal connected to the driver 15 and a fifth resistor 2r having a first end connected to the second end of the fourth resistor R, and a second end connected to the ground. Compared with the known voltage adapter in the first figure, it can be seen that the power loss caused in the voltage adapter of the present invention during standby operation is Vin ² /(1/2R+1/2R+r), however The power loss inside the known voltage adapter during standby operation is Vin ² /(3RX)+Vin ² /(R+r). Since the resistance 1/2R+1/2R+r must be equal to the resistance value of 3RX, this circuit will save the standby power consumption of Vin ² /(R+r). Therefore, the present invention can greatly improve the power loss caused by the resistance when operating in the standby state, and can further save internal power consumption.

It will be appreciated that changes may be made to the embodiments described above without departing from the broad inventive concepts thereof. It is intended, therefore, that this invention not be limited to the particular embodiments disclosed, but it is intended to cover all modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims (8)

1. A power detection circuit for saving standby power, for receiving an input voltage and converting the input voltage into an output voltage having a voltage level different from the input voltage, comprising: An electromagnetic interference filter, used to eliminate the differential mode noise of the input voltage; a bridge rectifier connected to the electromagnetic interference filter for full-wave rectification of the input voltage; a transistor switch connected to the bridge rectifier; a driver, connected to the transistor switch, for driving the transistor switch on/off according to a feedback value of the output voltage; and a sampling and detection circuit, connected to the electromagnetic interference filter, the bridge rectifier and the driver, for providing a discharge path to the electromagnetic interference filter, and simultaneously sampling the input voltage so as to detect the input voltage Variety. 2. The power detection circuit as claimed in claim 1, wherein the power detection circuit is an AC/DC adapter. 3. The power detection circuit as claimed in claim 1, wherein the EMI filter comprises at least one input power filter capacitor. 4. The power detection circuit as claimed in claim 1, wherein the bridge rectifier is composed of several diodes. 5. The power detection circuit according to claim 1, further comprising an energy storage component connected between the bridge rectifier and the transistor switch, which transmits an energy storage element according to the on/off operation of the transistor switch. DC voltage. 6. The power detection circuit according to claim 5, further comprising an output filter connected to the energy storage component for filtering the output voltage, and the output filter comprises a diode and a capacitance. 7. The power detection circuit as claimed in claim 1, wherein the sampling and detection circuit comprises: a first resistor having a first end connected to the EMI filter, and a second end; a second resistor having a first end connected to the second end of the first resistor, and a second end; a third resistor having a first end connected to the second end of the second resistor, and a second end connected to the electromagnetic interference filter; a first diode having a first terminal connected to the first terminal of the second resistor and the second terminal of the first resistor, and a second terminal; a second diode having a first terminal connected to the first terminal of the third resistor and the second terminal of the second resistor, and a second terminal; a fourth resistor having a first terminal connected to the second terminal of the first diode and the second terminal of the second diode, and a second terminal connected to the driver; and A fifth resistor has a first terminal connected to the second terminal of the fourth resistor, and a second terminal connected to a ground terminal. 8. The power detection circuit as claimed in claim 7, wherein the first end and the second end of the first diode are respectively an anode and a cathode, and the first end and the second end of the second diode are anode and cathode, respectively.

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