CN211791226U - Novel real-time signal sampling circuit and switching power supply using same - Google Patents
Novel real-time signal sampling circuit and switching power supply using same Download PDFInfo
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- CN211791226U CN211791226U CN202020135025.3U CN202020135025U CN211791226U CN 211791226 U CN211791226 U CN 211791226U CN 202020135025 U CN202020135025 U CN 202020135025U CN 211791226 U CN211791226 U CN 211791226U
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Abstract
The utility model relates to a novel real-time signal sampling circuit and applied this circuit's switching power supply, real-time signal sampling circuit is by sampling control circuit, charging current control unit, discharge current control unit, delay unit electric connection in proper order and constitutes, produce charging current and discharge current after connecting through the auxiliary winding partial pressure of transformer and first divider resistance, second divider resistance, third divider resistance to control the trip point of comparator, accomplish the demagnetization time control sampling moment in the current cycle; the switching power supply comprises a transformer and a control circuit, wherein the control circuit accurately samples the partial pressure of an auxiliary winding of the transformer in real time and accurately adjusts the output voltage of the switching power supply, the control circuit comprises the real-time signal sampling circuit, and the switching power supply can achieve high constant-voltage output precision.
Description
Technical Field
The utility model relates to a power electronics field, especially a novel real-time signal sampling circuit and applied this circuit's switching power supply.
Background
The power supply is used as power supply equipment of all electronic products, various primary side feedback flyback power supply control ICs used in constant-current and constant-voltage occasions are developed, and the application range of the power supply comprises a power adapter, a charger, a standby power supply of mobile equipment and the like.
The switching power supply applying the conventional control is shown in fig. 1, and comprises an output module connected to two ends of a secondary winding of a transformer T1, an absorption circuit connected to two ends of a main winding of a transformer T1, a drain electrode of a switching tube Q1 connected to one end of the main winding, a gate electrode of the switching tube Q1 connected to an output end of a conventional controller, a source electrode of the switching tube Q1 connected to a sampling resistor Rcs, a feedback winding connected to one end of a voltage dividing resistor RFB _ h, the other end of the RFB _ h connected to one end of a voltage dividing resistor RFB _ l, and a controller, wherein the other end of the RFB _ l is grounded.
The controller detects the demagnetization time of the transformer T1 through an internal demagnetization detection circuit, the obtained detection signal controls the sampling circuit to obtain the information of the output voltage, the sampling circuit samples the output feedback voltage and then compares the output feedback voltage with the reference voltage in the constant voltage control circuit, the modulation signal is output to control the logic circuit, finally, a modulation signal sw is obtained to control the pulse width and the frequency of the transformer, and further the output voltage Vo is controlled.
In a sampling circuit in a conventional controller, a demagnetization time signal of one period needs to be obtained first to generate a sampling delay time, that is, the output demagnetization time determines the sampling time of the next period, not the sampling time of the current period.
As shown in fig. 2, in a conventional real-time signal sampling time diagram, a Tdemag signal in a previous period, that is, demagnetization time Tdemag1 of a secondary winding of a transformer, is first obtained, and then a sampling time of Tsp, that is, a Tdelay signal, is obtained according to Tdemag1, if a load changes at this time and an output voltage changes, sampling is inaccurate, an ideal output sampling voltage point is V2, but due to a sampling mechanism, the sampling voltage point at this time is V1, so that accuracy of the output voltage is not high, and a ripple is large.
As shown in fig. 3, it is another schematic diagram of the conventional implementation of real-time signal sampling, and after the secondary side coil is determined to be demagnetized, a fixed delay time is used to obtain a sampling time of Tsp, when a load changes, an output voltage changes, and a fixed time is used to cause a practical sampling point V1 to be higher, and an ideal sampling point is V2, so that an offset of the output voltage is caused after system feedback, and the accuracy of the output voltage is not high.
The two traditional control modes have certain defects in real-time signal sampling of the output voltage, so that when the signal of the secondary winding changes, a sampling error occurs, the accuracy of the constant voltage output Vo of the switching power supply is low, and the ripple is large.
Disclosure of Invention
In view of this, the present invention provides a novel real-time signal sampling circuit and a switching power supply using the same, wherein the novel real-time signal sampling circuit improves the accuracy of the output voltage of the switching power supply.
The utility model discloses a following scheme realizes: a novel real-time signal sampling circuit comprises a sampling control circuit, a charging current control unit, a discharging current control unit and a time delay unit; the electric current control unit, the discharge current control unit and the time delay unit are electrically connected with the sampling control circuit.
Further, the sampling control circuit comprises a first voltage-dividing resistor R1, a second voltage-dividing resistor R1a, a third voltage-dividing resistor R1b, a first switch K1, a second switch K2, a third switch K3, a first capacitor C1, a comparator, a first AND gate, a first OR gate, a first inverter, a second inverter, a third inverter and a D flip-flop; one end of the first voltage-dividing resistor R1 is connected with the sampling port, and the other end of the first voltage-dividing resistor R1 is connected with one end R1a of the second voltage-dividing resistor and is connected to the input port of the charging current control unit; the other end of the second voltage-dividing resistor R1a and one end of a third voltage-dividing resistor R1b are connected to each other and to the input port of the discharge current control unit, and the other end of the third voltage-dividing resistor R1b is grounded; the output port of the charging current control unit is connected with the output port of the discharging current control unit and is connected to one end of a first capacitor C1 and the negative phase input end of the comparator through a first switch K1; one end of the first capacitor C1 is further connected to the positive input terminal of the comparator through the second switch K2, and the positive input terminal of the comparator is further connected to the reference voltage Vref; the other end of the first capacitor C1 is grounded, and the output end of the comparator is connected with the input port of the delay unit and grounded through a third switch K3; the output of the comparator is also connected with the first input end of the first AND gate; the output of the first or gate is used for controlling a third switch K3; the Q end of the D trigger outputs a signal t2, is connected with the second input end of the first OR gate and simultaneously controls a second switch K2; the output end of the delay unit is connected with the second input end of the first AND gate, the output end of the first AND gate outputs a Tsp signal and is connected with the input end of a first phase inverter, and the output end of the first phase inverter is connected with the clock end of the D trigger; the output end of the second inverter is connected with the reset end of the D flip-flop, the Q end of the D flip-flop is also connected with the input end of a third inverter, and the output end of the third inverter outputs a signal t2n for controlling a first switch K1; the first input end of the first OR gate and the input end of the second inverter are both connected with a modulation signal sw; and the D end of the D trigger is externally connected with a power supply Vdd.
Further, the charging current control unit includes a first current mirror P, a second current mirror Q, and a second capacitor C2; the first current mirror P is electrically connected with the second current mirror Q; the second current mirror Q is further connected to one end of the second capacitor C2, and serves as an input port of the charging current control unit, so as to convert the voltage signal connected between the first voltage dividing resistor R1 and the second voltage dividing resistor R1a into a current signal and output the current signal by the first current mirror P; the other end of the second capacitor C2 is grounded.
Further, the discharge current control unit includes a third current mirror P1, a fourth current mirror N, a fourth resistor R1c, and a fourth switch K4; the third current mirror P1 is electrically connected with the fourth current mirror N; the third current mirror P1 is further connected to one end of the fourth resistor R1c, and serves as an input port of the discharge current control unit, so as to convert the voltage signal connected to the second voltage-dividing resistor R1a and the third voltage-dividing resistor R1b into a current signal and output the current signal by the fourth current mirror N; the fourth current mirror N is also connected with one end of the fourth switch K4; the other end of the fourth resistor R1c and the other end of the fourth switch K4 are both grounded.
Further, the delay circuit includes a first bias current source, a delay capacitor C3, a schmitt trigger, a fourth inverter, a fifth switch K5, and a sixth switch K6; the input of the delay unit respectively controls a fifth switch and a sixth switch; the power supply Vdd is connected to one end of a delay capacitor C3 through a fifth switch K5, and one end of a delay capacitor C3 is also connected to the ground through a sixth switch K6 and the first bias current source; one end of the delay capacitor C3 is also connected with the input end of a Schmitt trigger, and the output end of the Schmitt trigger is connected with the input end of the fourth inverter; the output end of the fourth inverter is used as the output end of the delay unit; the other end of the delay capacitor C3 is grounded.
1. Furthermore, the invention also provides a switching power supply applying the novel real-time signal sampling circuit, which comprises a transformer T1, a peripheral circuit of the transformer T1 and a control circuit of the transformer T1; the control circuit comprises a real-time signal sampling circuit, a demagnetization detection circuit, a constant current circuit, a constant voltage circuit and a logic circuit; the demagnetization detection circuit is electrically connected with the constant current circuit and the real-time signal sampling circuit respectively; the constant current circuit is also electrically connected with the logic circuit; the real-time signal sampling circuit is also electrically connected with the constant voltage circuit; the logic circuit is also electrically connected with the constant voltage circuit;
the transformer and the peripheral circuit thereof comprise a transformer T1, an absorption circuit, a power tube Q1, a detection resistor RCS, a first diode D1, a first capacitor Co and a transformer T1 feedback winding unit; the control circuit is connected with a feedback winding unit of the transformer T1 and used for generating a switching signal sw to adjust the pulse width and the frequency of the transformer;
the dotted terminal of the secondary winding on the primary side of the transformer T1 is connected with the feedback winding unit of the transformer T1; the synonym end of the secondary winding on the primary side of the transformer T1 is grounded; the dotted terminal of the primary side first winding of the transformer T1 is respectively connected with the drain electrode of the power tube Q1 and the absorption circuit; the source electrode of the power tube Q1 is respectively connected with one end of the detection resistor RCS and the control circuit; the grid electrode of the power tube Q1 is connected with the logic circuit, and the logic circuit outputs a switch signal sw; the other end of the detection resistor RCS is grounded; the synonym end of the primary side first winding of the transformer T1 is connected with the absorption circuit and is connected with an input voltage in parallel; the dotted terminal of the transformer T1 side winding is connected with the anode of the first diode D1; the cathode of the first diode D1 is connected with one end of the first capacitor Co and serves as a voltage output end; the other end of the first capacitor Co is connected with the synonym end of the width-side winding of the transformer T1 and is grounded at the same time;
the feedback winding unit of the transformer T1 comprises a voltage dividing resistor RFB_hAnd a voltage dividing resistor RFB_l(ii) a The voltage-dividing resistor RFB_hAnd the voltage dividing resistor RFB_lOne end of the output signal is connected with the demagnetization detection circuit and the real-time signal sampling circuit respectively; the voltage-dividing resistor RFB_lThe other end of the first and second electrodes is grounded; the voltage-dividing resistor RFB_hAnd the other end of the first winding is connected with the same-name end of the secondary winding on the primary side of the transformer T1.
Compared with the prior art, the utility model discloses following beneficial effect has:
the utility model discloses real-time signal sampling circuit's clock by switching power supply system's switching signal sw decide to be demagnetization signal in the same sw switching cycle has decided the sampling moment in the same sw switching cycle, avoided the sampling error that arouses when output voltage changes, make the utility model discloses a switching power supply output voltage reaches higher precision.
Drawings
Fig. 1 is a schematic diagram of a switching power supply conversion system based on the conventional technology.
Fig. 2 is a schematic diagram of a first conventional switching power supply.
Fig. 3 is a schematic diagram of a second conventional switching power supply.
Fig. 4 is a schematic circuit diagram of a real-time signal sampling circuit according to an embodiment of the present invention, wherein fig. 4(a) is a schematic circuit diagram of a sampling control circuit, fig. 4(b) is a schematic circuit diagram of a charging current control unit, fig. 4(c) is a schematic circuit diagram of a discharging current control unit, fig. 4(D) is a schematic circuit diagram of a delay circuit, 101 is a charging current control unit, 102 is a discharging current control unit, 103 is a comparator, 105 is a delay circuit, 111 is a first or gate, 112 is a first and gate, 113 is a first inverter, 114 is a second inverter, 115 is a D flip-flop, 116 is a third inverter, 117 is a fourth inverter, 118 is a first bias power supply, and 119 is a schmitt trigger 119.
Fig. 5 is a block diagram of a switching power supply applying the novel real-time signal sampling circuit according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of the embodiment of the present invention for sampling a novel switching power supply.
Detailed Description
The present invention will be further explained with reference to the drawings and the embodiments.
The embodiment provides a novel real-time signal sampling circuit, which comprises a sampling control circuit, a charging current control unit 101, a discharging current control unit 102 and a time delay unit; the electric current control unit, the discharge current control unit 102 and the time delay unit are all electrically connected with the sampling control circuit.
In this embodiment, the sampling control circuit includes a first voltage-dividing resistor R1, a second voltage-dividing resistor R1a, a third voltage-dividing resistor R1b, a first switch K1, a second switch K2, a third switch K3, a first capacitor C1, a comparator 103, a first and gate 112, a first or gate 111, a first inverter 113, a second inverter 114, a third inverter, and a D flip-flop 115; one end of the first voltage-dividing resistor R1 is connected to a sampling port, the sampling port is externally connected to an auxiliary winding voltage-dividing signal of the transformer, and the other end of the first voltage-dividing resistor R1 is connected to one end R1a of the second voltage-dividing resistor and is connected to the input port of the charging current control unit 101; the other end of the second voltage-dividing resistor R1a and one end of a third voltage-dividing resistor R1b are connected to each other and to the input port of the discharge current control unit 102, and the other end of the third voltage-dividing resistor R1b is grounded; an output port of the charging current control unit 101 is connected with an output port of the discharging current control unit 102 and is connected to one end of a first capacitor C1 and a negative phase input terminal of a comparator 103 through a first switch K1; one end of the first capacitor C1 is further connected to the non-inverting input terminal of the comparator 103 via the second switch K2, and the non-inverting input terminal of the comparator 103 is further connected to the reference voltage Vref; the other end of the first capacitor C1 is grounded, and the output end of the comparator 103 is connected with the input port of the delay unit and grounded through a third switch K3; the output of the comparator 103 is further connected to a first input of the first and gate 112; the output of the first or gate 111 is used to control the third switch K3; the Q end of the D flip-flop 115 outputs a signal t2 and is connected with the second input end of the first OR gate 111, and simultaneously controls a second switch K2; the output end of the delay unit is connected with the second input end of the first and gate 112, the output end of the first and gate 112 outputs a Tsp signal and is connected with the input end of a first inverter 113, and the output end of the first inverter 113 is connected with the clock end of the D flip-flop 115; the output end of the second inverter 114 is connected to the reset end of the D flip-flop 115, the Q end of the D flip-flop 115 is further connected to the input end of the third inverter, and the output end of the third inverter outputs a signal t2n for controlling the first switch K1; a modulation signal sw is connected to both a first input end of the first or gate 111 and an input end of the second inverter 114; the D end of the D trigger 115 is externally connected with a power supply Vdd.
In the present embodiment, the charging current control unit 101 includes a first current mirror P, a second current mirror Q, and a second capacitor C2; the first current mirror P is electrically connected with the second current mirror Q; the second current mirror Q is further connected to one end of the second capacitor C2, and serves as an input port of the charging current control unit 101, so as to convert the voltage signal connected between the first voltage dividing resistor R1 and the second voltage dividing resistor R1a into a current signal and output the current signal by the first current mirror P; the other end of the second capacitor C2 is grounded; the output end of the first current mirror P serves as the output port of the charging current control unit 101.
In the present embodiment, the discharge current control unit 102 includes a third current mirror P1, a fourth current mirror N, a fourth resistor R1c, and a fourth switch K4; the third current mirror P1 is electrically connected with the fourth current mirror N; the third current mirror P1 is further connected to one end of the fourth resistor R1c, and serves as an input port of the discharge current control unit 102, so as to convert the voltage signal connected by the second voltage-dividing resistor R1a and the third voltage-dividing resistor R1b into a current signal and output the current signal by the fourth current mirror N; the fourth current mirror N is also connected with one end of the fourth switch K4; the other end of the fourth resistor R1c and the other end of the fourth switch K4 are both grounded; the output end of the fourth current mirror N serves as the output port of the discharge current control unit 102.
In the present embodiment, the delay circuit 105 includes a first bias current source, a delay capacitor C3, a schmitt trigger 119, a fourth inverter 117, a fifth switch K5, and a sixth switch K6; the input of the delay unit respectively controls a fifth switch and a sixth switch; the power supply Vdd is connected to one end of a delay capacitor C3 through a fifth switch K5, and one end of a delay capacitor C3 is also connected to the ground through a sixth switch K6 and the first bias current source; one end of the delay capacitor C3 is further connected to the input end of the schmitt trigger 119, and the output end of the schmitt trigger 119 is connected to the input end of the fourth inverter 117; the output end of the fourth inverter 117 serves as the output end of the delay unit; the other end of the delay capacitor C3 is grounded.
Preferably, the embodiment further provides a switching power supply applying the novel real-time signal sampling circuit, which includes a transformer T1, a peripheral circuit thereof, and a control circuit; the control circuit comprises a real-time signal sampling circuit, a demagnetization detection circuit, a constant current circuit, a constant voltage circuit and a logic circuit; the demagnetization detection circuit is electrically connected with the constant current circuit and the real-time signal sampling circuit respectively; the constant current circuit is also electrically connected with the logic circuit; the real-time signal sampling circuit is also electrically connected with the constant voltage circuit; the logic circuit is also electrically connected with the constant voltage circuit;
the transformer and the peripheral circuit thereof comprise a transformer T1, an absorption circuit, a power tube Q1, a detection resistor RCS, a first diode D1, a first capacitor Co and a transformer T1 feedback winding unit; the control circuit is connected with a feedback winding unit of the transformer T1 and used for generating a switching signal sw to adjust the pulse width and the frequency of the transformer;
the dotted terminal of the secondary winding on the primary side of the transformer T1 is connected with the feedback winding unit of the transformer T1; the synonym end of the secondary winding on the primary side of the transformer T1 is grounded; the dotted terminal of the primary side first winding of the transformer T1 is respectively connected with the drain electrode of the power tube Q1 and the absorption circuit; the source electrode of the power tube Q1 is respectively connected with one end of the detection resistor RCS and the control circuit; the grid electrode of the power tube Q1 is connected with the logic circuit, and the logic circuit outputs a switch signal sw; the other end of the detection resistor RCS is grounded; the synonym end of the primary side first winding of the transformer T1 is connected with the absorption circuit and is connected with an input voltage in parallel; the dotted terminal of the transformer T1 side winding is connected with the anode of the first diode D1; the cathode of the first diode D1 is connected with one end of the first capacitor Co and serves as a voltage output end; the other end of the first capacitor Co is connected with the synonym end of the width-side winding of the transformer T1 and is grounded at the same time;
the feedback winding unit of the transformer T1 comprises a voltage dividing resistor RFB_hAnd a voltage dividing resistor RFB_l(ii) a The voltage-dividing resistor RFB_hAnd the voltage dividing resistor RFB_lOne end of the output signal is connected with the demagnetization detection circuit and the real-time signal sampling circuit respectively; the voltage-dividing resistor RFB_lThe other end of the first and second electrodes is grounded; the voltage-dividing resistor RFB_hAnd the other end of the first winding is connected with the same-name end of the secondary winding on the primary side of the transformer T1.
Preferably, in this embodiment, the real-time signal sampling circuit is integrated in an integrated package, and the switching power supply includes the real-time signal sampling circuit, the demagnetization detection circuit, the constant current circuit, the constant voltage circuit, and the logic circuit, and is integrated in an integrated package. The output voltage of the switching power supply can reach higher precision.
Preferably, as shown in fig. 4, in the present embodiment, the first current mirror P is composed of MOS transistors P0, P0a and P0b, wherein the source of the MOS transistor P0b is used as the output terminal of the first current mirror P; the second current mirror Q is comprised of transistors Q0 and Q0 a. The third current mirror is composed of transistors P1 and P1 a; the fourth current mirror is composed of transistors N0 and N0a, and the drain of the transistor N0a is used as the output end of the fourth current mirror.
Preferably, in the present embodiment, the meaning of each symbol in the drawing is:
n0, N0 a: NMOS transistor
P0, P0a, P0b, P1, P1 a: PMOS transistor
Q0, Q0 a: NPN transistor
FB: auxiliary winding voltage division port
sw: q1 control signal
Tdeamg: system demagnetization time signal
Tsp: sampling control clock
Vref: reference voltage
Vc: peak voltage of capacitor C1
Vin: input line voltage
142: node 142 voltage waveform
Vdd: supply voltage
t 2: d flip-flop 115Q end waveform
Vo: output voltage of switching power supply
V1, V2: voltage at sampling point
Preferably, in this embodiment, one end of a voltage dividing resistor R1 in the sampling circuit is connected to the divided voltage of the auxiliary winding, the other end of R1 is connected to one end of R1a, a node 144 thereof is connected to the charging current control unit 101, the other end of R1a is connected to one end of R1b, a node 145 thereof is connected to the discharging current control unit 102, the other end of R1b is grounded, one end of the charging current generation unit is connected to the internal power supply, the other end thereof is connected to the discharging unit, a first switch K1 whose node 143 is controlled by an output t2n of the third inverter is connected to the upper plate of a capacitor C1, an upper plate node 142 of C1 is connected to the negative phase input terminal of the comparator 103, a second switch K2 whose node 142 is controlled by a Q terminal output t2 of the D flip-flop 115 is connected to the non-phase input terminal of the comparator 103, while a non-phase input terminal 141 of the comparator 103 is connected to the reference voltage Vref, a lower plate of the C1, an output, the node 144 is connected to the ground through a third switch K3 controlled by a first or gate 111111, the node 144 is connected to a first input terminal of a first and gate 112112, an output terminal of the delay unit is connected to a second input terminal of the first and gate 112, a first input terminal of the first or gate 111 is connected to a sw signal, a second input terminal of the first or gate 111 is connected to t2, an output of the first and gate 112 is a Tsp signal, an output terminal of the first and gate 112 is connected to an input terminal of a first inverter 113, an output terminal of the first inverter 113 is connected to a clock terminal of a D flip-flop 115, a D terminal of the D flip-flop 115 is connected to an internal power supply, an input terminal of a second inverter 114 is connected to the sw signal, an output terminal of the second inverter 114 is connected to a reset terminal of the D flip-flop 115, a Q terminal of the D flip-flop 115 is connected to an input terminal of a third inverter.
Preferably, the real-time signal sampling circuit of this embodiment is formed by electrically connecting a sampling control circuit, a charging current control unit, a discharging current control unit, and a delay unit in sequence, and generates a charging current and a discharging current after connecting an auxiliary winding voltage division resistor of a transformer with a first voltage division resistor, a second voltage division resistor, and a third voltage division resistor, so as to control a turning point of a comparator, and control a sampling time in a current period by a demagnetization time in the current period; the switching power supply comprises a transformer and a control circuit, wherein the control circuit accurately samples the partial pressure of an auxiliary winding of the transformer in real time and accurately adjusts the output voltage of the switching power supply, the control circuit comprises the real-time signal sampling circuit, and the switching power supply can achieve high constant-voltage output precision.
In particular, in order to make the general skilled person better understand the present embodiment, the following further describes the operation principle of the present embodiment with reference to the circuit:
referring to fig. 4, one end of the first voltage dividing resistor R1 is connected to the divided voltage FB signal of the auxiliary winding, the node 144 is connected to the charging current control circuit, the node 145 is connected to the discharging current control circuit, sw is the switching signal of the switching power supply system, i.e., the switching signal of the transformer winding T1, the output signal of the first and gate 112 is Tsp, the output signal of the D flip-flop 115 is T2, and the phases of the output signals T2n and T2 of the third inverter are opposite.
Referring to fig. 6, the FB signal is a signal obtained by dividing the voltage of the auxiliary winding, sw is a switching signal of the power supply system, 142 is a waveform of an inverting input terminal of the comparator 103 in fig. 4, t2 is a waveform of an output from the Q terminal of the D flip-flop 115, and Tsp is a waveform of a sampling time finally obtained in this embodiment. When the sw signal is at a high potential, as can be seen from the connection relationship in fig. 4, the switch K2 is closed, the switch K4 is closed, the Tsp output is at a ground potential, the sw controls the D flip-flop 115 to reset, the t2 output is at a ground potential, the t2n is at a high potential, the t2 controls the switch K3 to be opened, and the t2n controls the switch K1 to be closed; the signal of FB is negative potential at this time, and a current is generated from the input terminal of the charging unit 101 through the first voltage dividing resistor R1, assuming that the proportionality coefficient of the current mirror P0 and P0b is a, so that the output current of the charging unit is obtained as formula (1):
from the connection relationship of the switching power supply system given in fig. 5, equation (2) is obtained:
naux and Np in the formula (2) represent the turn ratio of the auxiliary winding to the primary winding of the transformer T1, RFB_lAnd RFB_hRepresenting the divider resistance of the auxiliary winding.
From the states of the switches, the output of the charging unit at this time charges the capacitor C1 of the node 142, the charging time, i.e., the time of high potential of sw, is given as Ton, and equation (3) can be obtained according to the current formula of the primary inductor:
where Lp represents the inductance of the primary winding and Ipk represents the peak current flowing through the primary winding.
From the above formula, when sw is at high level, the relation between the voltage and the current charging time of the capacitor C1 is as shown in formula (4):
the (1), (2) and (3) are arranged and then are substituted into the formula (4) to obtain:
when the sw signal jumps to the ground potential from a high potential, as can be seen from the connection relationship in fig. 4, the switch K2 is turned off, the switch K4 is turned off, and at this time, the FB signal is pulled high due to flyback, so that no charging current is generated, the node 145 generates a discharging current through R1c, and assuming that the proportionality coefficient from the current mirror P1 to the current mirror N0a is B, the discharging current is as shown in formula (6):
the discharge time Tdelay can be found:
bringing (5), (6) into (7) yields:
the formula (9) can be obtained according to the formula of the demagnetization time of the flyback switching power supply:
bringing formula (9) into formula (8) to obtain (10):
the sampling time after Tdelay can be obtained by the formula (10) is related to Tdemag, and a reasonable Tsp time can be obtained by reasonably setting the proportion of the current mirror and the proportion of the resistance. Compared with a traditional sampling moment circuit, the demagnetization time is not introduced in the process of establishing the sampling moment in the embodiment, and the demagnetization time is directly controlled through the sw signal, so that the phenomenon that sampling is inaccurate when output voltage changes in the traditional circuit is avoided, and higher constant voltage precision of the output voltage can be realized.
It is worth mentioning that the utility model protects a hardware structure, as for the control method does not require protection. The above is only a preferred embodiment of the present invention. However, the present invention is not limited to the above embodiments, and any equivalent changes and modifications made according to the present invention do not exceed the scope of the present invention, and all belong to the protection scope of the present invention.
Claims (6)
1. A novel real-time signal sampling circuit is characterized in that: the device comprises a sampling control circuit, a charging current control unit, a discharging current control unit and a time delay unit; and the charging current control unit, the discharging current control unit and the time delay unit are electrically connected with the sampling control circuit.
2. The novel real-time signal sampling circuit of claim 1, wherein: the sampling control circuit comprises a first voltage-dividing resistor R1, a second voltage-dividing resistor R1a, a third voltage-dividing resistor R1b, a first switch K1, a second switch K2, a third switch K3, a first capacitor C1, a comparator, a first AND gate, a first OR gate, a first inverter, a second inverter, a third inverter and a D trigger; one end of the first voltage-dividing resistor R1 is connected with the sampling port, and the other end of the first voltage-dividing resistor R1 is connected with one end R1a of the second voltage-dividing resistor and is connected to the input port of the charging current control unit; the other end of the second voltage-dividing resistor R1a and one end of a third voltage-dividing resistor R1b are connected to each other and to the input port of the discharge current control unit, and the other end of the third voltage-dividing resistor R1b is grounded; the output port of the charging current control unit is connected with the output port of the discharging current control unit and is connected to one end of a first capacitor C1 and the negative phase input end of the comparator through a first switch K1; one end of the first capacitor C1 is further connected to the positive input terminal of the comparator through the second switch K2, and the positive input terminal of the comparator is further connected to the reference voltage Vref; the other end of the first capacitor C1 is grounded, and the output end of the comparator is connected with the input port of the delay unit and grounded through a third switch K3; the output of the comparator is also connected with the first input end of the first AND gate; the output of the first or gate is used for controlling a third switch K3; the Q end of the D trigger outputs a signal t2, is connected with the second input end of the first OR gate and simultaneously controls a second switch K2; the output end of the delay unit is connected with the second input end of the first AND gate, the output end of the first AND gate outputs a Tsp signal and is connected with the input end of a first phase inverter, and the output end of the first phase inverter is connected with the clock end of the D trigger; the output end of the second inverter is connected with the reset end of the D flip-flop, the Q end of the D flip-flop is also connected with the input end of a third inverter, and the output end of the third inverter outputs a signal t2n for controlling a first switch K1; the first input end of the first OR gate and the input end of the second inverter are both connected with a modulation signal sw; and the D end of the D trigger is externally connected with a power supply Vdd.
3. The novel real-time signal sampling circuit of claim 2, wherein: the charging current control unit includes a first current mirror P, a second current mirror Q, and a second capacitor C2; the first current mirror P is electrically connected with the second current mirror Q; the second current mirror Q is further connected to one end of the second capacitor C2, and serves as an input port of the charging current control unit, so as to convert the voltage signal connected between the first voltage dividing resistor R1 and the second voltage dividing resistor R1a into a current signal and output the current signal by the first current mirror P; the other end of the second capacitor C2 is grounded.
4. The novel real-time signal sampling circuit of claim 1, wherein: the discharge current control unit comprises a third current mirror P1, a fourth current mirror N, a fourth resistor R1c and a fourth switch K4; the third current mirror P1 is electrically connected with the fourth current mirror N; the third current mirror P1 is further connected to one end of the fourth resistor R1c, and serves as an input port of the discharge current control unit, so as to convert the voltage signal connected to the second voltage-dividing resistor R1a and the third voltage-dividing resistor R1b into a current signal and output the current signal by the fourth current mirror N; the fourth current mirror N is also connected with one end of the fourth switch K4; the other end of the fourth resistor R1c and the other end of the fourth switch K4 are both grounded.
5. The novel real-time signal sampling circuit of claim 1, wherein: the delay unit comprises a first bias current source, a delay capacitor C3, a Schmitt trigger, a fourth inverter, a fifth switch K5 and a sixth switch K6; the input of the delay unit respectively controls a fifth switch and a sixth switch; the power supply Vdd is connected to one end of a delay capacitor C3 through a fifth switch K5, and one end of a delay capacitor C3 is also connected to the ground through a sixth switch K6 and the first bias current source; one end of the delay capacitor C3 is also connected with the input end of a Schmitt trigger, and the output end of the Schmitt trigger is connected with the input end of the fourth inverter; the output end of the fourth inverter is used as the output end of the delay unit; the other end of the delay capacitor C3 is grounded.
6. A switching power supply applying the novel real-time signal sampling circuit of any one of claims 1 to 5, characterized in that: the transformer T1, its peripheral circuit and control circuit; the control circuit comprises a real-time signal sampling circuit and a demagnetization detection circuit as claimed in any one of claims 1 to 5, a constant current circuit, a constant voltage circuit, a logic circuit; the demagnetization detection circuit is electrically connected with the constant current circuit and the real-time signal sampling circuit respectively; the constant current circuit is also electrically connected with the logic circuit; the real-time signal sampling circuit is also electrically connected with the constant voltage circuit; the logic circuit is also electrically connected with the constant voltage circuit;
the transformer and the peripheral circuit thereof comprise a transformer T1, an absorption circuit, a power tube Q1, a detection resistor RCS, a first diode D1, a first capacitor Co and a transformer T1 feedback winding unit; the control circuit is connected with a feedback winding unit of the transformer T1 and used for generating a switching signal sw to adjust the pulse width and the frequency of the transformer;
the dotted terminal of the secondary winding on the primary side of the transformer T1 is connected with the feedback winding unit of the transformer T1; the synonym end of the secondary winding on the primary side of the transformer T1 is grounded; the dotted terminal of the primary side first winding of the transformer T1 is respectively connected with the drain electrode of the power tube Q1 and the absorption circuit; the source electrode of the power tube Q1 is respectively connected with one end of the detection resistor RCS and the control circuit; the grid electrode of the power tube Q1 is connected with the logic circuit, and the logic circuit outputs a switch signal sw; the other end of the detection resistor RCS is grounded; the synonym end of the primary side first winding of the transformer T1 is connected with the absorption circuit and is connected with an input voltage in parallel; the dotted terminal of the transformer T1 side winding is connected with the anode of the first diode D1; the cathode of the first diode D1 is connected with one end of the first capacitor Co and serves as a voltage output end; the other end of the first capacitor Co is connected with the synonym end of the width-side winding of the transformer T1 and is grounded at the same time;
the feedback winding unit of the transformer T1 comprises a voltage dividing resistor RFB_hAnd a voltage dividing resistor RFB_l(ii) a The voltage-dividing resistor RFB_hAnd the voltage dividing resistor RFB_lOne end of the output signal is connected with the demagnetization detection circuit and the real-time signal sampling circuit respectively; the voltage-dividing resistor RFB_lThe other end of the first and second electrodes is grounded; the voltage-dividing resistor RFB_hAnd the other end of the first winding is connected with the same-name end of the secondary winding on the primary side of the transformer T1.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202020135025.3U CN211791226U (en) | 2020-01-20 | 2020-01-20 | Novel real-time signal sampling circuit and switching power supply using same |
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| CN202020135025.3U CN211791226U (en) | 2020-01-20 | 2020-01-20 | Novel real-time signal sampling circuit and switching power supply using same |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114188920A (en) * | 2021-09-01 | 2022-03-15 | 杰华特微电子股份有限公司 | Current detection circuit, control chip and switching power supply |
| CN117713832A (en) * | 2024-02-18 | 2024-03-15 | 深圳市芯茂微电子有限公司 | Method and device for adjusting sampling time node |
-
2020
- 2020-01-20 CN CN202020135025.3U patent/CN211791226U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114188920A (en) * | 2021-09-01 | 2022-03-15 | 杰华特微电子股份有限公司 | Current detection circuit, control chip and switching power supply |
| CN114188920B (en) * | 2021-09-01 | 2024-03-22 | 杰华特微电子股份有限公司 | Current detection circuit, control chip and switching power supply |
| CN117713832A (en) * | 2024-02-18 | 2024-03-15 | 深圳市芯茂微电子有限公司 | Method and device for adjusting sampling time node |
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