CN218041203U - Circuit for starting flexible charging of power port and switching power supply system - Google Patents

Abstract

The utility model provides a circuit and switching power supply system to flexible charging start-up of power port relates to power starting circuit technical field, and a switching power supply system is applied to the circuit, and the circuit is including starting charging module, constant current feedback temperature drift control module, enabling decision module and short circuit detection module to ground. The constant-current feedback temperature drift control module is respectively connected with the starting charging module, the enabling judgment module and the ground short circuit detection module; the starting charging module is also respectively connected with the ground short circuit detection module, a control starting port ST of the switch power supply system and a power supply port VDD; the enabling judging module is connected with an enabling end EN of the switching power supply system. The startup charging module and the constant current feedback temperature drift control module are arranged to control the startup port ST to flexibly start and charge the power supply port VDD, so that the service life of the switching power supply system is prevented from being damaged when the power supply port VDD is short-circuited to the ground.

Description

Circuit for starting flexible charging of power port and switching power supply system

Technical Field

The utility model relates to a power starting circuit technical field especially relates to a circuit and switching power supply system to the flexible start-up that charges of power port.

Background

Power supplies, as a power supply for all electronic products, need to meet more stringent safety standards and energy efficiency. The traditional switching power supply system is started by adopting a resistor, so that the current severe standby power consumption requirement is difficult to be satisfied, and the current popular switching power supply converter is shown as a graph 1, and the working waveform of the current popular switching power supply converter is shown as a graph 2. The existing switching power supply system generates a square wave signal V with variable pulse width by sampling the voltage in the secondary coil of the transformer TR to the FB port of the conventional switching power supply system 10 through the feedback device 12, and sampling the current ICS of the primary coil of the transformer to the CS port of the switching power supply controller integrated circuit 11 through the power tube M1 and the current limiting resistor Rcs _PWM Square wave signal V _PWM The driving signal Vsw generated by the driving circuit DRIVER controls the power transistor M1 to be turned on or off. It can be seen that, in order to improve the standby efficiency, the conventional switching power supply system 10 directly sets the ultra-high voltage switch from the high voltage input terminal ST to perform large current charging start on the power supply VDD port, and turns off the high voltage switch after the start is completed, so as to save power consumption. The power supply system can easily meet the standby power consumption energy efficiency standard, but the conventional ultra-high voltage starting switch starting technology is that the high-current direct-filling type starting is carried out on a power supply port VDD, a starting path is cut off after the power supply starting process is finished, and when the power supply port VDD is short-circuited to the ground, the power supply is easily damaged or the service life is seriously damaged.

Therefore, a new switching power supply system is needed to meet the standby power consumption standard, reduce the damage to the power supply, and efficiently and safely protect the electric equipment.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a flexible circuit and switching power supply system that charges and start power port through the flexible start-up of control start port ST to power port VDD to the life-span of losing switching power supply system when avoiding power supply port VDD to ground short circuit.

In order to achieve the above object, the utility model provides a following scheme:

a circuit for starting flexible charging of a power port is applied to a switching power supply system, and comprises:

the method comprises the following steps of starting a charging module, a constant current feedback temperature drift control module, an enabling judgment module and a ground short circuit detection module;

the constant-current feedback temperature drift control module is respectively connected with the starting charging module, the enabling judging module and the ground short circuit detection module; the starting charging module is also respectively connected with the ground short circuit detection module, a control starting port ST of the switch power supply system and the power supply port VDD; the enabling judging module is connected with an enabling end EN of a power-on and power-off enabling circuit in the switching power supply system;

the enabling judging module is used for receiving an enabling signal;

the starting charging module generates a first signal V when the enabling signal is 0 _S1 Or generating a second signal when the enable signal is 1;

the constant current feedback temperature drift control module generates a third signal V when the enabling signal is 0 _G1 ；

The first signal V _S1 And said third signal V _G1 The device is used for flexibly charging a power supply port VDD; the third signal is used for stopping charging the power supply port VDD;

the ground short circuit detection module is used for detecting whether a ground short circuit exists;

the constant current feedback temperature drift control module is also used for inhibiting and controlling the charging current temperature drift of the starting port ST to the power supply port VDD when the charging current temperature drift is short-circuited to the ground.

Optionally, the start charging module includes:

a switching tube J50, a switching tube HN50, a switching tube HP50 and a diode D50;

the drain electrode of the switching tube J50 is connected with a control starting port ST;

the grid electrode of the switching tube J50 is grounded;

the source electrode of the switching tube J50 is respectively connected with the drain electrode of the switching tube HN50 and the constant current feedback temperature drift control module;

the source electrode of the switching tube HN50 is respectively connected with the source electrode of the switching tube HP50 and the constant-current feedback temperature drift control module;

the drain electrode of the switching tube HP50 is respectively connected with the grid electrode of the switching tube HP50, the constant-current feedback temperature drift control module, the ground short circuit detection module and the anode of the diode D50;

the cathode of the diode D50 is connected to the power supply port VDD.

Optionally, the constant-current feedback temperature drift control module includes:

a constant current feedback circuit and a temperature drift control circuit;

the constant current feedback circuit is respectively connected with the starting charging module, the enabling judging module, the ground short circuit detection module and the temperature drift control circuit;

the temperature drift control circuit is also connected with the enabling judgment module and the ground short circuit detection module.

Optionally, the constant current feedback circuit includes:

the resistor R57, the clamping tube Z50, the switch tube HP51, the switch tube HN52 and the resistor R55;

a first end of the resistor R57 is connected to the source of the switch tube J50 and the drain of the switch tube HN50, respectively;

a second end of the resistor R57 is connected to the gate of the switching tube HN50, the cathode of the clamping tube Z50, the enable determination module, and the drain of the switching tube HN52, respectively;

the anode of the clamping tube Z50 is respectively connected with the source electrode of the switching tube HP51, the source electrode of the switching tube HN50 and the source electrode of the switching tube HP 50;

the source electrode of the switching tube HN52 is connected with the temperature drift control circuit;

the grid electrode of the switching tube HN52 is respectively connected with the first end of the resistor R55 and the temperature drift control circuit;

the second end of the resistor R55 is respectively connected with the drain electrode of the switch tube HP51 and the temperature drift control circuit;

the grid electrode of the switching tube HP51 is respectively connected with the grid electrode of the switching tube HP50, the drain electrode of the switching tube HP50, the ground short circuit detection module and the anode of the diode D50.

Optionally, the temperature drift control circuit includes:

a clamp tube Z51, a resistor R53 and a resistor R54;

the cathode of the clamp tube Z51 is respectively connected with the gate of the switch tube HN52 and the first end of the resistor R55;

the anode of the clamping tube Z51, the source of the switching tube HN52 and the first end of the resistor R54 are all grounded;

a second end of the resistor R54 is respectively connected with the ground short-circuit detection module and a first end of the resistor R53;

a second end of the resistor R53 is connected to a second end of the resistor R55 and a drain of the switching tube HP51, respectively.

Optionally, the enabling determination module includes:

resistor R56 and switching tube HN53;

the first end of the resistor R56 is respectively connected with the grid of the switching tube HN53 and the enabling end EN of the up-down power enabling circuit in the switching power supply system;

the second end of the resistor R56 and the source electrode of the switching tube HN53 are both grounded;

the drain of the switching tube HN53 and the second end of the resistor R57 are connected to the gate of the switching tube HN50, the cathode of the clamp tube Z50 and the drain of the switching tube HN52, respectively.

Optionally, the ground short circuit detection module includes:

the resistor R51, the resistor R52, the clamping tube Z52 and the switching tube HN51;

a first end of the resistor R51 is connected to the gate of the switching tube HP51, the gate of the switching tube HP50, the drain of the switching tube HP50, and the anode of the diode D50, respectively;

the second end of the resistor R51 is connected to the first end of the resistor R52, the cathode of the clamping tube Z52 and the gate of the switching tube HN51, respectively;

the second end of the resistor R52, the anode of the clamping tube Z52 and the source of the switching tube HN51 are all grounded;

the drain of the switching tube HN51 is connected to the second end of the resistor R54 and the first end of the resistor R53, respectively.

Optionally, the switching tube J50 is an ultra-high voltage switch;

the switching tube HN50, the switching tube HN51, the switching tube HN52 and the switching tube HN53 are all high-voltage N-type switches;

the switching tube HP50 and the switching tube HP51 are both high-voltage P-type switches.

A switch power supply system applies the circuit for starting the flexible charging of the power supply port.

According to the utility model provides a concrete embodiment, the utility model discloses a following technological effect:

the utility model provides a circuit and switching power supply system to the flexible start-up that charges of power port, circuit are applied to a switching power supply system, and the circuit is including starting the module of charging, constant current feedback temperature drift control module, enabling decision module and short circuit detection module to ground. The constant current feedback temperature drift control module is respectively connected with the starting charging module, the enabling judging module and the ground short circuit detection module; the starting charging module is also respectively connected with the ground short circuit detection module, a control starting port ST of the switch power supply system and a power supply port VDD; the enabling judging module is connected with an enabling end EN of the switching power supply system. The startup charging module and the constant current feedback temperature drift control module are arranged to control the startup port ST to flexibly start and charge the power supply port VDD, so that the service life of the switching power supply system is prevented from being damaged when the power supply port VDD is short-circuited to the ground.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

FIG. 1 is a circuit diagram of a prior art switching power supply system;

FIG. 2 is a waveform diagram illustrating operation of a switching power supply system according to the prior art;

fig. 3 is a circuit diagram of the flexible charging start of the power port in embodiment 1 of the present invention;

fig. 4 is a circuit diagram of a switching power supply system according to embodiment 3 of the present invention;

fig. 5 is a timing diagram of the operation of the switching power supply system in the external connection mode a according to embodiment 3 of the present invention;

fig. 6 is a timing chart of the operation of the switching power supply system in the external connection mode B according to embodiment 3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts all belong to the protection scope of the present invention.

The utility model aims at providing a flexible circuit and switching power supply system that charges and start power port through the flexible start-up of control start port ST to power port VDD to the life-span of losing switching power supply system when avoiding power supply port VDD to ground short circuit.

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the following detailed description.

In fig. 1 to 6, 10 denotes a commercially available switching power supply system not provided with the present invention; 10A represents a switching power supply system of the present invention; 11 represents a switch power supply controller integrated circuit which is popular in the market and is not provided with the utility model; 11A represents the switching power supply controller integrated circuit of the present invention; 12. a presentation FEEDBACK (FEEDBACK); 20 a power up/down enable circuit (UVLO); 30 denotes a Pulse Width Modulator (PWM); 40 denotes a DRIVER circuit (DRIVER); 50 denotes a start-up circuit function block of the switching power supply controller 10; 50A represents the flexible charge start circuit (StartUp) to the power port of the present invention; option (a) represents an external connection mode a of the ST port of the present invention 11A; option (B) represents an external connection mode B of the ST port of the present invention 11A; 60A represents the working timing diagram of the switching power supply system in the external connection mode A; 60B represents a working timing diagram of the switching power supply system in the external connection mode B; and 70, an operation timing diagram of the switching power supply system in the prior art is shown.

M1 represents an external power switch tube; TR represents a transformer; lp represents the primary coil of TR; ls represents the secondary coil of TR; la denotes the auxiliary winding of TR, responsible for the capacitance C to the VDD port _VDD Supplying power; d1 represents a full-wave rectifier diode of an ac input; d2, D3, D4, D5 and D50 each represent a diode; r1, rx, rcs, R50, R51, R52, R53, R54, R55, R56, and R57 each represent a resistor; c1, cx, C _VDD And C2 each represents a capacitor; j50 denotes an extra high voltage switch; HN50, HN51, HN52, HN53 and HN54 all represent high-voltage N-type switches, namely high-voltage N-type pipes; HP50 and HP51 denote high voltage P-type galvano mirror tubes; z50, Z51 and Z52 all represent clamp tubes; VDD represents a power port; ST represents a start port; FB denotes a feedback port; CS represents a current monitoring port of a primary coil of the transformer; DRV denotes the drive output port; GND denotes a ground port.

VAC represents the input ac voltage; VACN denotes one end of the input ac voltage; vo represents the dc output voltage of the switching power supply system 10; ics represents the primary coil current of the transformer TR; vsw represents a switching signal that drives the output; v _FB Representing a feedback voltage; v _DD Represents a supply port voltage; v _PWM Representing the pulse width comparator output signal; EN denotes an enable signal output by the UVLO block.

I _J Represents the on current of J50; i is _{CH_VDD} Represents the conduction current of HP 50; i50 denotes the charging current I _{CH_VDD} The mirror feedback current of HP 51; v _JS A third terminal voltage representing J50; v _S1 Represents the third terminal voltage of HN50, i.e. the source voltage of HN 50; v _GS1 Representing the second and third ends of HN50The voltage difference of the terminals, namely the gate-source voltage difference of HN 50; v _G1 Represents the second terminal voltage of HN50, i.e. the gate voltage of HN 50; v _G2 Represents the second terminal voltage of HN52, i.e. the gate voltage of HN 52; v _G3 Represents the second terminal voltage of HN51, i.e. the gate voltage of HN51; v _D3 Represents the first terminal voltage of HN51, i.e. the drain voltage of HN51; v _DD1 Represents the voltage at the first terminal of HP50, i.e., the drain voltage of HP 50; i51 represents the current of R51; i52 represents the on current of HN 52; v _ST A signal representing an ST port; v _THN Representing the turn-on threshold voltage of all N-type switching tubes; v _{DD_SCP_TH} Voltage decision threshold, V, represented as a short circuit of the VDD port to ground _DD Below V _{DD_SCP_TH} The charging current of the VDD port is compressed by multiple times to avoid damage to the control circuit when the VDD port is determined to be short-circuited to the ground.

I _CH0 Indicating that the VDD port voltage exceeds V _{DD_SCP_TH} Charging current constant current value of a time VDD port; I.C. A _CH1 The constant current value of the charging current of the VDD port when the VDD port is short-circuited to the ground is represented; k is a radical of _HN52 Represents the electrical constant of HN 52; k is a radical of _HN50 Represents the electrical constant of HN 50; v _THJ Representing the pinch-off threshold of J50.

Example 1

As shown in fig. 3, this embodiment provides a circuit for starting flexible charging of a power port, where the circuit is applied to a switching power supply system, and the circuit includes: the device comprises a starting charging module, a constant current feedback temperature drift control module, an enabling judgment module and a ground short circuit detection module.

The constant-current feedback temperature drift control module is respectively connected with the starting charging module, the enabling judgment module and the ground short circuit detection module; the starting charging module is also respectively connected with the ground short circuit detection module, a control starting port ST of the switch power supply system and a power supply port VDD; the enabling judging module is connected with an enabling end EN of the switching power supply system; the enabling judging module is used for receiving an enabling signal; the starting charging module generates a first signal V when the enabling signal is 0 _S1 Or generating a second signal when the enable signal is 1; the constant current feedback temperature drift control module generates a third signal V when the enable signal is 0 _G1 (ii) a First signal V _S1 And a third signal V _G1 The device is used for flexibly charging a power supply port VDD; the third signal is used for stopping charging the power supply port VDD; the ground short circuit detection module is used for detecting whether a ground short circuit exists; the constant current feedback temperature drift control module is also used for inhibiting the charging current temperature drift of the control starting port ST to the power supply port VDD when the ground is in short circuit.

Specifically, the start charging module includes: a switching tube J50, a switching tube HN50, a switching tube HP50 and a diode D50; the drain electrode of the switching tube J50 is connected with the control starting port ST; the grid electrode of the switching tube J50 is grounded; the source electrode of the switching tube J50 is respectively connected with the drain electrode of the switching tube HN50 and the constant current feedback temperature drift control module; the source electrode of the switching tube HN50 is respectively connected with the source electrode of the switching tube HP50 and the constant-current feedback temperature drift control module; the drain electrode of the switching tube HP50 is respectively connected with the grid electrode of the switching tube HP50, the constant-current feedback temperature drift control module, the ground short circuit detection module and the anode of the diode D50; the cathode of the diode D50 is connected to the power supply port VDD.

In addition, the constant current feedback temperature drift control module comprises a constant current feedback circuit and a temperature drift control circuit; the constant current feedback circuit is respectively connected with the starting charging module, the enabling judging module, the ground short circuit detection module and the temperature drift control circuit; the temperature drift control circuit is also connected with the enabling judgment module and the ground short circuit detection module.

Specifically, the constant current feedback circuit includes: a resistor R57, a clamping tube Z50, a switching tube HP51, a switching tube HN52 and a resistor R55; the first end of the resistor R57 is connected with the source electrode of the switch tube J50 and the drain electrode of the switch tube HN50 respectively; the second end of the resistor R57 is connected with the gate of the switch tube HN50, the cathode of the clamping tube Z50, the enable determination module and the drain of the switch tube HN52 respectively; the anode of the clamping tube Z50 is respectively connected with the source electrode of the switching tube HP51, the source electrode of the switching tube HN50 and the source electrode of the switching tube HP 50; the source electrode of the switching tube HN52 is connected with the temperature drift control circuit; the grid electrode of the switching tube HN52 is respectively connected with the first end of the resistor R55 and the constant current feedback circuit; the second end of the resistor R55 is respectively connected with the drain electrode of the switch tube HP51 and the temperature drift control circuit; the grid of the switching tube HP51 is connected to the grid of the switching tube HP50, the drain of the switching tube HP50, the short-circuit-to-ground detection module and the anode of the diode D50, respectively.

In addition, the temperature drift control circuit comprises a clamping tube Z51, a resistor R53 and a resistor R54; the cathode of the clamp tube Z51 is connected with the gate of the switch tube HN52 and the first end of the resistor R55; the anode of the clamping tube Z51, the source of the switching tube HN52 and the first end of the resistor R54 are all grounded; a second end of the resistor R54 is respectively connected with the ground short-circuit detection module and a first end of the resistor R53; a second terminal of the resistor R53 is connected to a second terminal of the resistor R55 and a drain of the switching tube HP 51.

The enabling determination module includes: resistor R56 and switching tube HN53; a first end of the resistor R56 is connected to the gate of the switching tube HN53 and the enable end EN of the switching power supply system respectively; the second end of the resistor R56 and the source electrode of the switch tube HN53 are both grounded; the drain of the switch tube HN53 and the second end of the resistor R57 are connected to the gate of the switch tube HN50, the cathode of the clamp tube Z50, and the drain of the switch tube HN52, respectively.

In addition, the ground short detection module includes: a resistor R51, a resistor R52, a clamping tube Z52 and a switch tube HN51; a first end of the resistor R51 is connected to the gate of the switching tube HP51, the gate of the switching tube HP50, the drain of the switching tube HP50, and the anode of the diode D50, respectively; the second end of the resistor R51 is respectively connected with the first end of the resistor R52, the cathode of the clamping tube Z52 and the gate of the switching tube HN51; the second end of the resistor R52, the anode of the clamping tube Z52 and the source of the switching tube HN51 are all grounded; the drain of the switching tube HN51 is connected to the second terminal of the resistor R54 and the first terminal of the resistor R53, respectively.

Wherein, the switching tube J50 is an ultra-high voltage switch; the switch tube HN50, the switch tube HN51, the switch tube HN52 and the switch tube HN53 are all high-voltage N-type switches; the switching tube HP50 and the switching tube HP51 are both high-voltage P-type switches.

The circuit for starting the flexible charging of the power port provided by the embodiment is formed by electrically connecting an extra-high voltage switch J50, high voltage switches HN50, HN51, HN52 and HN53, resistors R51, R52, R53, R54, R55, R56 and R57, a diode D50, clamp tubes Z50, Z51 and Z52, and current sources HP50 and HP 51; according to the logic control signal EN and the input voltage signal V _ST Generation and output controlSignal V _G1 ，V _G1 And V _S1 Voltage difference V of _GS1 The switching tube HN50 is controlled to charge the VDD port through the extra-high voltage switch J50, the switching tube HN50, the switching tube HP50 and the diode D50. V _DD1 ＝V _DD + Vbe (Vbe is D50 forward junction drop) controls the charging current value I to the VDD port _{CH_VDD} 。V _DD The charging current at VDD port is very small when the voltage is close to 0, V _DD When the voltage is higher, the charging current of the VDD port is very large, so that the whole charging starting process can be flexibly finished by judging the voltage of the VDD port, and the circuit is prevented from being damaged due to the overlarge charging current when the VDD port is in short circuit with the ground. In addition, R53, R54 and HN52 also ensure that the charging current of the VDD port is close to zero temperature drift, ensure the consistency in the high-low temperature range in the starting process and protect the safety of electrical appliances. In addition, the diode D50 has the unidirectional conduction characteristic that the forward voltage is conducted and the reverse voltage is cut off, and the VDD port is connected with the cathode of the diode D50, so that the phenomenon that the current from the VDD port to the ST port flows backwards when the ST port is connected with a low-voltage signal to cause the system to work and fail can be prevented.

The flexible charging starting circuit of the power supply port responds to the enabling end EN to draw current at the control starting port ST of the flexible charging starting circuit to start the power supply port VDD of the flexible charging starting circuit; the power supply port flexible charging starting circuit responds to the enable end EN and the power supply port VDD to draw current at the control starting port ST to flexibly start the power supply port VDD, so that the service life of the ultrahigh voltage switch J50 can be prevented from being damaged when the VDD is short-circuited to the ground, and a better safety effect is achieved; the flexible charging starting circuit of the power supply port responds to the enable end EN of the flexible charging starting circuit to generate charging for closing the power supply port VDD from the outside at the control starting port ST, so that the effect of saving the power consumption of the system can be achieved;

the internal device clamp tubes (Z50, Z51 and Z52) can protect the gate oxide layers of the high-voltage switches (HN 50, HN51 and HN 52) from being safe; the internal device diode D50 can prevent the power supply port VDD from flowing backward to the control start port ST. The current sources (HP 50 and HP 51), the high voltage switches (HN 51 and HN 52), and the resistors (R51, R52, R53 and R54) may define the maximum value of the charging current that controls the start port ST to the power port VDD. The high voltage switch HN52 and the resistors (R53 and R54) can suppress the temperature drift of the charging current of the power port VDD to the control start port ST of the power port flexible charging start circuit.

The embodiment can be applied to the transformer secondary side feedback type switch power supply and can also be applied to the transformer primary side feedback type switch power supply.

The working principle of the embodiment is as follows:

when VDD is charged from 0, V _DD <VDD _ON Time (VDD) _ON Power-up threshold), EN is logic "0", controlling HN53 to turn off, when:

V _DD1 ＝V _DD +Vbe (1)

V _G3 ＝V _DD1 (R52/(R52+R51)) (2)

V _G3 ＝(V _DD +Vbe)(R52/(R52+R51)) (3)

V _THN the resistors R52 and R51 are matched to have a proportionality coefficient of beta (beta) for the conduction threshold of the N-type switch>1) The resistors R53 and R54 are matched with a proportionality coefficient theta (theta)>>1) The accurate resistance R56 and R57 are super resistors, so that power consumption is saved.

R51＝βR52(4)

R54＝θR53(5)

If V _G3 <V _THN Then V is _G3 To logic "0", HN51 is controlled to turn off. The gate voltage of HN52 is V _G2 Then, there are:

V _G2 ＝I50(R53+R54)>V _THN (6)

I52＝k _HN52 (V _G2 -V _THN ) ² (7)

V _G1 ＝V _JS -I52×R57 (8)

V _GS1 ＝V _G1 -V _S1 ＝V _JS -I52×R57-V _S1 (9)

wherein, V _G1 、V _S1 Gate and source voltages, V, of HN50 _GS1 Is the voltage difference between the gate and source of HN 50. V _JS The third terminal of J50, the source voltage, is also the drain voltage of HN 50. k is a radical of formula _HN52 Is an electrical constant of HN52。

I _J ＝I52+I _{CH_VDD} +I50＝k _J50 (V _THJ ) ² ×(1-V _JS /V _THJ ) ² (10)

Wherein, I _J Is a conduction current of J50, V _THJ Pinch-off threshold voltage, k, of J50 _J50 Is an electrical constant of J50. V _S1 Gate and source voltages, V, of HN50 _GS1 Is the voltage difference between the gate and source of HN 50. Formula (10) can determine V _JS 。

Therefore, V is shown by the formula (6) _G2 Is logic '1', controls HN52 to be conducted, V _G1 Decrease then V _GS1 ＝V _G1 -V _S1 Becomes low, HN50 becomes weak to be conducted, and HN50 has conduction current of I50+ I _{CH_VDD} It becomes small because HP50 and HP51 are a pair of current mirrors, and therefore:

I50+I _{CH_VDD} ＝k _HN50 (V _GS1 -V _THN ) ² (11)

I50＝αI _{CH_VDD} (12)

(α+1)I _{CH_VDD} ＝k _HN50 (V _GS1 -V _THN ) ² (13)

I _{CH_VDD} ＝k _HN50 (V _GS1 -V _THN ) ² /(α+1) (14)

substituting formula (14) for formula (12):

I50＝αk _HN50 (V _GS1 -V _THN ) ² /(α+1) (15)

here, k _HN50 Is the electrical constant of HN50, α is the mirror scaling factor of the HP50 and HP51 current mirrors, and α<<1。

In a constant current feedback loop consisting of the switching tube HN50, the switching tube HP51, the resistor R53, the resistor R54, the switching tube HN52 and the resistor R57, if I50+ I _{CH_VDD} ＝(α+1)I50/ α＝(α+1)I _{CH_VDD} Become large, resulting in I _{CH_VDD} I50 becomes large, so V _G2 = I50 (R53 + R54) high, resulting in HN52 turn on becoming strong, I52= k _HN52 (V _G2 -V _THN ) ² Become larger, thatHow V _G1 ＝V _JS I52 XR 57 decreased.

Because of I _{CH_VDD} The voltage difference V between the gate and the source of HP50 is increased _GS(HP50) ＝V _S1 -V _DD1 Become large, resulting in V _S1 Increase the voltage difference between the gate and the source of HN50 _GS1 ＝V _G1 -V _S1 Becomes low, resulting in I50+ I _{CH_VDD} ＝k _HN50 (V _GS1 -V _THN ) ² Becomes low, so that the constant current feedback loop (equivalent to a galvanostat) in the embodiment forms a negative feedback effect, and finally, I50+ I _{CH_VDD} Is limited to the value defined by equation (11). The flow path of the VDD port charge current is from ST → J50 → HN50 → HP50 → D5 → VDD.

At V _G3 ＝(V _DD +Vbe)(R52/(R52+R51))＝(V _DD +Vbe)/(β+1)<V _THN At this time, HN51 is turned off, and at this time:

I _{CH_VDD} ＝I _CH1 ＝I50/α＝V _G2 /(α(R53+R54)) (16)

I51＝VDD1/(R51+R52)＝(V _DD +Vbe)/(R51+R52)<<I _{CH_VDD} (17)

charging current to port VDD is (I) _{CH_VDD} + I51), I51 is much smaller than I as can be seen from formula (17) _{CH_VDD} At this time, the charging current to the VDD port is approximately equal to I _{CH_VDD} ＝I _CH1 。

V _{DD_SCP_TH} ＝(β+1)V _THN –Vbe (18)

Wherein, the first and the second end of the pipe are connected with each other, _{DD_SCP_TH} ＝(β+1)V _THN vbe is the VDD port to ground short threshold, V _DD Below V _{DD_SCP_TH} Is determined as a short circuit between VDD port and ground, and a charging current I of VDD port _{CH_VDD} Is compressed by several times and becomes a low current value I _CH1 To avoid damage to the control line.

At V _G3 ＝(V _DD +Vbe)(R52/(R52+R51))＝(V _DD +Vbe)/(β+1)≥V _THN I.e. V _DD ≥V _{DD_SCP_TH} ＝(β+1)V _THN at-Vbe, HN51 is on, V _D3 Equal to 0.

I _{CH_VDD} ＝I _CH0 ＝I50/α＝V _G2 /(αR54) (19)

I51<<I _{CH_VDD} (20)

Charging current to port VDD is (I) _{CH_VDD} + I51), it is clear from formula (17) that I51 is much smaller than I _{CH_VDD} Therefore, according to the equations (19) and (20), the charging current to the VDD port is approximately equal to I _{CH_VDD} ＝I _CH0 。

When VDD is charged from 0, V _DD >VDD _ON When EN is logic "1", HN53 is controlled to be conducted, V _G1 Goes low, HN50 is turned off, and the starting charge current I at the VDD port _{CH_VDD} At 0, the VDD port boot ends. Since R57 is very resistive, the current I flowing through R57 and J50 _J Which is very small and approximately equal to 0, the power consumption of the circuit 50A is approximately equal to 0 at this time.

After start-up I _{CH_VDD} Is 0, then V _DD1 Is 0 and V _DD Higher than VDD _ON >>0, therefore, the D50 is required to reversely isolate the VDD pin, so as to avoid the power loss and the start-up failure of the VDD pin for the reverse current flowing through the circuit 50A.

In addition, due to I in the starting process _{CH_VDD} ＝I _CH0 ＝V _G2 /(. Alpha.R 54) or I _{CH_VDD} ＝I _CH1 ＝V _G2 /(. Alpha. (R53 + R54)), R53, R54 and V _G2 Has the same temperature coefficient, so no matter whether the temperature is high or low I _{CH_VDD} All keep almost unchanged, and realize ultra-low temperature drift.

The clamp tubes Z51, Z52 and Z53 in the circuit 50A are Zener tubes, which can protect the gate oxide layers of the switch tubes HN50, HN51 and HN52 from being broken down, thereby increasing the stability and safety of the circuit 50A in operation. The resistor R56 can ensure V _DD The logic signal EN must be equal to "0" at the time of the ultra-low, ensuring the working stability of the charging operation of the circuit 50A.

Example 2

The present embodiment provides a switching power supply system, which employs the circuit for starting flexible charging of a power port described in embodiment 1.

Example 3

As shown in fig. 4, the embodiment provides a switching power supply system, which includes a transformer, a switching power supply controller integrated circuit, a power switch tube, and a feedback device, where the feedback device is disposed at an output end of the transformer, and the switching power supply controller integrated circuit is coupled to the feedback device to generate a switching signal to adjust a pulse width of the transformer through the power switch; the switch power supply controller integrated circuit is formed by coupling a flexible charging starting circuit for a power supply port, a power-up and power-down enabling circuit, a pulse width modulator and a driving circuit. Flexible actuation through ST port: the starting system has the advantages that the low-current flexible starting is carried out during the initial starting, then the high-current rapid starting is carried out, the damage and the life breakage condition caused by the short circuit of the power supply port VDD to the ground can be avoided, the starting path can be automatically cut off after the power supply system is started, the energy consumption is saved, the safety and the high efficiency of user electric equipment are guaranteed to the maximum extent, the control of the ultra-low temperature drift can be completed by starting and charging current of the power supply system, and the consistency of the charging starting process in a high-low temperature range is guaranteed.

The switching power supply controller integrated circuit can be applied to transformer secondary side feedback isolation type and transformer primary side feedback isolation type switching power supply systems. The switch power supply controller integrated circuit is embedded in the same integrated circuit by a starting circuit, an up-down power enabling circuit, a pulse width modulator and a driving circuit so as to save external devices; as shown in fig. 4, there are two external connection modes of the st port, which is convenient for users to design programmability for the highest standby efficiency of the switching power supply system. The system of the switching power supply controller integrated circuit can be a secondary side feedback type switching power supply system; or a primary side feedback mode switching power supply system.

The switching power supply system of the embodiment realizes the safety and the consistency of wide-temperature operation, and simultaneously has the minimum standby power consumption. The start-up timing waveforms are as shown in fig. 5 and 6, the charging current of the switching power supply system provided in this embodiment goes through a soft increase process after VAC is input, whereas the charging current of the conventional switching power supply system in fig. 2 goes to the maximum charging I immediately after VAC is input _{CH_VDD} The power consumption is large, and accidents such as damage or life-time breakage can occur when the VDD port is short-circuited to the ground. When special conditions VDD occurAfter the port short circuit to ground, the utility model discloses a switching power supply system starts charging current minimum, and the consumption is close to 0, can not take place the accident of damage or breaking life-span.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. Meanwhile, for those skilled in the art, the idea of the present invention may be changed in the specific embodiments and the application range. In summary, the content of the present specification should not be construed as a limitation of the present invention.

Claims (9)

1. A circuit for starting flexible charging of a power port is applied to a switching power supply system, and comprises:

starting a charging module, a constant current feedback temperature drift control module, an enabling judgment module and a ground short circuit detection module;

the constant-current feedback temperature drift control module is respectively connected with the starting charging module, the enabling judging module and the ground short circuit detection module; the starting charging module is also respectively connected with the ground short circuit detection module, a control starting port ST of the switch power supply system and the power supply port VDD; the enabling judging module is connected with an enabling end EN of a power-on and power-off enabling circuit in the switching power supply system;

the enabling judging module is used for receiving an enabling signal;

the starting charging module generates a first signal V when the enabling signal is 0 _S1 Or generating a second signal when the enable signal is 1;

the constant current feedback temperature drift control module generates a third signal V when the enabling signal is 0 _G1 ；

The first signal V _S1 And said third signal V _G1 The device is used for flexibly charging a power supply port VDD; the third signal is used for stopping charging the power supply port VDD;

the ground short circuit detection module is used for detecting whether a ground short circuit exists;

the constant current feedback temperature drift control module is also used for inhibiting and controlling the charging current temperature drift of the starting port ST to the power supply port VDD when the charging current temperature drift is short-circuited to the ground.

2. The circuit for starting flexible charging of a power port according to claim 1, wherein the start charging module comprises:

a switching tube J50, a switching tube HN50, a switching tube HP50 and a diode D50;

the drain electrode of the switching tube J50 is connected with a control starting port ST;

the grid electrode of the switching tube J50 is grounded;

the source electrode of the switching tube J50 is respectively connected with the drain electrode of the switching tube HN50 and the constant current feedback temperature drift control module;

the source electrode of the switching tube HN50 is respectively connected with the source electrode of the switching tube HP50 and the constant-current feedback temperature drift control module;

the drain electrode of the switching tube HP50 is respectively connected with the grid electrode of the switching tube HP50, the constant-current feedback temperature drift control module, the ground short circuit detection module and the anode of the diode D50;

the cathode of the diode D50 is connected to the power supply port VDD.

3. The circuit for starting up flexible charging of the power port according to claim 2, wherein the constant current feedback temperature drift control module comprises:

a constant current feedback circuit and a temperature drift control circuit;

the constant current feedback circuit is respectively connected with the starting charging module, the enabling judging module, the ground short circuit detection module and the temperature drift control circuit;

the temperature drift control circuit is also connected with the enabling judgment module and the ground short circuit detection module.

4. The circuit for starting up flexible charging of a power port according to claim 3, wherein the constant current feedback circuit comprises:

the resistor R57, the clamping tube Z50, the switch tube HP51, the switch tube HN52 and the resistor R55;

a first end of the resistor R57 is connected to the source of the switching tube J50 and the drain of the switching tube HN50, respectively;

a second end of the resistor R57 is connected to the gate of the switching tube HN50, the cathode of the clamping tube Z50, the enable determination module, and the drain of the switching tube HN52, respectively;

the anode of the clamping tube Z50 is respectively connected with the source electrode of the switching tube HP51, the source electrode of the switching tube HN50 and the source electrode of the switching tube HP 50;

the source electrode of the switching tube HN52 is connected with the temperature drift control circuit;

the grid electrode of the switching tube HN52 is respectively connected with the first end of the resistor R55 and the temperature drift control circuit;

the second end of the resistor R55 is respectively connected with the drain electrode of the switch tube HP51 and the temperature drift control circuit;

the grid electrode of the switching tube HP51 is respectively connected with the grid electrode of the switching tube HP50, the drain electrode of the switching tube HP50, the short-circuit to ground detection module and the anode electrode of the diode D50.

5. The circuit for starting up a flexible charge for a power port of claim 4, wherein the temperature drift control circuit comprises:

a clamp tube Z51, a resistor R53 and a resistor R54;

the cathode of the clamp tube Z51 is respectively connected with the gate of the switch tube HN52 and the first end of the resistor R55;

the anode of the clamping tube Z51, the source of the switching tube HN52 and the first end of the resistor R54 are all grounded;

a second end of the resistor R54 is respectively connected with the ground short-circuit detection module and a first end of the resistor R53;

a second end of the resistor R53 is connected to a second end of the resistor R55 and a drain of the switching tube HP51, respectively.

6. The circuit for starting flexible charging of a power port of claim 5, wherein the enabling determination module comprises:

resistor R56 and switching tube HN53;

the first end of the resistor R56 is respectively connected with the grid of the switching tube HN53 and the enabling end EN of the up-down power enabling circuit in the switching power supply system;

the second end of the resistor R56 and the source electrode of the switch tube HN53 are both grounded;

the drain of the switching tube HN53 and the second end of the resistor R57 are connected to the gate of the switching tube HN50, the cathode of the clamp tube Z50 and the drain of the switching tube HN52, respectively.

7. The circuit for starting up a flexible charge for a power port of claim 6, wherein the ground short detection module comprises:

a resistor R51, a resistor R52, a clamping tube Z52 and a switch tube HN51;

a first end of the resistor R51 is connected to the gate of the switching tube HP51, the gate of the switching tube HP50, the drain of the switching tube HP50, and the anode of the diode D50, respectively;

the second end of the resistor R51 is connected to the first end of the resistor R52, the cathode of the clamping tube Z52 and the gate of the switching tube HN51;

the second end of the resistor R52, the anode of the clamping tube Z52 and the source of the switching tube HN51 are all grounded;

the drain of the switching tube HN51 is connected to the second end of the resistor R54 and the first end of the resistor R53, respectively.

8. A circuit for flexible charging activation of a power port according to claim 7,

the switching tube J50 is an ultrahigh voltage switch;

the switching tube HN50, the switching tube HN51, the switching tube HN52 and the switching tube HN53 are all high-voltage N-type switches;

the switching tube HP50 and the switching tube HP51 are both high-voltage P-type switches.

9. A switching power supply system, characterized in that it employs a circuit for flexible charge activation of a power port according to any of claims 1-8.

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