CN113541105A - Power conversion controller with short circuit protection threshold voltage - Google Patents
Power conversion controller with short circuit protection threshold voltage Download PDFInfo
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- CN113541105A CN113541105A CN202010305425.9A CN202010305425A CN113541105A CN 113541105 A CN113541105 A CN 113541105A CN 202010305425 A CN202010305425 A CN 202010305425A CN 113541105 A CN113541105 A CN 113541105A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/125—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for rectifiers
- H02H7/1257—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for rectifiers responsive to short circuit or wrong polarity in output circuit
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- Dc-Dc Converters (AREA)
Abstract
The invention discloses a power conversion controller, which has a short-circuit protection threshold voltage not higher than an overcurrent protection threshold voltage, and can detect any abnormal voltage or excessive current of a semiconductor component in time through a current sensing pin when a short circuit occurs, so that the damage of the semiconductor component is effectively avoided.
Description
Technical Field
The invention relates to a power conversion controller, in particular to a power conversion controller which utilizes a short-circuit protection threshold voltage not higher than an overcurrent protection threshold voltage to detect a short-circuit abnormal state in advance, can effectively reduce the voltage stress or the current stress of each part, and simultaneously adjusts better short-circuit protection leading edge blank time and overcurrent protection leading edge blank time so as to avoid false triggering, prevent a power supply from being damaged and ensure the safety of a system.
Background
As is well known, in the conventional Switching Power Supply (Switching Power Supply), one of the most common control methods is Pulse Width Modulation (PWM) control, and the Integrated Circuit (IC) for the control is generally referred to as PWM IC. Generally, the PWM IC is responsible for controlling the output voltage and current of the power supply, and must also have many protection mechanisms to prevent the risk of smoke generation, fire generation, or electric shock caused by the burnout of the power supply when the power supply is improperly used or abnormal conditions occur, and even to prevent the whole system from being damaged. The protection mechanisms of a PWM IC typically include at least output overcurrent, output short circuit, output overvoltage, and over-temperature protection, among others.
In the prior art, PWMIC mainly uses a Feedback Pin (FB Pin) and a Current sensing Pin (CS Pin), wherein the Feedback Pin is used as a secondary side load level magnitude input terminal (Compensation Pin or Feedback Pin), and the Current sensing Pin is used as a primary side Current input detection terminal (Current Sense) for detecting a Peak Current (Peak Current) on the primary side, so as to achieve a pulse modulation (PWM) mechanism of a Peak Current Mode (Peak Current Mode).
In addition, PWMIC is responsible for detecting over-current and short-circuit current. In addition to the PWM comparator, the internal circuit of the PWM IC is generally configured with 2 additional comparators, namely, an overload Limit (Limit1) comparator and a short-circuit Limit (Limit2) comparator.
The Limit1 comparator is usually the maximum current detection, when the output is overloaded, the peak current of the CS pin will rise to the over-current protection threshold voltage, at this time, the Limit1 comparator is triggered, after a period of delay (Timer), the PWMIC stops outputting, achieving the over-current protection purpose.
When the output is short-circuited or a larger load occurs, the peak current of the CS pin will rise to the short-circuit protection threshold voltage, at this time, the Limit2 comparator is triggered, and the PWMIC immediately stops outputting to ensure that the power supply is not damaged.
It is generally recognized in the industry that the short-circuit protection threshold voltage is set to be greater than the over-current protection threshold voltage, and the reason for this is that the primary current during the short circuit is very large, and the current sensing voltage of the CS pin is enough to trigger the Limit2 comparator, so that the power output can be immediately stopped. In addition, another reason why the short-circuit protection threshold voltage is larger than the overcurrent protection threshold voltage is to avoid false triggering during a short overcurrent, which causes the power supply to stop outputting. In other words, if the total time of the current sensing voltage of the CS pin when it is greater than VSS and lower than VOV is very short and does not exceed the predetermined delay, the output power should not be stopped, for example, at the moment of power-on or power-on, because the current sensing voltage still falls within the tolerable range, the power output does not need to be stopped, otherwise the current sensing voltage will cause false triggering and fail.
Generally, the Over Current Protection Threshold Voltage is used for Over Current Protection (OCP), and is referred to as a maximum Current Limit (Max Current Limit), an OCP Current sensing Voltage clamp (CS Voltage), a Current Limit Threshold Voltage (Current Limit Threshold), a Limit Voltage (Limit Voltage), or a Max CS Threshold Voltage as a Limit value of a maximum input Current peak. In addition, the SHORT-circuit protection threshold voltage is used for SHORT-circuit (SHORT) protection, mainly aiming at the protection of output abnormity, such as SHORT circuit of an output end, SHORT circuit of a transformer winding, or SHORT circuit of a secondary rectifier component, and the SHORT-circuit protection is immediately obtained by triggering the VOV. The Short-circuit Protection Threshold Voltage is also generally referred to as a Short-circuit Protection Threshold Voltage (Short-circuit Protection Voltage), or a Diode Short-circuit Protection Voltage (Diode Short-circuit Protection Voltage), or a Secondary side Diode Short-circuit Protection (Secondary Diode Short-circuit Protection), or an Abnormal Over-current Fault Threshold (Abnormal Over-current Threshold), or an Over-current Threshold (Over-current Threshold).
For example, the conventional control chips include OB/OB2283IC, Richtek/RT7738IC, leadtrand/LD 5538IC, ONSEMI/NCP1342, and TI/UCC28742, and the over-current protection threshold voltage/short-circuit protection threshold voltage of each control chip are 0.69V/1.4V, 0.40V/1.1V, 0.85V/1.5V, 0.80V/1.2V, and 0.77V/1.5V, so it is obvious that the short-circuit protection threshold voltage is set to be higher than the over-current protection threshold voltage in the conventional technology.
The above prior art has the disadvantage that the occurrence of short circuit cannot be detected early, and the occurrence of short circuit abnormality must be confirmed and the power supply output is stopped after the current sensing voltage of the CS pin rises to the over-current protection threshold voltage after a period of time, however, during this period, each component has been subjected to the voltage stress or the current stress applied by the primary current, which may cause the potential risk of damage to the power supply.
Therefore, there is a need in the electronic/electrical industry for a power conversion controller with a novel design, which can detect the abnormal short-circuit state in advance by using the short-circuit protection threshold voltage not higher than the overcurrent protection threshold voltage, effectively reduce the voltage stress or current stress of each component, and adjust the better blank time of the short-circuit protection leading edge and the better blank time of the overcurrent protection leading edge, so as to avoid the false triggering, prevent the power supply from being damaged, and further overcome the problems in the prior art.
Disclosure of Invention
The invention mainly aims to provide a power conversion controller with a short-circuit protection threshold voltage, which comprises a current sensing pin, a feedback pin, a Pulse Width Modulation (PWM) driving pin, a grounding pin and an input power supply pin, and the power conversion controller with the default short-circuit protection threshold voltage of the protection threshold voltage has preset short-circuit protection leading edge blank time, overcurrent protection threshold voltage and short-circuit protection threshold voltage, and performs power control operation under the matching of a rectifying unit, a transformer, a switching unit and a power output unit so as to convert an external power transmission source into an output power source to supply a load. In particular, the short-circuit protection threshold voltage is not greater than the overcurrent protection threshold voltage, and the short-circuit protection leading edge blank time is a small overcurrent protection leading edge blank time.
Specifically, the input power pin is connected to the input power, the ground pin is connected to the ground potential, the pulse width modulation driving pin is connected to the gate of the switching unit, and the current sensing pin is connected to the source of the switching unit, wherein the source is further connected to the ground potential through the current sensing resistor, and the current sensing pin generates the current sensing voltage. In addition, the feedback pin is connected to the feedback unit, and the feedback unit is further connected to the power output unit for generating a feedback voltage corresponding to the output power.
Furthermore, the rectifying unit receives an external power supply and converts the external power supply into a rectified power supply, and the transformer comprises a primary side winding and a secondary side winding, wherein the primary side winding receives the rectified power supply and is connected with the rectifying unit and a drain electrode of the switching unit, the secondary side winding is connected with the power output unit, and the power output unit is connected with a load.
More specifically, the power control operation includes: receiving a feedback voltage and a current sensing voltage; generating a PWM driving voltage according to the feedback voltage and the current sensing voltage, wherein the PWM driving voltage comprises a turn-on level and a turn-off level which alternately appear periodically; when the PWM driving voltage is a conducting level and the switching unit is conducted, timing operation is conducted to generate judgment time, and whether the current sensing voltage is larger than the short-circuit protection threshold voltage or not is judged; if the current sensing voltage is equal to or greater than the short-circuit protection threshold voltage and not greater than the overcurrent protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the short-circuit protection leading edge blank time, and if the judgment time is not less than the short-circuit protection leading edge blank time and not greater than the overcurrent protection leading edge blank time, stopping generating the PWM driving voltage; and if the current sensing voltage is greater than the overcurrent protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the overcurrent protection leading edge blank time, and stopping generating the PWM driving voltage after a preset overcurrent delay time when the judgment time is equal to or greater than the overcurrent protection leading edge blank time.
In addition, another objective of the present invention is to provide a power conversion controller having a short-circuit protection threshold voltage, which has a predetermined Lead Edge Blank (LEB) time, an overcurrent protection threshold voltage, and a short-circuit protection threshold voltage, and includes a current sensing pin, a PWM driving pin, a ground pin, and an input power pin, and further performs a power control operation by cooperating with a rectifying unit, a transformer, a switching unit, and a power output unit to convert an external power source into an output power source.
Furthermore, the input power pin is connected with the input power, the grounding pin is connected with the grounding potential, the PWM driving pin is connected with the gate of the switching unit, the current sensing pin is connected with the source of the switching unit through the current limiting resistor, the source is further connected with the grounding potential through the current sensing resistor, and the current sensing pin generates the current sensing voltage.
Specifically, the power supply control operation described above includes: receiving a current sense voltage; generating a PWM driving voltage according to the current sensing voltage, wherein the PWM driving voltage comprises an on level and an off level which alternately appear periodically; when the PWM driving voltage is a conducting level and the switching unit is conducted, timing operation is conducted to generate judgment time, and whether the current sensing voltage is larger than the short-circuit protection threshold voltage or not is judged; if the current sensing voltage is equal to or greater than the short-circuit protection threshold voltage and not greater than the overcurrent protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the short-circuit protection leading edge blank time, and if the judgment time is not less than the short-circuit protection leading edge blank time and not greater than the overcurrent protection leading edge blank time, stopping generating the PWM driving voltage; and if the current sensing voltage is greater than the overcurrent protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the overcurrent protection leading edge blank time, and stopping generating the PWM driving voltage after a preset overcurrent delay time when the judgment time is equal to or greater than the overcurrent protection leading edge blank time.
Therefore, the invention uses the short-circuit protection threshold voltage which is not higher than the overcurrent protection threshold voltage to detect the abnormal state of the short circuit in advance, can effectively reduce the voltage stress or the current stress of each part, and simultaneously adjusts the better blank time of the short-circuit protection front edge and the better blank time of the overcurrent protection front edge so as to avoid the false triggering, prevent the power supply from being damaged and ensure the system safety.
Drawings
FIG. 1 is a diagram of a power conversion controller with a short-circuit protection threshold voltage according to a first embodiment of the present invention.
Fig. 2 shows a flowchart of the power control operation in the first embodiment of the present invention.
Fig. 3 shows an exemplary waveform diagram of the first embodiment of the present invention.
Fig. 4 shows another exemplary waveform diagram of the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a power conversion controller with a short-circuit protection threshold voltage according to a second embodiment of the present invention.
Fig. 6 shows a flowchart of the power control operation in the second embodiment of the present invention.
Description of the reference numerals
10. 10A power conversion controller
20. 20A rectifying unit
30. 30A transformer
40. 40A switching unit
50. 50A power output unit
60. 60A current sensing resistor
70 feedback unit
S10, S11, S12, S13, S14, S15 and S16 steps
S20, S21, S22, S23, S24, S25 and S26 steps
CS current sensing pin
FB feedback pin
DR drive pin
GND grounding pin
VCC input power supply pin
FL full load
IP primary side current
IS secondary side current
Primary winding of LP, LPA
Secondary winding of LS, LSA
RL load
RLT current limiting resistor
Ton PWM on time
LEB _ OV overcurrent protection leading edge blanking time
LEB _ SS short protection leading edge blanking time
VAC external power transmission source
VCS current sense Voltage
VCS1, VCS2 current sense voltage
VCS3, VCS4 current sense voltage
VDD input power supply
VFB feedback voltage
VGND ground potential
VGS PWM drive Voltage
VIN rectification power supply
VOUT output power supply
VOV over-current protection threshold voltage
VSS short circuit protection threshold voltage
Detailed Description
The following description of the embodiments of the present invention will be provided in conjunction with the drawings and reference numerals to enable those skilled in the art to make and use the invention.
Referring to fig. 1, a power conversion controller with a short-circuit protection threshold voltage according to a first embodiment of the invention is shown. As shown in fig. 1, a power conversion controller 10 having a short-Circuit protection threshold voltage not higher than an overcurrent protection threshold voltage according to a first embodiment of the present invention belongs to a Pulse Width Modulation (PWM) controller, and is implemented by an Integrated Circuit (IC) of a semiconductor technology, and includes a current sensing pin CS, a feedback pin FB, a Pulse Width Modulation (PWM) driving pin DR, a ground pin GND and an input power pin VCC, the power supply circuit has a preset Leading Edge Blanking (LEB) time LEB _ SS, an overcurrent protection Leading Edge Blanking time LEB _ OV, an overcurrent protection threshold voltage VOV, and a short-circuit protection threshold voltage VSS, and is particularly configured to perform a power supply control operation in cooperation with the rectifying unit 20, the transformer 30, the switching unit 40, and the power output unit 50, and convert an external power supply VAC into an output power VOUT to supply a load RL.
Specifically, the input power pin VCC is connected to the input power VDD, the ground pin GND is connected to the ground potential VGND, the PWM driving pin DR is connected to the gate of the switching unit 40, and the current sensing pin CS is connected to the source of the switching unit 40, particularly, the source is connected to the ground potential VGND through the current sensing resistor 60, and the current sensing pin CS generates the current sensing voltage VCS. In addition, the feedback pin FB is connected to the feedback unit 70, and the feedback unit 70 is further connected to the power output unit 50 for generating the feedback voltage VFB corresponding to the output power VOUT.
For example, the feedback unit 70 may include an optical coupler.
Specifically, the short-circuit protection threshold voltage VSS is not greater than the over-current protection threshold voltage VOV, and the short-circuit protection leading edge blanking time LEB _ SS is smaller than the over-current protection leading edge blanking time LEB _ OV.
Further, the rectifying unit 20 receives the external power VAC and converts the external power VAC into the rectified power VIN, for example, through rectification, filtering, and voltage stabilization.
The transformer 30 includes a primary winding LP and a secondary winding LS, wherein the primary winding LP receives the rectified power VIN and is connected to the rectifying unit 20 and the drain of the switching unit 40. In addition, the secondary winding LS is connected to the power output unit 50, and the power output unit 50 is further connected to the load RL.
The main feature of the present invention is that the power conversion controller 10 performs a specific power control operation, as shown in fig. 2, wherein the power control operation mainly comprises steps S10, S11, S12, S13, S14, S15 and S16, which will be described in detail in sequence hereinafter.
First, in step S10, the power conversion controller 10 receives the feedback voltage VFB and the current sense voltage VCS via the feedback pin FB and the current sense pin CS, respectively. Then, step S11 is proceeded to generate a PWM driving voltage VGS according to the feedback voltage VFB and the current sensing voltage VCS, wherein the PWM driving voltage VGS includes an on level and an off level alternately appearing periodically. For example, the on level may be high and the off level may be low, or the on level may be low and the off level may be high.
Furthermore, the switching unit 40 may be a Metal-Oxide-Semiconductor (MOS) transistor, a gallium nitride field effect transistor (gan) FET, or a silicon carbide-Metal Oxide Semiconductor field effect transistor (SiC-MOSFET).
Then, step S12 is executed, and when the PWM driving voltage VGS is at the conducting level and the switching unit 40 is turned on, a timing operation is performed to generate a determination time and determine whether the current sensing voltage VCS is greater than the short-circuit protection threshold voltage VSS.
Next, in step S13, if the current sensing voltage VCS is equal to or greater than the short-circuit protection threshold voltage VSS and not greater than the over-current protection threshold voltage VOV, the comparison is performed to determine whether the time generated by the timing operation reaches the short-circuit protection leading edge blank time LEB _ SS, and if the time is not less than the short-circuit protection leading edge blank time LEB _ SS and not greater than the over-current protection leading edge blank time LEB _ OV, the generation of the PWM driving voltage VGS is stopped.
In other words, the current sensing voltage VCS equal to or greater than the short-circuit protection threshold voltage VSS indicates a short-circuit abnormality only when the current sensing voltage VCS is equal to or greater than the short-circuit protection leading edge space time LEB _ SS, and the generation of the PWM driving voltage VGS must be stopped immediately to protect the components of the system, whereas the current sensing voltage VCS is regarded as instantaneous spike noise even if the current sensing voltage VCS is equal to or greater than the short-circuit protection threshold voltage VSS during the short-circuit protection leading edge space time LEB _ SS.
Next, in step S14, if the current sensing voltage VCS is greater than the over-current protection threshold voltage VOV, the comparison is made as to whether the determination time generated by the timing operation reaches the over-current protection leading edge blank time LEB _ OV, and when the determination time is equal to or greater than the over-current protection leading edge blank time LEB _ OV, the process proceeds to step S15, a preset over-current delay time elapses, and then the process proceeds to step S16, and the generation of the PWM driving voltage VGS is stopped. In other words, if the current sense voltage VCS reaches the current protection threshold voltage VOV within the overcurrent protection leading edge margin time LEB _ OV but does not continue to the overcurrent protection leading edge margin time LEB _ OV, the step S15 returns to the step S11 to continue generating the PWM drive voltage VGS.
Particularly, when the PWM driving voltage VGS IS not generated in step S13 or step S16, the switching unit 40 IS turned off and IS not turned on, that IS, the primary side current IP of the primary side winding LP cannot flow to the switching unit 40 and IS reduced to zero, so that the secondary side current IS flowing through the secondary side winding LS cannot be generated by the electromagnetic induction with the primary side current IP any more, in other words, the power output unit 50 cannot generate the output power VOUT, so that the output power VOUT IS reduced to zero voltage, thereby achieving the protection effect and preventing the overall system from being damaged.
Referring next to fig. 3 and 4, operation waveforms of two exemplary examples are shown, respectively, in which the over-current protection threshold voltage VOV of fig. 3 is greater than the short-circuit protection threshold voltage VSS, and the over-current protection threshold voltage VOV of fig. 4 is equal to the short-circuit protection threshold voltage VSS.
Taking the operation waveforms of fig. 3 as an example, the PWM on-time Ton refers to a time when the PWM driving voltage VGS turns on the switching unit 40, and the PWM on-time Ton is greater than the short protection leading edge blank time LEB _ SS and the overcurrent protection leading edge blank time LEB _ OV.
When the current sensing voltage VCS1 rises to full load within the PWM on-time Ton, since the current sensing voltage VCS1 is not greater than the short-circuit protection threshold voltage VSS, the step S13 is not entered after the determination of step S12, and the steps S15 and S16 are not entered after the determination of step S14, but the PWM driving voltage VGS is continuously generated. In other words, the current sensing voltage VCS1 indicates that the system is operating normally and no short circuit or over current abnormal condition occurs.
Moreover, the current sensing voltage VCS2 rises to be greater than the short-circuit protection threshold voltage VSS within the short-circuit protection leading edge blank time LEB _ SS, but does not continue to fall to be lower than the short-circuit protection threshold voltage VSS or to 0V in the figure until the short-circuit protection leading edge blank time LEB _ SS, so that the step S13 is not performed after the determination of the step S12, and the steps S15 and S16 are not performed after the determination of the step S14, that is, the current sensing voltage VCS2 rises to the short-circuit protection threshold voltage VSS only by the disturbing noise, and is not in an abnormal state, and the whole system still operates normally.
Now, looking at the current sensing voltage VCS3, when the current sensing voltage VCS3 rises to be greater than the short-circuit protection threshold voltage VSS and less than the over-current protection threshold voltage VOV after being greater than the short-circuit protection leading edge blanking time LEB _ SS, the step S13 is performed after the determination of the step S12, that is, the current sensing voltage VCS3 is short-circuited abnormally, and the switching unit 40 is immediately turned off to stop generating the PWM driving voltage VGS, so that the output power VOUT is no longer generated or supplied to the load RL, thereby achieving the short-circuit protection effect.
Then, observing the current sensing voltage VCS4, the current sensing voltage VCS4 rises to be greater than the over-current protection threshold voltage VOV after being greater than the over-current protection leading edge blank time LEB _ OV, so the step S14 is performed after the determination of the step S12, and the steps S15 and S16 are performed after the determination of the step S14, that is, the current sensing voltage VCS4 indicates that an over-current or an overload abnormality occurs, the switching unit 40 should be immediately turned off, the PWM driving voltage VGS is stopped, the output power VOUT is no longer generated to the load RL, and the overload protection effect is achieved.
In short, the preset short-circuit protection leading edge blank time LEB _ SS is mainly set to be not more than the overcurrent protection leading edge blank time LEB _ OV, and is used for judging whether short-circuit abnormality occurs or not, so that malfunction caused by interference of transient noise of a system can be avoided.
Similarly, in fig. 4 where the over-current protection threshold voltage VOV is equal to the short-circuit protection threshold voltage VSS, the current sensing voltages VCS1 and VCS2 are both in a normal operating state, and do not go to step S13 or step S16, i.e., the PWM driving voltage VGS is still generated, but the short-circuit abnormality and the over-current abnormality occur in the current sensing voltages VCS3 and VCS4, respectively, so as to start the short-circuit protection and the over-current protection.
In addition, the power control operation performed by the power conversion controller 10 according to the first embodiment of the present invention may further include an additional current sensing resistor short-circuit protection step, mainly in step S14, if the current sensing voltage VCS is greater than the over-current protection threshold voltage VOV and the determination time generated by the timing operation is equal to or greater than the over-current protection leading edge blank time LEB _ OV, then further comparing whether the current sensing voltage VCS is lower than the default current sensing short-circuit voltage, for example, the current sensing short-circuit voltage may be one hundredth or even one thousandth of the input power VDD, and if the current sensing voltage VCS is not lower than the current sensing short-circuit voltage, returning from step S15 to step S11, continuing to generate the PWM driving voltage VGS, but if the current sensing voltage VCS is lower than the current sensing short-circuit voltage, indicating that the current sensing resistor 60 has short-circuited, the switching unit 40 must be immediately turned off to stop the generation of the PWM driving voltage VGS. Specifically, when the current sensing resistor 60 is short-circuited, the current sensing voltage VCS is too low, and a large current flows through the current sensing resistor to damage the switching unit 40.
Referring to fig. 5, a power conversion controller 10A having a short-circuit protection threshold voltage not higher than an overcurrent protection threshold voltage according to a second embodiment of the present invention is similar to the power conversion controller 10 according to the first embodiment of the present invention, and has a preset short-circuit protection leading edge margin time LEB _ SS, an overcurrent protection leading edge margin time LEB _ OV, an overcurrent protection threshold voltage VOV and a short-circuit protection threshold voltage VSS, but only includes a current sensing pin CS, a Pulse Width Modulation (PWM) driving pin DR, a ground pin GND and an input power pin VCC, but does not include a feedback pin FB.
In addition, the power conversion controller 10A of the second embodiment is used to perform power control operation in cooperation with the rectifying unit 20A, the transformer 30A, the switching unit 40A and the power output unit 50A, and convert the external power supply VAC into the output power VOUT. Furthermore, the current sensing pin CS is connected to the source of the switching unit 40 through the current limiting resistor RLT, and the source of the switching unit 40 is connected to the ground potential VGND through the current sensing resistor 60A, and the current sensing pin CS generates the current sensing voltage VCS.
Further, the transformer 30A includes a primary winding LPA and a secondary winding LSA, wherein the primary winding LPA is connected between the drains of the rectifying unit 20A and the switching unit 40A, the drain is further connected to the power output unit 50A, and the secondary winding LSA is connected between the input power pin VCC and the ground potential VGND. Further, the rectifying unit 20A receives an external power supply VAC and converts the received external power supply VAC into a rectified power supply VIN.
Furthermore, the power control operation performed by the power conversion controller 10A of the second embodiment is similar to the power control operation of the first embodiment, as shown in fig. 6, including steps S20, S21, S22, S23, S24, S25 and S26, but the main difference is that step S20 only receives the current sense voltage VCS, since the second embodiment does not use a feedback unit, no feedback voltage is provided, and step S21 generates the PWM drive voltage VGS only according to the current sense voltage VCS, and the remaining steps S22, S23, S24, S25 and S26 are the same as the first embodiment, and thus are not repeated hereinafter.
Moreover, the power control operation performed by the power conversion controller 10A according to the second embodiment of the present invention may also include an additional current sensing resistor short-circuit protection step, which is used to immediately turn off the switching unit 40A when the current sensing resistor 60A is short-circuited, and stop generating the PWM driving voltage VGS, so as to prevent the switching unit 40A from being damaged due to the flowing of a large current.
In addition, the operation waveforms of the second embodiment are similar to those shown in fig. 3 and 4 of the first embodiment, so that the short-circuit protection and the overload protection can be realized, and the malfunction caused by the transient noise interference can be avoided.
Overall, the short-circuit protection leading edge margin time LEB _ SS, the over-current protection leading edge margin time LEB _ OV, the over-current protection threshold voltage VOV, and the short-circuit protection threshold voltage VSS are very important parameters, and can be set or updated according to actual needs to achieve the optimization effect.
In summary, the present invention is characterized in that the short-circuit protection threshold voltage not greater than the over-current protection threshold voltage is utilized to detect any abnormal voltage or excessive current of the semiconductor device in time through the current sensing pin when a short circuit occurs, so as to effectively prevent the semiconductor device from being damaged. In addition, the invention can simultaneously adjust the better short-circuit protection leading edge blank time and the better over-current protection leading edge blank time so as to provide the best protection function, not only avoid false triggering, but also effectively prevent the power supply from being damaged and ensure the operation safety of the whole system.
The foregoing is illustrative of the preferred embodiment of the present invention and is not to be construed as limiting thereof, since any modification or variation thereof within the spirit of the invention is intended to be covered thereby.
Claims (9)
1. A power conversion controller with a short-circuit protection threshold voltage, having a preset Leading Edge Blanking (LEB) time of short-circuit protection, an over-current protection Leading Edge Blanking time, a short-circuit protection threshold voltage and an over-current protection threshold voltage, and performing a power control operation in cooperation with a rectifying unit, a transformer, a switching unit and a power output unit to convert an external power into an output power to supply a load, comprising:
an input power pin connected to an input power;
a ground pin connected to a ground potential;
a Pulse Width Modulation (PWM) driving pin connected to a gate of the switching unit;
a current sensing pin connected to a source of the switching unit, the source being connected to the ground potential through a current sensing resistor, the current sensing pin generating a current sensing voltage; and
a feedback pin connected to a feedback unit, the feedback unit being further connected to the power output unit for generating a feedback voltage corresponding to the output power,
wherein the short-circuit protection threshold voltage is not greater than the over-current protection threshold voltage, the short-circuit protection leading edge blanking time is less than the over-current protection leading edge blanking time, the rectifying unit receives the external power and converts the external power into a rectified power, the transformer comprises a primary side winding and a secondary side winding, the primary side winding receives the rectified power and is connected with the rectifying unit and a drain of the switching unit, the secondary side winding is connected with the power output unit, the power output unit is connected with the load, and the power control operation comprises:
receiving the feedback voltage and the current sensing voltage;
generating a PWM driving voltage according to the feedback voltage and the current sensing voltage, wherein the PWM driving voltage comprises an on level and an off level which alternately appear periodically;
when the PWM driving voltage is the conducting level and the switching unit is conducted, a timing operation is carried out to generate a judgment time and judge whether the current sensing voltage is greater than the short-circuit protection threshold voltage or not;
if the current sensing voltage is equal to or greater than the short-circuit protection threshold voltage and not greater than the overcurrent protection threshold voltage, comparing whether the determination time generated by the timing operation reaches the short-circuit protection leading edge blank time, and if the determination time is not less than the short-circuit protection leading edge blank time and not greater than the overcurrent protection leading edge blank time, stopping generating the PWM driving voltage; and
if the current sensing voltage is greater than the over-current protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the over-current protection leading edge blank time, and stopping generating the PWM driving voltage after a preset over-current delay time when the judgment time is equal to or greater than the over-current protection leading edge blank time.
2. The power conversion controller of claim 1, wherein the turn-on level is a high level and the turn-off level is a low level.
3. The power conversion controller of claim 1, wherein the turn-on level is a low level and the turn-off level is a high level.
4. The power conversion controller of claim 1, wherein the switching unit is a Metal-Oxide-Semiconductor (MOS) transistor, a gallium nitride field effect transistor (GaN) FET, or a silicon carbide-Metal Oxide Semiconductor field effect transistor (SiC-MOSFET).
5. The power conversion controller of claim 1, wherein the feedback unit comprises an optocoupler.
6. A power conversion controller with short-circuit protection threshold voltage is characterized in that the power conversion controller is provided with a preset short-circuit protection leading edge blank time, an over-current protection leading edge blank time, a short-circuit protection threshold voltage and an over-current protection threshold voltage, and is matched with a rectifying unit, a transformer, a switching unit and a power output unit to carry out power control operation so as to convert an external power input into an output power, and the power conversion controller comprises:
an input power pin connected to an input power;
a ground pin connected to a ground potential;
a Pulse Width Modulation (PWM) driving pin connected to a gate of the switching unit; and
a current sensing pin connected to a source of the switching unit via a current limiting resistor, the source being connected to the ground potential via a current sensing resistor, the current sensing pin generating a current sensing voltage,
wherein the short-circuit protection threshold voltage is not greater than the over-current protection threshold voltage, the short-circuit protection leading edge blanking time is less than the over-current protection leading edge blanking time, the rectifying unit receives the external power and converts the external power into a rectified power, the transformer comprises a primary side winding and a secondary side winding, the primary side winding receives the rectified power and is connected with the rectifying unit and a drain of the switching unit, the secondary side winding is connected with the power output unit, the power output unit is connected with the load, and the power control operation comprises:
receiving the current sensing voltage;
generating a PWM driving voltage according to the current sensing voltage, wherein the PWM driving voltage comprises a turn-on level and a turn-off level which alternately appear periodically;
when the PWM driving voltage is the conducting level and the switching unit is conducted, a timing operation is carried out to generate a judgment time and judge whether the current sensing voltage is greater than the short-circuit protection threshold voltage or not;
if the current sensing voltage is equal to or greater than the short-circuit protection threshold voltage and not greater than the overcurrent protection threshold voltage, comparing whether the determination time generated by the timing operation reaches the short-circuit protection leading edge blank time, and if the determination time is not less than the short-circuit protection leading edge blank time and not greater than the overcurrent protection leading edge blank time, stopping generating the PWM driving voltage; and
if the current sensing voltage is greater than the over-current protection threshold voltage, comparing whether the judgment time generated by the timing operation reaches the over-current protection leading edge blank time, and stopping generating the PWM driving voltage after a preset over-current delay time when the judgment time is equal to or greater than the over-current protection leading edge blank time.
7. The power conversion controller of claim 6, wherein the turn-on level is a high level and the turn-off level is a low level.
8. The power conversion controller of claim 6, wherein the turn-on level is a low level and the turn-off level is a high level.
9. The power conversion controller of claim 8, wherein the switching unit is a Metal Oxide Semiconductor (MOS) transistor, a gallium nitride field effect transistor, or a silicon carbide-MOS field effect transistor.
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