JP2011244659A - Insulated switching dc/dc converter - Google Patents

Insulated switching dc/dc converter Download PDF

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JP2011244659A
JP2011244659A JP2010116684A JP2010116684A JP2011244659A JP 2011244659 A JP2011244659 A JP 2011244659A JP 2010116684 A JP2010116684 A JP 2010116684A JP 2010116684 A JP2010116684 A JP 2010116684A JP 2011244659 A JP2011244659 A JP 2011244659A
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output
switching
control
control coupler
circuit
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Tomohiro Kanehira
智広 兼平
Toshio Shibata
敏夫 柴田
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FDK Corp
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Abstract

PROBLEM TO BE SOLVED: To provide an insulated switching DC/DC converter, which can rapidly and certainly respond and transmit instantaneously feedback signals to a primary side at the outputting of short-circuiting, thereby protecting a circuit and components and making manufacturing inexpensive without impairing efficiency.SOLUTION: There is provided an insulated switching DC/DC converter, in which an error amplifier 10 of output voltage and a control coupler light-emitting part 12 are incorporated in the secondary side of a switching transformer, the error amplifier controls current flowing in the control coupler light-emitting part and a control coupler feeds the current back to a switching control IC of the primary side and controls oscillation of the primary side switch element to stabilize the secondary side output voltage. An output short circuit protection circuit 14 in which the control coupler light-emitting part and the secondary side output line are directly connected with direct serial connection of an OR diode D1 and a resistor R1 is provided to directly change the amount of current flowing in the control coupler light-emitting part at the outputting of short-circuiting.

Description

本発明は、絶縁型スイッチングＤＣ−ＤＣコンバータ関し、更に詳しく述べると、出力短絡時に、１次側へのフィードバック制御のための制御カプラを流れる電流を、出力ラインに接続したＯＲダイオードにより直接大幅に変化させ、それによって出力短絡時の応答を改善するようにした出力短絡保護回路を備えている絶縁型スイッチングＤＣ−ＤＣコンバータに関するものである。   The present invention relates to an isolated switching DC-DC converter. More specifically, when an output is short-circuited, the current flowing through the control coupler for feedback control to the primary side is greatly directly controlled by an OR diode connected to the output line. The present invention relates to an isolated switching DC-DC converter having an output short-circuit protection circuit that is changed to improve the response at the time of output short-circuit.

絶縁型スイッチングＤＣ−ＤＣコンバータは、トランスを用いて１次側と２次側を絶縁し、２次側出力電圧を１次側にフィードバックして１次側のスイッチ素子を制御することで２次側出力電圧を安定化させるスイッチング電源装置である。２次側出力の１次側制御ＩＣへのフィードバックには、制御カプラとして、本質的に電気絶縁機能を備えているホトカプラが使用される。近年、絶縁型スイッチングＤＣ−ＤＣコンバータには益々高効率化が要求されており、その内部損失を低減させるために、１次側のスイッチ素子にはＦＥＴが、また２次側にもＦＥＴによる同期整流回路が用いられている。このような絶縁型スイッチングＤＣ−ＤＣコンバータでは、もし、負荷である電子機器の故障などにより出力に異常（過電流や出力短絡など）が生じた時には、ＦＥＴ等の回路部品保護のために瞬時に１次側スイッチ素子の発振を制御し、スイッチングを停止させるなどの措置を執る必要がある。そのため、様々な保護回路が組み込まれている。   The isolated switching DC-DC converter uses a transformer to insulate the primary side from the secondary side, feed back the secondary side output voltage to the primary side, and control the switching element on the primary side. This is a switching power supply device that stabilizes the side output voltage. For feedback of the secondary side output to the primary side control IC, a photocoupler that essentially has an electrical insulation function is used as a control coupler. In recent years, insulation switching DC-DC converters have been required to have higher efficiency. In order to reduce the internal loss, FETs are used for the primary side switching elements, and the secondary side is also synchronized by the FETs. A rectifier circuit is used. In such an insulation-type switching DC-DC converter, if an output abnormality (overcurrent, output short circuit, etc.) occurs due to a failure of an electronic device that is a load, it is instantly used to protect circuit components such as FETs. It is necessary to take measures such as controlling the oscillation of the primary side switch element and stopping the switching. For this reason, various protection circuits are incorporated.

従来、この種の保護回路としては過電流保護回路がある。これは、２次側の出力ラインに組み込んだ電流検出抵抗で電流／電圧変換を行い、電圧変換した信号を過電流検出アンプ（電流アンプ）に入力して基準電圧と比較し、異常検出時には、その過電流検出アンプの出力信号により制御カプラに流れる電流を引き抜き、その電流量の変化を１次側にフィードバックし、１次側のスイッチング制御ＩＣによってスイッチ素子の発振を制御する構成である。出力短絡時には瞬間的に大電流が流れるので、原理的には過電流保護回路を利用して出力短絡保護を図ることができる。そのため、一般的には、過電流保護回路を利用して出力短絡保護が行われていた。しかし、この回路構成では、過電流検出アンプ及び制御カプラの応答速度よりも出力短絡時に１次側／２次側ＦＥＴが定格電流をオーバーするまでの時間の方が短いため、出力短絡時に１次側／２次側ＦＥＴに過大な電流が流れてしまい、ＦＥＴが破損する恐れがあった。従って、このような過電流保護回路では、迅速な出力短絡保護動作は期待できない。   Conventionally, there is an overcurrent protection circuit as this type of protection circuit. This is a current / voltage conversion performed by a current detection resistor built into the secondary output line, and the voltage converted signal is input to an overcurrent detection amplifier (current amplifier) and compared with a reference voltage. The current flowing through the control coupler is extracted by the output signal of the overcurrent detection amplifier, the change in the amount of current is fed back to the primary side, and the oscillation of the switch element is controlled by the primary side switching control IC. Since a large current flows instantaneously when the output is short-circuited, in principle, output short-circuit protection can be achieved using an overcurrent protection circuit. Therefore, in general, output short-circuit protection is performed using an overcurrent protection circuit. However, in this circuit configuration, the time until the primary / secondary FET exceeds the rated current when the output is short-circuited is shorter than the response speed of the overcurrent detection amplifier and control coupler. There was a risk that an excessive current would flow to the side / secondary side FET and the FET would be damaged. Therefore, with such an overcurrent protection circuit, a quick output short circuit protection operation cannot be expected.

出力短絡保護回路としては、ダイオードと抵抗の直列接続を、出力ラインとシャントレギュレータのリファレンス電圧端子との間に設ける構成がある（特許文献１参照）。この回路では、出力短絡時に、ダイオードと抵抗の直列回路が動作し、シャントレギュレータのリファレンス電圧を低下させることで該シャントレギュレータをオフにして、シャントレギュレータのカソード−アノード間に電流が流れないようにする。シャントレギュレータに電流が流れなくなると、シャントレギュレータと直列に接続されている制御カプラにも電流が流れなくなる。制御カプラに流れる電流量により、１次側スイッチ素子の発振のパルス幅制御を行っているため、電流が流れなくなるとパルス幅の絞り込みが行われ、最終的には発振が停止し、出力短絡保護を図ることができる。   As an output short circuit protection circuit, there is a configuration in which a series connection of a diode and a resistor is provided between an output line and a reference voltage terminal of a shunt regulator (see Patent Document 1). In this circuit, when the output is short-circuited, a series circuit of a diode and a resistor operates, and the shunt regulator is turned off by lowering the reference voltage of the shunt regulator so that no current flows between the cathode and anode of the shunt regulator. To do. When no current flows through the shunt regulator, no current flows through the control coupler connected in series with the shunt regulator. Since the pulse width of the oscillation of the primary side switch element is controlled by the amount of current flowing through the control coupler, the pulse width is narrowed down when the current stops flowing, and finally the oscillation stops and output short circuit protection Can be achieved.

しかし、シャントレギュレータは、そのリファレンス電圧が、例えば１．２２５Ｖというように低電圧の品種が主流となりつつある。低電圧の方が速く動作させることができるし、ＩＣ等の回路電源電圧Ｖccにおける選択の自由度（回路設計の自由度）が大きくなるからである。他方、ダイオードについて見ると、リーク電流が小さい品種は順方向電圧降下Ｖf が大きいという特性がある。また、シャントレギュレータやダイオードなど使用部品の特性のばらつき、抵抗値のばらつきなども考慮する必要があるし、更には環境温度の変化（例えば−４０℃〜＋８０℃）にも対応できなければならない。そのような条件を考慮したとき、前記のような回路構成で、リファレンス電圧の低いタイプのシャントレギュレータを用い、出力短絡時に１次側の発振を瞬時に確実に止められるかが大きな問題となる。Ｖf の小さなダイオードを使用し、使用部品の更なる選別などを行えば、この問題を解決できる可能性はあるが、低Ｖf ダイオード（ショットキーバリアダイオード）はリーク電流が大きいため効率低下を招くことになり、更にはリーク電流による誤動作誘発の危険性があることから、賢明な手法とは言えない。   However, shunt regulators are becoming mainstream with low voltage types such as a reference voltage of 1.225V, for example. This is because the low voltage can be operated faster, and the degree of freedom in selecting the circuit power supply voltage Vcc such as an IC (the degree of freedom in circuit design) is increased. On the other hand, in terms of diodes, the type with a small leakage current has a characteristic that the forward voltage drop Vf is large. In addition, it is necessary to take into account variations in the characteristics of components used, such as shunt regulators and diodes, variations in resistance, and the like, and it is also necessary to be able to cope with changes in environmental temperature (for example, −40 ° C. to + 80 ° C.). When such a condition is taken into consideration, a major problem is whether or not the primary side oscillation can be stopped instantaneously and reliably when the output is short-circuited by using a shunt regulator with a low reference voltage in the circuit configuration as described above. There is a possibility that this problem can be solved by using a diode with a small Vf and further selecting the parts to be used. However, a low Vf diode (Schottky barrier diode) causes a reduction in efficiency because of a large leakage current. Furthermore, since there is a risk of inducing malfunction due to leakage current, it is not a wise method.

特開平５−３０７５３号公報JP-A-5-30753

本発明が解決しようとする課題は、出力短絡時に高速で確実に応答して１次側へのフィードバック信号を瞬時に伝達できるようにすることで、回路や部品を保護し、しかも効率を損なうことなく且つ安価に作製できるようにすることである。   The problem to be solved by the present invention is to protect a circuit and parts and to reduce efficiency by allowing a feedback signal to the primary side to be instantaneously transmitted by responding quickly and reliably when the output is short-circuited. It is possible to produce it at low cost.

本発明は、スイッチングトランスの２次側に出力電圧の誤差増幅器と制御カプラ発光部とを組み込み、該誤差増幅器により前記制御カプラ発光部を流れる電流を制御し、該制御カプラによって１次側のスイッチング制御ＩＣにフィードバックして１次側スイッチ素子の発振を制御することで２次側出力電圧を安定化する絶縁型スイッチングＤＣ−ＤＣコンバータにおいて、前記制御カプラ発光部と２次側出力ラインとの間をＯＲダイオードと抵抗の直列接続で直接接続した出力短絡保護回路を設け、出力短絡時に制御カプラ発光部を流れる電流量を直接変化させるようにしたことを特徴とする絶縁型スイッチングＤＣ−ＤＣコンバータである。   The present invention incorporates an output voltage error amplifier and a control coupler light-emitting unit on the secondary side of the switching transformer, and controls the current flowing through the control coupler light-emitting unit by the error amplifier. In an isolated switching DC-DC converter that stabilizes the secondary output voltage by controlling the oscillation of the primary side switch element by feeding back to the control IC, between the control coupler light emitting section and the secondary side output line. An isolated switching DC-DC converter characterized in that an output short-circuit protection circuit in which an OR diode and a resistor are directly connected in series is provided, and the amount of current flowing through the control coupler light-emitting portion is directly changed when the output is short-circuited. is there.

ここで、前記出力短絡保護回路とは別に、２次側の出力ラインに電流／電圧変換を行う電流検出抵抗を組み込み、電圧変換した信号を過電流検出アンプに入力し、該過電流検出アンプの出力信号により過電流制御用のＯＲダイオードを介して制御カプラ発光部を流れる電流を変化させる過電流保護回路を設けるのがよい。   Here, apart from the output short circuit protection circuit, a current detection resistor for performing current / voltage conversion is incorporated in the output line on the secondary side, and the voltage converted signal is input to the overcurrent detection amplifier. It is preferable to provide an overcurrent protection circuit that changes the current flowing through the control coupler light-emitting section via an OR diode for overcurrent control according to the output signal.

本発明に係る絶縁型スイッチングＤＣ−ＤＣコンバータは、制御カプラ発光部と２次側出力ラインとの間をＯＲダイオードと抵抗の直列接続で直接接続した出力短絡保護回路を設けるだけなので、必要な部品はダイオードと抵抗のみでよく、安価に作製できる。動作的には、出力短絡時に制御カプラ発光部を流れる電流量を直接変化させる方式なので、電流量を瞬時に大幅に増大させることができる。そのため、出力短絡時の応答速度が改善され、１次側／２次側ＦＥＴなどの回路部品に過大な電流が流れるのを阻止でき、それら回路部品の破損の恐れがなくなる。また、回路的には、ダイオードの順方向電圧降下Ｖf が大きくても構わないため、リーク電流が小さい品種のダイオードが使用でき、内部損失を低減できるし、部品特性のばらつきや環境温度の変動にも余裕が生じるので、装置の設計や製作が容易となる。   Since the isolated switching DC-DC converter according to the present invention is simply provided with an output short circuit protection circuit in which an OR diode and a resistor are directly connected in series between the control coupler light emitting section and the secondary output line, the necessary components Can be manufactured at low cost by using only a diode and a resistor. In terms of operation, since the amount of current flowing through the control coupler light-emitting portion is directly changed when the output is short-circuited, the amount of current can be increased greatly instantaneously. Therefore, the response speed when the output is short-circuited is improved, and it is possible to prevent an excessive current from flowing through the circuit components such as the primary / secondary FET, and there is no possibility of damaging these circuit components. In terms of circuit, the diode forward voltage drop Vf may be large, so a diode with a small leakage current can be used, internal loss can be reduced, and variations in component characteristics and environmental temperature can be reduced. Since there is a margin, the design and manufacture of the device becomes easy.

本発明の要部を示す説明図。Explanatory drawing which shows the principal part of this invention. 本発明に係る絶縁型スイッチングＤＣ−ＤＣコンバータの一実施例を示す回路図。The circuit diagram which shows one Example of the insulation type switching DC-DC converter which concerns on this invention.

本発明は、出力短絡保護専用の回路を組み込んだ絶縁型スイッチングＤＣ−ＤＣコンバータである。図１では、出力短絡保護回路が組み込まれるスイッチングトランスの２次側を簡略化し、要部のみを示している。   The present invention is an isolated switching DC-DC converter incorporating a circuit dedicated to output short-circuit protection. In FIG. 1, the secondary side of the switching transformer in which the output short circuit protection circuit is incorporated is simplified and only the main part is shown.

スイッチングトランスの２次側には、出力電圧の誤差増幅器１０と制御カプラ（ホトカプラ）発光部１２とが組み込まれ、該誤差増幅器１０により前記制御カプラ発光部１２を流れる電流を制御し、該制御カプラによって１次側にフィードバックして２次側出力電圧を安定化制御する。出力短絡保護回路１４は、前記制御カプラ発光部１２と２次側出力ラインＶo との間をＯＲダイオードＤ１と抵抗Ｒ１との直列接続で直接接続するように構成されている。ここで、負荷装置に異常が生じて出力短絡が発生した時は、出力ラインＶo が０Ｖ（ＧＮＤ）に落ちる。すると、回路電源電圧Ｖccラインから抵抗Ｒ２、制御カプラ発光部１２、出力短絡保護回路１４（ＯＲダイオードＤ１と抵抗Ｒ１の直列接続）を通って電流が流れる。つまり、制御カプラ発光部１２の電流量が直接的に急激に増大する。このため、出力短絡を示す１次側へのフィードバック信号が素早く伝達され、より迅速に１次側スイッチ素子の発振を停止させることができる。   On the secondary side of the switching transformer, an output voltage error amplifier 10 and a control coupler (photocoupler) light emitting unit 12 are incorporated, and the current flowing through the control coupler light emitting unit 12 is controlled by the error amplifier 10. To feed back to the primary side and stabilize the secondary side output voltage. The output short-circuit protection circuit 14 is configured to directly connect the control coupler light emitting unit 12 and the secondary output line Vo by a series connection of an OR diode D1 and a resistor R1. Here, when an abnormality occurs in the load device and an output short circuit occurs, the output line Vo falls to 0 V (GND). Then, a current flows from the circuit power supply voltage Vcc line through the resistor R2, the control coupler light emitting unit 12, and the output short circuit protection circuit 14 (a series connection of the OR diode D1 and the resistor R1). That is, the amount of current of the control coupler light emitting unit 12 increases directly and rapidly. For this reason, the feedback signal to the primary side which shows an output short circuit is transmitted quickly, and the oscillation of a primary side switch element can be stopped more rapidly.

図２では、本発明に係る絶縁型スイッチングＤＣ−ＤＣコンバータの一実施例を簡略化して示している。なお、説明を分かりやすくするため、図１と共通する部分については同一符号を付している。コンバータ本体は次のような回路構成である。１次側では、ＤＣ入力をコンデンサとコイルからなる平滑回路２０で平滑化し、２個のコンデンサＣ１，Ｃ２と２個のＦＥＴ（スイッチ素子）Ｑ１，Ｑ２からなるハーフブリッジ型のスイッチング部２２でスイッチングする。２個のＦＥＴＱ１，Ｑ２が交互にオン／オフすることによってスイッチングトランス２４の１次巻線にパルス電流が流れる。スイッチングトランス２４は、１次側と２次側の間を絶縁すると共に、必要な電圧変換を行う。２次側では、２個のＦＥＴＱ３，Ｑ４からなる同期整流回路２６で整流し、コイルとコンデンサからなる平滑回路２８で平滑化する。これによって出力端子間にＤＣ出力が生じる。   FIG. 2 shows a simplified example of an isolated switching DC-DC converter according to the present invention. In addition, in order to make the explanation easy to understand, portions common to FIG. The converter body has the following circuit configuration. On the primary side, the DC input is smoothed by a smoothing circuit 20 composed of a capacitor and a coil, and is switched by a half-bridge type switching unit 22 composed of two capacitors C1 and C2 and two FETs (switch elements) Q1 and Q2. To do. When the two FETs Q1 and Q2 are alternately turned on / off, a pulse current flows through the primary winding of the switching transformer 24. The switching transformer 24 insulates the primary side and the secondary side and performs necessary voltage conversion. On the secondary side, rectification is performed by a synchronous rectification circuit 26 including two FETs Q3 and Q4, and smoothing is performed by a smoothing circuit 28 including a coil and a capacitor. This produces a DC output between the output terminals.

２次側の出力電圧は、誤差増幅器１０の一方の入力端子に印加され、他方の入力端子の基準電圧Ｖref1と比較される。回路電源電圧Ｖccから抵抗Ｒ２を介して制御カプラ発光部１２が接続され、更にＯＲダイオードＤ２を介して前記誤差増幅器１０の出力端に接続される。誤差増幅器１０での比較結果によって制御カプラ発光部１２の電流が制御され、光信号で１次側にフィードバックされる。   The output voltage on the secondary side is applied to one input terminal of the error amplifier 10 and compared with the reference voltage Vref1 of the other input terminal. The control coupler light emitting unit 12 is connected from the circuit power supply voltage Vcc through the resistor R2, and further connected to the output terminal of the error amplifier 10 through the OR diode D2. The current of the control coupler light emitting unit 12 is controlled based on the comparison result in the error amplifier 10, and is fed back to the primary side with an optical signal.

一次側には駆動ＩＣ３０、スイッチング制御ＩＣ３２、制御カプラ受光部３４が設けられており、該制御カプラ受光部３４で２次側からのフィードバック信号を受け、それが前記スイッチング制御ＩＣ３２に入力する。２個のＦＥＴＱ１，Ｑ２は、前記スイッチング制御ＩＣ３２の出力に基づきパルス幅制御される。ここでは、大きな駆動電流がひつようなため、ＦＥＴ駆動ＩＣ３０によって両ＦＥＴを駆動している。これによって出力電圧の定電圧化が図られる。   A drive IC 30, a switching control IC 32, and a control coupler light receiving unit 34 are provided on the primary side. The control coupler light receiving unit 34 receives a feedback signal from the secondary side and inputs it to the switching control IC 32. The two FETs Q1 and Q2 are subjected to pulse width control based on the output of the switching control IC 32. Here, since a large drive current is necessary, both FETs are driven by the FET drive IC 30. As a result, the output voltage is made constant.

通常、このような絶縁型スイッチングＤＣ−ＤＣコンバータには、過負荷などの出力異常時における回路部品保護のために過電流保護回路が組み込まれている。これは、２次側の出力ラインに直列に低抵抗の電流検出抵抗Ｒ３を組み込み、該電流検出抵抗Ｒ３で電流／電圧変換を行い、電圧変換した信号を過電流検出アンプ３６に入力して基準電圧Ｖref2と比較し、その過電流検出アンプ３６の出力信号によりＯＲダイオードＤ３を介して制御カプラ発光部１２に流れる電流を引き抜き、その電流量の変化を制御カプラ発光部１２と制御カプラ受光部３４で１次側にフィードバックさせ、１次側のスイッチング制御ＩＣ３２によってＦＥＴＱ１，Ｑ２の発振を制御する構成である。   Usually, such an insulation type switching DC-DC converter incorporates an overcurrent protection circuit for protecting circuit components at the time of output abnormality such as overload. This is because a low-resistance current detection resistor R3 is incorporated in series with the secondary output line, current / voltage conversion is performed by the current detection resistor R3, and a voltage-converted signal is input to the overcurrent detection amplifier 36 as a reference. Compared with the voltage Vref2, the current flowing to the control coupler light emitting unit 12 is extracted via the OR diode D3 by the output signal of the overcurrent detection amplifier 36, and the change in the current amount is controlled by the control coupler light emitting unit 12 and the control coupler light receiving unit 34. In this configuration, feedback to the primary side is performed and the oscillation of the FETs Q1 and Q2 is controlled by the primary side switching control IC 32.

本実施例では、このような過電流保護回路の他に、出力短絡時における回路部品保護専用の出力短絡保護回路１４を設ける。これは、制御カプラ発光部１２と２次側出力ラインとの間を、ＯＲダイオードＤ１と抵抗Ｒ１との直列接続で直接接続した回路である。出力短絡時には出力ラインが０Ｖ（ＧＮＤ）に落ちるため、回路電源電圧Ｖccから抵抗Ｒ２、制御カプラ発光部１２、ＯＲダイオードＤ１、抵抗Ｒ１を通る経路で電流が流れる。つまり、制御カプラ発光部１２を流れる電流は、過電流保護回路などを経由することなく、直接、出力短絡保護回路１４を通って流れる。この時、制御カプラ発光部１２を流れる電流量は瞬時に大きく変化（増大）する。そのため、制御カプラによる１次側へのフィードバック信号が素早く伝達され、スイッチング制御ＩＣ３２によってスイッチング部２２のスイッチング動作を、より素早く停止させることができる。これによって、１次側／２次側のＦＥＴなどの回路部品に過大な電流が流れるのを防止でき、そのため破損が生じる恐れが無くなるのである。   In the present embodiment, in addition to such an overcurrent protection circuit, an output short circuit protection circuit 14 dedicated to circuit component protection in the event of an output short circuit is provided. This is a circuit in which the control coupler light emitting unit 12 and the secondary output line are directly connected by a series connection of an OR diode D1 and a resistor R1. Since the output line falls to 0 V (GND) when the output is short-circuited, a current flows from the circuit power supply voltage Vcc through a path passing through the resistor R2, the control coupler light emitting unit 12, the OR diode D1, and the resistor R1. That is, the current flowing through the control coupler light-emitting unit 12 flows directly through the output short circuit protection circuit 14 without passing through the overcurrent protection circuit or the like. At this time, the amount of current flowing through the control coupler light emitting unit 12 changes (increases) greatly instantaneously. Therefore, the feedback signal to the primary side by the control coupler is quickly transmitted, and the switching operation of the switching unit 22 can be stopped more quickly by the switching control IC 32. As a result, it is possible to prevent an excessive current from flowing through circuit components such as the primary / secondary FETs, thereby eliminating the possibility of damage.

１０ 誤差増幅器
１２ 制御カプラ発光部
１４ 出力短絡保護回路
Ｄ１ ＯＲダイオード
Ｒ１ 抵抗 DESCRIPTION OF SYMBOLS 10 Error amplifier 12 Control coupler light emission part 14 Output short circuit protection circuit D1 OR diode R1 Resistance

Claims (2)

スイッチングトランスの２次側に出力電圧の誤差増幅器と制御カプラ発光部とを組み込み、該誤差増幅器により前記制御カプラ発光部を流れる電流を制御し、該制御カプラによって１次側のスイッチング制御ＩＣにフィードバックして１次側スイッチ素子の発振を制御することで２次側出力電圧を安定化する絶縁型スイッチングＤＣ−ＤＣコンバータにおいて、前記制御カプラ発光部と２次側出力ラインとの間をＯＲダイオードと抵抗の直列接続で直接接続した出力短絡保護回路を設け、出力短絡時に制御カプラ発光部を流れる電流量を直接変化させるようにしたことを特徴とする絶縁型スイッチングＤＣ−ＤＣコンバータ。   An output voltage error amplifier and a control coupler light-emitting unit are incorporated on the secondary side of the switching transformer, the current flowing through the control coupler light-emitting unit is controlled by the error amplifier, and the control coupler feeds back to the switching control IC on the primary side. In the isolated switching DC-DC converter that stabilizes the secondary side output voltage by controlling the oscillation of the primary side switching element, an OR diode is provided between the control coupler light emitting unit and the secondary side output line. An insulated switching DC-DC converter characterized in that an output short-circuit protection circuit directly connected by a series connection of resistors is provided, and the amount of current flowing through the control coupler light-emitting unit is directly changed when the output is short-circuited. 前記出力短絡保護回路とは別に、２次側の出力ラインに電流／電圧変換を行う電流検出抵抗を組み込み、電圧変換した信号を過電流検出アンプに入力し、該過電流検出アンプの出力信号により過電流制御用のＯＲダイオードを介して制御カプラ発光部を流れる電流を変化させる過電流保護回路が設けられている請求項１記載の絶縁型スイッチングＤＣ−ＤＣコンバータ。   In addition to the output short-circuit protection circuit, a current detection resistor for performing current / voltage conversion is incorporated in the output line on the secondary side, the voltage converted signal is input to the overcurrent detection amplifier, and the output signal of the overcurrent detection amplifier is used. 2. The isolated switching DC-DC converter according to claim 1, further comprising an overcurrent protection circuit that changes a current flowing through the control coupler light-emitting unit via an overcurrent control OR diode.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9906141B2 (en) 2014-07-25 2018-02-27 Smk Corporation DC-DC converter
CN115291123A (en) * 2022-09-19 2022-11-04 伏达半导体(合肥)有限公司 Method for characterizing a plurality of battery cells, battery parameter estimation device and method

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JPH03265462A (en) * 1990-03-14 1991-11-26 Sanyo Electric Co Ltd Switching power supply
JPH0530735A (en) * 1991-07-17 1993-02-05 Matsushita Electric Ind Co Ltd Short circuit protector for switching power supply
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9906141B2 (en) 2014-07-25 2018-02-27 Smk Corporation DC-DC converter
CN115291123A (en) * 2022-09-19 2022-11-04 伏达半导体(合肥)有限公司 Method for characterizing a plurality of battery cells, battery parameter estimation device and method
CN115291123B (en) * 2022-09-19 2023-03-07 伏达半导体(合肥)股份有限公司 Method for characterizing a plurality of battery cells, battery parameter estimation device and method

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