JP4668473B2 - Switching power supply - Google Patents
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- JP4668473B2 JP4668473B2 JP2001225855A JP2001225855A JP4668473B2 JP 4668473 B2 JP4668473 B2 JP 4668473B2 JP 2001225855 A JP2001225855 A JP 2001225855A JP 2001225855 A JP2001225855 A JP 2001225855A JP 4668473 B2 JP4668473 B2 JP 4668473B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Description
【０００１】
【発明の属する技術分野】
本発明はスイッチング電源に関し、待機状態における省エネ対策として、スイッチング電源の待機電力を低減させる手段を備えたスイッチング電源に関するものである。
【０００２】
【従来の技術】
この種のスイッチング電源として、図２のものが提案されている。ＩＣ３は、出力電圧検出用ＩＣであり、出力電圧が定格電圧より上昇するとＩＣ３に接続されたフォトカプラＰＣ２のダイオードに流れる電流が増加して、フォトカプラＰＣ２のトランジスタが接続されている、電源制御用ＩＣ（ＩＣ４）のフィードバック（ＦＢ）端子の電圧が下がり、下がる量に応じて一定周波数動作しているスイッチング素子Ｑ１のオフ時間デューティが大きくなり、出力電圧を下げて定格電圧を安定供給することができる。
しかし、上記のスイッチング電源回路においては図４に示すように、スイッチング電源の動作状態にかかわらず、一定周波数でスイッチング素子Ｑ１が動作しているため、スイッチングロスが常に発生し、スイッチング電源の待機電力を悪化させるという問題があった。
【０００３】
【発明が解決しようとする課題】
上記のような問題があったため、スイッチング電源の待機状態において、スイッチングロスを大幅に減少させ、待機電力を低減することができる回路構成が要求されていた。
【０００４】
【課題を解決するための手段】
本発明は、上記課題を解決するもので、整流して得られる直流電圧を一次側のスイッチング素子Ｑ１でオン／オフし、ダイオードと平滑コンデンサとを有する二次側の整流・平滑回路を介して電圧を安定供給するスイッチング電源において、スイッチング電源の（＋）出力端子と（−）出力端子との間に第１の抵抗Ｒ１および第２の抵抗Ｒ２を直列接続し、第１の抵抗Ｒ１および第２の抵抗Ｒ２の接続点を第１のオペアンプＩＣ１の（＋）入力端子に接続し、第１のオペアンプＩＣ１の（＋）入力端子と出力端子とを第４の抵抗Ｒ４で接続し、第１のオペアンプＩＣ１の出力端子と第２のオペアンプＩＣ２の出力端子とを、直列接続した第１のフォトカプラＰＣ１のダイオードと第３の抵抗Ｒ３で接続し、第１のオペアンプＩＣ１の（−）入力端子をツェナーダイオードＤ１のカソードに接続し、該ツェナーダイオードＤ１のアノードをスイッチング電源の(−)出力端子に接続し、該ツェナーダイオードＤ１のカソード側と二次巻線側との間に第５の抵抗Ｒ５および第６の抵抗Ｒ６を直列接続し、第５の抵抗Ｒ５および第６の抵抗Ｒ６の接続点を第２のオペアンプＩＣ２の（−）入力端子に接続し、第６の抵抗Ｒ６の二次巻線側と第２のオペアンプＩＣ２の（＋）入力端子との間に第７の抵抗Ｒ７を接続し、かつ第７の抵抗Ｒ７と第２のオペアンプＩＣ２の（＋）入力端子の接続点をスイッチング電源の（−）出力端子側に接続し、スイッチング電源の（＋）出力端子と（−）出力端子から出力される出力電圧を検出する出力電圧検出用ＩＣ３に第２のフォトカプラＰＣ２のダイオードを接続し、第２のフォトカプラＰＣ２のトランジスタを一次側電源制御用ＩＣ４のフィードバック端子に接続し、第１のフォトカプラＰＣ１のトランジスタを一次側電源制御用ＩＣ４のＯＮ／ＯＦＦ端子に接続して、最低出力電圧および出力電流の検出回路を構成し、該検出回路からの信号でスイッチング素子Ｑ１の動作／停止を制御することを特徴とするスイッチング電源である。
【０００５】
上記の検出回路で検出した出力電流が所定の値以下であり、かつ、検出した出力電圧が定格出力電圧から設定電圧に下がるまでの間、第１のフォトカプラを動作させ、一次側の電源制御用ＩＣ（ＩＣ４）のＯＮ／ＯＦＦ端子に信号を伝え、スイッチング素子Ｑ１を停止させる。
【０００６】
そして、検出した出力電圧が設定電圧となった時、第１のフォトカプラを停止させてスイッチング素子Ｑ１を動作させ、出力電圧が定格出力電圧とほぼ等しい電圧まで上昇させる。
検出回路で検出した出力電流が所定の値以下である間、上記動作を繰り返す。
【０００７】
また、上記検出回路で検出した出力電流が所定の値より大きい時、第１のフォトカプラを動作停止させ、通常のスイッチング動作をさせる。
【０００８】
【発明の実施の形態】
以下、本発明の実施の形態について、図面を参照しながら詳細に説明する。図１は本発明の実施形態が適用されるスイッチング電源の一例である。
この回路は、フライバックコンバータと呼ばれるものであり、図１はその回路構成を示したものである。Ｔは一次側に蓄積されたエネルギーを二次側へ伝達するためのコンバータトランス、Ｑ１はスイッチング素子であるＦＥＴ、Ｃ１は電源入力平滑用コンデンサ、Ｒ８は電源起動用抵抗、Ｃ２は二次側出力平滑用コンデンサであり、ＩＣ４はスイッチング電源制御用ＩＣ、ＩＣ３は出力電圧検出用ＩＣであり、ＰＣ１は二次側回路に電圧を安定供給するための信号を一次側にフィードバックするフォトカプラ、Ｒ７は出力電流検出用抵抗、Ｒ５、Ｒ６は基準電圧を分圧する抵抗、ＩＣ２は出力電流が増加しＲ７の両端電圧が上昇したことを検出するオペアンプ、ＩＣ１およびＲ１、Ｒ２、Ｒ４は負荷側が許容できる最低出力電圧を検出するオペアンプと抵抗、Ｄ１はＩＣ１とＩＣ２の基準電圧となるツェナーダイオード、ＰＣ１は負荷側が許容できる最低出力電圧になるまでスイッチング素子Ｑ１を停止させる信号を一次側にフィードバックするフォトカプラ、Ｒ３はフォトカプラの電流を制限する抵抗である。
【０００９】
出力電圧が定格電圧より上昇すると、出力電圧検出用ＩＣ３に接続されたフォトカプラＰＣ２のダイオードに流れる電流が増加して、フォトカプラＰＣ２のトランジスタが接続されている電源制御用ＩＣ（ＩＣ４）のフィードバック（ＦＢ）端子電圧が下がり、下がる量に応じて一定周波数動作しているスイッチング素子Ｑ１のオフ時間デューティが大きくなり、出力電圧を下げて定格電圧を安定供給することができる。
負荷側が待機状態となり、電源の出力電流が非常に小さくなると、抵抗Ｒ７の両端電圧と基準電圧となるツェナーダイオードＤ１の電圧を抵抗Ｒ５とＲ６で分圧して得られる電圧を比較し、Ｒ７の両端電圧が低くなるとオペアンプＩＣ２の出力はＬレベルとなる。
二次側出力平滑用コンデンサＣ２の両端電圧は安定化出力電圧になっており、抵抗Ｒ１、Ｒ２、およびＲ４で分圧し得られたＲ２両端電圧と、基準電圧となるツェナーダイオードＤ２の電圧を比較し、Ｒ２両端電圧が高くなっている間、オペアンプＩＣ１の出力はＨレベルとなり、オペアンプＩＣ１の出力端子から電流がフォトカプラＰＣ１のダイオード、抵抗Ｒ３、ＬレベルとなっているオペアンプＩＣ２の出力端子に流れ込み、フォトカプラＰＣ１のトランジスタ側がオンとなり、電源制御用ＩＣ（ＩＣ４）のＯＮ／ＯＦＦ端子がＬレベルとなり、電源制御用ＩＣ（ＩＣ４）はＯＮ／ＯＦＦ端子がＬレベルになると発振停止となる機能を有しているため、スイッチング素子Ｑ１は停止する。
二次側出力平滑用コンデンサＣ２の両端電圧は、微小待機負荷電流とＣ２に接続されている電源内部回路で消費される微小電流によって徐々に放電され、負荷側が許容できる最低出力電圧に達すると、抵抗Ｒ２の両端電圧が基準電圧であるＤ１の電圧より低くなるため、オペアンプＩＣ１の出力端子はＬレベルとなり、フォトカプラＰＣ１のダイオードに電流が流れなくなり、フォトカプラＰＣ１のトランジスタ側がオフし、電源制御用ＩＣ（ＩＣ４）のＯＮ／ＯＦＦ端子がＨレベルになるので、スイッチング素子Ｑ１は動作を開始する。
【００１０】
図３は電源の動作状態と時間との関係を示した図である。
負荷側が待機状態の間は、図３のＡ部分に示すように、定格出力電圧と負荷側が許容できる最低出力電圧の間になるようにスイッチング素子Ｑ１はオン／オフを繰り返す。図３のＡ部分のタイムチャートから分かるように、停止時間が動作時間に対して非常に長く、停止中はスイッチングロスがゼロになるので、電源の待機電力を低減することができる。
待機状態から電源の出力電流を若干増加させると、図３のＢ部分に示すように、増加させた電流に応じて出力平滑コンデンサＣ２の放電される時間が短くなり、上記スイッチング素子Ｑ１の停止時間が短くなる。
さらに電源の出力電流を増加させ、抵抗Ｒ７の両端電圧が抵抗Ｒ５とＲ６で分圧して得られる電圧に対して高くなると、オペアンプＩＣ２の出力はＨレベルとなり、今までオペアンプＩＣ１の出力端子からフォトカプラＰＣ１のダイオード、抵抗Ｒ３、オペアンプＩＣ２の出力端子へ流れていた電流が流れなくなり、スイッチング素子Ｑ１のオフ信号が一次側にフィードバックできなくなるため、電源の動作状態は本来の一定周波数動作に移行する（図３のＣ部分）。
上記したように、負荷側が待機状態の時、定格出力電圧と負荷側が許容できる最低出力電圧の間になるようにスイッチング素子Ｑ１はオン／オフ動作を繰り返し、停止時間が動作時間に対して非常に長く、停止中はスイッチングロスがゼロになるので、電源の待機電力が低減される。
ところが、従来例では図４に示すように、スイッチング電源の動作状態にかかわらず、一定周波数でスイッチング素子Ｑ１が動作しているため、スイッチングロスが常に発生する。
実施例と従来例とで、待機電力を比較した結果を表１に示す。
【００１１】
【表１】
入力電圧ＡＣ１００Ｖ、定格出力電圧１３Ｖ、負荷側が許容できる最低出力電圧１０Ｖ、コンデンサＣ２の容量３０００μＦ、発振周波数７０ｋＨｚ、待機負荷２ｍＡの場合、従来回路方式では入力電力が０．３Ｗに対して、本回路方式ではスイッチング素子Ｑ１のオフ時間が１．５秒、スイッチング素子Ｑ１のオン時間が１００ｍｓｅｃで、入力電力は０．０７２Ｗと従来例の２４％にまで低減することができた。
【００１３】
【発明の効果】
以上説明したように、本発明によれば、負荷側が待機状態の時、定格出力電圧と負荷側が許容できる最低出力電圧の間で、スイッチング素子がオン／オフを繰り返し、停止時間を動作時間に対して長くとることができ、この間はスイッチングロスがゼロになるので、電源の待機電力が低減でき、待機時の省エネに貢献することができる。
【図面の簡単な説明】
【図１】本発明の実施例によるスイッチング電源の回路図である。
【図２】従来のスイッチング電源の回路図である。
【図３】図１の実施例による電源の動作状態を示すタイムチャートである。
【図４】図２の従来例による電源の動作状態を示すタイムチャートである。
【符号の説明】
Ｑ１ スイッチング素子（ＦＥＴ）
ＩＣ１ 第１のオペアンプ（最低出力電圧検出用）
ＩＣ２ 第２のオペアンプ（出力電流検出用）
ＩＣ３ 出力電圧検出用ＩＣ
ＩＣ４ 電源制御用ＩＣ
ＰＣ１ 第１のフォトカプラ（電源停止信号フィードバック用）
ＰＣ２ 第２のフォトカプラ（出力電圧検出信号フィードバック用）
Ｃ１ 平滑コンデンサ（電源入力平滑用）
Ｃ２ 平滑コンデンサ（出力平滑用）
Ｒ１ 第１の抵抗（最低出力電圧検出用）
Ｒ２ 第２の抵抗（最低出力電圧検出用）
Ｒ３ 第３の抵抗（電流制限用）
Ｒ４ 第４の抵抗（最低出力電圧検出用）
Ｒ５ 第５の抵抗（基準電圧分圧用）
Ｒ６ 第６の抵抗（基準電圧分圧用）
Ｒ７ 第７の抵抗（出力電流検出用）
Ｒ８ 第８の抵抗（電源起動用）
Ｔ コンバータトランス
Ｄ１ ツェナーダイオード（基準電圧設定用）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a switching power supply, and relates to a switching power supply provided with means for reducing standby power of the switching power supply as an energy saving measure in a standby state.
[0002]
[Prior art]
FIG. 2 has been proposed as this type of switching power supply. IC3 is an output voltage detection IC. When the output voltage rises above the rated voltage, the current flowing through the diode of the photocoupler PC2 connected to the IC3 increases and the transistor of the photocoupler PC2 is connected. The voltage at the feedback (FB) terminal of the IC for IC (IC4) decreases, and the off-time duty of the switching element Q1 operating at a constant frequency increases according to the amount to decrease, and the rated voltage is stably supplied by decreasing the output voltage. Can do.
However, in the above switching power supply circuit, as shown in FIG. 4, the switching element Q1 operates at a constant frequency regardless of the operating state of the switching power supply. There was a problem of worsening.
[0003]
[Problems to be solved by the invention]
Because of the above problems, a circuit configuration that can significantly reduce the switching loss and reduce the standby power in the standby state of the switching power supply has been required.
[0004]
[Means for Solving the Problems]
The present invention solves the above-described problem, and a DC voltage obtained by rectification is turned on / off by a switching element Q1 on the primary side, via a rectification / smoothing circuit on the secondary side having a diode and a smoothing capacitor. In a switching power supply that stably supplies a voltage, a first resistor R1 and a second resistor R2 are connected in series between a (+) output terminal and a (−) output terminal of the switching power supply, and the first resistor R1 and the first resistor R1 The connection point of the two resistors R2 is connected to the (+) input terminal of the first operational amplifier IC1, the (+) input terminal and the output terminal of the first operational amplifier IC1 are connected by the fourth resistor R4, and the first the output terminal of the operational amplifier IC1 and the output terminal of the second
[0005]
While the output current detected by the detection circuit is below a predetermined value and the detected output voltage falls from the rated output voltage to the set voltage, the first photocoupler is operated to control the power supply on the primary side. A signal is transmitted to the ON / OFF terminal of the IC (IC4), and the switching element Q1 is stopped.
[0006]
When the detected output voltage becomes the set voltage, the first photocoupler is stopped to operate the switching element Q1, and the output voltage is increased to a voltage substantially equal to the rated output voltage.
The above operation is repeated while the output current detected by the detection circuit is below a predetermined value.
[0007]
When the output current detected by the detection circuit is larger than a predetermined value, the first photocoupler is stopped and a normal switching operation is performed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an example of a switching power supply to which an embodiment of the present invention is applied.
This circuit is called a flyback converter, and FIG. 1 shows its circuit configuration. T is a converter transformer for transmitting energy accumulated on the primary side to the secondary side, Q1 is an FET as a switching element, C1 is a power input smoothing capacitor, R8 is a power source starting resistor, and C2 is a secondary side output. A smoothing capacitor, IC4 is a switching power supply control IC, IC3 is an output voltage detection IC, PC1 is a photocoupler that feeds back a signal for stably supplying a voltage to the secondary side circuit, and R7 is Output current detection resistors, R5 and R6 are resistors that divide the reference voltage, IC2 is an operational amplifier that detects that the output current has increased and the voltage across R7 has increased, and IC1 and R1, R2, and R4 are the lowest allowable on the load side Operational amplifier and resistor for detecting output voltage, D1 is a Zener diode that serves as a reference voltage for IC1 and IC2, and PC1 is allowed on the load side Optocoupler feeding back a signal to stop the switching element Q1 to a minimum output voltage that can on the primary side, R3 is a resistor for limiting the current of the photo coupler.
[0009]
When the output voltage rises above the rated voltage, the current flowing through the diode of the photocoupler PC2 connected to the output voltage detection IC3 increases, and feedback of the power supply control IC (IC4) to which the transistor of the photocoupler PC2 is connected. (FB) The off-time duty of the switching element Q1 operating at a constant frequency increases according to the amount that the terminal voltage decreases and decreases, and the rated voltage can be stably supplied by decreasing the output voltage.
When the load side is in a standby state and the output current of the power supply becomes very small, the voltage obtained by dividing the voltage across the resistor R7 and the voltage of the Zener diode D1 serving as the reference voltage by the resistors R5 and R6 is compared. When the voltage is lowered, the output of the operational amplifier IC2 becomes L level.
The voltage across the secondary output smoothing capacitor C2 is a stabilized output voltage, and the voltage across the R2 obtained by dividing by the resistors R1, R2, and R4 is compared with the voltage of the Zener diode D2 serving as the reference voltage. While the voltage across R2 is high, the output of the operational amplifier IC1 is at the H level, and the current from the output terminal of the operational amplifier IC1 goes to the diode of the photocoupler PC1, the resistor R3, and the output terminal of the operational amplifier IC2 at the L level. When the transistor side of the photocoupler PC1 is turned on, the ON / OFF terminal of the power supply control IC (IC4) becomes L level, and the power supply control IC (IC4) stops oscillation when the ON / OFF terminal becomes L level. Therefore, the switching element Q1 stops.
When the voltage across the secondary side output smoothing capacitor C2 is gradually discharged by the minute standby load current and the minute current consumed by the power supply internal circuit connected to C2, and reaches the minimum output voltage that the load side can tolerate, Since the voltage across the resistor R2 is lower than the reference voltage D1, the output terminal of the operational amplifier IC1 becomes L level, no current flows through the diode of the photocoupler PC1, the transistor side of the photocoupler PC1 is turned off, and the power supply control Since the ON / OFF terminal of the IC for IC (IC4) becomes H level, the switching element Q1 starts its operation.
[0010]
FIG. 3 is a diagram showing the relationship between the operating state of the power supply and time.
While the load side is in the standby state, as shown in part A of FIG. 3, the switching element Q1 is repeatedly turned on / off so as to be between the rated output voltage and the minimum output voltage allowable on the load side. As can be seen from the time chart of part A in FIG. 3, the stop time is very long with respect to the operation time, and the switching loss becomes zero during the stop, so that the standby power of the power source can be reduced.
When the output current of the power supply is slightly increased from the standby state, the time during which the output smoothing capacitor C2 is discharged becomes shorter according to the increased current, as shown in part B of FIG. Becomes shorter.
When the output current of the power supply is further increased and the voltage across the resistor R7 becomes higher than the voltage obtained by dividing by the resistors R5 and R6, the output of the operational amplifier IC2 becomes H level, so far from the output terminal of the operational amplifier IC1 to the photo Since the current flowing to the diode of the coupler PC1, the resistor R3, and the output terminal of the operational amplifier IC2 does not flow, and the OFF signal of the switching element Q1 cannot be fed back to the primary side, the operating state of the power supply shifts to the original constant frequency operation. (C part of FIG. 3).
As described above, when the load side is in the standby state, the switching element Q1 repeats the on / off operation so that it is between the rated output voltage and the allowable minimum output voltage on the load side, and the stop time is very large with respect to the operation time. Since the switching loss is zero during a long stop, the standby power of the power source is reduced.
However, in the conventional example, as shown in FIG. 4, the switching element Q1 operates at a constant frequency regardless of the operating state of the switching power supply, and therefore a switching loss always occurs.
Table 1 shows the result of comparison of standby power between the example and the conventional example.
[0011]
[Table 1]
When the input voltage is AC100V, the rated output voltage is 13V, the minimum output voltage is 10V that the load side can accept, the capacity of the capacitor C2 is 3000μF, the oscillation frequency is 70kHz, and the standby load is 2mA. In the system, the off time of the switching element Q1 is 1.5 seconds, the on time of the switching element Q1 is 100 msec, and the input power can be reduced to 0.072 W, which is 24% of the conventional example.
[0013]
【The invention's effect】
As described above, according to the present invention, when the load side is in a standby state, the switching element is repeatedly turned on / off between the rated output voltage and the minimum output voltage allowable on the load side. Since the switching loss is zero during this period, the standby power of the power source can be reduced, contributing to energy saving during standby.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a switching power supply according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a conventional switching power supply.
FIG. 3 is a time chart showing an operation state of a power supply according to the embodiment of FIG. 1;
4 is a time chart showing an operation state of a power supply according to the conventional example of FIG. 2;
[Explanation of symbols]
Q1 Switching element (FET)
IC1 1st operational amplifier (for minimum output voltage detection)
IC2 Second operational amplifier (for output current detection)
IC3 Output voltage detection IC
IC4 Power control IC
PC1 1st photocoupler (for power stop signal feedback)
PC2 Second photocoupler (for output voltage detection signal feedback)
C1 smoothing capacitor (for power input smoothing)
C2 smoothing capacitor (for output smoothing)
R1 first resistor (for minimum output voltage detection)
R2 2nd resistor (for minimum output voltage detection)
R3 3rd resistor (for current limiting)
R4 4th resistor (for minimum output voltage detection)
R5 5th resistor (for reference voltage division)
R6 6th resistor (for reference voltage division)
R7 7th resistor (for output current detection)
R8 8th resistor (for power activation)
T converter transformer D1 Zener diode (for reference voltage setting)
Claims (1)
スイッチング電源の（＋）出力端子と（−）出力端子との間に第１および第２の抵抗を直列接続し、第１および第２の抵抗の接続点を第１のオペアンプの（＋）入力端子に接続し、第１のオペアンプの（＋）入力端子と出力端子とを第４の抵抗で接続し、第１のオペアンプの出力端子と第２のオペアンプの出力端子とを直列接続した第１のフォトカプラのダイオードと第３の抵抗で接続し、第１のオペアンプの（−）入力端子をツェナーダイオードのカソードに接続し、該ツェナーダイオードのアノードをスイッチング電源の(−)出力端子に接続し、該ツェナーダイオードのカソード側と二次巻線側との間に第５および第６の抵抗を直列接続し、第５および第６の抵抗の接続点を第２のオペアンプの（−）入力端子に接続し、第６の抵抗の二次巻線側と第２のオペアンプの（＋）入力端子との間に第７の抵抗を接続し、かつ第７の抵抗と第２のオペアンプの（＋）入力端子の接続点をスイッチング電源の（−）出力端子側に接続し、スイッチング電源の（＋）出力端子と（−）出力端子から出力される出力電圧を検出する出力電圧検出用ＩＣに第２のフォトカプラのダイオードを接続し、第２のフォトカプラのトランジスタを一次側電源制御用ＩＣのフィードバック端子に接続し、第１のフォトカプラのトランジスタを一次側電源制御用ＩＣのＯＮ／ＯＦＦ端子に接続して、最低出力電圧および出力電流の検出回路を構成し、該検出回路からの信号でスイッチング素子の動作／停止を制御することを特徴とするスイッチング電源。In a switching power supply that stably supplies a voltage via a secondary side rectification / smoothing circuit that turns on / off a DC voltage obtained by rectification by a primary side switching element, and has a diode and a smoothing capacitor.
The first and second resistors are connected in series between the (+) output terminal and the (−) output terminal of the switching power supply, and the connection point of the first and second resistors is the (+) input of the first operational amplifier. The first operational amplifier's (+) input terminal and the output terminal are connected by a fourth resistor, and the first operational amplifier's output terminal and the second operational amplifier's output terminal are connected in series . The photocoupler diode is connected with a third resistor, the (−) input terminal of the first operational amplifier is connected to the cathode of the Zener diode , and the anode of the Zener diode is connected to the (−) output terminal of the switching power supply. The fifth and sixth resistors are connected in series between the cathode side and the secondary winding side of the Zener diode , and the connection point of the fifth and sixth resistors is the (−) input terminal of the second operational amplifier. Connected to the sixth resistor A seventh resistor is connected between the winding side and the (+) input terminal of the second operational amplifier, and the connection point of the seventh resistor and the (+) input terminal of the second operational amplifier is connected to the switching power supply ( −) Connect to the output terminal side, connect the diode of the second photocoupler to the output voltage detection IC that detects the output voltage output from the (+) output terminal and the (−) output terminal of the switching power supply, The photocoupler transistor of No. 2 is connected to the feedback terminal of the primary side power supply control IC, the transistor of the first photocoupler is connected to the ON / OFF terminal of the primary side power supply control IC, and the minimum output voltage and output current are connected. A switching power supply comprising: a detection circuit configured to control an operation / stop of a switching element by a signal from the detection circuit.
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| JP4859207B2 (en) * | 2006-02-28 | 2012-01-25 | キヤノン株式会社 | Switching power supply |
| JP2012130123A (en) * | 2010-12-14 | 2012-07-05 | Makita Corp | Charger |
| JP6146812B2 (en) * | 2013-10-09 | 2017-06-14 | ニチコン株式会社 | Switching power supply |
| CN115296528B (en) * | 2022-09-30 | 2023-03-24 | 广东东菱电源科技有限公司 | Circuit for improving wide input and output voltage LLC topological efficiency |
| CN116418249B (en) * | 2023-06-08 | 2023-10-10 | 深圳市斯康达电子有限公司 | AC/DC bidirectional conversion circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002044942A (en) * | 2000-07-19 | 2002-02-08 | Nichicon Corp | Switching power source |
| JP2003033020A (en) * | 2001-07-19 | 2003-01-31 | Nichicon Corp | Switching power supply |
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| JPH11235036A (en) * | 1998-02-09 | 1999-08-27 | Murata Mfg Co Ltd | Self-excited oscillation switching powder supply |
| JP3497075B2 (en) * | 1998-03-20 | 2004-02-16 | シャープ株式会社 | Switching power supply circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002044942A (en) * | 2000-07-19 | 2002-02-08 | Nichicon Corp | Switching power source |
| JP2003033020A (en) * | 2001-07-19 | 2003-01-31 | Nichicon Corp | Switching power supply |
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