JPH02106162A - Switching power supply - Google Patents

Switching power supply

Info

Publication number
JPH02106162A
JPH02106162A JP25853488A JP25853488A JPH02106162A JP H02106162 A JPH02106162 A JP H02106162A JP 25853488 A JP25853488 A JP 25853488A JP 25853488 A JP25853488 A JP 25853488A JP H02106162 A JPH02106162 A JP H02106162A
Authority
JP
Japan
Prior art keywords
voltage
power supply
thermistor
switching power
switching element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP25853488A
Other languages
Japanese (ja)
Inventor
Nobuhiko Eguchi
信彦 江口
Toshimi Ito
伊藤　利美
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP25853488A priority Critical patent/JPH02106162A/en
Publication of JPH02106162A publication Critical patent/JPH02106162A/en
Pending legal-status Critical Current

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  • Dc-Dc Converters (AREA)
  • Electronic Switches (AREA)

Abstract

PURPOSE:To detect a drooping current always at a constant point without being influenced by the ambient temperature of an apparatus by using a thermistor in a drooping current-sensing circuit. CONSTITUTION:When the voltage across the ends of a thermistor 10 is higher than that between the base and emitter of a transistor 9 if the voltage detected across the ends of the thermistor 10 is compared with that between the base and emitter of the transistor 9, the driving pulse of a switching element 5 is cut OFF and a drooping current is detected. As a result, because the resistance value of the thermistor 10 also varies according to the change of the ambient temperature of an apparatus even if such change takes place, the drooping current can be detected always at a constant point.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明はスイッチング電源装置に関し、特に垂下電流検
出回路を有するスイッチング電源装置に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switching power supply, and more particularly to a switching power supply having a drooping current detection circuit.

〔従来の技術〕[Conventional technology]

従来、スイッチング電源の垂下電流検出は抵抗によって
行われていた。すなわち、従来のスイッチング電源の垂
下電流検出回路は抵抗の両端で検出した電圧とトランジ
スタのベース・エミッタ間の電圧とを比較して、抵抗の
両端の電圧がベース・エミッタ間の電圧より高くなった
時にスイッチング素子の駆動パルスを遮断していた。Conventionally, the drooping current of switching power supplies has been detected using resistors. In other words, a conventional switching power supply's droop current detection circuit compares the voltage detected across the resistor with the voltage between the base and emitter of the transistor, and finds that the voltage across the resistor is higher than the voltage between the base and emitter. At times, the drive pulses for the switching elements were cut off.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

上述した従来のスイッチング電源の垂下電流検出回路で
は、抵抗両端の検出電圧とトランジスタのベース・エミ
ッタ間の電圧とを比較して行っていた。しかしベース・
エミッタ間の電圧は周囲温度によって変動するため、周
囲温度が変化すると垂下電流のポイントが変動するとい
う欠点がある。In the conventional drooping current detection circuit of the switching power supply described above, the detection voltage across the resistor is compared with the voltage between the base and emitter of the transistor. However, the base
The voltage across the emitter varies depending on the ambient temperature, so a drawback is that the drooping current point varies as the ambient temperature changes.

〔課題を解決するための手段〕[Means to solve the problem]

本発明のスイッチング電源装置は、出力電圧と基準電圧
との差を増幅する誤差増幅器と、この誤差増幅器の出力
電圧と発振回路の出力電圧とを比較してパルスを得るパ
ルス幅変調回路と、このパルス幅変調回路の出力パルス
によって駆動されるスイッチング素子を備えるスイッチ
ング電源装置において、前記スイッチング素子と直列に
接続されたサーミスタの両端の電圧を検出しこの端子電
圧がトランジスタのベース・エミッタ間の電圧を超えた
時に前記スイッチング素子の駆動パルスを遮断すること
を特徴とする。The switching power supply device of the present invention includes: an error amplifier that amplifies the difference between an output voltage and a reference voltage; a pulse width modulation circuit that obtains a pulse by comparing the output voltage of the error amplifier and the output voltage of an oscillation circuit; In a switching power supply device equipped with a switching element driven by an output pulse of a pulse width modulation circuit, the voltage across a thermistor connected in series with the switching element is detected, and this terminal voltage determines the voltage between the base and emitter of the transistor. It is characterized in that the drive pulse for the switching element is cut off when the threshold is exceeded.

〔実施例〕〔Example〕

次に、本発明について図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.

第１図は本発明のスイッチング電源装置の一実施例を示
す回路図である。FIG. 1 is a circuit diagram showing an embodiment of the switching power supply device of the present invention.

第１図において、１は本装置の入力の直流電源であり、
電圧変換用トランス２を介してスイッチング素子５に接
続されている。電圧変換用トランス２の二次側は整流平
滑回路３を経て負荷４に接続されている。本スイッチン
グ電源装置の出力電圧は抵抗１３．１４で分圧されて誤
差増幅器１２の一方の入力に接続されている。誤差増幅
器１２の他方の入力には基準電圧１６が接続されている
。In FIG. 1, 1 is the input DC power supply of this device,
It is connected to a switching element 5 via a voltage conversion transformer 2. The secondary side of the voltage conversion transformer 2 is connected to a load 4 via a rectifier and smoothing circuit 3. The output voltage of this switching power supply device is divided by resistors 13 and 14 and connected to one input of the error amplifier 12. A reference voltage 16 is connected to the other input of the error amplifier 12.

誤差増幅器１２の出力と発振回路１５の出力とはパルス
幅変調回路１１に入力され、パルス幅変調回路１１の出
力はＡＮ、Ｄ６とＮＡＮＤ７のそれぞれ一方の入力に接
続されている。ＡＮＤ６の他方の入力にはＮＡＮＤ７の
出力が、またＮＡＮＤ７の他方の入力にはＮＡＮＤ８の
出力が接続されている。ＮＡＮＤ８の入力はＮＡＮＤ７
の出力とトランジスタ９に接続されている。また、ＡＮ
Ｄ　６の出力はスイッチング素子５に接続され、スイッ
チング素子５からサーミスタ１０を経てトランジスタ９
に接続されている。The output of the error amplifier 12 and the output of the oscillation circuit 15 are input to the pulse width modulation circuit 11, and the output of the pulse width modulation circuit 11 is connected to one input of each of AN, D6, and NAND7. The output of NAND7 is connected to the other input of AND6, and the output of NAND8 is connected to the other input of NAND7. The input of NAND8 is NAND7
is connected to the output of transistor 9. Also, AN
The output of D6 is connected to the switching element 5, and from the switching element 5 to the transistor 9 via the thermistor 10.
It is connected to the.

次に、本実施例の動作について説明する。Next, the operation of this embodiment will be explained.

スイッチング電源装置の出力電圧は抵抗１３゜１４で分
圧され、この分圧電圧と基準電圧１６との差を誤差増幅
器１２で増幅する。誤差増幅器１２の出力電圧と発振回
路１５の出力電圧をパルス幅変調回路１１で比較し、Ａ
ＮＤ６を介してスイッチング素子５を駆動する。The output voltage of the switching power supply device is divided by resistors 13 and 14, and the difference between this divided voltage and a reference voltage 16 is amplified by an error amplifier 12. The output voltage of the error amplifier 12 and the output voltage of the oscillation circuit 15 are compared by the pulse width modulation circuit 11, and A
The switching element 5 is driven via the ND6.

垂下電流の検出方法は次のように行われる。サーミスタ
１０の両端で検出した電圧とトランジスタ９のベース・
エミッタ間の電圧を比較して、サーミスタ１０の両端の
電圧がベース・エミッタ間の電圧より高くなった時、ス
イッチング素子５の駆動パルスを遮断して垂下電流を検
出する。The method of detecting the drooping current is performed as follows. The voltage detected across the thermistor 10 and the base of the transistor 9
The voltage between the emitters is compared, and when the voltage across the thermistor 10 becomes higher than the voltage between the base and emitter, the driving pulse of the switching element 5 is cut off and a drooping current is detected.

本実施例によれば、周囲温度が変化しても、それに応じ
てサーミスタ１０の抵抗値も変動するため、常に一定の
ポイントで垂下電流を検出することが可能である。According to this embodiment, even if the ambient temperature changes, the resistance value of the thermistor 10 changes accordingly, so it is possible to always detect the drooping current at a constant point.

〔発明の効果〕〔Effect of the invention〕

以上説明したように本発明は、垂下電流検出回路にサー
ミスタを使用することにより、周囲温度の影響を受けず
常に一定のポイントで検出することができるという効果
がある。As explained above, the present invention has the effect that by using a thermistor in the drooping current detection circuit, detection can always be made at a constant point without being affected by the ambient temperature.

整流平滑回路、４・・・負荷、５・・・スイッチング素
子、６・・・ＡＮＤ、７，８・・・ＮＡＮＤ、９・・・
トランジスタ、１０・・・サーミスタ、１１・・・パル
ス幅変調回路、１２・・・誤差増幅器、１３．１４・・
・抵抗、１５・・・発振回路、１６・・・基準電圧。Rectifier and smoothing circuit, 4...Load, 5...Switching element, 6...AND, 7, 8...NAND, 9...
Transistor, 10... Thermistor, 11... Pulse width modulation circuit, 12... Error amplifier, 13.14...
-Resistance, 15...Oscillation circuit, 16...Reference voltage.

Claims (1)

【特許請求の範囲】[Claims] 出力電圧と基準電圧との差を増幅する誤差増幅器と、こ
の誤差増幅器の出力電圧と発振回路の出力電圧とを比較
してパルスを得るパルス幅変調回路と、このパルス幅変
調回路の出力パルスによって駆動されるスイッチング素
子を備えるスイッチング電源装置において、前記スイッ
チング素子と直列に接続されたサーミスタの両端の電圧
を検出しこの端子電圧がトランジスタのベース・エミッ
タ間の電圧を超えた時に前記スイッチング素子の駆動パ
ルスを遮断することを特徴とするスイッチング電源装置
。an error amplifier that amplifies the difference between the output voltage and a reference voltage; a pulse width modulation circuit that obtains a pulse by comparing the output voltage of the error amplifier and the output voltage of the oscillation circuit; In a switching power supply device that includes a switching element to be driven, a voltage across a thermistor connected in series with the switching element is detected, and when this terminal voltage exceeds a voltage between the base and emitter of the transistor, the switching element is driven. A switching power supply device characterized by cutting off pulses.
JP25853488A 1988-10-14 1988-10-14 Switching power supply Pending JPH02106162A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP25853488A JPH02106162A (en) 1988-10-14 1988-10-14 Switching power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP25853488A JPH02106162A (en) 1988-10-14 1988-10-14 Switching power supply

Publications (1)

Publication Number Publication Date
JPH02106162A true JPH02106162A (en) 1990-04-18

Family

ID=17321557

Family Applications (1)

Application Number Title Priority Date Filing Date
JP25853488A Pending JPH02106162A (en) 1988-10-14 1988-10-14 Switching power supply

Country Status (1)

Country Link
JP (1) JPH02106162A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017070092A (en) * 2015-09-30 2017-04-06 京セラドキュメントソリューションズ株式会社 Electrical machine

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017070092A (en) * 2015-09-30 2017-04-06 京セラドキュメントソリューションズ株式会社 Electrical machine

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