JPH051828Y2 - - Google Patents
Info
- Publication number
- JPH051828Y2 JPH051828Y2 JP17176685U JP17176685U JPH051828Y2 JP H051828 Y2 JPH051828 Y2 JP H051828Y2 JP 17176685 U JP17176685 U JP 17176685U JP 17176685 U JP17176685 U JP 17176685U JP H051828 Y2 JPH051828 Y2 JP H051828Y2
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- drain
- current
- mosfet
- source
- 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.)
- Expired - Lifetime
Links
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- Testing Of Individual Semiconductor Devices (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Description
【考案の詳細な説明】
〔考案の属する技術分野〕
本考案は電力変換器などのスイツチング素子と
して使用するMOSFETのドレイン電流検出回路
に関する。[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a drain current detection circuit for a MOSFET used as a switching element in a power converter or the like.
MOSFETを電力変換器などのスイツチング素
子として用いる場合、この主回路の電流は従来第
３図、第４図に示すように変流器または電流検出
抵抗器で検出されている。第３図において、
MOSFET１のドレインＤに変流器２が接続さ
れ、ゲートＧに与えられる信号でドレインからソ
ースＳに電流Idが流れると変流器２の二次側の抵
抗３に電流が流れるから、この抵抗３の両端の電
圧降下Vdで変流器２の一次側の電流Idを検出す
る。また第４図において、MOSFET１のドレイ
ンには電流検出抵抗４が直列に接続され、ゲート
に与えられる信号でドレインからソースに電流Id
が流れると抵抗４に電圧降下Vdを生ずるからこ
の電圧降下Vdで電流Idを検出する。
When a MOSFET is used as a switching element in a power converter or the like, the current in the main circuit is conventionally detected by a current transformer or a current detection resistor as shown in FIGS. 3 and 4. In Figure 3,
A current transformer 2 is connected to the drain D of MOSFET 1, and when a current I d flows from the drain to the source S due to the signal given to the gate G, current flows through the resistor 3 on the secondary side of the current transformer 2, so this resistance The current I d on the primary side of the current transformer 2 is detected at the voltage drop V d across the current transformer 2 . In addition, in FIG. 4, a current detection resistor 4 is connected in series to the drain of MOSFET 1, and a current I d flows from the drain to the source in response to a signal applied to the gate.
Flows, a voltage drop V d occurs across the resistor 4, and the current I d is detected based on this voltage drop V d .
ところで第３図のように電流の検出に変流器を
用いると変流器は高価であり、装置全体が高価に
なるという欠点がある。またMOSFETのドレイ
ンに電流検出抵抗を接続するとこの抵抗中の損失
が電力損失として加わるという欠点がある。 However, when a current transformer is used to detect current as shown in FIG. 3, the current transformer is expensive and the entire device becomes expensive. Another disadvantage is that when a current detection resistor is connected to the drain of the MOSFET, the loss in this resistor is added as power loss.
本考案は安価で電力損失の少ないMOSFETの
ドレイン電流を検出する回路を提供することを目
的とする。
The purpose of the present invention is to provide an inexpensive circuit for detecting the drain current of a MOSFET with low power loss.
本考案は、ドレインとゲームにそれぞれダイオ
ードのカソードを接続し、この両ダイオードのア
ノードを共通に接続して電圧を印加した低電位優
先回路でドレイン・ソース間電圧とゲート・ソー
ス間電圧のうち低い方の電圧を選出し、この電圧
からドレイン電流を検出するもので、導通中のド
レイン・ソース間の電圧はこの間の抵抗とドレイ
ン電流の積に比例し、MOSFETが導通中ドレイ
ン・ソース間の電圧はゲート・ソース間の電圧よ
りも低いことに着目し、このドレイン・ソース間
の電圧が低いときだけ電流検出信号を取り出そう
というものである。
This invention is a low potential priority circuit in which the cathodes of diodes are connected to the drain and the game, respectively, and the anodes of both diodes are connected in common and a voltage is applied. The voltage between the drain and the source is selected and the drain current is detected from this voltage.The voltage between the drain and the source during conduction is proportional to the product of the resistance between them and the drain current. focuses on the fact that the voltage is lower than the voltage between the gate and source, and attempts to extract the current detection signal only when the voltage between the drain and source is low.
第１図は本考案の一実施例を示す結線図で
MOSFET１のドレインとソースとの間、ゲート
とソースとの間にはこの間の低い方の電圧を選出
する低電位優先回路５が設けられている。この低
電位優先回路５はドレインとゲートにそれぞれダ
イオード６，７のカソードを接続し、この両ダイ
オード６，７のアノードを共通に接続して、電流
制限抵抗８を介して直流電源９に接続した回路
で、ドレイン電流Idは両ダイオード６，７のアノ
ードとMOSFET１のソースとの間の端子10−12
間に現われる電圧Vsで検出する。11はMOSFET
１をスイツチング制御する制御回路である。
Figure 1 is a wiring diagram showing one embodiment of the present invention.
A low potential priority circuit 5 is provided between the drain and the source of the MOSFET 1 and between the gate and the source to select the lower voltage therebetween. This low potential priority circuit 5 has the cathodes of diodes 6 and 7 connected to its drain and gate, respectively, and the anodes of both diodes 6 and 7 are connected in common, and connected to a DC power source 9 via a current limiting resistor 8. In the circuit, the drain current I d is connected to terminals 10-12 between the anodes of both diodes 6 and 7 and the source of MOSFET 1.
It is detected by the voltage V s that appears between the two. 11 is MOSFET
This is a control circuit that performs switching control of 1.
第１図に示す回路の動作を第２図の波形図を参
照しながら説明する。MOSFET１のドレイン・
ソース間に図示しない所定回路を介して電圧Vds
が印加され、この電圧Vdsは比較的高いが、ゲー
トに制御回路１１で電圧Vgsのような矩形波電圧
が印加されると、この電圧Vgsが印加されている
間、ドレイン電流Idが流れ、電圧Vdsは内部電圧
降下Viに低下する。このドレイン・ソース間の電
圧Vdsが電源９の電圧より高い間、電源９からの
電流はダイオード６で阻止されて、ドレインから
ソースへ電流が流れないから端子10−12間には電
流検出信号は送出されない。しかしゲート・ソー
ス間電圧Vgsが高くなり、ドレイン・ソース間が
導通してこの間の電圧が電圧降下Viに低下する
と、ダイオード６のカソード側電圧が低いから電
源９から抵抗８−ダイオード６−ドレイン−ソー
スに電流が流れ、端子10−12間に電流検出信号
Vsが送出される。すなわちMOSFET１が不導通
のときはドレインソース間の電圧は端子10−12側
からしや断され、MOSFET１が導通していると
きだけドレイン電流Idに比例する電流検出信号Vs
を検出することができ、結果としてドレイン電流
Idを検出することができる。 The operation of the circuit shown in FIG. 1 will be explained with reference to the waveform diagram in FIG. 2. MOSFET1 drain
A voltage V ds is applied between the sources through a predetermined circuit (not shown).
is applied, and this voltage V ds is relatively high, but when a rectangular wave voltage such as voltage V gs is applied to the gate by the control circuit 11, the drain current I d increases while this voltage V gs is applied. flows, and the voltage V ds drops to the internal voltage drop V i . While this drain-source voltage V ds is higher than the voltage of the power supply 9, the current from the power supply 9 is blocked by the diode 6, and no current flows from the drain to the source, so a current detection signal is connected between terminals 10 and 12. is not sent. However, when the voltage V gs between the gate and source increases and conducts between the drain and source, and the voltage between them decreases to the voltage drop V i , the voltage on the cathode side of the diode 6 is low, so the power supply 9 connects the resistor 8 to the diode 6 to Current flows between drain and source, and current detection signal is generated between terminals 10 and 12.
V s is sent out. That is, when MOSFET 1 is non-conducting, the voltage between the drain and source is cut off from the terminals 10-12, and only when MOSFET 1 is conducting, the current detection signal V s proportional to the drain current I d is generated.
can be detected, and as a result the drain current
I d can be detected.
なお、第２図のVs′は第１図においてダイオー
ド７が無い場合の端子10−12間に現れる電圧波形
を示す。図に示すように、ダイオード７が無いと
MOSFET１が不導通のときに、電源９の電圧が
端子10−12間に出力される。MOSFET１不導通
時のこの電源９の電圧をカツトするために、ダイ
オード７を挿入している。 Note that V s ' in FIG. 2 shows the voltage waveform appearing between terminals 10 and 12 in the case where diode 7 is not provided in FIG. As shown in the figure, without diode 7
When MOSFET 1 is non-conducting, the voltage of power supply 9 is output between terminals 10-12. A diode 7 is inserted to cut off the voltage of this power supply 9 when the MOSFET 1 is off.
本考案によればMOSFETに通電したときだけ
ドレイン電流に比例するドレイン・ソース間の電
圧降下を検出することにより、安価で電力損失の
少ないMOSFETのドレイン電流を検出すること
ができ効果は大きい。
According to the present invention, by detecting the voltage drop between the drain and source that is proportional to the drain current only when the MOSFET is energized, it is possible to detect the drain current of the MOSFET at low cost and with little power loss, which is highly effective.
第１図は本考案によるMOSFETのドレイン電
流検出回路の一実施例を示す結線図、第２図は第
１図の各部における波形図、第３図、第４図はそ
れぞれ従来のMOSFETのドレイン電流検出回路
を示す結線図である。
１……MOSFET、５……低電位優先回路、
６，７……ダイオード。
Figure 1 is a wiring diagram showing one embodiment of the MOSFET drain current detection circuit according to the present invention, Figure 2 is a waveform diagram at each part of Figure 1, and Figures 3 and 4 are drain currents of conventional MOSFETs. FIG. 3 is a wiring diagram showing a detection circuit. 1...MOSFET, 5...Low potential priority circuit,
6, 7...diode.
Claims (1)
ードを接続し、この両ダイオードのアノードを共
通に接続して電圧を印加した低電位優先回路でド
レイン・ソース間電圧とゲート・ソース間電圧の
うち低い方の電圧を選出し、この電圧からドレイ
ン電流を検出することを特徴とするMOSFETの
ドレイン電流検出回路。 A low potential priority circuit connects the cathodes of diodes to the drain and gate, and connects the anodes of both diodes in common to apply a voltage. A MOSFET drain current detection circuit is characterized in that the drain current is detected from the selected voltage and the drain current is detected from this voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17176685U JPH051828Y2 (en) | 1985-11-08 | 1985-11-08 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17176685U JPH051828Y2 (en) | 1985-11-08 | 1985-11-08 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6281071U JPS6281071U (en) | 1987-05-23 |
| JPH051828Y2 true JPH051828Y2 (en) | 1993-01-18 |
Family
ID=31107695
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17176685U Expired - Lifetime JPH051828Y2 (en) | 1985-11-08 | 1985-11-08 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH051828Y2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6293623B2 (en) * | 2014-09-05 | 2018-03-14 | 株式会社東芝 | Semiconductor inspection equipment |
| US10094863B2 (en) * | 2016-03-02 | 2018-10-09 | Texas Instruments Incorporated | High-resolution power electronics measurements |
-
1985
- 1985-11-08 JP JP17176685U patent/JPH051828Y2/ja not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6281071U (en) | 1987-05-23 |
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