SWITCHING POWER SUPPLY

• Main Author: SATO MASAYOSHI
• Format: Patent
• Language: English; Japanese
• Published: 25.04.2019
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION

To prevent occurrence of malfunction or delay in detection of a current flowing through a synchronous rectification transistor MN1.SOLUTION: A switching power supply includes a first source resistor R2 connected with the source of a first gate ground transistor MN4, a second source resistor R3 connected with the source of a second gate ground transistor MN5, a first control transistor MN6 connected in parallel with the first source resistor R2, and a second control transistor MN7 connected in parallel with the second source resistor R3. A current detection transistor MN2 is connected with the common connection point Lx of a switch transistor MP1 and a synchronous rectification transistor MN1, and the source of the second gate ground transistor MN5, the first control transistor MN6 is controlled by the synchronous rectification transistor MN1 and a drive signal φ1, and the second control transistor MN7 is controlled by the inverted signal φ2 of the second drive signal φ1. The current flowing through the synchronous rectification transistor MN1 is detected by comparing the voltages of load resistors R4, R5.SELECTED DRAWING: Figure 1 【課題】同期整流トランジスタＭＮ１に流れる電流検出に誤動作や遅延が生じないようにする。【解決手段】第１ゲート接地トランジスタＭＮ４のソースに接続された第１ソース抵抗Ｒ２と、第２ゲート接地トランジスタＭＮ５のソースに接続された第２ソース抵抗Ｒ３と、第１ソース抵抗Ｒ２に並列接続された第１制御トランジスタＭＮ６と、第２ソース抵抗Ｒ３に並列接続された第２制御トランジスタＭＮ７とを備える。電流検出トランジスタＭＮ２は、スイッチトランジスタＭＰ１と同期整流トランジスタＭＮ１の共通接続点Ｌｘと第２ゲート接地トランジスタＭＮ５のソースに接続され、第１制御トランジスタＭＮ６は同期整流トランジスタＭＮ１と駆動信号φ１によって制御され、第２制御トランジスタＭＮ７は第２駆動信号φ１の反転信号φ２によって制御される。負荷抵抗Ｒ４と負荷抵抗Ｒ５の電圧を比較して同期整流トランジスタＭＮ１に流れる電流を検出する。【選択図】図１