Switching control circuit and switching power supply device

一种开关控制电路、电路的技术，应用在输出功率的转换装置、电气元件、对过电流起反应的保护等方向，能够解决成本单价增大、IC管理复杂化、制造工艺复杂化等问题

Active Publication Date: 2012-12-26
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this case, the number of types of ICs will increase, and not only the manufacturing process but also the management of ICs will become complicated. As a result, there is a problem that the unit cost of ICs will increase.
[0005] In general, the more multi-functionality is required, the easier it is to become larger. However, in recent years, the required functions of even a small switch control circuit have increased.

Method used

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  • Switching control circuit and switching power supply device
  • Switching control circuit and switching power supply device
  • Switching control circuit and switching power supply device

Examples

Experimental program
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Effect test

no. 1 Embodiment approach 》

[0059] figure 2 , image 3 It is a circuit diagram of switching power supply devices 304A, 304B according to the first embodiment of the present invention. The switching power supply devices 304A and 304B include the switching control IC 200 corresponding to the switching control circuit of the present invention. exist figure 2 and image 3 Among them, the difference lies in the external circuit connected to the soft start (soft start) terminal SS of the IC 200 for switch control.

[0060] The voltage of the DC input power supply Vi is input between the input terminals PI(+)-PI(G) of the switching power supply devices 304A, 304B. Then, a predetermined DC voltage is output to a load connected between the output terminals PO(+)-PO(G) of the switching power supply devices 304A, 304B.

[0061] A first series circuit in which a capacitor Cr, an inductor Lr, a primary coil np of a transformer T, a first switching element Q1, and a resistor R7 for current detection are connect...

no. 2 Embodiment approach 》

[0102] Figure 6 , Figure 7 It is a circuit diagram of switching power supply devices 312A, 312B according to the second embodiment of the present invention. The switching power supply devices 312A and 312B include the switching control IC 200 corresponding to the switching control circuit of the present invention. The secondary sides of the transformers T of the switching power supply devices 312A and 312B are both in the forward mode. exist Figure 6 and Figure 7 Among them, the connection position of the resonant capacitor Cr on the primary side is different.

[0103] In this way, a rectification and smoothing circuit composed of diodes Ds, Df, inductor Lro, and capacitor Co can also be provided on the secondary side of the transformer T, and a forward mode can be used.

[0104] In addition, since the resonance capacitor Cr on the primary side only needs to be inserted in series in the closed loop formed when the switching element Q2 on the high side is turned on, as...

no. 3 Embodiment approach 》

[0107] Figure 8 It is a circuit diagram of the switching power supply device 313 which concerns on 3rd Embodiment of this invention. The switching power supply device 313 includes the switching control IC 200 corresponding to the switching control circuit of the present invention. The secondary side of the transformer T of the switching power supply device 313 is a forward mode.

[0108] and figure 2 The illustrated switching power supply device 304A is different in that it constitutes a simple forward converter without providing the inductor Lr, the capacitor Cr, and the second switching element Q2.

[0109] In this way, it can also be applied to a simple forward converter and achieve the same function and effect.

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PUM

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Abstract

The length of a soft start period is set by the time constant of an external circuit connected to a soft start terminal (SS) of a switching control IC (200). A current flowing through a switching element (Q1) is detected by a current detection terminal (IS), when the current exceeds a first predetermined current value, a second overcurrent protection function operates to stop a switching operation, and when the current exceeds a second predetermined current value, the second overcurrent protection function operates to rapidly turn off the switching element (Q1) to thereby limit the current peak value. The setting / unsetting of a first overcurrent protection function is selected according to the voltage of the soft start terminal (SS) at the end of the soft start period. After the voltage of the soft start terminal (SS) reaches a predetermined voltage, the ON pulse width of the switching element (Q1) is limited to the maximum value. Consequently, the increase of the number of terminals is prevented, and an appropriate overcurrent protection method can be selected from among a plurality of overcurrent protection methods.

Description

technical field [0001] The present invention relates to an IC-formed switching control circuit used in a switching power supply device and a switching power supply device including the switching control circuit. Background technique [0002] A switching power supply device is provided with circuits for enabling switching control ICs to realize various functions such as output control operation, startup operation, overcurrent protection operation, overvoltage protection operation, standby operation, and power factor improvement operation. Through the increase of these functions, the function of the switch control IC is improved. [0003] In order to set each function of the switching control IC in accordance with the operating specifications of the application, a plurality of terminals for interfacing with an external circuit are required for each function. Therefore, when the number of mounted functions increases, the number of terminals naturally increases. When the numbe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M3/28
CPCH02H3/08H02M1/36H02M3/28H02M3/335H02M1/32H02M3/33507H02M3/3376H02M3/33538H02M3/33553
Inventor 细谷达也
Owner MURATA MFG CO LTD
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