NCL30125 5-V/300-A Two-Switch Forward Ac-Dc Converter

PublishTime：2021-12-14

●Description:
■ This design note provides elementary information about a two- switch forward converter built with the NCL30125 operated in current-mode control. This controller offers many features to build an energy- efficient converter with all the needed protections like cycle-by-cycle current limit with a 500-mV sense voltage, over temperature protection with a dedicated NTC pin and brown-out feature. In addition to the low side MSOFET drive, the controller integrates also an high-side section to drive the floating N-channel power MOSFET. Dedicated pins are available to adjust the switching frequency (RT pin – pin 6) or the soft-start duration (SS pin – pin 7). Finally, a high-voltage current source with Dynamic-Self Supply (DSS) is embedded to quickly start the power supply and maintain the V-cc voltage in light load or standby.
■ The primary-side section drives a transformer whose primary inductance is 3.8 mH. The energy accumulated in this inductance is sending back to the bulk capacitor thanks to the freewheel components. One of the classical freewheel diode has been replaced by a MOSFET M₉ driven by the controller in order to refresh the bootstrap capacitor. The current is sensed via a 87-m Ω resistance. The switching frequency of 100 kHz and the soft-start duration are set by two individual components (R₂₃ for f SW and C₂₂ for SS).
■ The power stage is made of two switching N-channel transistors M₁ and M₈ . These two transistors are switched in same time and seen the input voltage as maximum. In the secondary side, three MOSFETs are self-driven by the transformer but require regulation transistors Q₉ and Q₁₀ to limit the maximum V-GS these elements can accept. The three forward MOSFETs M₂ , M₃ and M₄ are driven by the NCP4306 synchronous rectification controller. The regulation is ensured by a TL431 wired in a type-2 configuration. Loop gain measurements show a 74° phase margin at a 60- A output obtained with a 230-V rms source.
●Key Features:
■ Integrated High-side driver
■ Adjustable switching frequency up to 300 kHz
■ Peak current-mode control
■ Skip mode to maximize performance in light load conditions
■ Internal 600-V start-up source operated in dynamic self-supply during start-up or skip mode.
■ Brown-out (BO) detection
■ Adjustable soft-start duration
■ 15-ms timer-based short-circuit protection with auto-recovery or latched operation
■ Auto-recovery or Latched OVP on V-cc
■ Latched OVP/OTP input for improved robustness
■ +0.9 A/-1.2 A peak source/sink drive capability Devices

Brand of Product：	ON Semiconductor
Part#：	NCL30125 、 NCP4306 、 750317590 More Part#
Product Category：	Two-Switch Forward Ac-Dc Converter 、 synchronous rectification controller More
Application：	More
Data Type：	Application note & Design Guide More
Safety & Environment Standards：	More
Operating Temperature：	Please see the document for details
Qualification Grade：	More
Qualification Approval：	More
Package：
Language：	English Chinese Chinese and English Japanese
Date of Creation：	Oct. 2019
Version Number：	Rev. 0
Data Encoding：	DN05131/D
Data Size：	2.2 MB

Data section preview(2pages)

- The full preview is over. If you want to read the whole 13 page document,please Sign in/Register -

Download

+1 Like
Add to Favorites

Recommend

New Products & Solutions

More>

Technical Resources

More>

All reproduced articles on this site are for the purpose of conveying more information and clearly indicate the source. If media or individuals who do not want to be reproduced can contact us, which will be deleted.

Integrated Circuits