Fairchild Design Guidelines for Replacing SG6742 with FAN6754A
Summary
Optimize your power electronics with the highly integrated FAN6754A PWM controller. This guide provides engineers with replacement details and advanced features for designing high-efficiency switched-mode power supplies. Key capabilities include green mode operation, constant power limiting, adaptive protection functions, and ultra-low standby consumption, ensuring peak reliability while meeting stringent modern regulations.
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AN-6754A Design Guideline to Replace SG6742 with FAN6754A
Introduction
FAN6754A is a highly integrated PWM controller featuring increasing system cost. This application note explains how green mode, frequency hopping, constant power limit, and a to replace PWM controller SG6742 with FAN6754A. These number of protection functions. The green-mode function, two devices have the same pin configuration and direct burst-mode function, and a low operating current maximize replacement can be achieved without PCB layout change. the light-load efficiency so that the power supply can meet However, functional improvements to the FAN6754A for stringent standby power regulations. Frequency hopping higher efficiency and better performance requires several reduces the Electro-Magnetic Emission (EMI) by spreading external components to be changed accordingly. Table 1 the frequency spectrum. The constant-power-limit function summarizes the difference between these two devices. The minimizes the component stress in abnormal conditions and pulse-by-pulse current limit threshold voltage is reduced helps optimize the power stage design. Protection functions almost by half to reduce the current sensing loss, which such as brownout protection, overload / open-loop results in 0.4~0.5% efficiency improvement. The operating protection (OLP), over-voltage protection (OVP), sense pin current is also reduced to achieve less than 100m W standby short-circuit protection (SSCP), and over-temperature power consumption for most designs. The typical protection (OTP) are fully integrated to improve the application circuit and internal block diagram are shown in reliability of the switched-mode power supply without Figure 1 and Figure 2 , respectively.
Table 1. Comparison of SG6742 and FAN6754A
SG6742 FAN6754A
Brownout Protection No Line Sensing Using HV Pin
Line Voltage Compensation for Pulse-by- Pulse Current Limit (VLimit-L / VLimit-H) Saw-Limit (0.9V / 0.56V) Adjusted by HV Pin (0.46V / 0.39V)
Sense Pin Short-Circuit Protection V <0.15V Longer than 150µs V <0.05V Longer than 120µs SENSE SENSE
Gate Drive Clamping Voltage 18V 13V FB Impedance (ZFB) 5KΩ 15.5KΩ Operating Current (IDD_OP) 2.7m A 1.7m A Leading-Edge Blanking Time (t LEB) 150ns 280ns
Soft-Start 5ms 8ms Maximum Duty Cycle 65% 89% VFB-G/VFB-N for Green Mode 2.4V / 3.0V 2.3V / 2.8V VZDC/VZDCR for Burst Mode 1.6V / 1.7V 2.0V / 2.1V
© 2010 Fairchild Semiconductor Corporation www.fairchildsemi.com Rev. 1.0.0 • 10/8/10
Page Summary Contents For Fairchild Design Guidelines for Replacing SG6742 with FAN6754A
Manual Details
| Brand | Fairchild |
|---|---|
| Pages | 9 |
| File Size | 464.54 KB |
| Published | July 22, 2026 |
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Frequently Asked Questions
What are the key benefits of switching from SG6742 to FAN6754A?
FAN6754A is a highly integrated PWM controller offering features like green mode and constant power limit, enabling replacements without PCB layout changes.
How does the FAN6754A improve efficiency in standby modes?
It minimizes component stress and has been designed to ensure less than 100mW standby power consumption, meeting stringent standby regulations.
What are general layout considerations for using the FAN6754A?
The area enclosed by the transformer's auxiliary winding, D1, C2, D2, and C3 should be kept small. Place C3 close to the controller for good decoupling.
Does the FAN6754A offer protection against network fluctuations?
Yes, it includes multiple protection functions such as brownout protection (No Line Sensing), over-voltage (OVP), and open-loop protection (OLP).