Summary of ISOLATED 2W 24VDC-TO-5VDC FLYBACK DC-DC – REFERENCE DESIGN
The MAXREFDES111# is a compact 24V input flyback converter module by Maxim Integrated, delivering 5V at 400mA with up to 79% peak efficiency. It utilizes the MAX17498B controller and supports various qualified transformers from Wurth Electronics, HanRun, and Sumida. Designed for industrial and telecom applications, it features through-hole pins for easy integration and operates within an 18V to 36V input range with built-in protection against undervoltage and overvoltage conditions.
Parts used in the MAXREFDES111#:
- MAXREFDES111# reference design
- Wurth Electronics 750315847 transformer
- HanRun HR041087 transformer
- Sumida 06343-T588 transformer
- MAX17498B peak-current-mode controller
- Internal n-channel MOSFET
The MAXREFDES111# reference design from Maxim Integrated is a compact 24V input flyback-converter module that features 5V at 400mA output. Transformer selection is often the most difficult step in isolated power design. Multiple transformers (Wurth Electronics 750315847, HanRun HR041087, and Sumida 06343-T588) have been qualified for this design, simplifying the process of transformer selection.
The reference design delivers a peak efficiency of 79% with the supplied components when the input is 24V. This general-purpose power solution can be used in many different types of power applications, such as programmable logic controllers (PLC), industrial process control, industrial sensors, telecom power supplies, isolated battery chargers, servers, and embedded computing.
Through-hole pins on the bottom side of the module allows quick and easy integration of this power converter into the main system. Pins are 15mm (0.6in) from power to ground, and 28mm (1.1in) from the input side to the output side.
The MAX17498B is a peak-current-mode controller for design of wide input-voltage flyback and boost regulators. The reference design operates over an 18V to 36V input voltage range, and provides up to 400mA (plus 20% overhead) at 5V output.
The device uses an internal n-channel MOSFET to implement switching and internal current sensing for current-mode control and overcurrent protection of the flyback converter. The device incorporates a flexible error amplifier and an accurate reference voltage to enable the end user to regulate both positive and negative outputs. The device has a fixed switching frequency of 500kHz.
The input undervoltage lockout (EN/UVLO) is provided for programming the input-supply start voltage (set to 18V in the design), and to ensure proper operation during brownout conditions. The EN/UVLO input is also used to turn on/off the IC. The overvoltage input (OVI) protection scheme is provided to make sure that the controller shuts down when the input supply exceeds its maximum allowed value (set to 36V in the design).
Read more: ISOLATED 2W 24VDC-TO-5VDC FLYBACK DC-DC – REFERENCE DESIGN
- What is the output specification of the MAXREFDES111#?
The module provides 5V at 400mA output. - Can I use different transformers with this design?
Yes, multiple transformers including Wurth Electronics 750315847, HanRun HR041087, and Sumida 06343-T588 are qualified for this design. - How efficient is the MAXREFDES111# at 24V input?
The design delivers a peak efficiency of 79% when the input is 24V. - Does the module support negative outputs?
Yes, the device incorporates a flexible error amplifier to enable regulation of both positive and negative outputs. - What is the fixed switching frequency of the controller?
The device has a fixed switching frequency of 500kHz. - How do I turn on or off the IC?
The EN/UVLO input is used to turn on or off the IC. - What happens if the input supply exceeds 36V?
The overvoltage input protection scheme ensures the controller shuts down when the input supply exceeds its maximum allowed value. - Is there overcurrent protection in the design?
Yes, the internal current sensing provides overcurrent protection for the flyback converter.
