New Industry Products

Isolated Push-Pull DC-DC Converter Delivers 1W from SOT23-6

October 07, 2019 by MORNSUN

This article features Mornsun SCM1201A push-pull dc-dc converter chip IC with integrated mosfets that can deliver up to 1W through an isolation transformer.

Chinese chip maker Mornsun has created a push-pull dc-dc converter chip IC with integrated MOSFETs that can deliver up to 1W through an isolation transformer - and the firm offers a selection of transformers. To maximize reliability, the chip design has incorporated three key technologies: a soft start function, output short-circuit protection and integrated over-temperature protection. A range of SMD mounted transformers that can be tailored to your design is also available.

SCM1201A is actually an unregulated oscillator/power-driver, specifically designed for the small form factor, isolated supplies. Being unregulated, output voltage depends on input voltage, transformer turns-ratio and, to a lesser extent, load current.

It drives a low-profile, center-tapped transformer primary with a supply rail between 4.5 and 8V wide DC power supply. The secondary can be wound to provide any isolated voltage based on the transformer turns ratio, providing the voltage reflected back to the integrated MOSFET drains (see diagram) is below 20V (minimum drain breakdown voltage is 27V). The minimum drain pin voltage is -0.7V. The maximum operating current is 350mA (600mA abs max peak).

To minimize the degree of magnetic biasing from the push-pull topology, the drive to the two internal MOSFETs is “highly symmetrical”.


Typical Chip Consumption is 800μA from 5V

It comes in an SOT23-6 package and is specified for operation with its junctions between -40°C and 125°C. Soft start is included to avoid potential device harm when booting up under high current conditions. Output short-circuit protection will not be impaired by any deviation in power supply parameters, not temperature, even down to -40°C.

Over-temperature protection puts the chip into ‘sleep’ if the temperature exceeds the specified range – and subsequently self recovers once the temperature drops below a threshold within the safe operating range. The datasheet has alternative output stage suggestions – for full-wave and half-wave unipolar and bipolar outputs, and includes two transformer examples:

TTB0505-1T is 6.5 x 8.8 x 3.6mm and designed for 5Vin and 5Vout 1W operation with what looks like 1,650Vdc isolation between input and output – operating over -40°C to 125°C. There is also a 5Vin 9Vout version. TSHT5.8-01 is 12.5 x 8.7 x 5.9mm, again for 5Vin 5Vout 1W operation.



MORNSUN, a national high-tech enterprise headquartered in China, has grown into a leading vertical industrial power supply manufacturer.

Keeping the spirit of being forerunner, MORNSUN specializes in magnetic isolation technology and product research and application, and manufactures high-quality products include AC/DC converter, DC/DC converter, adapter, isolation transmitter, IGBT driver and LED driver , etc. most of which got UL, CE, CSA, CB and DoE Level VI certification.

As an IPR Demonstration Enterprises in Guangdong, MORNSUN is one of few power supply manufactures that have its own independent Intellectual Property Rights of integrated circuit, innovative transformer structure, assembly system and appearance design. Over the past 20 years, MORNSUN applied 470+ patents for inventions.

Guided by the service principle of “trust worthy”, MORNSUN established its subsidiaries in America and Germany, expanded its distribution network in 40+ countries and operated sample inventory in Germany, North America, India, Japan and others to offer the best service to local clients in those locations.

As part of society, MORNSUN focuses on teamwork and persistent hard work, and it’s deeply devoted to her role as a responsible corporate citizen around the world. Based on it, MORNSUN holds the core value of “creating value for her employees, clients, shareholders and developing our business to repay the society” and takes it as her mission to make contribution to the development of society and progress of the humankind by pursuing excellence unremittingly.

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