Rohm has introduced a new isolated flyback DC-DC converter control IC for auxiliary power supplies for high-power industrial equipment such as FA / solar inverters and power storage systems.
Following the BD7F100, the company now extends the series with the new BD7F200, covering all applications with power requirements from 1W to 10W, and includes two different packaging options. In addition, the BD7F100 evaluation kit simplifies the design of flyback isolated applications.
Isolation is almost always built into electronic equipment to provide shock and damage protection. In this regard, a wide range of applications such as power metering, industrial programmable logic controllers (PLCVs), industrial fieldbuses, industrial automation, insulated gate bipolar transistors (IGBTs), and SiC MOSFET gate drivers require isolated DC-DC conversion Device. These devices provide galvanic isolation, improve safety, and enhance the noise immunity of the system.
Use them to generate multiple output voltage rails and bipolar (positive and negative) rails. High-voltage, high-power industrial applications (including the increasing use of energy storage systems and solar inverters) are no exception. Due to harsher temperature conditions and continuous, long-term operation requirements, reliability requirements are even higher .
Conventional solutions use optocouplers and other components for flyback isolated power control of the feedback loop.
However, this poses challenges related to current consumption and reliability, including circuit size and product life. Because the BD7F series uses an optocoupler-free architecture, designers can simplify transformer development and reduce costs.
By eliminating the need for optocouplers and phase compensation networks, it reduces the number of external parts by nearly half, which saves more energy, improves reliability, and enables miniaturization. In addition, a newly developed adaptive on-time control method is used to improve load response time (the disadvantage of traditional isolated power ICs), while voltage fluctuations during load transients are limited to less than 200mV, thereby further improving reliability. Various protection functions are also added.
To further support designers during device evaluation and therefore during the application design phase, ROHM also released a new evaluation kit, BD7F100HFN-EVK-001, which implements the BD7F100HFN and has six different input and output configurations.
This evaluation board enables the system to be designed for 24V input voltage and 5V output voltage. Its output current range is 13.8mA to 800mA, and the maximum output power is 4W.
The BD7F series of isolated power control ICs have been optimized for industrial equipment that requires continuous, long-term operation under extreme conditions. Utilizing the most advanced power BiCDMOS process and utilizing proprietary advanced analog technology, Rohm can detect the secondary side voltage and current from the primary side. This eliminates the need for optocouplers or three-level transformer windings required for conventional configurations, reducing the number of external parts by half, which helps improve reliability, save power, and ultimately reduce the size of the product.
Adopt the on-time control of the conventional isolated power supply control IC to minimize the output voltage fluctuation caused by the instantaneous change of the load current. Rohm's new adaptive on-time control method limits output voltage fluctuations to 200mV, which is 65% lower than traditional solutions (at a load current of 1A and a rise time of 100us). As a result, the load response to transient load current fluctuations is improved, thereby greatly improving reliability.
In addition to the control IC, an evaluation board (BD7F100HFN-EVK-001) integrated with BD7F100HFN-LB is provided to easily evaluate the operation of the isolated power supply (24V input, 5V / 800mA output). Romain also plans to prepare six evaluation boards (BD7F100HFN-EVK-30x) that have passed CE certification in October 2016.
