Optocoupler-less Isolated Flyback Converter - BD7F200HFN-LB

This product guarantees long time supply availability in the industrial instrumentation market.
BD7F200 is an optocoupler-less Isolated Flyback Converter. An optocoupler or the tertiary winding feedback circuit which was needed to obtain a stable output voltage isolated by a transformer in the conventional application becomes unnecessary, thus, the number of parts is reduced drastically, producing a small-sized and high-reliability application isolated type power supply. Furthermore, a highly by the use of the Original Adapted-Type ON-Time Control Technology, it makes the external phase compensation parts become unnecessary, therefore a highly efficient isolated type power supply application can easily be produced.


Conventionally, in order to stabilize the output voltage of isolated power supplies methods using limited life components such as Optocouplers and/or auxiliary winding are employed.
In contrast, ROHM has developed isolated flyback DC/DC converter controllers that eliminate the need for these types of feedback circuits.
The simple, efficient design is ideal for industrial power supplies (i.e. FA equipment), power storage systems, and high power inverters.

Samples/Evaluation Board

Evaluation Board Materials「BD7F100HFN-EVK-001」

In addition to samples of the BD7F100xxx-LB and BD7F200xxx-LB, an evaluation board integrating the BD7F100HFN-LB will be available for purchase through online distributors.
The BD7F100HFN-EVK-001 evaluation board makes it easy to evaluate and verify operation of ROHM's isolated flyback DC/DC converter controller (24V input, 5V/800mA output).


Part No. Technical
Package Output
Input Voltage
Voltage Range
BD7F100HFN-LB Download Distribution
1W (Vin=5V)
5W (Vin=24V)
45V 3.0~40V 1.25A 400kHz
Enable Soft Start Efficient Light
Load Mode UVLO Over Current
Protection Theminal Protection
BD7F100EFJ-LB Download Distribution
BD7F200HFN-LB Download Distribution
10W(Vin=24V) 8.0~40V 2.75A
BD7F200EFJ-LB Download Distribution

Feature 1:No Optocoupler or auxiliary winding required contributes to greater miniaturization

Conventional Method and New BD7F100HFN

Applying feedback at the primary side in order to detect the voltage and current at the secondary side eliminates the need for a Optocoupler or auxiliary winding along with other necessary components. This simplifies design considerably, resulting in improved reliability, greater energy savings, and increased miniaturization. Stable output voltage is achieved using just a single resistor.

Feature 2:Adaptive ON time control improves load response characteristics

Adaptive On-Time

Conventional isolated power supply control ICs are susceptible to large variations in output voltage with instantaneous load current fluctuations. In response, ROHM developed an adaptive ON time control method based on the market-proven ON time control design utilized for non-isolated power supply control ICs.
This new method significantly improves response characteristics against instantaneous load current fluctuations, reducing output voltage variations by more than 65% - to less than 200mV (at a load current of 1A and rise time of 100µs) - resulting in improved reliability.