New BD7F series of isolated flyback-type DC/DC converters

No Optocoupler or auxiliary winding required contributes to greater miniaturization. BD7F100xxx-LB/BD7F200xxx-LB series of isolated flyback DC/DC converters

Overview

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.

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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).

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Lineup

Part No. Data sheet Package Output
Power
Max.
Input Voltage
Input
Voltage Range
Over
current
Limit
Switching
Frequency
Operating
Temperature
Functions
BD7F100HFN-LB PDF HSON8
(2.9×3.0
×0.6mm)
1W (Vin=5V)
5W (Vin=24V)
45V 3.0~40V 1.25A 400kHz (Typ.) -40°C ~ +125°C Enable Soft Start
Efficient Light
Load Mode UVLO
Over Current
Protection
Theminal Protection
BD7F100EFJ-LB PDF HSOP-J8
(4.9×6.0
×1.0mm)
BD7F200HFN-LB PDF HSON8
(2.9×3.0
×0.6mm)
10W(Vin=24V) 8.0~40V 2.75A
BD7F200EFJ-LB PDF HSOP-J8
(49×6.0×
1.0mm)

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.