ROHM's Isolated Power Supply Control ICs for Industrial Inverters

No optocoupler or auxiliary winding contributes to greater miniaturization, power savings, and reliability

ROHM's Isolated Power Supply Control ICs BD7F Series

Kyoto and Santa Clara, Calif., – August 16, 2016 – ROHM has recently announced the availability of isolated flyback-type DC/DC converter control ICs for inverters in high power industrial equipment such as FA/solar inverters and power storage systems.

Isolation is almost always built into electronic equipment to provide protection against shock and damage. High voltage, high power industrial applications (including power storage systems and solar inverters which are seeing increased adoption) are no exception, requiring even more stringent reliability demands due to the harsher temperature conditions and the need for continuous, long-term operation.

Conventional solutions utilize a optocoupler and other components for flyback-type isolated power supply control. However, this presents challenges associated with current consumption and reliability (including circuit scale and product life). In contrast, the BD7F series reduces the number of external parts by nearly half by eliminating the need for a optocoupler, providing greater energy savings, reliability, and miniaturization. In addition, a newly developed adaptive ON time control method is used to improve load response time (a drawback of conventional isolated power supply ICs), while voltage fluctuation is limited to under 200mV, contributing to even higher reliability.

Samples, along with an evaluation board, BD7F100HFN-EVK-001, integrating the BD7F100HFN-LB, will be available for purchase. This board enable to be designed for 24V input voltage and 5V output voltage with output current range of 13.8mA to 800mA for maximum output power of 4W.

Optocoupler-less design achieves greater reliability and compactness

The BD7F100 Series
Availability: Now
Pricing: Starting from $4.30 /unit (1,000 pcs)

The BD7F200 Series
Availability: Now (Sample), October 2016 (OEM Quantities)
Pricing: Starting from $4.69 /unit (1,000 pcs)

The BD7F100HFN-EVK-100
Availability: Fall, 2016
NOTE: Available now in Japan (Chip One Stop , Zaikostore).

Key Features

1.High reliability isolation performance
The BD7F series of isolated power supply control ICs are optimized for industrial equipment requiring continuous, long-term operation under extreme conditions. Utilizing state-of-the-art power BiCDMOS processes and leveraging proprietary advanced analog technology allow ROHM to detect the secondary side voltage and current from the primary side. This eliminates the need for a optocoupler or tertiary transformer winding required with conventional configurations, reducing the number of external parts by half which contributes to greater reliability, power savings, and end-product miniaturization.

2.Improved load response characteristics through adaptive ON time control
ON time control, typically used in conventional isolated power supply control ICs, is adopted to minimize output voltage fluctuations caused by instantaneous changes in load current.
ROHM's new adaptive ON time control method limits output voltage fluctuations to 200mV, 65% less than conventional solutions (at a load current of 1A and rise time of 100us). As a result, load response against instantaneous load current fluctuations is improved, increasing reliability considerably.

Adaptive ON Time Control

3. Optional evaluation board makes it easy to verify performance
In addition to the control ICs, an evaluation board (BD7F100HFN-EVK-001) is offered integrating the BD7F100HFN-LB, making it easy to evaluate isolated power supply operation (24V input, 5V/800mA output).

Evaluation Board (BD7F100HFN-EVK-001)


Part No. Package Output
Operating Temp. Functions
(2.9 x 3.0 x 0.6mm)
1W (VIN=5V)
5W (VIN=24V)
45V 3.0 to 40V 1.25A 400kHz
-40ºC to
Enable Soft Start
Efficient Light Load Mode
Over Current Protection
Thermal Shutdown
(4.9 x 6.0 x 1.0mm)
(2.9 x 3.0 x 0.6mm)
10W(VIN=24V) 8.0 to 40V 2.75A
(4.9 x 6.0 x 1.0mm)