BD9870 Switching Regulator

900 kHz Single-Channel Step-Down Switching Regulator Delivers Space Savings and High Efficiency

BD9870 Switching RegulatorThe BD9870's integrated protection and compensation circuitry, smaller external components and ceramic input/output capacitor compatibility result in space savings of up to 60%.

ROHM developed the BD9870, a single-channel step-down switching regulator that offers high efficiency, exceptional space savings, design simplicity and high reliability for a variety of applications, including TVs, DVD players, gaming consoles, PCs, car audio and navigation systems, industrial and office equipment, and entertainment systems.

The BD9870 integrates a switching voltage regulator, 1.5 A-rated p-channel power MOSFET and compensation circuitry into a compact TO-252S-5 package. Eliminating external feedback compensation components makes complete design possible using only an external coil, diode and output capacitor. In addition, the device's industry-leading 900 kHz operation permits use of a smaller coil and ceramic output capacitor, which, when combined with the regulator's internal features, results in a 60% board-space savings compared with current solutions on the market.

Compared with competitive, compensation-integrated switchers, the BD9870 IC offers the industry's highest efficiency (88%) and output accuracy (±1.0%), the lowest bias current (3mA) and zero standby current. The input voltage can range from 8 V to 35 V, with output voltage adjustable down to 1.0 V. A soft-start feature (5ms, fixed) is also included. Reliability is enhanced by internal protection circuits, including thermal shutdown (TSD) and over-current protection (OCP).

The combined benefits of the BD9870's small package size, high switching frequency, minimal external components and integrated protection circuitry results in a compact, efficient, and highly reliable switching power supply that is as simple to design in and use as an LDO.


  • High efficiency, even with integrated compensation circuitry
  • High voltage resistance, low ON-resistance, large current Pch MOSFET and compensation circuitry built into a compact, 5-pin package
  • Wide output range configurable with external resistance
  • High frequency 900 kHz operation reduces the size of the capacitor and coil required

BD9870 Switching Regulators

ImageManufacturer Part NumberDescriptionOutput ConfigurationTopologyAvailable QuantityView Details
BD9870FPS-E2 datasheet linkIC REG BUCK ADJ 1.5A TO252SBD9870FPS-E2IC REG BUCK ADJ 1.5A TO252SPositiveBuck2798 - Immediate
BD9870FPS-E2 product page link
Published: 2008-08-14