Switching Regulator Saves Space, Boosts Efficiency

To free up board space, the BD9870 single-channel, step-down switching regulator integrates protection plus compensation circuitry and allows for smaller external components. The device integrates a switching voltage regulator, 1.5A p-channel power MOSFET and the compensation circuitry into a TO-252S-5 package. Eliminating external feedback-compensation components makes a complete design possible using only an external coil, diode, and output capacitor. Operating at 900 kHz allows the use of a smaller coil and ceramic output capacitor. Other features include an efficiency of 88%, output accuracy of ±1.0%, a bias current of 3 mA, and zero standby current. Input voltage ranges from 8V to 35V with an output voltage adjustable down to 1V. A 5 ms, fixed soft-start feature is also on chip. Price for the BD9870 is $1.20 each in OEM quantities. ROHM ELECTRONICS, San Diego, CA. (858) 625-3630.