Slew-Rate Controller Reduces Spikes And Disturbances

By tightly controlling the switching rate of an external P-channel MOSFET, the FDG901D slew-rate controller IC reduces current inrush spike voltages and bus disturbances associated with turning on and off capacitive loads in battery-powered products, such as cell phones, PDAs and portable POS terminals. During the turn-on portion of the switching cycle, the IC drives the P-channel FETÕs gate using a constant current source that is said to deliver an accurate and consistent timing of voltage transition states. And for efficient turn-off, the device quickly pulls up the FETÕs gate. The device offers a choice of three programmed dv/dt states: 80 µA, 1 µA and 10 nA of typical gate-drive current. The slew rate controller is housed in a SC70-5 package and costs $0.29 each/5,000. FAIRCHILD SEMICONDUCTOR, Customer Response Group, San Jose, CA. (888) 522-5372.